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Fall 2003 Vol. 3 No. 3

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İVictoria Kann Cut the Fat to Lose the Dioxins

We all know that cutting back on saturated fat could help prevent heart disease, obesity, and other chronic health problems, but who would think that an environmental pollutant is another good reason for Americans to trim the fat?

Produced by waste incineration, forest fires, and various industrial processes, dioxins and dioxin-like compounds are ubiquitous pollutants in the soil, water, and air. Animals take in dioxins during feeding, accumulating the toxic compounds in their fatty tissues where they persist for years. Consumption of these fats, in turn, is the principal route of exposure in humans.

Studies of accidental or industrial exposures to high levels of dioxins indicate that they can cause cancer and affect reproduction, development, and immunity. However, because information on the health effects of smaller amounts is so limited and tests to quantify dioxins in samples are so expensive -- costing as much as $1,000 per sample -- the scientific jury is still out on the extent to which low levels of dioxins trigger health problems and how small an amount still presents a risk. Moreover, changes in industrial processes have dramatically reduced overall dioxin levels in the environment, by as much as 76 percent over the past three decades.

Given the gaps in knowledge, the government should encourage people to minimize their consumption of animal fat to reduce their dioxin exposure while more information is gathered, says a new report from the Institute of Medicine.

"Because we don't know for certain what health effects may be associated with the levels of dioxins present in foods, we outlined simple, prudent steps that the government could take now to help Americans decrease their exposure without necessitating any radical lifestyle changes or new regulations," explained Robert Lawrence, associate dean of the Bloomberg School of Public Health, Johns Hopkins University, Baltimore, and chair of the committee that wrote the report. "We're essentially saying, follow the U.S. Dietary Guidelines."

Specifically, the federal agencies responsible for food safety should encourage Americans, particularly girls and women of childbearing age, to keep their consumption of saturated fat to no more than 10 percent of their daily calories, as recommended by the guidelines. The agencies should educate people about the importance of choosing lower-fat milk and other dairy products, selecting lean cuts of meat, and trimming fat from meats, among other strategies. In addition, making lower-fat milk more widely available in the National School Lunch Program and urging participants in various public food programs to choose low-fat products can also foster less animal-fat consumption.

The report's emphasis on young girls and women stems from the particular vulnerability of developing fetuses and breast-feeding infants to the effects of toxic compounds. Because dioxins are passed on through the placenta and the fat in breast milk, fetuses' and nursing infants' exposure to dioxin is a direct result of how much of the compounds have accumulated in their mothers' bodies over the years. The only practical way to reduce their exposure is to minimize their mothers' intake of dioxins well before pregnancy. Given the health and social benefits of breast-feeding, the committee opposed any strategies that would discourage its practice.

Fatty fish present unique challenges because it is difficult to trim away the fat. Moreover, omega-3 fatty acids in fish are beneficial for health. Therefore, the report seconded the U.S. Dietary Guidelines' recommendation that people eat two fish meals a week.

While regulatory limits on dioxins in foods should not be set until more complete data are available, the government and food producers should collaborate on voluntary actions to stem accumulation of the compounds in food animals. One route of animal exposure is the recycling of rendered animal fats and contaminated grasses into feeds. The government should make it a priority to work with food producers on ways to curtail this recycling and to develop voluntary guidelines for practices that would minimize animals' exposure.
  -- Christine Stencel

Dioxins and Dioxin-like Compounds in the Food Supply: Strategies to Decrease Exposure. Committee on the Implications of Dioxins in the Food Supply, Food and Nutrition Board, Institute of Medicine (2003, approx. 295 pp.; ISBN 0-309-08961-1; available from the National Academies Press, tel. 1-800-624-6242; $42.00 plus $4.50 shipping for single copies).

The committee was chaired by Robert S. Lawrence, associate dean for professional practice and programs, Bloomberg School of Public Health, Johns Hopkins University, Baltimore. The study was funded by the U.S. Department of Agriculture and Food and Drug Administration.

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Copyright 2003 by the National Academy of Sciences