"Can Meat and Fish Consumption Be Sustainable?" That's the provocative title of a press release just sent to us by the Worldwatch Institute, a small but venerable think tank that focuses on natural resource issues.

It's also the theme of a chapter in Worldwatch's 2008 State of the World report, its 25th annual book-length analysis of resource trends and economics. Here, its analysts take on the substantial—and often hidden—costs of producing animal protein to satisfy human hunger.

In 2006, "farmers produced an estimated 276 million tons of chicken, pork, beef, and other meat—four times as much as in 1961," Worldwatch has just reported. As for fish, some 140 million tons were hauled in globally during 2005, the most recent year for which data are available. "That was eight times as much as in 1950," note Brian Halweil and Danielle Nierenberg, the chapter's authors.

Part of the growth in production reflects a growing demand, fueled by world population and increasing wealth that allows increased consumption of animal protein, even within formerly impoverished nations. For meat, it has doubled over the past 45 years; fish consumption quadrupled over a 55-year span.

Bottom line: "Meat and seafood are the two most rapidly growing ingredients in the global diet," Halweil and Nierenberg find, and "two of the most costly." Demand for both are slated to go the way of oil—up, up, up, with prices following—as incomes in China, India, and hosts of developing countries rise.

Industrial meat production and fish harvests have dropped the economic cost of animal proteins in recent decades. But much of that fiscal savings has come at the expense of the environment. Wastes are not captured and destroyed or recycled. They're allowed to run into the ground or waterways, degrading ecosystems all along the way. These are costs that are not captured in traditional accounting.

Anyone who has tried fishing in the Gulf of Mexico's annual dead zone has experienced one cost of allowing livestock wastes from the upper Midwest to flow through the ground and into waters that feed the mighty Mississippi—and Gulf of Mexico (SN: 6/12/04, p. 378). Anyone who lives with the pervasive stench downwind of animal feedlots knows there's a cost that they're being asked to subsidize with their discomfort—and perhaps health.

Fishers, in recent years, have been mining the ocean's top and middle predators, substantially distorting the balance of ecosystems (SN: 6/4/05, p. 360). The net primary productivity of the oceans probably hasn't changed much: that is to say, about the same mass of living cells probably inhabits it. However, instead of tuna, cod, sharks, and trout, the bulk of the mass may be shifting to alewives, smelt, jellyfish, and algae (SN: 2/7/98, p. 86). One solution, fish farming, has proven moderately successful—but can also prove harmful to nonfarmed species and the environment generally.

"Part of the reason that livestock and fish farms have become ecological disasters is that they have moved away from mimicking the environment in which animals exist naturally," the Worldwatch report maintains.

There's another problem as well. People the world over want to eat the same few species—cows, pigs, and lambs, salmon, tuna, and trout—even if their own environment cannot support the production of these animals. Moreover, as relatively large and high-in-the-food-chain animals, these species grow at the expense of hosts of plants, animals, and other energy inputs. The land and energy needed to produce 1,000 calories of grain, legumes (like soy), or algae is a fraction of what it takes to produce 1,000 calories of beef or catfish.

Many people don't want to eat just greens, grains, and pulses (like beans). In truth, I don't.

BETTER THAN BEEF? This smorgasbord offers ant pupae and yellow bamboo caterpillars around a pile of ordinary scrambled eggs. Meyer-Rochow photographed this platter of appetizers during his foreign travels. He and other researchers have shown such bugs to be nutritious. Many researchers argue that their harvesting can also be better for the environment than is the production of conventional meat animals. Meyer-Rochow

However, there is another source of animal protein that may prove dramatically more sustainable than fish and hoofed livestock: Insects.

All right, it may take a bit of work to wrap your head around this idea—especially if you grew up in the U.S.A. We're talking ants, grasshoppers, and beetles.

There was a time and place where the arrival of hordes of locusts blackening the skies was a period for rejoicing. Hungry farmers would see this as a smorgasbord of animal protein that could be gathered by the bucketsful. Eaten raw, fried with onion and chilies, or roasted for consumption throughout the months ahead, this was nutritionally high-quality animal protein. And you didn't have to chase it. It came to you.

Those old enough to remember shipments of food aid to starving masses in Ethiopia and Somalia during the '70s and '80s may also remember scandals describing hundreds if not thousands of tons of wheat flour that arrived at its destinations spoiled by infestations of beetles, notes Victor B. Meyer-Rochow of Jacobs University in Bremen, Germany. "But that's really nonsense," he argues, "because those beetles were nutritionally more valuable than [the grain] that people were trying to protect."

Bottom line, diets throughout the globe have been changing. And if we all want reliable access to animal protein, we may have to embrace mini-livestock—the six-legged kinds.

You'll be able to read more about this topic—a serious one—soon in the pages of Science News and at Science News for Kids, our online sister publication. So stay tuned.

And who knows, one day we may read that termites, popular for millennia in nations throughout the world, have become a growth industry for New Orleans. It's home to permanent hordes of the Formosan variety (SN: 11/29/03, p. 344)—insects that weathered Hurricane Katrina far better than did the region's taxpayers.

References:

Halweil, B., and D. Nierenberg. 2008. Meat and seafood: The global diet's most costly ingredients. In State of the World 2008: Innovations for a Sustainable Economy. Washington, D.C.: Worldwatch Institute. Available at www.worldwatch.org/taxonomy/term/38.

Paoletti, M.G., ed. 2005. Ecological Implications of Minilivestock. Enfield, N.H.: Science Publishers. Available at www.scipub.net/entomology/
ecological-implications-minilivestock.html.

Further Readings:

Raloff, J. 2005. Empty nets. Science News 167(June 4):360-362. Available at www.sciencenews.org/articles/20050604/bob8.asp.

______. 2004. Limiting dead zones. Science News 165(June 12):378-380. Available at www.sciencenews.org/articles/20040612/bob9.asp.

______. 2004. Dead waters. Science News 165(June 5):360-362. Available at www.sciencenews.org/articles/20040605/bob9.asp.

______. 2003. Munching along. Science News 164(Nov. 29):344-346. Available at www.sciencenews.org/articles/20031129/bob9.asp.

______. 1998. A grilling analysis. Science News Online (July 4). Available at www.sciencenews.org/pages/sn_arc98/7_4_98/food.htm.

______. 1998. How low will we go in fishing for dinner? Science News 153(Feb. 7):86. Available at www.sciencenews.org/pages/sn_arc98/2_7_98/fob1.htm.

______. 1997. Overfishing imperils cod reproduction. Science News 151(Feb. 22):124. Available at www.sciencenews.org/pages/pdfs/data/
1997/151-08/15108-16.pdf.

______. 1996. Fishing: Out of control? Science News 149(June 8):367. Available at www.sciencenews.org/pages/pdfs/data/
1996/149-23/14923-17.pdf.

Sources:

Brian Halweil and Danielle Nierenberg
c/o Worldwatch Institute
1776 Massachusetts Avenue, NW
Washington, DC 20036

Victor B. Meyer-Rochow
Jacobs University
Faculty of Engineering and Sciences
P.O. Box 750561
D-28725 Bremen
Germany

In the 1967 film classic The Graduate, a businessman corners Benjamin Braddock at a cocktail party and gives him a bit of career advice. "Just one word…plastics."

Although Benjamin didn't heed that recommendation, plenty of other young graduates did. Today, the planet is awash in products spawned by the plastics industry. Residues of plastics have become ubiquitous in the environment—and in our bodies.

A federal government study now reports that bisphenol A (BPA)—the building block of one of the most widely used plastics—laces the bodies of the vast majority of U.S. residents young and old.

Manufacturers link BPA molecules into long chains, called polymers, to make polycarbonate plastics. All of those clear, brittle plastics used in baby bottles, food ware, and small kitchen appliances (like food-processor bowls) are made from polycarbonates. BPA-based resins also line the interiors of most food, beer, and soft-drink cans. With use and heating, polycarbonates can break down, leaching BPA into the materials they contact. Such as foods.

And that could be bad if what happens in laboratory animals also happens in people, because studies in rodents show that BPA can trigger a host of harmful changes, from reproductive havoc to impaired blood-sugar control and obesity (SN: 9/29/07, p. 202).

For the new study, scientists analyzed urine from some 2,500 people who had been recruited between 2003 and 2004 for the National Health and Nutrition Examination Survey (NHANES). Roughly 92 percent of the individuals hosted measurable amounts of BPA, according to a report in the January Environmental Health Perspectives. It's the first study to measure the pollutant in a representative cross-section of the U.S. population.

Typically, only small traces of BPA turned up, concentrations of a few parts per billion in urine, note chemist Antonia M. Calafat and her colleagues at the Centers for Disease Control and Prevention. However, with hormone-mimicking agents like BPA, even tiny exposures can have notable impacts.

Overall, concentrations measured by Calafat's team were substantially higher than those that have triggered disease, birth defects, and more in exposed animals, notes Frederick S. vom Saal, a University of Missouri-Columbia biologist who has been probing the toxicology of BPA for more than 15 years.

The BPA industry describes things differently. Although Calafat's team reported urine concentrations of BPA, in fact they assayed a breakdown product—the compound by which BPA is excreted, notes Steven G. Hentges of the American Chemistry Council's Polycarbonate/BPA Global Group. As such, he argues, "this does not mean that BPA itself is present in the body or in urine."

On the other hand, few people have direct exposure to the breakdown product.

Hentges' group estimates that the daily BPA intake needed to create urine concentrations reported by the CDC scientists should be in the neighborhood of 50 nanograms per kilogram of bodyweight—or one millionth of an amount at which "no adverse effects" were measured in multi-generation animal studies. In other words, Hentges says, this suggests "a very large margin of safety."

No way, counters vom Saal. If one applies the ratio of BPA intake to excreted values in hosts of published animal studies, concentrations just reported by CDC suggest that the daily intake of most Americans is actually closer to 100 micrograms (µg) per kilogram bodyweight, he says—or some 1,000-fold higher than the industry figure.

Clearly, there are big differences of opinion and interpretation. And a lot may rest on who's right.

Globally, chemical manufacturers produce an estimated 2.8 million tons of BPA each year. The material goes into a broad range of products, many used in and around the home. BPA also serves as the basis of dental sealants, which are resins applied to the teeth of children to protect their pearly whites from cavities (SN: 4/6/96, p. 214). The industry, therefore, has a strong economic interest in seeing that the market for BPA-based products doesn't become eroded by public concerns over the chemical.

