Human beings have been eating soy for thousands of years. There is evidence of soybean cultivation dating back as far as 9,000 BC, and the crop has become a staple in many influential food cultures. Across Asia, it’s almost impossible to eat without at some point spotting tofu, miso or soy sauce on the menu. Today, soy has become a useful substitute for milk and other allergenic substances in the West, which has seen its popularity soar still further. For a while it looked like soy could do no wrong.
However, as we have come to understand more about how the food we eat affects us, scientists have become taking a more critical look at how soy may impact our health. Through careful testing and close examination, it has become clear that, though it may contain many benefits, soy is much more of a mixed bag than we first thought.
One of the most common criticisms of soy is the possible link between the bean and breast cancer. This belief stems from the fact that the isoflavone proteins present in soy act like estrogen, which is a fuel for many forms of cancer and can cause tumours to spread more quickly. In reality, several recent studies have suggested that whole or fermented soybeans may actually have the opposite effect, but the science on the issue remains inconclusive.
Another rumour that refuses to go away revolves around the food’s impact on male sex hormones. Again, the evidence is sketchy, but enough to give you pause for thought. In 2008, the Harvard School of Public Health found that men who ate an average of half a serving of soy per day had a lower concentration of sperm than those that didn’t. Similarly, a study in 2011 linked one patient’s erectile dysfunction and hyposexuality to his soy consumption. Though there have since been other studies that point out this evidence is nothing more than circumstantial, the honest answer is that we still don’t know the effect that soy may actually have on the male body.
One area where scientists are more certain that soy may have a negative impact is in thyroid function. According to Healthline, “soy contains goitrogens, substances that may negatively impact the thyroid by blocking iodine absorption.” Subsequent lab and animal testing has shown that this is indeed the case. Though extensive human studies have yet to be carried out, some scientists believe that excessive soy consumption may indeed have a negative impact.
Despite the doubts over some aspects of soy, it is also clear that it can also have a number of health benefits. We know, for instance, that it can help with heart health and cholesterol, and is also a rich source of protein and fibre. Some experts have variably claimed that including soy in your diet can help with everything from weight loss to increasing fertility in women. It’s small wonder that is has earned its status as a health food. Nonetheless, the uncertainty in the scientific community means that you’d be well advised to treat soy with some respect. It might well be amazing for you. But it also might be way worse than you think.