Soy, doctors say, can help prevent cancer and heart disease, and even lower blood cholesterol
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Step aside, beta carotene. Take a back seat, complex carbos. The hottest new nutrients are “isoflavones,” natural compounds credited with preventing everything from heart disease and cancer to osteoporosis and hot flashes. The principle source of isoflavones? Foods made with soybeans, such as soy milk, soy burgers and tofu.
Vegetarians have known for decades that soy protein is a healthy—and inexpensive—alternative to meat. It has none of meat’s cholesterol and is low in fat. But only in recent years have researchers begun to uncover the bean’s seemingly miraculous qualities.
Soy made headlines nationwide last August when The New England Journal of Medicine reported that replacing animal protein with soy protein could prevent heart disease. Dr. James Anderson and his colleagues at the Veterans Affairs Medical Center in Lexington, Kentucky found that people who switched to soy lowered their blood cholesterol levels up to 20 percent. Patients with the highest levels experienced the greatest declines. Unlike cholesterol-lowering medications and even the highly-touted oat bran, soy foods affected only low-density lipoprotein, better known as bad cholesterol. Levels of beneficial high-density lipoprotein remained the same and sometimes increased.
How It Works
Soy’s healing touch comes from isoflavones, which are a type of plant estrogen. Plant estrogens behave much like the human form of the hormone, slipping into our estrogen receptors like a key in a lock. They’re found in many food plants, including rye, wheat, apples, carrots and corn. But none are as rich in isoflavones as soy.
Many researchers believe a diet high in isoflavones may prevent breast cancer. Japanese women consume a lot of soy and have a breast cancer rate that’s one fourth that of women in the United States. Victims of breast cancer, on the other hand, typically have low soy concentrations in their urine.
“Evidence is now clear that people who use soy foods do seem to have a lower cancer risk,” says William Shurtleff, founder and director of the California-based Soyfoods Center. Soy’s estrogens also may ward off hot flashes, night sweats and the other scourges of menopause, when women’s estrogen levels take a nose dive.
“A third as many Asian women report menopausal symptoms as American women,” says Mark Messina, a nutrition consultant and author of the book The Simple Soybean and Your Health. Hot flashes are so rare among the Japanese that they have no words to describe them.
“I think we need more data,” Messina says, “but we could get to the point where soy could be viewed as a natural alternative to hormone-replacement therapy.” As if that wasn’t enough to convince every American to pass up a Big Mac for a soy burger, scientists believe soy’s isoflavones also may help prevent osteoporosis, kidney disease and complications from diabetes.
“In animal studies, you can show that soy products may have a slight benefit to the skeletal system,” says John Anderson, a professor of nutrition at the University of North Carolina at Chapel Hill. Anderson points out that tofu and soy milk are rich in calcium, which is critical to preventing the crippling effects of osteoporosis. Research, he adds, suggests that animal protein may actually remove calcium from the body. Vegetarians, then, would store calcium more efficiently than their meat-eating peers.
The Daily Dose
So how can the average American get his RDA of isoflavones? Fortunately, it’s pretty easy. Soy foods that were rarely found outside health-food stores and Oriental markets just five years ago now appear regularly on supermarket shelves. And if the thought of eating soybean curd makes your stomach churn, don’t despair. There are enough soy foods to please even the most particular palate. Between 1980 and 1990 alone, more than 2,000 new soy products were introduced, from meatless hot dogs, sausage and bacon to sweets and dairy alternatives.
One of the easiest ways to add soy to your diet is with soy milk. This sweet, milk-like liquid is made from ground soybeans and water. Soy milk can stand in for cow’s milk in recipes, cereal or in a tall, cool glass. “I like soy milk for cereal,” says Messina. “You can use soy milk in all the ways you now use dairy milk.”
Perhaps the best known soy food is tofu, that cheesy-looking white block that’s long been a favorite of vegetarians. Tofu is curd made from coagulated soy milk. It works well in many dishes, including stir-fries, casseroles, mock egg salad, even “cheesecake.” Textured vegetable protein (TVP), is made from compressed soy flour. These tiny nuggets have a texture similar to ground beef and can replace meat in spaghetti sauce, sloppy Joe’s and chili. “Tofu takes on the taste of whatever you cook with it, so it lends itself to a lot of different recipes,” Messina says.
People looking for a little insurance against cancer, heart disease or the effects of menopause could replace one daily serving of animal protein with soy. Those seeking to lower their cholesterol levels might want to consider three daily soy servings. But don’t think of soy as a magic bullet. A pound of tofu will be hard pressed to lower your cholesterol if it’s topped off with a pint of Chunky Monkey. And yes, we still need to get enough beta-carotene and complex carbohydrates, even if they’re no longer the nutrients du jour.
But be sure to cut down on meat, dieticians warn, or risk an overload of protein. “The average American already consumes more protein than he needs,” says dietician Belinda Smith of the Veterans’ Administration Medical Center in Lexington, Kentucky. In spite of their cholesterol-lowering isoflavones, however, some soy products are high in fat. The fat is polyunsaturated, a safer bet than the saturated form found in meat and dairy products. Still, fat is fat, and anyone on a restrictive diet should avoid it.
Fortunately, dieters can have their tofu and eat it, too. “Choose the low-fat varieties,” Smith advises. Light tofu has only three grams of fat, half the amount found in regular tofu. Soy milk also is available in low-fat variations. Smith urges soy converts to incorporate the protein into their diets gradually. After all, soy products are made from beans, and have all the bean’s sometimes embarrassing side effects.
“Soy isn’t a panacea,” Messina said. “It’s not a miracle food, but it does warrant a bigger role in the American diet.”