And that could happen. About 2 years after a Japanese research team showed that BPA leached out of baby bottles and plastic food ware (see What's Coming Out of Baby's Bottle?), manufacturers of those consumer products voluntarily found BPA substitutes for use in food cans. Some 2 years after that, a different group of Japanese scientists measured concentrations of BPA residues in the urine of college students. About half of the samples came from before the switch, the rest from after the period when BPA was removed from food cans.

By comparing urine values from the two time periods, the researchers showed that BPA residues were much lower—down by at least 50 percent—after Japanese manufacturers had eliminated BPA from the lining of food cans.

Concludes vom Saal, in light of the new CDC data and a growing body of animal data implicating even low-dose BPA exposures with the potential to cause harm, "the most logical thing" for the United States to do would be to follow in Japan's footsteps and "get this stuff [BPA] out of our food."

For more information, see this week's Food for Thought column.

References:

Calafat, A.M., et al. 2008. Exposures of the U.S. Population to bisphenol A and 4-tertiary-octylphenol: 2003-2004. Environmental Health Perspectives 116(January):39-44. Available at http://dx.doi.org/10.1289/ehp.10753.

______. 2005. Urinary concentrations of bisphenol A and 4-nonylphenol in a human reference population. Environmental Health Perspectives 113(April):391-395. Available at http://dx.doi.org/10.1289/ehp.7534.

Mahalingaiah, S., . . . A.M. Calafat, et al. 2008. Temporal variability and predictors of urinary bisphenol A concentrations in men and women. Environmental Health Perspectives 116(February):173-178. Available at http://dx.doi.org/10.1289/ehp.10605.

Matsumoto, A., et al. 2003. Bisphenol A levels in human urine. Environmental Health Perspectives 111(January):101-104. Available at http://dx.doi.org/10.1289/ehp.5512.

Taylor, J.A., W.V. Welshons, and F.S. vom Saal. In press. No effect of route of exposure (oral; subcutaneous injection) on plasma bisphenol A throughout 24 hr after administration in neonatal female mice. Reproductive Toxicology. Abstract available at http://dx.doi.org/10.1016/j.reprotox.2008.01.001.

Vandenberg, L.N., et al. 2007. Human exposure to bisphenol A (BPA). Reproductive Toxicology 24(August-September):139-177. Abstract available at http://dx.doi.org/10.1016/j.reprotox.2007.07.010.

Further Readings:

Harder, B. 2006. Diabetes from a plastic? Estrogen mimic provokes insulin resistance. Science News 169(Jan. 21):36. Available at http://www.sciencenews.org/articles/20060121/fob4.asp.

Morgan, K. 2003. Wrong number: Plastic ingredient spurs chromosomal defects. Science News 163(April 5):213. Available to subscribers at http://www.sciencenews.org/articles/20030405/fob6.asp.

Raloff, J. 2007. Clearly concerning. Science News 172(Sept. 29):202-204. Available at http://www.sciencenews.org/articles/20070929/bob9.asp.

______. 2007. Bad for baby: New risks found for plastic constituent. Science News 172(Aug. 11):84. Available at http://www.sciencenews.org/articles/20070811/fob3.asp.

______. 1999. What's coming out of baby's bottle? Science News Online (July 24). Available at http://www.sciencenews.org/pages/sn_arc99/7_24_99/food.htm.

______. 1997. Dental sealant safety reconsidered. Science News 152(Nov. 22):324. Available at http://www.sciencenews.org/pages/sn_arc97/11_22_97/fob1.htm.

______. 1997. A pollutant that can alter growth. Science News 152(October 18): 255. Available at www.sciencenews.org/pages/pdfs/
data/1997/152-16/15216-18.pdf.

______. 1996. Estrogenic agents leach from dental sealant. Science News 149(April 6):214. Available at www.sciencenews.org/pages/pdfs/
data/1996/149-14/14914-08.pdf.

______. 1995. Additional sources of dietary estrogens. Science News 147(June 3):341.

______. 1993. Plastics may shed chemical estrogens. Science News 144(July 3):12.

Sources:

Antonia M. Calafat
Division of Laboratory Sciences
National Center for Environmental Health
Centers for Disease Control and Prevention
4770 Buford Hwy., NE
Mailstop F53
Atlanta, GA 30341

Steven G. Hentges
Polycarbonate/BPA Global Group
American Chemistry Council
1300 Wilson Boulevard
Arlington, VA 22209

Frederick S. vom Saal
105 Lefevre Hall
Division of Biological Sciences
University of Missouri
Columbia, MO 65211

Brewers prize hops for the characteristic bitter flavors they impart to ales, lagers, and other beers. But aficionados of another class of brews—certain herbal teas—would prefer their hops bitterfree. And federal scientists may have come up with just what the doctor ordered.

"People have used hops medicinally for a long time. It's a fairly ancient remedy," notes plant physiologist Barbara M. Reed with the U.S. Department of Agriculture, in Corvallis, Ore.

The bitter tonic made from hops has putative sedative, hypnotic, and antianxiety properties. Hops tea has been offered as a folk remedy for conditions ranging from fever and insomnia to bruises and cancer, according to a report by botanist James A. Duke, who has authored several books on medicinal plants. A quick browse on the Internet will turn up numerous sources of hop tea.

The new cultivar, named Teamaker, may produce an especially palatable brew owing to a unique ratio of certain acid components. Moreover, the components that predominate in Teamaker have long-established antimicrobial properties. Indeed, their germ-fighting function appears to have won the appreciation of brewers more than a millennium ago, notes John A. Henning, who leads hop genetics and breeding at a USDA research center, also in Corvallis. Beer producers realized that when their recipe included hops, brews not only proved tasty, but had a longer shelf life.

Hops breeder Alfred Haunold and his colleagues at the Corvallis center will formally register their debittered cultivar this month.

What brewers of all stripes refer to as hops are actually the cone-shaped dried female flowers of the Humulus lupulus L. plant. Inside are glands that contain flavorful oils and some fairly bitter water-soluble components.

This hop cone has been split apart to reveal its lupulin glands. They produce the nonbitter beta acids that impart a distinct flavor and aroma to teas and beer. ARS/Stephen Ausmus

To extract the flavorings for use in beer, or merely to make a cup of tea, brewers boil the cones to release their characteristic flavorings. However, the altered chemistry of USDA's new hop has dramatically boosted the production of flavorings possessing natural, antibiotic properties.

In fact, the elevated antibiotic attributes of the new hop might open new markets for this crop, observes Henning. For instance, sugar producers might turn to it as a preservative to prevent microbial degradation of their product during processing. Alternatively, he notes, manufacturers and others may substitute it for the formaldehyde used to control pests and fungal growth in everything from animal feed and plywood to tissues that are being stored for use in research.

Alpha vs. beta

The key flavor compounds in hops trace to two families of chemicals: water-soluble alpha acids, and beta acids that develop in the plants' essential oils. Breweries prize the alpha acids for their hearty, if bitter, taste: These serve as a natural foil to the sweet compounds that develop in many beers. Indeed, some brewers just buy isolated hop-derived alpha acids and dispense with the beta acids entirely.

The new Teamaker hop derives from experiments several decades ago when Haunold wanted to see the extent to which he could preferentially maximize a plant's production of alpha or beta acids. One successful beta-rich cultivar proved virtually devoid of alpha acids. A technician who tasted it jokingly said the bitterfree product would be great for tea—eventually giving rise to its name.

In the January Journal of Plant Registrations, Henning, Haunold, and their coauthors describe Teamaker's pedigree—at least as much as is known. Most of its initial ancestors appear to have come from old English lines, such as cultivars known as Fuggle and Late Grape. However, Henning points out, because these lines are rich in alpha acids, there must have also been beta-rich ancestors. He now suspects that these were probably wild U.S. hops that pollinated their English cousins growing openly in Oregon fields, early in the last century.

Currently, U.S. farmers produce some 55 million pounds of hops annually. Since the big market for hops has always been beer, the alpha acids-shy Teamaker languished in a few test plots for decades. A beer company or two checked the variety out, but ultimately exhibited no commercial interest.

Recently, however, interest in beta acids—and their antimicrobial prowess—has been growing, independent of hops' use in beer. For instance, European sugar refiners have begun buying beta-acid extracts—essentially leftovers from alpha-acid production for breweries—as a bitterfree, all-natural preservative for use during manufacturing. At the same time, some feed suppliers have begun substituting beta acids for low-dose antibiotics as a livestock growth-promoting dietary additive. Feed producers couldn't use conventional hops directly, Henning notes, because the alpha acids' bitter taste would have soured the animals' interest in their chow.

However, with Teamaker, the hop is essentially alpha acids-free: It certainly has the lowest quantity of alpha acids of any commercially available hop.

Teamaker is available to breeders through the National Clonal Germplasm Repository—essentially a federal library with holdings that include more than 510 different hops. Some are wild natives collected throughout the United States. Others are cultivated varieties collected from throughout the world.

The National Clonal Germplasm Repository in Oregon stores some of its hops samples as potted plants, the rest as shoot tips and seeds, which are bagged and put in cold storage at 4ºC. Barbara Reed (right) and a colleague examine some of the hop plantlets—clonal shoots—destined for refrigerated storage at the facility in semipermeable plastic bags for up to 3 years. ARS/Stephen Ausmus

But if the idea of bitterfree hops appeals, Henning says, stay tuned. In a year or two his group expects to announce a new and improved variety. Think of it, he says, as bitter-Terminator 2.

References:

Henning, J.A., et al. In press. Registration of 'Teamaker' hop. Journal of Plant Registrations. See http://jpr.scijournals.org/.

Further Readings:

Carter, P.R., et al. 1990. Hop cultivation and use information. In Alternative Field Crops Manual. University of Wisconsin Cooperative Extension Service. Available at http://www.hort.purdue.edu/newcrop/afcm/Hop.html.

DeNoma, J.S. 2000. Background information on Hops. USDA ARS National Clonal Germplasm Repository. Available at http://www.ars-grin.gov/cor/humulus/huminfo.html.

Duke, J.A. 1983. Humulus lupulus L. In Handbook of Energy Crops . Available at http://www.hort.purdue.edu/newcrop/duke_energy/
Humulus_lupulus.html.

Sources:

John A. Henning
Forage Seed and Cereal Research
U.S. Department of Agriculture
Agricultural Research Service
3450 SW Campus Way
Corvallis, OR 97331

Barbara M. Reed
National Clonal Germplasm Repository
U.S. Department of Agriculture
Agricultural Research Service
33447 Peoria Road
Corvallis, OR 97333-2521

As 2007 winds down, thoughts naturally turn towards what might lie ahead. Meals rich in high-carb tubers, perhaps? That's what the United Nations would like everyone to contemplate throughout 2008, which it is designating the International Year of the Potato.

Farmers now harvest more than 300 million tons of potatoes (Solanum tuberosum) worldwide. That makes it the fourth biggest food crop, trailing only corn, wheat, and rice.

For 8,000 years, the humble potato has been a staple in the South American Andes, its homeland. Spanish adventurers encountered the New World crop roughly 500 years ago and brought various types back to Europe. Today, potatoes are cultivated not only throughout the Americas, but also from China's uplands to India's subtropical lowlands—even on Ukraine's arid steppes.

A testament to the potato's Western roots, production of this crop in the States and southward leads the world. Fully 40 percent of the 2006 potato harvest came from North America, with Latin American farmers contributing another 16 percent.

However, appreciation for this nutritious starch within developing countries outside of the Americas—especially in Asia—has been growing steadily, with production of the crop in those regions climbing some 5 percent annually. Indeed, 2005 marked the first time in recent history that production of potatoes in the developing world exceeded that in developed nations.

Although most people think of potatoes as a commodity, in fact, more potatoes are processed to make fast foods, snacks, and convenience items than are sold fresh in the market place. Today, China is the leading producer of spuds, followed by the Russian states and India. International trade in potatoes—worth $6 billion annually—has also been growing within developing nations.

You might then ask why, with all of this pre-existing global interest in potatoes, the UN feels compelled to devote a year of workshops, research contests, and other focused attention on this one particular food. And the reason, the UN's Food and Agricultural Organization argues, is that much of the spud's potential to feed the poor remains untapped.

For instance, although Asians eat nearly half of the world's potatoes, per capita consumption even in Asia remains modest—just 25 kilograms per year, or roughly 45 percent of U.S. consumption and just 27 percent of what's typical in Europe.

Even were potatoes to win greater respect for their nutritional attributes and ability to serve as industrial feedstocks, they couldn't necessarily make a big contribution in new regions of the world without significantly more research. The tubers are vulnerable to a host of major diseases—like the one that set off Ireland's 1845 potato famine. Some varieties of potato are especially resistant to particular diseases, but may not grow well in new regions of the world or taste that yummy.

That's where potato scientists come in. They can identify the climate, soil types, day length, and native diseases with which any new potato crop would have to contend. Then they'll cross lines of wild or cultivated spuds to develop ones with traits that will allow them to thrive outside the Americas. The good news, the UN program notes: "The potato has the richest genetic diversity of any cultivated plant." So there's plenty of potential to tailor a new cultivar to meet the needs of farmers in most places on the globe.

But the potato's biggest advantage, according to the International Potato Center, based in Lima, Peru, is that it yields more food, more quickly, on less land, and in harsher climates than any other major crop. Up to 85 percent of the plant is edible, compared to only about 50 percent for cereal grains. Moreover, the Center notes, potatoes "are ideally suited to places where land is limited and labor is abundant—conditions in much of the developing world."

To help get this word out to agricultural agencies in parts of the world not already turned on to spuds, and from them to farmers, the International Potato Center will be sponsoring a March 2008 meeting: Potato Science for the Poor–Challenges for the New Millennium (http://www.cipotato.org/Cuzco_conference/). Those who attend will have the opportunity to explore the possibility of cooperating to fine tune existing potatoes into higher-yielding varieties.

The International Potato Center's gene bank safeguards the largest biodiversity of potatoes—7,500 different varieties, of which 1,950 are not cultivated. Research on spuds, especially studies aimed at fostering food security and the alleviation of poverty, have become a focus for the center.

With all of this talk of potatoes, are you hungry yet? The UN program has so far identified 172,000 web pages containing recipes for using potatoes. Stay tuned, it says: "We will gather the best of them" and share them on the Year of the Potato website.

References:

United Nations Food and Agricultural Organization. 2008. International Year of Potato website: http://www.potato2008.org/en/index.html

Further Readings:

Gorman, J. 2000. Novel sensing system catches the dud spud. Science News 158(Nov. 25):341. Available at http://www.sciencenews.org/articles/20001125/fob5ref.asp.

C. Graves, Ed. 2001. The Potato, Treasure of the Andes: From Agriculture to Culture. Lima, Peru: International Potato Center (208 pp). Available at http://www.cipotato.org/publications/books/potato_treasure_andes_online/.

Raloff, J. 2005. Food colorings: Pigments make fruits and veggies extra healthful. Science News 167(Jan. 8):27. Available at http://www.sciencenews.org/articles/20050108/bob9.asp.

______. 2004. How carbs can make burgers safer. Science News Online (Dec. 4). Available at http://www.sciencenews.org/articles/20041204/food.asp.

______. 2004. Coming soon—Spud lite. Science News Online (June 19). Available at http://www.sciencenews.org/articles/20040619/food.asp.

______. 2003. How olives might enhance potatoes—and strawberries. Science News Online (May 24). Available at http://www.sciencenews.org/articles/20030524/food.asp.

______. 2002. Acrylamide—From spuds to gingerbread. Science News Online (Dec. 14). Available at http://www.sciencenews.org/articles/20021214/food.asp

______. 1998. Taters for tots provide an edible vaccine. Science News 153(March 7):149. Available at http://www.sciencenews.org/pages/sn_arc98/3_7_98/fob1.htm

Sources:

International Year of Potato (IYP) Secretariat
Food and Agriculture Organization of the United Nations
Room C-776
Viale delle Terme di Caracalla
00153 Rome
Italy

International Potato Center
Apartado Postal 1558
Lima 12,
Peru

Peanuts are a protein-rich snack food packing plenty of vitamins and trace nutrients. However, these legumes can elicit potentially life-threatening immune reactions within the one in 100 American adults who are allergic to them. Rates of peanut allergy are even higher among children. And the really disturbing news: A new study finds that the age at which this common food allergy first shows up is falling.

NOT NUTS. Despite their name, peanuts are legumes akin to soy and peas. However, like true nuts—those that grow on trees—peanuts can cause serious food allergies. Indeed, these tasty legumes are the most common source of food allergy in the United States. iStockphoto

Today, peanut allergy typically emerges in early toddlerhood, a team of Duke University researchers reports in the December Pediatrics. "That's almost a year earlier than what we knew, scientifically, a decade ago, "explains A. Wesley Burks, a pediatric allergist who coauthored the new study.

Although children outgrow many allergies, peanut allergy is not typically one of them. Among people who develop immune reactions to this food, 80 percent retain their allergy for life.

The new study began, Burks says, after Duke immunologists noticed that they were encountering younger patients with peanut allergy. To investigate, the researchers pulled entry records and medical charts for all 140 young patients who had come in with the allergy since 1988. Poring over the records confirmed a fall in age at first diagnosis throughout this period—one that proved more dramatic than expected, Burks told Science News Online.

Nationally, the rate of food allergy appears to be increasing, according to a 2006 report of a National Institutes of Health expert panel. The most striking increase, it noted, has been for peanut allergy, which is also the most common food sensitivity. Because some allergies can be avoided by delaying a child's initial introduction to certain foods, in 2000 the American Academy of Pediatrics recommended that parents "consider" keeping peanuts, tree nuts, fish and shellfish out of the diet of kids under age 3.

Burks acknowledges that most parents aren't aware of this recommendation. On the other hand, most peanut allergy shows up in children that had already exhibited allergic reactions to other foods—typically eggs or milk. Many affected children also had skin sensitivities as infants, such as eczema or atopic dermatitis, and a parent or sibling with allergies, although not necessarily to food.

Against that background, you would think parents of the most vulnerable kids would be especially careful about introducing peanuts into the diet. And they might well have been. Indeed, Burks suspects that most initial introductions to peanuts in his young patients were inadvertent. Either a child encountered items that contained unlabeled traces of peanuts—perhaps a jelly bean, certain flavorings used in medicines, or any of several baby lotions (see Unexpected Sources of Peanut Allergy). Or perhaps the kids encountered peanut allergen in the air when others were eating, handling, or cooking foods that contained the legume.

But for now, Burks' team has no firm leads on why peanut allergies are showing up earlier. The Duke group and others will be probing that in the next few years.

For more information, see this week's Food for Thought column.

References:

Green, T.D. . . . and A.W. Burks. 2007. Clinical characteristics of peanut-allergic children: Recent changes. Pediatrics 120(December):1304-1310. Abstract available at http://dx.doi.org/10.1542/peds.2007-0350.

Hallett, R., L.A.D. Haapanen, and S.S. Teuber. 2002. Food allergies and kissing. New England Journal of Medicine 346(June 6):1833-1834. Extract available at http://content.nejm.org/cgi/content/extract/346/23/1833.

National Institute of Allergy and Infectious Disease. 2006. Report of the NIH Expert Panel on Food Allergy Research. March 13-14. Washington, D.C.: National Institutes of Health. Available at http://www3.niaid.nih.gov/topics/foodAllergy/ReportFoodAllergy.htm.

Further Readings:

Helmuth, L. 1999. Allergy vaccine may take fear out of nuts. Science News 155(April 3):213. Available at www.sciencenews.org/pages/pdfs/
data/1999/15514/15514-04.pdf.

Long, A. 2002. The nuts and bolts of peanut allergy. New England Journal of Medicine 346(April 25):1320-1322. Extract available at http://content.nejm.org/cgi/content/extract/346/17/1320.

Raloff, J. 2003. Unexpected sources of peanut allergy. Science News Online (March 15). Available at http://www.sciencenews.org/articles/20030315/food.asp.

______. 2002. A rash of kisses. Science News 162(July 20):40. Available at http://www.sciencenews.org/articles/20020720/bob9.asp.

______. 1998. The mango that thought it was poison ivy. Science News Online (Aug. 8). Available at http://www.sciencenews.org/pages/sn_arc98/8_8_98/food.htm.

______. 1997. A whiff, a sniff—then asthma. Science News Online (Feb. 1). Available at http://www.sciencenews.org/pages/sn_arc97/2_1_97/food.htm.

______. 1996. Peanut allergy found common and increasing. Science News 150(Sept. 7):150. Available at www.sciencenews.org/pages/pdfs/
data/1996/150-10/15010-10.pdf.

_____. 1996. Family allergies? Keep nuts away from kids. Science News 149(May 4):279. Available at www.sciencenews.org/pages/pdfs/
data/1996/149-18/14918-11.pdf.

Seppa, N. 2003. Tough nut is cracked: Antibody treatment stifles peanut reactions. Science News 163(March 15):163. Available at http://www.sciencenews.org/articles/20030315/fob1.asp.

Sources:

American Academy of Pediatrics
141 Northwest Point Boulevard
Elk Grove Village, IL 60007
Web site: http://www.aap.org

A. Wesley Burks
Division of Pediatric Allergy and Immunology
Duke University Medical Center
DUMC 2644
Durham, NC 27710

National Institutes of Health
National Institute of Allergy and Infectious Diseases
Office of Communications and Government Relations
6610 Rockledge Drive, MSC 6612
Bethesda, MD 20892-6612
Web site: http://www3.niaid.nih.gov

Canadian pediatricians certainly aren't shirking controversy when it comes to a vitamin guideline they've developed for pregnant women and nursing moms. They're asking these women to boost their intake of vitamin D dramatically—to 10 times the daily doses advocated by most health organizations in the States. This new prescription is aimed at combating rickets—leg deformations caused by soft bones—in youngsters who get too little of the sunshine vitamin.

EATING FOR TWO. To ensure baby's bones are strong, moms-to-be should boost their vitamin-D intake greatly, Canadian pediatricians contend. Photodisc

Vitamin D helps build strong bones by helping the body absorb calcium. Getting pregnant and nursing women to take more of the vitamin ensures that plenty will reach developing children.

In the past, most people had little trouble getting enough vitamin D—they just went outdoors where ultraviolet rays from the sun trigger chemical reactions in skin to make this vital nutrient. However, some people always had trouble making enough. Canadian kids at highest risk of vitamin deficits generally live in First Nations and Inuit communities. With sun-filtering pigments in their skin, and living at high latitudes, they must glean most of their vitamin D from the diet—generally a poor source—not the sun.

Most North American women—including those in the United States—eat diets delivering only about 100 international units, or IU, of vitamin D daily, according to the Institute of Medicine (IOM), in Washington, D.C. That is half of what IOM recommends and a mere 5 percent of what Canadian pediatricians are now advocating for new and soon-to-be moms.

Although IOM's dietary recommendations are for the United States, the Canadian health establishment has tended to rubber stamp them. In this case, though, Canada's health agency took the unusual tack of signing off on a Canadian Paediatric Society proposal to boost the recommended intake by women who are pregnant or breast feeding to 2,000 IU per day. This new guideline appears in a consensus statement published in September by the society in its journal, Paediatrics & Child Health.

Soon the society will begin sending its new guideline to every provincial, territorial, and aboriginal health department across Canada, notes Marie Adèle Davis, the group's executive director. The goal, she told Science News Online, is to make sure all public health officials learn about it—not just pediatricians.

The higher recommendation equals the amount that IOM has designated as the safe upper limit for vitamin D's daily consumption. Most nutritionists don't really consider that value is a true ceiling for safe intake—especially since sunbathing on a bright summer day can generate 10,000 to 20,000 IU in the body without harm. Still, for political and legal reasons, most organizations shy away from advocating intakes near what IOM has flagged as a potential maximum for safe consumption.

Now a number of researchers suspect that intakes by pregnant and lactating women much below 2,000 IU per day could actually prove unsafe for child health.

Reinhold Vieth of the University of Toronto explained why, recently, to officials with Health Canada, a counterpart to the U.S. Food and Drug Administration. To prevent rickets, he argued, a baby needs 400 IU of vitamin D per day. And in many parts of Canada, he said, nursing women may require several thousand IU of vitamin D per day to get 400 IU into their breast milk. Vieth had been recruited by the Canadian Paediatric Society to help defend its proposed guideline to government officials.

U.S. physicians won't quibble over the 400 IU figure for babies and young children, notes pediatrician Frank R. Greer, chair of the American Academy of Pediatrics' (AAP) committee on nutrition. Although the 1997 IOM report says 200 IU of vitamin D per day should be sufficient for anyone under 50—including children—few researchers buy that. "Everybody feels that we should be taking more than 200 IU," says Greer, of the University of Wisconsin–Madison.

Unlike the Canadian Paediatric Society, though, "We [at AAP] don't really have any influence on what pregnant and lactating women take," Greer says. "However, I can say that AAP's committee on nutrition has recommended to the board that we go back to [recommending] 400 IU for all children." That's the amount in a teaspoon of cod liver oil—the vitamin D supplement of choice throughout the early 20th century. Greer expects his committee's recommendation to be approved by AAP's board, perhaps within the next month.

Optimal needs vary

For most of the past century, nutrient guidelines have been set to prevent gross deficiencies—shortfalls that could cause disease. Those recommendations tended to represent minimally adequate intakes. Over the past decade, however, considerable debate has surrounded what vitamin D consumption levels would be optimal versus merely adequate.

The controversy has been fueled by a steady stream of studies that have emerged since the IOM set its vitamin D guidelines. Nearly all demonstrate substantial health benefits from relatively high intakes of vitamin D—amounts well in excess of what most individuals now get. Moreover, those benefits extend well beyond protecting bone. More vitamin D seems to diminish the risk of cancer, diabetes, autoimmune disorders, muscle loss, viral infections—even gum disease.

Researchers gauge vitamin D sufficiency on the basis of 25-hydroxy vitamin D (25-HD). This is not the form of the vitamin that is consumed—nor the hormonal form that the body actually uses—but an intermediary. To achieve optimal concentrations of 25-HD, growing numbers of nutrition and health scientists suggest, most of us would need intakes of 800 to 4,000 IU per day (see Vitamin D: What's Enough?).

How much vitamin D someone needs can vary widely, largely depending on the amount of skin that gets exposed to the sun each day—and for how long. Further complicating the picture, some skin is heavily pigmented, filtering sunlight out. Many people cover up with clothes or sunblock when they go outdoors. Still others live at high latitudes—as Canadians do—where little ultraviolet radiation makes it through the atmosphere during much of the year.

Even for women in the southern United States, however, "we've found that lactating women need about 6,000 IU a day to transfer enough vitamin D into their milk to supply adequate amounts to a nursing infant," says Bruce W. Hollis of the Medical University of South Carolina in Charleston.

Nor are nursing moms the only individuals who may need relatively large doses of the vitamin. Hollis' research has shown that black women may sometimes need 4,000 IU a day for months at a time to compensate for little time outdoors, heavy skin pigmentation, and/or obesity—a factor that appears to diminish the body's ability to use vitamin D efficiently (see Understanding Vitamin D Deficiency).

Another reason for moms' supplementation?

In March, researchers at Harvard Medical School reported evidence that ample vitamin D diminishes the chance a child will develop asthma, a scourge who's incidence has been rising, especially in black and low-income communities (see Childhood Vitamin D—A New Benefit?). Recently, an additional putative benefit has emerged for pregnant women and their developing babies.

A study linked elevated risk of preeclampsia—high blood pressure that develops in some women during the last half of pregnancy—with low intakes of vitamin D. This condition, which can lead to miscarriage and even the death of the mother—ordinarily develops in some three to seven percent of first pregnancies.

Pittsburgh researchers enrolled 1,198 women who were pregnant for the first time and measured their blood concentrations of vitamin D within the first 22 weeks of gestation. Subsequently, 59 women developed preeclampsia. Blood values from all but four were compared to a similar group of recruits who maintained normal blood pressure throughout their pregnancies.

The higher a woman's blood concentrations of 25-HD, the lower her chance of developing preeclampsia—and that risk fell steadily and "strikingly" with increasing vitamin D values, Lisa M. Bodnar of the University of Pittsburgh and her colleagues found.

Moreover, babies whose moms had developed preeclampsia were far more likely to have low vitamin-D values than were children whose moms had maintained normal blood pressure. "These differences were found in our population despite widespread prenatal/multivitamin use in the 3 months before delivery," Bodnar's group reports in the September Journal of Clinical Endocrinology and Metabolism.

Black women face far higher risks of developing this hypertensive syndrome. Overall, black women are also far likelier than other ethnic or racial groups to have low blood levels of vitamin D. Against this backdrop, Bodnar's group says, "our data linking vitamin D deficiency and preeclampsia risk raises the intriguing possibility that vitamin D may contribute to racial disparities in this [syndrome]."

"The story of deficiency begins with vitamin D itself and its primary mode of synthesis, which is from sunlight," argue Adekunle Dawodu of the University of Cincinnati and Carol L. Wagner of the Medical University of South Carolina in Charleston. In a commentary in the September Archives of Disease in Childhood, they report a resurgence of rickets around the world, not only in children at high latitudes, but also in the Arab world and Asia where culture or excessive temperatures may keep women and children indoors or covered up.

A shift from vitamin-D sufficiency to widespread deficiency has occurred rapidly—mostly throughout a half-century. The reason for it is clear, Dawodu and Wagner say: "insufficient sun exposure and inadequate corrective vitamin-D supplementation." They conclude, much as the Canadian Paediatric Society just has, that dosing moms during pregnancy and lactation "would achieve the double effect of preventing vitamin-D deficiency in both mothers and children." But unlike the Canadian society, they note that doses considerably higher than 2,000 IU may be necessary for some individuals and communities.

As a goal, achieving population-wide vitamin D sufficiency "may be one of the more important preventative public health initiatives," conclude Dawodu and Wagner.

References:

Bodnar, L.M., et al. 2007. Maternal vitamin D deficiency increases the risk of preeclampsia. Journal of Clinical Endocrinology and Metabolism 92(September):3517-3522. Abstract available at http://jcem.endojournals.org/cgi/content/abstract/92/9/3517.

