Soy milk, soy nuts, soy cheese, soy spaghetti, soy hot dogs, soy chicken.... Soy as far as the eye can see. You can even get soy in powdered drinks and in pills. Oh, and don't forget tofu.

Why the soy surge? It's good for you.

I encourage my patients to get soy in their diets, like soy milk and tofu, says JoAnn E. Manson, M.D., a principal investigator for the Women's Health Initiative, a professor of medicine at Harvard Medical School and chief of the Division of Preventive Medicine at Brigham and Women's Hospital.

More than 40 studies conclude soy can help lower cholesterol, she notes. And it might help with some symptoms of menopause such as hot flashes because it acts like a mild estrogen in the body.

But should you pop a pill or sip soymilk? And how much do you need?

I have safety concerns about taking large amounts in supplements. But I have no safety concerns about drinking soy milk, eating soy nuts and tofu in moderation, Manson says, saying people can overdo it if they drink five to 10 glasses of soy milk a day.

The problem is the concentration of the soy isoflavones, which are plant compounds acting like a weak estrogen in the body. No one knows what the long-term effects of extremely high, concentrated doses are. A single glass of soy milk with about 6 grams of soy protein can have 30 milligrams to 40 milligrams of isoflavones, which is ideal. However, those supplements that you can buy in a bottle are not regulated by the U.S. Food and Drug Administration, and can contain as much as 100 milligrams or more in each pill.

We don't know what that level of exposure to your body would do. We don't recommend it as a supplement, says Cynthia Sass, M.A., R.D., a dietitian at BayCare Health System in Tampa, Fla. and a spokeswoman for the American Dietetic Association.

Getting soy in foods throughout the day as your body burns and stores energy is the safest course.

The soy dogs are good substitutes for the high-animal fat franks, so both the soy milk and hot dogs have a place in a healthy eating pattern, says Gail Frank, Ph.D., R.D., C.H.E.S, an American Dietetic Association (ADA) spokeswoman, and a professor of nutrition and director of the dietetic internship program at California State University in Long Beach.

Be careful with the powdered drinks and bars as well.

If you take in a concentrated soy protein product, you will probably be getting much, much more soy protein in that concentrated product than you would in a 'whole' soy food such as soy beans, soy milk or tofu, Sass says.

However, Thomas B. Clarkson, D.V.M., professor of comparative medicine at the Comparative Medicine Clinical Research Center at Wake Forest University School of Medicine in Winston-Salem, N.C. and spokesman for the North American Menopause Society, says not all soy bars are bad. They might be a good way to help someone who may not like soy reach the 25 grams a day. Be sure to check the label, he says.

Some soy foods may not have much of the soy protein needed to help meet the recommended amount of 25 grams a day, Clarkson says. That's because of the way the beans are processed. To help minimize the strong taste of soybeans, manufacturers might wash them in alcohol, which could reduce the healthful benefits, he says.

Soybeans taste a little bitter. If the hotdog tastes good, there's a good chance you aren't getting a whole lot of soy, he says.

And there's another problem: Eating too much from any protein source - animal or plant - can cause a nutrient imbalance, kidney strain, dehydration and add too much body weight.

Frank says, The good news is that substituting soy protein for the over-abundant animal protein many women ingest provides a triple benefit -- heart health (less saturated fat), weight management (fewer calories) and health promoting (isoflavones).

We may soon have more answers. A national study is looking at the benefits of over-the-counter soy supplements in the prevention of osteoporosis in postmenopausal women.

A study called OPUS (Osteoporosis Prevention Using Soy) looks at the benefits, safety and correct dosages of soy isoflavone supplements. The project, headed by the Children's Nutrition Research Center in Texas Medical Center in Houston, expects to enroll 400 women at three sites across the country and follow them for two years.

Your best bet? Food first.

We knew that beta-carotene was good for you. But then, studies came out saying that as a supplement, it was risky, Sass says. Until we know how these nutrients work, we need to be cautious. We know that all nutrients are powerful chemicals. We need more time.