Soy is great for you. It can fight cancer. No, soy can be bad for you, especially if you’re a guy. It can lead to growth of breasts or lower testosterone levels. These are some of the conflicting statements about soy and its by products. But what is the low down on soy? Is it really good for you or not?
A study of children fed soy protein formula for more than six months showed no hormonal effects. A study of men in their 50s and 60s found that the men who ate soy foods twice a day for three months showed no change in testosterone levels, but had a 14 percent drop in levels of PSA (an indicator of prostate growth used in screening for prostate cancer).
She goes on to say that all the noise about the negative effects of soy on men is actually NOT based on sound scientific research. However, she also says that the idea that soy and other soy based products can prevent prostate cancer has NOT really been proven yet.
Another interesting thing that Collins points out is how different types of soy products can have different effects:
Fermentation may change how easily our bodies absorb isoflavones, which means that fermented soy foods (miso, tempeh, natto) may have a different effect on prostate cancer risk than non-fermented soy foods (soy milk, tofu and edamame). Some studies suggest that the effect of soy foods may depend on its interaction with other food compounds; the lycopene from tomatoes is one such interaction under study.
The bottom line is that you SHOULDN’T fear soy foods. If you like it, go ahead and eat it!