Dawodu, A., and C.L. Wagner. 2007. Mother-child vitamin D deficiency: An international perspective. Archives of Disease in Childhood 92(September):737-740. Available at http://adc.bmj.com/cgi/content/full/92/9/737.

First Nations, Inuit and Metis Health Committee, Canadian Paediatric Society. 2007. Vitamin D supplementation: Recommendations for Canadian mothers and infants. Paediatrics & Child Health 12 (September):583-589. Available at http://www.cps.ca/english/statements/II/FNIM07-01.htm.

Hollis, B.W., and C.L. Wagner. 2004. Assessment of dietary vitamin D requirements during pregnancy and lactation. American Journal of Clinical Nutrition 79(May):717-726. Available at http://www.ajcn.org/cgi/content/full/79/5/717.

Institute of Medicine and National Research Council. 1997. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Washington, D.C.: National Academies Press. Available at http://www.nap.edu/books/0309063507/html/.

Further Readings:

Cannell, J.J. In press. Autism and vitamin D. Medical Hypotheses. Abstract available at http://dx.doi.org/10.1016/j.mehy.2007.08.016.

Dijkstra, S.H., et al. 2007. High prevalence of vitamin D deficiency in newborn infants of high-risk mothers. Archives of Disease in Childhood 92(September):750-753. Available at http://adc.bmj.com/cgi/content/full/92/9/750.

Moore, C.E., M.M. Murphy, and M.F. Holick. 2005. Vitamin D intakes by children and adults in the United States differ among ethnic groups. Journal of Nutrition 135(October):2478-2485. Available at http://jn.nutrition.org/cgi/content/full/135/10/2478.

Raloff, J. 2007. Childhood vitamin D—A new benefit? Science News Online (May 19). Available at http://www.sciencenews.org/articles/20070519/food.asp.

______. 2007. Childhood vitamin D—A dark side? Science News Online (May 12). Available at http://www.sciencenews.org/articles/20070512/food.asp.

______. 2006. The antibiotic vitamin. Science News 170(Nov. 11):312-317. Available at http://www.sciencenews.org/articles/20061111/bob9.asp.

______. 2005. Breathing easier with vitamin D. Science News Online (Dec. 17). Available at http://www.sciencenews.org/articles/20051217/food.asp.

______. 2005. Vitamin D boosts calcium potency. Science News Online (Nov. 12). Available at http://www.sciencenews.org/articles/20051112/food.asp.

______. 2005. Understanding vitamin D deficiency. Science News Online (April 30). Available at http://www.sciencenews.org/articles/20050430/food.asp.

______. 2004. Vitamin D: What's enough? Science News 166(Oct. 16):248-249. Available at http://www.sciencenews.org/articles/20041016/bob9.asp.

______. 2004. Vitamin boost. Science News 166(Oct. 9):232-233. Available at http://www.sciencenews.org/articles/20041009/bob8.asp.

______. 2004. Should foods be fortified even more? Science News Online (Sept. 11). Available at http://www.sciencenews.org/articles/20040911/food.asp.

______. 2000. Calcium may become a dieter's best friend. Science News 157(April 29):277. Available at http://www.sciencenews.org/articles/20000429/fob2.asp.

Williams, A.F. 2007. Vitamin D in pregnancy: An old problem still to be solved? Archives of Disease in Childhood 92(September):740-741. Available at http://adc.bmj.com/cgi/content/full/92/9/740.

Sources:

American Academy of Pediatrics
141 Northwest Point Boulevard
Elk Grove Village, IL 60007-1098

Lisa M. Bodnar
Department of Epidemiology
University of Pittsburgh Graduate School of Public Health
A742 Crabtree Hall
130 DeSoto Street
Pittsburgh, PA 15261

John J. Cannell
Psychiatry Department
Atascadero State Hospital
10333 El Camino Real
Atascadero, CA 93423

Marie Adèle Davis
Canadian Paediatric Society
2305 St. Laurent Boulevard
Ottawa, Ont. K1G 4J8
Canada

Frank R. Greer
Department of Pediatrics
University of Wisconsin, Madison
Madison, WI 53792

Bruce W. Hollis
Department of Pediatrics
Medical University of South Carolina
P.O. Box 250917
171 Ashley Avenue, Room BM326
Charleston, SC 29425

Reinhold Vieth
Pathology and Laboratory Medicine
Mount Sinai Hospital
600 University Avenue
Toronto, ON M5G 1X5
Canada

As any pet owner knows, the more food that goes into an animal's mouth, the more wastes that eventually spew out the other end. The bigger the animal, the bigger its appetite. So imagine the volumes of manure—often tainted with germs—that farmers must manage for even a small feedlot with perhaps 3,500 head of cattle.

Ordinarily, beef producers house their animals in pens—some the size of football fields or larger. They're designed to leave each animal about 80 square feet of space. Cattle wastes just fall to the ground and collect—often for a month or more—before feedlot crews periodically scrape away the muck. After composting, the dried manure will be applied to fields as a rich fertilizer.

The real problem develops when it rains. Then, a manure-rich, watery slurry can drain off the fields. Conventionally, feedlot managers would divert this liquid into huge, smelly ponds or lagoons—some 10-feet deep or more, explains Bryan L. Woodbury, an agricultural engineer with the U.S. Department of Agriculture's Meat Animal Research Center in Clay Nebraska.

POOPED OUT. Cattle standing at the edge of their pen, as rain water washes manure into the narrow basin, and on down into a hayfield. Woodbury/USDA

His team has been developing a literally greener alternative to pond storage for manure-laced runoff from feedlot pens. The new system directs that runoff into a foot-deep drainage basin. Leading out of it are a series of narrow pipes. Because the interior diameters of these pipes are small, rain-deposited wastes temporarily back-up in this glorified drainage ditch. It typically takes hours for all of the liquids to fully drain out through the pipes. While they wait, solids in the rain-manure slurry tend to settle out as sediments that will accumulate on the basin's bottom.

Exiting liquids, meanwhile, flow gently into a mildly sloping field of grass, where the animal wastes will fertilize the plants' growth. At the end of the season, farmers harvest that grass as hay, bale it, and then feed it back to the herd.

For much of the past decade, Woodbury's team has tinkered with the system's design to optimize gravity's removal of solids from the initial rain-manure slurry and the pace at which fertilizing water enters the hayfield. In terms of those features, the system appears ready for prime time—at least in the Midwest, Woodbury says.

However, what hadn't been evaluated was the fate of germs that were shed by cattle along with those wastes. If the brief holding of the manure-water slurry and its subsequent release into fields promoted the growth of disease-causing microorganisms, those germs might eventually find their way into plants (see Not Just Hitchhikers). That would risk re-exposing animals that later dined on the tainted hay.

A new investigation now indicates that although the raw manure often hosts germs, most of the nasty microbes hitchhiking in it appear to settle out along with sediments in the initial holding basin. Bugs that remain suspended in the water long enough to travel on to the fields don't appear to survive there long, Woodbury and his colleagues report in the Nov. 1 Journal of Environmental Quality.

Indeed, the researchers note, while their new data "indicate that there is some risk for hay contamination, it appears to be low." For instance, on one day that hay was cut—two weeks after a major rainfall that shunted diluted manure into the field—only four of 10 tested soil samples hosted Escherichia coli O157.

Yet only one of the 30 samples of loose hay that was cut that day from parts of the field that had received manure-fertilized rainwater tested positive for that E. coli strain. Microbiologists also failed to later detect that E. coli O157 in hay following its baling and storage.

That's encouraging news because this bacterium has a long track record of causing disease. It was, for instance, responsible for the major food poisonings associated with tainted spinach in September 2006—an outbreak that sickened more than 200 people, killing five. These microbes can set up housekeeping in the bovine gut, causing no harm to the animal. However, germs shed in the cow's feces can infect people or crops that contact it.

The Nebraska researchers also probed for evidence of Campylobacter, another bacterium shed by cattle that can provoke gut-wrenching illness. And although three of 10 field-soil samples tested positive after one major rain, none did 2 weeks later. The germ also failed to show up in loose or baled hay.

Similarly, even though the test herd of 750 cattle had been periodically shedding large quantities of Cryptosporidium and Giardia—two common parasites responsible for substantial human disease, especially in persons with weakened immune systems—biologists found none of these microbes in field soil, much less the hay that had been grown on it.

Woodbury and his colleagues conclude that their vegetative filtering of manure washed off of feedlots is effective in dramatically sequestering and ultimately removing several of the major families of microbes responsible for human, food-related illness.

What they don't yet know is whether there will be significant rainfall constraints to their system's efficacy. Will arid regions benefit from it? Will very wet areas send so much fertilizer to hayfields that they burn the grass? "That's what we're in the process of testing right now," Woodbury says. "The jury's still out."

Other advantages

Earlier tests showed that the short-term basin storage of wastes upstream of the hayfield removes about half of the nitrogen in manure and almost all of the phosphorus, Woodbury says. That's important because one of the primary problems associated with fertilization of farm fields has been their release during rains of any unused nitrogen and fertilizer into streams.

CUTTIN' HAY. This grass will be cut, baled, and eventually fed to cattle. The hay (inset) was fertilized with wastes from those same animals. Woodbury/USDA

Eventually, the fertilizing effects of these nutrients in surface waters can fuel the growth of algae that ultimately suck most of the oxygen out of large patches of coastal waters, creating what are colloquially termed dead zones (see Limiting Dead Zones).

The new waste-sanitizing system's basin also removes most of the solid material suspended in the rain-manure slurry. This means that about once a year, people must excavate the buildup from the basin. However, what they remove is no longer a waste, but yet another fertilizing amendment for farm fields.

Oh, and Woodbury points to another potential advantage of his team's new system—something that he refers to as the "white picket fence effect." When people see a picket fence out front, they focus on that pleasant feature, and not every detrimental facet of a house or yard. Well, nobody views a big, smelly lagoon filled with bovine fecal material as the farm equivalent of a white picket fence, he says. A hayfield, on the other hand: That's almost Norman Rockwell Americana.

References:

Berry, E.D., B.L. Woodbury, et al. 2007. Incidence and persistence of zoonotic bacterial and protozoan pathogens in a beef cattle feedlot runoff control—vegetative treatment system. Journal of Environmental Quality 36(Nov. 1):1873-1882. Abstract available at http://jeq.scijournals.org/cgi/content/abstract/36/6/1873.

