Understanding Soy Foods: Questions Raised About Soy Products

Recently, some questions have been raised about the possible health risks of soy consumption. A prospective study found that Alzheimer's disease rates were slightly higher in individuals in Hawaii who had consumed significant amounts of tofu throughout their lives. This finding is contradicted by studies showing that in Asia, where soy intake is high, the population does not have a high rate of Alzheimer's disease.

Although the Alzheimer’s study was a well–conducted study, there may be an unaccounted–for factor that explains the results. It may be the tofu being consumed was processed with aluminum, while in the rest of the United States it is processed with calcium. Aluminum has been linked to Alzheimer's disease.

Researchers believe that certain chemicals in soybeans called isoflavones are responsible for the reduced risk for breast cancer among Asian women. Isoflavones are phytoestrogens (phyto means "plant"). They keep estrogen levels under control, as they can act like a weak estrogen when body estrogen levels are low and can inhibit estrogen's effects when body estrogen levels are high.

The question of whether soy consumption may contribute to an increased breast cancer risk due to estrogenic effects has been raised. However, there is evidence that consuming soy at a young age reduces cancer risk later in life. Other studies have found no effect or a favorable effect on breast tissue density in women consuming soy. For women who have had breast cancer, however, it may be prudent to restrict soy until further research reveals otherwise.

Some have raised the question as to whether soy can affect thyroid function. However, the results of human studies on the effects of soy consumption on thyroid function have been mixed. More research is needed on this topic before we can draw any conclusions.

Other problems that can arise from soy foods consumption:

• Many people think that by adding soy to a diet that contains meat, fish, chicken, eggs, and dairy products, they can somehow make the diet healthful. However, a good diet is one that is high in fiber, low in fat, and contains no cholesterol. That makes a plant–based diet the best choice.
• People who adopt a plant–based eating style may get stuck on soy products, such as veggie meats, and miss out on low–sodium, high–fiber beans, grains, fruit, and vegetables. The more we mimic a meat and dairy diet, the further away we get from healthier foods.
• Some soy products can be high in fat. This can be problematic for someone trying to lose weight or maintain a weight loss.