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Alternative Medicine—Good Food—Soy Story: The Sequel

By Dorothy Foltz-Gray

For a while, soy stumped me. My tofu turned mushy in stir-fries, and packaged tempeh looked too strange to eat. And why would I want a soy dog when I could have a nice fat knockwurst? But whenever soy diehards presented me with their favorite incarnations, I loved them—the nutty bite of lightly fried tempeh slices, the creamy sweetness of soy milk, the salty crunch of edamame. And the more soy foods I tried, the more natural they seemed in my kitchen. I even learned how to stir-fry without ending up with tofu mush.

The same revelations are sizzling in an increasing number of American kitchens. How do I know? One tip-off is the hefty display of soy products in my supermarket. Another is the result of a 2001 study by the United Soybean Board: Twenty-seven percent of Americans use soy products once a week or more, up from 15 percent in 1998. The upswing comes as Americans search for ways to eat fewer fatty meats and dairy products and learn the good news about soy’s health benefits. In 1999, for example, the Food and Drug Administration gave the nod to soy, allowing soy food packagers to claim that 25 grams of soy protein, or two servings a day (the amount found in 1 cup fresh soybeans, 1¼3 cup soy nuts, 31¼2 cups soymilk, or two soy burgers or soy dogs) lower cholesterol and reduce the risk of heart disease. It’s also been credited with easing menopausal hot flashes, strengthening bones, and lowering the risk of prostate cancer.

Yet just as we’re tempted to make a permanent place on our dinner table for soy, some not-so-good news trickles in: A few studies are finding that eating soy may, in fact, be a problem if you’re at high risk for breast cancer. And in spite of its reputation as a health food, many alternative practitioners think soy should be knocked off its pedestal, claiming that along with possibly raising breast cancer risk, it interferes with thyroid function, offers only minimal relief from hot flashes, falls short on a key essential nutrient, and leaves many diners feeling gassy and bloated.

Ironically, the very source of soy’s health-promoting qualities is also what makes it problematic for women worried about breast cancer. Soy foods are high in isoflavones, a group of phytoestrogens, or plant-derived estrogens, that resemble the estrogen in our bodies, but exert a much weaker effect. Because about one- to two-thirds of all breast cancers require the presence of estrogen to grow, the theory is that women who are at risk for breast cancer place themselves in greater danger by eating estrogen-like substances.

This may be a particular worry for postmenopausal women, says Walter Willett, professor of medicine at Harvard Medical School. We don’t know why, he says, but when your own estrogen levels decline, phytoestrogens seem more likely to stimulate the growth of breast cancer.

Cynthia Watson, a family physician and member of the clinical faculty at the University of California at Los Angeles, cautions women at high risk for breast cancer, particularly those with a personal or family history, to eat only one serving of soy a day. “The effect is much weaker than natural estrogen,” she says, “but you’re still adding more to the soup.”

But what if you’re a woman who’s not at high risk but just worried about the disease? Is eating soy still a potential problem?

“The studies are equivocal,” says soy expert Mark Messina, adjunct associate professor of nutrition at Loma Linda University in Loma Linda, California. “There is a sound theoretical basis for speculating that the estrogen-like effects of isoflavones might stimulate formation of estrogen-sensitive breast tumors.” But Messina cites two recent year-long studies that indicate isoflav-ones do not increase the risk of developing breast cancer. “Based on the data,” he says, “I think the concern is unwarranted.”

Another reason for reassurance is that women’s bodies have two types of estrogen receptors, alpha and beta. Researchers at the Complementary and Alternative Medicine Program at the University of California, San Francisco suspect that while human estrogen works through the alpha receptor, signaling breast cancer cells to multiply, soy’s estrogen, a phytoestrogen, acts through the beta receptor, which prevents breast cell proliferation.

And not everyone shares the concern of some alternative practitioners that phytoestrogens mess with the thyroid gland. It’s true that soy may affect thyroid function and interfere with the absorption of thyroid medications—but only if you eat an awful lot of it. Besides, says Messina, “the clinical trials show that soy does not adversely affect thyroid function in healthy people who consume sufficient iodine.” (Most Americans get plenty.)

Soy has also gotten a bad rap for being low in one essential amino acid, methionine. This major source of sulfur helps maintain skin, hair, and nails, and prevents fat from building up in the liver. But it’s easy enough to get it elsewhere in your diet; one food doesn’t have to provide every nutrient. “Cow’s milk is not a good source of iron,” Messina points out, “but it’s still viewed as highly nutritious.”

As for the gassiness some people experience? There’s a simple fix: Don’t eat so much. Says Cynthia Watson, “I caution patients to eat no more than one serving of soy food a day since it’s hard to digest.”

So where does that leave us when it comes to enjoying soy? Those at high risk of breast cancer might want to avoid it, or eat it only occasionally. But for the rest of us, it remains a good protein source, particularly if it helps us cut back on high-fat meat and dairy products.

Messina and Cyril W. C. Kendall, a research scientist who studies the effects of soy on blood fats at the University of Toronto, are more concerned that Americans eat too little soy food than too much. “The Japanese are eating far more soy than North Americans are, and they have far lower rates of heart disease and certain types of cancer, including breast cancer,” says Kendall. “I’m not saying that’s just due to soy. But soy has been in their diet for thousands of years.”

Another fan of soy is Mary Tagliaferri, a breast cancer survivor, founder of the UCSF program, and author of Breast Cancer: Beyond Convention. “It irks me when people look at soy in a tunnel, asking only ‘Am I going to get breast cancer,’ ” says Tagliaferri. “You have to look at the aggregate benefits.”