Woodbury, B.L., J.A. Nienaber, and R.A. Eigenberg. 2005. Effectiveness of a passive feedlot runoff control system using a vegetative treatment area for nitrogen control. Applied Engineering in Agriculture 21(July):581-588. Abstract available at http://asae.frymulti.com/abstract.asp?aid=18569&t=1.

______. 2003. Performance of passive feedlot runoff control and treatment system. Transactions of the ASAE 46(November/December):1525-1530. Abstract available at http://asae.frymulti.com/abstract.asp?aid=15641&t=1.

Further Readings:

Milius, S. 2007. Not just hitchhikers. Science News 172(Oct. 20):250-252. Available at http://www.sciencenews.org/articles/20071020/bob10.asp.

Raloff, J. 2006. Protozoa aid food-poisoning germs. Science News Online (March 18). Available at http://www.sciencenews.org/articles/20060318/food.asp.

______. 2004. Limiting dead zones. Science News 165(June 12):378-380. Available at http://www.sciencenews.org/articles/20040612/bob9.asp.

______. 2004. Marsh farming for profit and the common good. Science News Online (May 15). Available at http://www.sciencenews.org/articles/20040515/food.asp.

______. 2001. Retail meats host drug-resistant bacteria. Science News 160(Oct. 20):246. Available at http://www.sciencenews.org/articles/20011020/fob5.asp.

______. 2001. Germ-fighting germs. Science News Online (Aug. 18). Available at http://www.sciencenews.org/articles/20010818/food.asp.

______. 2001. Antibiotic resistance is coming to dinner. Science News 159(May 26):325. Available to subscribers at http://www.sciencenews.org/articles/20010526/fob3.asp.

______. 2000. Sickening food. Science News Online (Jan. 1). Available at http://www.sciencenews.org/articles/20000101/food.asp.

______. 1999. Food poisoning: Sprouts linked to bouts. Science News 155(Jan. 23):63. Available at http://www.sciencenews.org/pages/pdfs/
data/1999/15504/15504-21.pdf.

______. 1998. Hay! What a way to fight E. coli. Science News Online (Sept. 19). Available at http://www.sciencenews.org/pages/sn_arc98/9_19_98/food.htm.

Seppa, N. 2000. Venison can contain E. coli bacteria. Science News (Aug. 5):95. Available to subscribers at http://www.sciencenews.org/articles/20000805/note14.asp.

Sources:

Bryan L. Woodbury
Roman L. Hruska U.S. Meat Animal Research Center
Agricultural Research Service
U.S. Department of Agriculture
P.O. Box 166, Spur 18D
Clay Center, NE 68933-0166

Once a common top predator throughout coastal seas around the globe, sawfish have become remarkably rare. Indeed, today most populations are threatened with extinction. So spotting even one of these animals is reason to rejoice, notes Beau Yeiser of Mote Marine Laboratory in southern Florida. And this week, "we are nothing but giddy," he reports.

He and colleague Tonya Wiley just returned from a 2-day sawfish-scouting expedition during which they tagged a 7-foot male on Oct. 16. At that size, the strapping youth may be 5 to 7 years old, Yeiser says. He cautions, however, that estimating age is challenging "as we try and piece together the life history of this species. We don't even know its size at maturity yet."

BIG CATCH. Biologists outfitted this 7-foot male sawfish, caught in southern Florida last week, with a data-recording satellite tag (black and white device at bottom right). It's due to collect minute-by-minute information of the fish's environment through mid-March. Yeiser/Mote Marine Laboratory

These animals—essentially flattened sharks with wings—are members of the ray family. Only one species of this fish remains in U.S. waters, mostly off of Florida. Over the first half of the 20th century, this smalltooth sawfish (Pristis pectinata) was fished to the brink of extinction—largely by accident.

Although many cultures eat sawfish—the animals' fins are especially prized in Asia as the featured ingredient in a pricey soup—most of the animals in U.S. waters were landed and destroyed as bycatch, that is, nuisance species hauled in by commercial fishing fleets. The dire status of sawfish globally won these animals protection, last month, under a treaty banning international trade in endangered species (see Hammered Saws).

So far this year, Yeiser and Wiley have caught just 14 sawfish, most of them less than 4 feet long. Those would still be little kids, considering that these fish are almost a yard long at birth. Then again, the pair had expected only small ones because they've mainly been cruising coastal shallows this year in hopes of running into newborns and youngsters.

The scientists attach a numbered identification tag to the dorsal fin of every sawfish they catch—and then release the animal.

But last week's catch was so big that it qualified for a second identifier: a pop-up archival tag, or PAT. These recording devices are so heavy that they're reserved for large sawfish—at least 7-footers. To date, only some dozen of these animals have received PATs. Costing at least $4,000 each, these data-storage systems collect information every minute, for months, on the depth at which its host is swimming, the water temperature, and light levels. The latter information gets plugged into a computer program that roughly gauges the animal's geographic coordinates at any moment.

DOUBLE TAG. This close-up shows the permanent ID tag (orange) and satellite pop-up tag (black and gray) placed on an 11-foot sawfish this past May. Unfortunately, the satellite tag released prematurely and has been lost. Yeiser/Mote Marine Laboratory

Researchers program a PAT to pop off the fish on a particular date. Once it floats to the surface, it sends its stored information in spurts, twice a day, to a satellite. That orbiting relay station then shoots those data back to Earth and the scientists' email addresses.

Last week's sawfish encounter took place in a southern Florida national wildlife refuge, in very shallow water. Investigated as a possible nursery, Yeiser says "I was expecting any sawfish that I might catch to be perhaps 4 to 5 feet in length." Instead, he found a much older juvenile. "But that's the beauty of this [sawfish] project; you never know what you are going to get when you're scouting a species that has not been studied much!"

Yeiser named the youth that he tagged last week Raloff. Hmmm—I like the sound of that. Its tag is programmed to pop off on March 15. Stay tuned for an update on my namesake's travels.

If all goes well, that is.

A 7- and an 11-foot sawfish each received PATs in May. Although the satellite tags had been programmed to pop off 3 months later, they actually surfaced within just a couple weeks, Yeiser says—and were never recovered.

So, each time biologists deploy the pricey devices, he says, "we just cross our fingers that they won't pop up early—or get lost in the middle of the Gulf."

REWARDING. Because these satellite tags record valuable information, scientists have marked them with the Mote lab's phone number and email address—and the promise of a reward if retrieved by a boater. Yeiser/Mote Marine Laboratory

Don't try this yourself

The sawfish is an endangered species, so federal law forbids its capture—except by researchers who have been granted a waiver. And even they need to release an animal after measuring and tagging it.

It's against the law to even harass the animals. Still, anglers may inadvertently snag one of the toothy marvels. When that happens, this species "should be released by keeping the fish in the water and cutting the line as close to the hook as possible," according to guidelines issued late last year by the National Marine Fisheries Service in St. Petersburg, Fla. "If it can be done safely, untangle the line if it is wrapped around the saw. Do not handle the animal or attempt to remove any hooks on the saw, except for with a long-handled dehooker," NOAA says.

Biologists request that any anglers who sight a sawfish report their encounter to the Mote lab. Its scientists are maintaining a database to help them identify important habitat for these endangered animals.

As interesting as these piscine oddities are, biologists would prefer that the public give the fish a wide berth. The primary reason: Approaching the animals can stress them, chase them from what should be waters safe from predators, or even interfere with their reproduction.

But there's another reason to steer clear, according to Captain Harvey Lee Hamilton, who charters a fishing boat out of Pineland, Fla. "I've caught plenty of sawfish in my life, and I'll tell you: They're dangerous. I'm still scared to death of them." Their saws—which he terms blades—are edged with dozens of razor-sharp "teeth." The muscular animals slash those saws from side to side to kill prey or defend themselves.

Says Hamilton: "Those fish get big, with blades that can go to at least 5 foot." And they slash those blades "so fast," he says, "that they could slice your feet off." Indeed, he told Science News Online: "I'd rather fight a shark than a sawfish."

References:

Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Available at http://www.cites.org/eng/cop/14/prop/E14-P17.pdf.

Office of Protected Resources. National Marine Fisheries Service. National Oceanic and Atmospheric Administration. Smalltooth Sawfish (Pristis pectinata) Home page: http://www.nmfs.noaa.gov/pr/species/
fish/smalltoothsawfish.htm.

National Marine Fisheries Service. National Oceanic and Atmospheric Administration. 2006. Frequently asked questions on Endangered Species Act (ESA)-listed Sea Turtle and Smalltooth Sawfish Release Protocol for Commercial and For-hire Gulf of Mexico Permitted Reef Fish Vessels. (Dec. 4). Available at http://sero.nmfs.noaa.gov/sf/turtle/SFTurtleReleaseFAQ
%20120406.pdf.

National Marine Fisheries Service. National Oceanic and Atmospheric Administration. 2006. Draft Smalltooth Sawfish Recovery Plan (Pristis pectinata). (August). Available at http://www.nmfs.noaa.gov/pr/pdfs/recovery/
draft_smalltoothsawfish.pdf.

Further Readings:

2006. Mote scientists to help eBay identify species in new sawfish ban. Mote Marine Laboratory news release. Jan. 25. Available at http://www.mote.org.

Mote Marine Laboratory. How you can help save the U.S. smalltooth sawfish. Available at http://www.mote/org.

Raloff. J. 2007. Hammered saws. Science News 172(Aug. 11):90-92. Available at http://www.sciencenews.org/articles/20070811/bob9.asp.

______. 2002. Clipping the fin trade. Science News 162(Oct. 12):232-234. Available at http://www.sciencenews.org/articles/20021012/bob10.asp.

Sawfish in Peril: Sawfish Education Program. Available at http://www.flmnh.ufl.edu/fish/education/sawfishinperil.ppt.

Sources:

Beau Yeiser and Tonya R. Wiley
Center for Shark Research
Mote Marine Laboratory
1600 Ken Thompson Parkway
Sarasota, FL 34236

Smalltooth Sawfish Coordinator
National Marine Fisheries Service
Southeast Regional Office, Protected Resources Division
263 13th Avenue South
St. Petersburg, FL 33071

Women take note. Researchers find that a chemical that forms in overcooked meat, especially charred portions, is a potent mimic of estrogen, the primary female sex hormone. That's anything but appetizing, since studies have linked a higher lifetime cumulative exposure to estrogen in women with an elevated risk of breast cancer.

HORMONAL HAMBURGER? Depending on the temperature at which this burger was grilled—especially how hot its outer surface got—it may have hosted chemical reactions that created PhIP, a carcinogen that has a potent hormonal alter-ego. It can mimic the biological activity of estrogen, the primary female sex hormone. Photodisc

Indeed, the new finding offers a "biologically plausible" explanation for why diets rich in red meats might elevate breast-cancer risk, notes Nigel J. Gooderham of Imperial College London.

At the very high temperatures reached during frying and charbroiling, natural constituents of meats can undergo chemical reactions that generate carcinogens known as heterocyclic amines (see Carcinogens in the Diet). Because these compounds all have very long, unwieldy chemical monikers, most scientists refer to them by their abbreviations, such as IQ, MeIQ, MeIQx, and PhIP.

Of the nearly two dozen different heterocyclic amines that can form, PhIP dominates. It sometimes accumulates in amounts 10 to 50 times higher than that of any other member of this toxic chemical family, Gooderham says. Moreover, he adds, although heterocyclic amines normally cause liver tumors in exposed animals, PhIP is different: "It causes breast cancer in female rats, prostate cancer in male rats, and colon cancer in both." These are the same cancers that in people are associated with eating a lot of cooked meats.

However, the means by which such foods might induce cancer has remained somewhat elusive. So, building on his team's earlier work, Gooderham decided to probe what the heterocyclic amine did in rat pituitary cells. These cells make prolactin—another female sex hormone—but only when triggered by the presence of estrogen. Prolactin, like estrogen, fuels the growth of many breast cancers.

In their new test-tube study, Gooderham and coauthor Saundra N. Lauber show that upon exposure to PhIP, pituitary cells not only make progesterone, but also secrete it. If these cells do the same thing when they're part of the body, those secretions would circulate to other organs—including the breast.

But "what was startling," Gooderham told Science News Online, is that it took just trace quantities of the heterocyclic amine to spur prolactin production. "PhIP was incredibly potent," he says, able to trigger progesterone production at concentrations comparable to what might be found circulating in the blood of people who had eaten a couple of well-done burgers.

The toxicologist cautions that there's a big gap between observing an effect in isolated cells growing in a test-tube and showing that the same holds true in people.

However, even if PhIP does operate similarly in people, he says that's no reason to give up grilled meat. Certain cooking techniques, such as flipping hamburgers frequently, can limit the formation of heterocyclic amines. Moreover, earlier work by the Imperial College team showed that dining on certain members of the mustard family appear to detoxify much of the PhIP that might have inadvertently been consumed as part of a meal.

For more information, see this week's Food for Thought column.

Cho, E., et al. 2006. Red meat intake and risk of breast cancer among premenopausal women. Archives of Internal Medicine 166(Nov. 13):2253-2259. Abstract available at http://archinte.ama-assn.org/cgi/content/short/166/20/2253.

Felton, J.S., et al. 1995. Reduction of heterocyclic aromatic amine mutagens/carcinogens in fried beef patties by microwave pretreatment. Available at http://www.llnl.gov/str/pdfs/UCRL-JC-116450.pdf.

Gooderham, N.J., et al. 2007. Mechanisms of action of the carcinogenic heterocyclic amine PhIP. Toxicology Letters 168(Feb. 5):269-277. Abstract available at http://dx.doi.org/10.1016/j.toxlet.2006.10.022.

Lauber, S.N., and N.J. Gooderham. 2007. The cooked meat–derived genotoxic carcinogen 2-amino-3-methylimidazo[4,5-b]pyridine has potent hormone-like activity: Mechanistic support for a role in breast cancer. Cancer Research 67(Oct. 1):9597-9602. Abstract available at http://cancerres.aacrjournals.org/cgi/content/abstract/67/19/9597.

Murray, S., . . . and N.J. Gooderham. 2001. Effect of cruciferous vegetable consumption on heterocyclic aromatic amine metabolism in man. Carcinogenesis 22(September):1413-1420. Available at http://carcin.oxfordjournals.org/cgi/content/full/22/9/1413.

Steck, S.E., et al. 2007. Cooked meat and risk of breast cancer—Lifetime versus recent dietary intake. Epidemiology 18(May):373-382. Abstract available at http://www.epidem.com/pt/re/epidemiology/
abstract.00001648-200705000-00016.htm.

Taylor, E.F., et al. 2007. Meat consumption and risk of breast cancer in the UK Women's Cohort Study. British Journal of Cancer 96(April 10):1139-1146. Available at http://www.nature.com/bjc/journal/v96/n7/full/6603689a.html.

Walters, D.G. . . . N.J. Gooderham, et al. 2004. Cruciferous vegetable consumption alters the metabolism of the dietary carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in humans. Carcinogenesis 25(September):1659-1669. Available at http://carcin.oxfordjournals.org/cgi/content/full/25/9/1659.

Further Readings:

Raloff, J. 2007. Concerns over genistein, part II—Beyond the heart. Science News Online (July 7). Available at http://www.sciencenews.org/articles/20070707/food.asp.

______. 2007. Concerns over genistein, part I—The heart of the issue. Science News Online (June 16). Available at http://www.sciencenews.org/articles/20070616/food.asp.

______. 2006. Pesticides mimic estrogen in shellfish. Science News 170(Dec. 16):397. Available to subscribers at http://www.sciencenews.org/articles/20061216/note12.asp.

______. 2006. No-stick chemicals can mimic estrogen. Science News 170(Dec. 2):366. Available to subscribers at http://www.sciencenews.org/articles/20061202/note16.asp.

______. 2006. Meat poses exaggerated cancer risk for some people. Science News Online (March 25). Available at http://www.sciencenews.org/articles/20060325/food.asp.

______. 2005. Beer's well done benefit. Science News Online (March 5). Available at http://www.sciencenews.org/articles/20050305/food.asp.

______. 2005. Carcinogens in the diet. Science News Online (Feb. 19). Available at http://www.sciencenews.org/articles/20050219/food.asp.

______. 2004. How carbs can make burgers safer. Science News Online (Dec. 4). Available at http://www.sciencenews.org/articles/20041204/food.asp.

______. 2004. Uranium, the newest 'hormone'. Science News 166(Nov. 13):318. Available to subscribers at http://www.sciencenews.org/articles/20041113/note14.asp.

______. 2001. Fire retardant catfish? Science News Online (Dec. 8). Available at http://www.sciencenews.org/articles/20011208/food.asp.

______. 1999. Well-done research. Science News 155(April 24):264-266. Available at http://www.sciencenews.org/pages/sn_arc99/4_24_99/bob1.htm.

______. 1998. Very hot grills may inflame cancer risks. Science News 154(Nov. 28):341. Available at http://www.sciencenews.org/pages/sn_arc98/11_28_98/fob3.htm.

______. 1996. Another meaty link to cancer. Science News 149(June 8):365. Available at http://www.sciencenews.org/pages/pdfs/
data/1996/149-23/14923-13.pdf.

______. 1996. 'Estrogen' pairings can increase potency. Science News 149(June 8):356. Available at http://www.sciencenews.org/pages/
pdfs/data/1996/149-23/14923-03.pdf.

______. 1995. Beyond estrogens: Why unmasking hormone-mimicking pollutants proves so challenging. Science News 148(July 15):44. Available at http://www.sciencenews.org/pages/
pdfs/data/1995/148-03/14803-15.pdf.

______. 1994. Meaty carcinogens: A risk to the cook? Science News 146(Aug. 13):103.

______. 1994. Not so hot hot dogs? Science News 145(April 23):264-269.

______. 1994. How cooked meat may inflame the heart. Science News 145(March 12):165.

______. 1994. The gender benders. Science News 145(Jan. 8):24. Available at http://www.sciencenews.org/pages/sn_edpik/ls_7.htm.

Smith-Roe, S.L., et al. 2006. Induction of aberrant crypt foci in DNA mismatch repair-deficient mice by the food-borne carcinogen 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP). Cancer Letters. 244(Nov. 28):79-85. Abstract available at http://dx.doi.org/10.1016/j.canlet.2005.12.002.

______. 2006. Mlh1-dependent responses to 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP), a food-borne carcinogen. (Abstract # 514). Toxicologist 90(March):105.

______. 2006. Mlh1-dependent suppression of specific mutations induced in vivo by the food-borne carcinogen 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP). Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 594(Feb. 22):101-112. Abstract available at http://dx.doi.org/10.1016/j.mrfmmm.2005.08.011.

Sources:

Janet E. Cade
UK Women's Cohort Study
Centre for Epidemiology and Biostatistics
30/32 Hyde Terrace
The University of Leeds
Leeds LS2 9LN
United Kingdom

Eunyoung Cho
Channing Laboratory
Department of Medicine
Harvard Medical School
181 Longwood Avenue
Boston, MA 02115

Nigel J. Gooderham
Biomolecular Medicine
Imperial College London
Sir Alexander Fleming Building
London SW7 2AZ
United Kingdom

Susan Elizabeth Steck
Department of Epidemiology and Biostatistics
Statewide Cancer Prevention and Control Program
Arnold School of Public Health
University of South Carolina
2221 Devine Street, Room 231
Columbia, SC 29208

Health-care professionals typically refer to an extremely heavy person as being morbidly obese. The term reinforces the idea that the individual is at high risk of diabetes, fatty-liver disease, and heart attacks. Researchers who have been working with mice now report that certain chronic diseases don't have to be consequences of obesity.

The team accomplished the disconnect by tricking the animals' bodies into storing all their excess fat within their fat cells, or adipocytes.

HEALTHY MICE. Despite its enormous girth, the genetically engineered mouse at left is no more at risk for insulin resistance or diabetes than the normally slim mouse at right. The reason: Each rodent stores any excess calories it ingests into normal fat cells—not muscle and liver.

That's not what the bodies of rodents—or people—typically do. Initially, excess lipids—fat—are stored in these cells, making up what's called adipose tissue or simply body fat. These deposits lie primarily in the breasts, belly, and thighs. However, once adipocytes fill up, new storage sites take up the overflow. Those new depots usually develop in muscle and the liver.

