How Good Is Soy?
A little does a lot.
Soy's Not All Bad
But if some studies point to dangers from soy, others suggest important
benefits. For instance, isoflavones may prevent the growth of
estrogen-dependent breast cancer cells, according to findings published in the
March 2000 issue of the journal Cancer Research. That's because
isoflavones appear to encourage the body to break down estrogen more quickly --
before it can stimulate cancer cells to grow. Instead of lingering in the
blood, bits and pieces of estrogen molecules wind up in the urine.
Isoflavones can also slow prostate cancer cells from growing, according to a
study published in the June 2000 issue of the International Journal of
Oncology. Other studies hint that eating soy may help prevent heart
disease, endometriosis, and even osteoporosis in women, Gillespie says.
However, if you think you may have any of these conditions, see your doctor
before making any substantive changes to your diet.
Soy's biggest impact is on cholesterol levels, according to a mound of
studies. One published in the December 1998 issue of the American Journal of
Clinical Nutrition found that men who ate a low-fat diet and relied on soy
as their main protein source for five weeks saw their "bad" (LDL)
cholesterol levels decrease by as much as 14% and their "good" (HDL)
levels increase by as much as 8%. Men who ate a low-fat diet but instead relied
on meat as protein also saw their cholesterol levels significantly improve,
though not as much as the soy-eaters.
And eating soy helps to replace animal products, which are loaded with
saturated fats and cholesterol, says nutritionist Mark Messina, PhD, author of
The Simple Soybean and Your Health.
In the Kitchen
So what's the verdict on soy? Health experts say that although there's no
need to give up your favorite frosty shake made with soft tofu, frozen
strawberries, and a dab of honey, you may not want to eat soy for breakfast,
lunch, and dinner. Yet there's nothing wrong with incorporating soy into a
healthy diet of fruits, vegetables, and whole grains.
Messina, for instance, recommends a daily serving of soy: perhaps 1 cup of
soy milk or 3 to 4 ounces of tofu. "If 20 years from now researchers don't
find any benefits to soy, then you've lost nothing," Messina says. "If
they do find some benefits, then you've got a great trade-off."
As for my grandma, she successfully fought off breast cancer at the age of
80, and she couldn't be healthier now at 93. She still memorizes Bible passages
and spends afternoons sweating to the beat of an exercise video. Researchers
can't tell her what role, if any, soy has played in her life and health. It
doesn't, however, seem to have done her any harm.