Still, it’s probably wise to go easy on the tofu and tempeh. “Soy can be a good alternative to meat; just don’t overdo it,” says Willett, who wrote Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating. Until further research is done to establish the role of phytoestrogens in health, he advises aiming for a few servings of soy food each week, rather than a few each day.

For my part, I’m continuing to stalk the soy food shelves and indulge my hankering for scrambled tofu, fresh edamame, or a pot of soybeans simmered with ham hocks. Certainly I’m glad to know that these dishes do my heart and skeleton good, and when eaten in moderation probably won’t boost my risk of breast cancer. But when I’m savoring this still-exotic treat, I’m not thinking medicine. I’m thinking seconds.

Chinese Un-Chicken Salad
This salad gives you crunch, spicy heat, and nutrition in every forkful, and looks beautiful, too. It’s adapted from Amazing Soy by Dana Jacobi (William Morrow/HarperCollins, 2001).

Marinade
3 tablespoons rice vinegar
1 tablespoon soy sauce
1 tablespoon sugar
1¼2 teaspoon ground ginger
2 tablespoons peanut oil

7 ounces chicken-like soy meat cut in
1¼4-inch slices
1¼2 large peeled cucumber cut in 1¼2-inch crescents
4 cups cabbage cut in 1¼2-inch ribbons
2 ounces snow peas cut lengthwise in thin strips
1 11-ounce can mandarin oranges, drained
1¼4 cup chopped pecans
marinade (recipe above)

Combine the marinade ingredients in a saucepan and bring to a boil. Cover and remove from heat. Stir in the soy meat and set aside. Arrange the cucumber on top of the cabbage in a salad bowl.

Plunge the snow peas in boiling water for 30 seconds. Drain; put in a bowl of ice water. Drain and arrange in a ring on top of the other vegetables.

Heap the soy meat and marinade in the center of the salad bowl. Top with orange sections and pecans. Toss.

Spinach with Tofu
Garlic, chiles, and spinach make an irresistible combination, especially when you add a bite of sautéed tofu. Adapted from Pleasures of the Vietnamese Table by Mai Pham (HarperCollins, 2001).

6 ounces pan-seared tofu cut into 1-inch cubes
1 pound spinach (or any leafy green)
2 tablespoons vegetable oil
1 tablespoon chopped garlic
1 teaspoon chopped chiles
2 teaspoons soy sauce
Salt to taste

Cut a block of tofu into manageable slabs and fry in 2 to 3 tablespoons of vegetable oil over moderate heat, 5 minutes on each side.

For the spinach:
Cut stems and leaves in 3-inch pieces. Heat the oil in a skillet. Add the garlic, chiles, and soy sauce and stir until fragrant, about 30 seconds. Add the spinach and salt, and cook until tender, about 2 to 3 minutes. If the pan gets too dry, add 4 tablespoons of water. Add the tofu, toss, and serve.

In the Kitchen
Part of my initial reluctance about soy foods stemmed from ignorance: What to try and how? Below, experts untangle some of those mysteries.

Match the soy food to the recipe. When you’re adding soy milk to soup, use the unsweetened version. If you’re making a tofu cheesecake, use silken, not extra firm.

Segregate. If you throw the tofu in with the vegetables you’re apt to wind up with soggy curds, says Miriam Kasin Hospodar, author of Heaven’s Banquet: Vegetarian Cooking for Lifelong Health the Ayurveda Way. “The trick is to sauté tofu separately, browning it with a little soy sauce.” Then sprinkle it over your stir-fry.

Experiment. “Brands of all sorts of soy foods differ enormously in texture, flavor, color, and sweetness. If you don’t like one, try another,” says Dana Jacobi, author of Amazing Soy.

Drain before cooking. Jacobi suggests placing tofu between two paper towels, then placing a cutting board on top to squeeze out excess water. Or just use the extra-firm type.

Soy in a Pill
Is the soy in supplements as good as what you get in food? The answer depends, in part, on who you are.

Research suggests that isoflavones in supplements can deliver most of soy’s health benefits, says Mark Messina, a professor of nutrition at Loma Linda University in California. In recent studies, soy pills enhanced arterial flexibility, eased hot flashes, and increased bone density in postmenopausal women.

But some women may want to be careful. One thing we know for certain about soy food, says Walter Willett, a professor of medicine at Harvard Medical School, is that phytoestrogens are potent biological agents. Since it’s not clear whether they trigger, suppress, or have no effect on breast cancer, it’s probably best to avoid taking them in the form of concentrated soy supplements.

There’s another rationale for bypassing pills. “I strongly prefer soy food to supplements,” adds Willett, “in part because some of soy’s benefits come from the fact that you’re replacing meat in the diet.”

Numbers Game
Tofu may be soy’s best-known spin-off, but it has plenty of competition. Fermented soy, for instance, may offer an advantage when it comes to heart disease. We list a few other forms below along with their nutritional billing. The FDA recommends eating 25 g of soy protein, or 50 mg of isoflavones a day, to cut your risk of heart disease. In terms of general health, the isoflavones are the numbers to watch.

Soybeans (per half-cup): 70 mg isoflavones; 14.3 g protein; 1.1 g saturated fat; 149 calories.

Tempeh (fermented soy) (per half-cup): 60 mg isoflavones; 15.7 g protein; 0.8 g saturated fat; 165 calories.

Soy nuts (per quarter-cup): 60 mg isoflavones;15 g protein;
1.6 g saturated fat; 202 calories.

Tofu (per half-cup): 38 mg isoflavones; 10 g protein; 0.9 g saturated fat; 94 calories.

Soy milk (per half-cup): 10 mg isoflavones; 6.6 g protein; 0.5 g saturated fat; 79 calories