Soy: Healthy choice?

To eat soy or not to eat soy? That's the question many people concerned about their health are asking, says Jennifer Reilly, senior nutritionist for the Cancer Project, a nonprofit organization in Northwest that encourages a healthy diet as a means of cancer prevention and survival.

The consensus lately has been that soy, like most other foods, is good eaten in moderation as part of a balanced, low-fat diet of whole grains, fruits and vegetables, Ms. Reilly says. It may help prevent cancer, fight heart disease and make bones stronger, she says.

"The bulk of the research shows that soy is beneficial, especially when consumed as a typical Asian diet," Ms. Reilly says.

With about 30 to 40 studies published on soy every month, it is possible to find a study to back almost every position on the food, Ms. Reilly says.

One recent study, "Meta-Analysis of Soy Intake and Breast Cancer Risk," looked at 18 epidemiologic studies on soy exposure and breast cancer risk, finding that soy consumption is helpful for preventing breast cancer, she says. The study was conducted at John Hopkins School of Medicine in Baltimore and published in April's Journal of the National Cancer Institute.

"The gray area is when women have had estrogen-receptor-positive breast cancer," Ms. Reilly says. "Since it's a gray area, we're not sure how much soy is safe for that person. Although a lot of researchers say it's probably still fine to have two to three servings a day, other researchers say since it's a gray area that you might as well do without it."

The study didn't address soy consumption among breast cancer survivors, the use of supplements and powders made of soy and the effects of soy consumption at different stages of life.

Another area of debate has been how soy affects thyroid function, Ms. Reilly says. It has been thought that goitrogens, natural chemicals in soy, interfere with iodine absorption in the thyroid.

"These foods only will cause problems when someone is not getting enough iodine in the diet," Ms. Reilly says. "Eating soy is part of a healthy, balanced diet, making sure you have enough iodine. Iodine is in seaweed, sea vegetables and iodized salt."

Soy should be included in a healthy diet, says Cynthia Clark, oncology nutrition specialist at Washington Cancer Institute at the Washington Hospital Center in Northwest.

Some health experts have argued that because soy has phytochemicals, including estrogenic isoflavones, the estrogen could disrupt a person's hormonal balance.

Although phytochemicals battle cancers by removing toxins and preventing cancer cells from multiplying, there has been concern that isoflavones could adversely affect fertility in men, pregnant women and breast cancer patients.

However, only those people who eat an excessive amount of soy -- several servings a day, every day -- should cut back, Ms. Clark says. Further, research on these topics is inconclusive, she adds.

"I don't think there is any reason to be scared and cut all soy out of your life," Ms. Clark says. "Soy in general provides protein, calcium, soluble and insoluble fiber to regulate bowel movements, and polyunsaturated fats."

Lactose intolerant people who cannot eat milk products or those people trying to lower their cholesterol might benefit from soy products, she says.

Where science is especially uncertain is whether soy supplements are beneficial or if they are at all risky, she says. There are various soy pills and powders. When soy is processed, the levels of isoflavones changes.

"If people wanted to take soy supplements, I would not encourage that," Ms. Clark says. "If they eat a well-balanced diet, they will get the nutrients that they need."

Although researchers don't have full answers about soy, they have enough answers to ease people's minds and figure out a healthy eating strategy, says Karen Collins, nutrition adviser to the American Institute for Cancer Research in Northwest.

Any benefit of soy may depend on what point in the life cycle the person consumes it, she says. For instance, if soy is consumed during adolescence, it might change the way breast tissue is developed, she says. It possibly could become more resistant to developing breast cancer.

"Consumers need to be careful when they hear broad generalizations," Ms. Collins says. "We need to look at when the soy was consumed. We need to avoid generalizing [that] soy is protective."

More investigation about the full benefits and drawbacks of soy should be done, says Julie Leopold, nutrition program manager at Inova HealthSource in Fairfax.

Until then, people shouldn't drink 10 glasses of soy milk a day, but they also shouldn't be paranoid if they eat soy occasionally.

"It's a good option if you're a vegetarian or lactose intolerant," Mrs. Leopold says. "For the general population, it's a good supplement to a regular diet, to have soy once a day, as a good source of non-cholesterol protein. It definitely has some proven heart benefits."