Of those two depots, the liver is more dangerous when it becomes fatty. Straightforwardly named, fatty liver disease can arise and lead eventually to hepatitis, cirrhosis, and death.

A drop in the hormone called adiponectin is the body's signal to store fat outside adipose tissue. Sometimes referred to as the starvation hormone, adiponectin normally remains high in lean animals. With obesity, however, blood concentrations of the molecule fall.

Philipp E. Scherer of the University of Texas Southwestern Medical Center and his colleagues reasoned that keeping adiponectin concentrations high might fool the body into making extra adipocytes instead of sending surplus fat to muscles and the liver.

The team has now investigated the hypothesis in a strain of mice that make copious adiponectin regardless of how fat they become. In the Sept. 4 Journal of Clinical Investigation, the researchers report that as the novel mice mature, they become unbelievably huge. Indeed, muses Scherer, these are "the fattest mice ever reported," with fat comprising 60 percent or more of their body weight.

As hoped for, the mice deposit all their excess fat in adipose tissue. Also in sharp contrast to other obese mice, the high-adiponectin animals develop no signs of diabetes. They also avoid a metabolic disorder known as syndrome X, which puts animals, including people, at high risk of heart disease (SN: 4/8/2000, p. 236).

So, although these barely mobile, blubbery mounds of flesh look like wrecks, they don't appear to be at high risk for several chronic diseases associated with obesity, Scherer told Science News Online. Actually, he says, from the preliminary data, the mice "appear perfectly healthy."

He suspects that there's a lesson in this for investigators of human-obesity treatments. Drugs exist that raise adiponectin values in even overweight individuals. Most, like pioglitazone (Actos) and rosiglitazone (Avandia), are prescribed to treat diabetes. However, data suggest these drugs also reduce the buildup of fat in the liver.

Unfortunately, diminishing health risks in morbidly obese people may require far more than just supersizing their treatment with the diabetes drugs—especially since data reported earlier this year linked rosiglitazone with an increased risk of heart attack (SN: 6/23/07, p. 397).

For more information, see this week's Food for Thought column.

References:

Kim, J.-Y. . . . and P.E. Scherer. 2007. Obesity-associated improvements in metabolic profile through expansion of adipose tissue. Journal of Clinical Investigation 117(Sept. 4):2621-2637. Available at http://www.jci.org/cgi/content/full/117/9/2621.

Krall, R.L. 2007. Cardiovascular safety of rosiglitazone. Lancet 369(June 16):1995-1996. Abstract available at http://dx.doi.org/10.1016/S0140-6736(07)60824-1.

Nissen, S.E., and K. Wolski. 2007. Effect of rosiglitazone on the risk of myocardial infarction and death from cardiovascular causes. New England Journal of Medicine 356(June 14):2457-2471. Available at http://content.nejm.org/cgi/content/full/356/24/2457.

Further Readings:

Dormandy, J.A., et al. 2005. Secondary prevention of macrovascular events in patients with type 2 diabetes in the PROactive Study (PROspective pioglitAzone Clinical Trial In macroVascular Events): A randomised controlled trial. Lancet 366(Oct. 8):1279-1289. Abstract available at http://dx.doi.org/10.1016/S0140-6736(05)67528-9.

Harder, B. 2007. Fixes for fatty liver. Science News 171(March 3):136-137. Available at http://www.sciencenews.org/articles/20070303/bob9.asp.

Pawlak, D.B., et al. 2001. High glycemic index starch promotes hypersecretion of insulin and higher body fat in rats without affecting insulin sensitivity. Journal of Nutrition 131(January):99-104. Available at http://jn.nutrition.org/cgi/content/full/131/1/99.

Psaty, B.M., and C.D. Furberg. 2007. Rosiglitazone and cardiovascular risk. New England Journal of Medicine 356(June 14):2522-2524. Available at http://content.nejm.org/cgi/content/full/356/24/2522.

Raloff, J. 2007. Fattening carbs—Some promote obesity and worse. Science News Online (Sept. 29). Available at http://www.sciencenews.org/articles/20070929/food.asp.

______. 2007. Infectious foie gras? Science News Online (June 30). Available at http://www.sciencenews.org/articles/20070630/food.asp.

______. 2007. Super-size mice—Fast food hurts rodents. Science News Online (June 9). Available at http://www.sciencenews.org/articles/20070609/food.asp.

______. 2004. Inflammatory fat. Science News 165(Feb. 28):139-140. Available at http://www.sciencenews.org/articles/20040228/bob9.asp.

______. 2000. The new GI tracts. Science News 157(April 8):236-238. Available at http://www.sciencenews.org/articles/20000408/bob9.asp.

Seppa, N. 2007. Diabetes drug might hike heart risk. Science News 171(June 23):397. Available at http://www.sciencenews.org/articles/20070623/note11.asp.

Sources:

Philipp E. Scherer
Touchstone Center for Diabetes Research
Department of Internal Medicine
University of Texas Southwestern Medical Center
5323 Harry Hines Boulevard
Dallas, TX 75390-9077

Nutritionists call them carbohydrates. To most of us, they're simply sugars and starches. And although the fructose in soft drinks and the refined flour in white bread taste quite different, "nutritionally and metabolically they're the same as table sugar," explains endocrinologist David S. Ludwig. That's because the body digests all carbohydrate-rich foods into glucose, or blood sugar.

FUEL FOR OBESITY. A new animal study finds that a diet rich in easy-to-digest starch, like the type in white bread, fosters the development of excess body fat. Eyewire

However, all carbs don't break down at the same rate. The body digests those in many whole-grain products quite slowly. Others become converted to glucose almost immediately.

Rapidly digested carbs aren't healthy for people with diabetes and others watching their blood sugar. A new study by Ludwig and his colleagues at Children's Hospital Boston suggests that such carbs are also problematic for people looking to shed body fat. Indeed, the findings indicate that consumption of the wrong carbs can spur the development of body fat, even with no gain in weight.

In the study, mice that chowed down on a type of rapidly digestible starch didn't gain any more weight than did animals eating a starch that digests slowly. But the first group did accumulate lots of excess fat. The data indicate that something about rapidly digesting carbs signaled the body to convert more of a meal's energy into body fat, into fatty lipids that circulate in blood, and into deposits of fat throughout the liver.

Ludwig considers the observed effect on the animals' livers the most troubling one. Fatty-liver disease has traditionally been regarded as the first stage of damage from alcoholism that can progress to hepatitis, cirrhosis, and death. But researchers in recent years have discerned the beginnings of an epidemic of fatty-liver disease unrelated to alcoholism but correlated strongly with being overweight. Recent data suggest that as much as one-third of children and even a higher proportion of adults have the condition. Ludwig told Science News Online that he suspects that "up to half of the [U.S.] population" now has fatty-liver disease.

The question has been what's fueling this epidemic. Because the disease so often accompanies obesity, many researchers have suspected that high-fat diets and junk foods are responsible. Ludwig's group had another idea.

In recent years, the mushrooming incidence of obesity in the United States has led to a push to get people to lower their intakes of fat. However, reducing fat consumption almost always translates into increasing the intake of carbs (see Counting Carbs). Moreover, the carbs most people reach for first are the refined—easy to digest—types found in white flour, white rice, pasta, and potatoes.

Ludwig's team decided to see whether a diet rich in a similar carb promotes fat buildup. They used a proportion of carbs that people on a low-fat diet might eat and compared its effects with that of a diet equal in all respects except that its carbs were mainly a slowly digested starch.

In the September Obesity, the researchers show that animals eating rapidly digested carbs accumulated more fat throughout their bodies—including their livers—than did animals eating primarily the slow-to-digest starch.

Says Ludwig, "This is the first study in which a single dietary factor—varied within normal ranges—affected whether the liver remained normal or accumulated seriously elevated levels of fat."

For more information, see this week's Food for Thought column.

References:

Jenkins, D.J.A., et al. 2007. Nonalcoholic fatty liver, nonalcoholic steatohepatitis, ectopic fat, and the glycemic index. American Journal of Clinical Nutrition 84(July):3-4. Available at http://www.ajcn.org/cgi/content/full/84/1/3.

Scribner, K.B., D.B. Pawlak, and D.S. Ludwig. 2007. Hepatic steatosis and increased adiposity in mice consuming rapidly vs. slowly absorbed carbohydrate. Obesity 15(September):2190-2199. Abstract available at http://www.obesityresearch.org/cgi/content/abstract/15/9/2190.

Valtueña, S., et al. 2006. Dietary glycemic index and liver steatosis. American Journal of Clinical Nutrition 84(July):136-142. Available at http://www.ajcn.org/cgi/content/abstract/84/1/136.

Further Readings:

Pawlak, D.B., et al. 2001. High glycemic index starch promotes hypersecretion of insulin and higher body fat in rats without affecting insulin sensitivity. Journal of Nutrition 131(January):99-104. Available at http://jn.nutrition.org/cgi/content/full/131/1/99.

Raloff, J. 2007. Super-size mice—Fast food hurts rodents. Science News Online (June 9). Available at http://www.sciencenews.org/articles/20070609/food.asp.

______. 2004. Counting carbs. Science News 166(July 17):40-42. Available at http://www.sciencenews.org/articles/20040717/bob8.asp.

______. 2004. Coming soon—Spud lite. Science News Online (June 19). Available at http://www.sciencenews.org/articles/20040619/food.asp.

______. 2000. The new GI tracts. Science News 157(April 8):236-238. Available at http://www.sciencenews.org/articles/20000408/bob9.asp.

Sloth, I., et al. 2004. No difference in body weight decrease between a low-glycemic-index and a high-glycemic-index diet but reduced LDL cholesterol after 10-wk ad libitum intake of the low-glycemic-index diet. American Journal of Clinical Nutrition 80(Aug. 1):337-347. Available at http://www.ajcn.org/cgi/content/full/80/2/337.

Sources:

David J.A. Jenkins
Clinical Nutrition and Risk Factor Modification Center
St. Michael's Hospital
61 Queen Street, East
Toronto, ON M5C 3E2
Canada

David S. Ludwig
Children's Hospital Boston
Department of Medicine
333 Longwood Avenue
Boston, MA 02115

Silvia Valtueña
Department of Internal Medicine and Biomedical Sciences
University of Parma
43100 Parma
Italy