Editor's Note: Kaayla Daniel is a certified clinical nutritionist with a Ph.D. in nutritional sciences and anti-aging therapies from the Union Institute and University of Cincinnati, Ohio. She is the author of The Whole Soy Story: The Dark Side of America's Favorite Health Food (New Trends, 2005).

What health problems do you see in your practice that can be traced back to overconsumption of soy?
I work mostly with midlife women, and they're likely to eat a lot of soy and drink a lot of soy milk. They're taking soy isoflavone supplements because they've heard that it's going to help them through menopause. A lot of these women are very intelligent and educated, and, unfortunately, they get this idea that if a little of something might be good, then they should do a lot of it. They start gaining weight, feeling fatigued; they get lethargic and depressed, and when they go to a regular doctor, they're told 'Well, what do you expect, you're getting old,' and that this is typical of menopause. In fact, the symptoms are almost entirely coming from that change in their diet, which had to do with soy.

How much soy does the average person consume in a day?
Someone on a junk-food diet is getting soy flour in the fast-food hamburger bun, soy protein in the burger itself, and soy oil in the fries; soy is in every one of these products because it's cheap and abundant. You'll find soy hidden in so many foods, and small quantities add up.

People often start by drinking a lot of soy milk. If they are taking supplements, they can be getting really high doses. Even scientists working for the soy industry will say they support soy food but do not support use of soy supplements. It is so dangerous at such a high level, and it's harming many people.

How does marketing affect soy consumption?
It's very much about marketing. If we look back, the soybean was used in this country for soy oil. They take apart the bean and take out the oil and turn it into margarines and shortenings and all those liquid vegetable oils. Once the oil is out, what they had left over was a whole lot of protein.

What's happened is that some of the things they tried to get rid of they're now marketing as things that can prevent cancer or prevent problems. They take something that's bad and turn it into something that's good. Every time they remove a component of soy, they have another thing they can sell.

In Kenya, the soy industry is talking to bakers, teaching them to use soy flour in baked goods, and down in Johannesburg they're working on using soy protein shake powders to help AIDS patients. When the tsunami hit [in 2004], the soy industry was right there giving people assistance and free soy products. Rather than helping people pick up the pieces and get their small farms back together, they're replacing local foods with something that's global.