This is an excerpt from the page on Dr. McDougall's website he mentioned in the video – the link to the whole article is below.
Soy-food consuming populations of people, like the Chinese and Japanese, have a much lower incidence of heart disease, osteoporosis, and cancer of the breast and prostate. From this observation, many researchers have come to the conclusion that ingredients in the soybean have anticancer, antihypertensive, and anti-cholesterol benefits, and also act as a natural alternative to hormone replacement therapy. Soy foods have become synonymous with health food and vegetarianism. Their popularity is tied to the belief that soy has “wonder-drug” benefits – so powerful that many people suppose they can safely eat their bacon and eggs for breakfast as long as they finish off their morning meal with a cup of soy yogurt.
We recommend that you use traditional soy foods, like soy milk and tofu, only as a small part of your diet, at most 5% of your daily calories. “Synthetic soy foods,” like meats, cheeses, and soy bars, should rarely, if ever, be consumed.
Examples of sensible uses might be:
- Soy milk to moisten cereal, not glassfuls as a beverage.
- Tofu pieces in a “stir-fry” rice dish, not as a soy burger entrée
- An occasional tofu-based dessert, not daily soy “candy” bars.
However, there is a dark side to the soy story that warns that these foods may increase your risk for cancer, impair your thyroid, immune, and brain function, and cause you bone loss and reproductive problems. Fortunately, these worries are relevant mostly for people lured into consuming “fake foods” synthesized from man-made components of soy and other foods, and high potency soy supplements – not for those who consume traditional soy foods as a small portion of their diet.
By Dr. John McDougall
His complete article: