Soy beans turn up in a lot of processed foods, and also in soy-based foods and drinks like edamame, tofu, and soy milk. Soy is also found in soy sauce, miso, and other flavorings. It’s considered a low-fat, low cholesterol alternatives to animal foods. But is soy good for you?
Soybeans provide protein and a range of vitamins and minerals, with the benefits of plant foods and without the drawbacks of meat. At the same time, you may have seen claims that soy mimics estrogen and can cause problems because of that.
Good things about soy
There are a lot of good things about soy:
- It’s high in protein, and contains complete protein, which is less common in plant proteins.
- It’s low in fat, and the fat it contains is healthy fat.
- It’s high in fiber.
- It’s vegan and lactose-free, for people with special nutritional needs.
- It contains no cholesterol, and some studies show that it can reduce bad cholesterol.
- It’s high in potassium and iron, two important minerals.
- Soy contains isoflavones, which may improve bone strength in post-menopausal women.
Not so good things about soy
Harvard School of Public Health published a review of research on soy which concluded that research on soy’s effects is inconclusive. Some studies have found that eating soy, especially fermented soy foods, reduces cognitive impairment from Alzheimer’s disease. Other studies don’t show this kind of benefit.
This is true for breast cancer, prostate cancer, and thyroid function as well.
There is not much evidence that soy increases chances of these conditions, but some people worry about the possibilities. Some of the specific concerns about soy include the possibility that the isoflavones might mimic estrogen in the body, which could either increase the chance of breast cancer or of enlarged breast tissue and decreased testosterone in men.
However, there is very little evidence for these claims. One analysis of 38 studies on the subject found no evidence. Some anecdotal claims have been found to be based on very large quantities of soy; the most famous case was a man who drank 3 quarts of soy milk every day.
Some people are allergic to soy. If you have stomach cramps, rashes, or vomiting after eating soy foods, you are probably allergic and should avoid it.
What’s the bottom line?
There is not enough strong evidence to claim either that soy is dangerous or that it is miraculously healthy. It makes sense to eat soy foods as part of a balanced, varied diet.