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Ode to Soy: The Health Benefits Fueled by research touting soy's health benefits, soy sales have nearly tripled, from $1.2 billion in 1996 to $3.3 billion today, according to the United Soybean Board. In a recent USB survey, 27 percent of Americans reported eating soy at least once a week, while 42 percent said they ate soy once a month. Whether in the form of cereal, burgers, milk, green pods or nuts, there's a soy product for virtually every slot on the food pyramid. Soy has become the yogurt of the 2000s, says Mark Messina, senior editor of Loma Linda University's Vegetarian Nutrition and Health Letter and former program director of the National Cancer Institute's diet and cancer branch. "In the early '70s, yogurt was healthy food that you only ate if you wanted to live to be 110,'' Messina said. "Yogurt moved into the mainstream. The buzz about health effects has created a similar window of opportunity for soy.'' A staple in Asian countries, soy is a complete protein containing all of the amino acid building blocks. Soy also provides an anti-oxidant boost from plant chemicals called isoflavones. Forty percent of soy calories are fat calories. But as a plant food, soy is low in saturated fat - the bad kind of fat. Soy is credited with a wide range of health benefits. Some are speculative, based in part on the lower incidences of cancer and other diseases in countries with high soy consumption, such as Japan. Messina gave an overview of where the research stands. HEALTH CLAIM: Lowers cholesterol and the risk of heart disease. REALITY: Studies have shown soy has an effect on cholesterol levels. People with high cholesterol levels saw a 10 to 12 percent decrease. Data also suggest that isoflavones may improve other factors that contribute to coronary heart disease, such as flexibility of the arteries. The Food and Drug Administration recommends eating 25 grams (about four servings) per day to achieve cholesterol reduction benefits. HEALTH CLAIM: Reduces calcium loss. REALITY: Soy protein decreases the amount of calcium excreted from the skeletal system. Lack of calcium can lead to osteoporosis, a condition that results in weakened and brittle bones. HEALTH CLAIM: Prevents breast cancer. REALITY: Although studies are promising, there's no conclusive evidence as of yet that eating soy as an adult will reduce the risk of breast cancer, though research suggests preventive benefits if eaten regularly in childhood and teen-age years. However, eating soy as an alternative to hormone replacement therapy (HRT) will nullify the risks of breast cancer attributed to using HRT. HEALTH CLAIM: Eliminates hot flashes in menopausal women. REALITY: Soy may provide modest improvements. In some studies, women taking placebos had similar improvements. HEALTH CLAIM: Prevents prostate cancer. REALITY: Early studies show promise that eating soy can reduce the odds of getting prostate cancer. Some scientists have raised concerns that soy could have an adverse effect on the body's hormones and increase the risk of cancer because isoflavones act as a weak form of estrogen. In approving health claims for soy on food labels, the FDA differentiated between soy protein, where the benefits are backed by dozens of clinical trials, and soy isoflavones, where debate continues. The FDA extended the health claim to soy foods, but did not include dietary supplements that isolate isoflavones. Dr. Michael Hirt, director of the Center for Integrative Medicine at Encino-Tarzana Regional Medical Center, advises his patients against taking isoflavone tablets, saying more research needs to be done. He does advocate a diet with moderate amounts of soy foods. "There have been some studies giving animals high unnatural doses of soy, things you can't imagine a human coming close to consuming,'' Hirt said. "There are no studies showing normal human consumption of two to four servings a day would have any detrimental effect.'' Experts say those in good health should strive for 15 grams, or two servings per day, to receive the nutritional benefits of soy. When shopping for soy products check the labels for soy protein. Condiments like soy sauce don't contain the powerful punch of soy protein products. The easiest way to add soy to your daily diet is at breakfast, by choosing soy milk and soy-based cereal. For mainstream tastes, Messina also likes the freshness and convenience of edamame, the green vegetable soy pods. At Japanese restaurants, they're served boiled and salted. But they also make a tasty addition to stir-fries, rice dishes and pasta dishes. Edamame, shelled and unshelled, can be found in the freezer section of most supermarkets. National Institute of Health Key Recommendations from the Expert Panel on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults Professional Education Materials Patient and Public Education Materials National Heart, Lung and Blood Institute National Institutes of Health Date Published: 2002-07-23 |