A Meaty debate
Critics point to meat as the culprit responsible for elevating blood cholesterol, along with raising risks for heart disease, cancer and other conditions. Supporters cite the lack of compelling science to justify such allegations; they emphasize the nutritional benefits of meat protein, vitamins and minerals. Indeed, studies in developing countries demonstrate health improvements when growing children are fed even small amounts of meat.
But because bacteria in a cow's rumen attach hydrogen atoms to unsaturated fatty acids, beef fat is highly saturated -- the kind of fat that increases the risk of coronary heart disease. All fats and oils contain some saturated fatty acids, but animal fats, especially those from beef, have more saturated fatty acids than vegetable fats. Nutritionists recommend eating no more than a heaping tablespoon (20 grams) of saturated fatty acids a day. Beef eaters easily meet or exceed this limit. The smallest McDonald's cheeseburger contains 6 grams of saturated fatty acids, but a Hardee's Monster Thickburger has 45 grams.
Why meat might boost cancer risks, however, is a matter of speculation. Scientists began to link meat to cancer in the 1970s, but even after decades of subsequent research they remain unsure if the relevant factor might be fat, saturated fat, protein, carcinogens or something else related to meat. By the late 1990s experts could conclude only that eating beef probably increases the risk of colon and rectal cancers and possibly enhances the odds of acquiring breast, prostate and perhaps other cancers. Faced with this uncertainty, the American Cancer Society suggests selecting leaner cuts, smaller portions and alternatives such as chicken, fish or beans -- steps consistent with today's basic advice about what to eat.
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Marion Nestle is Paulette Goddard Professor in the department of nutrition, food studies and public health and professor of sociology at New York University. She received a Ph.D. in molecular biology and an M.P.H. in public health nutrition from the University of California, Berkeley. Nestle's research focuses on scientific and social factors that influence food choices and recommendations. She is author of Food Politics (2002, revised 2007), Safe Food (2003) and What to Eat (2006). She also writes a popular nutrition blog, Food Politics.
Reprinted with permission. Copyright © 2007 by Scientific American, a division of Nature America, Inc. All rights reserved. For more information about the issue, go to: