Is Soy Good or Bad for You? An Explainer

From tofu to tempeh, soy sauce to soy milk, the versatile soybean has seen its fair share of acclaims and controversies. When research suggested it could significantly reduce the risk for chronic diseases in the '80s, the native Asian bean became all the rage—an OG member of the health food movement that gave rise to the plant-based revolution. But alarming misconceptions linked to soy—breast cancer risks, thyroid problems, dementia—prevented it from fully reaching plant stardom.

With the amount of conflicting information out there, what's the good word? Can soy heal us or hurt us? Is it a health booster or risky food? We're here to clear up the confusion. Below, we break down whether soy is a healthy alternative and how much of it you should eat.

But first, a brief science lesson.

The human body needs 20 different amino acids to build muscle and regulate immune function. Our bodies create 11 of them on their own (called non-essential amino acids), so we have to get the other nine from food (aka, essential amino acids).

While animal protein provides all nine essential amino acids, it can also contain high levels of saturated fat and cholesterol associated with cardiovascular disease. A complete plant protein that will stack up against eggs and meat, soy is a nutritional powerhouse that touts an abundance of health benefits: a good source of fiber, vitamins, minerals, and nutrients including folate, riboflavin, vitamin K, selenium, potassium, and magnesium.

It is also one of few legumes that contain a high volume of omega-3 fatty acids (found mostly in fish), which help our bodies use insulin more efficiently and lower the incidence of diabetes. Studies have shown that a diet that includes whole soy foods may help reduce menopause-related hot flashes, and the American Heart Association has stated soy can diminish the risk of heart disease if it replaces animal protein consumption, especially for younger and postmenopausal women.

Whole, authentic forms of soy include edamame, tofu, tempeh, and soy milk. But the protein inside soy can also be extracted and transformed for commercial uses such as soy protein isolate, soy lecithin, and other soy extracts. Refined soy is almost everywhere, and this is the stuff that is giving soy a bad rap.

Many scientific studies that have linked soy to negative health effects were one, conducted on soy protein isolate, not whole soy (the plant) and two, administered on animals, so there were no human studies.

While consistent research and academic medical centers have lauded soy as a superfood, the problem is that food manufacturers have saturated soy protein isolate—or any of its other monikers—into a majority of processed foods, infiltrating everything from crackers to cereal, protein bars, deli meats, and even canned tuna. Deconstructed and remade into additives, thickeners, flavoring, and preservatives to the point where the byproduct that lines supermarket shelves is unrecognizable, the former high-quality protein is now another heavily processed and refined food that has almost nothing to offer nutritionally.

Additionally, over 90% of soy grown in the U.S. is genetically modified from industrial farms (hello, pesticides), which means the soy you are probably eating is not only chemically modified and processed, but it's also filled with pesticides! Bottom line: It's not just refined soy foods we need to refrain from; it's also GMO soy (in whole form).

It depends. If you don't mess with the natural version of it—in other words, if you avoid eating processed or GMO soy—then yes, it is good for you. In moderate amounts, soy products are functional foods that can offer significant health benefits. How about soy as a good meat alternative? Again, it depends. Look for minimally processed whole soy products like edamame or tofu to retain full nutrients, and whenever possible, buy organic. Gut-friendly fermented soy foods such as tempeh, miso, or natto are healthy protein foods that will help boost immune function and digestion. Of course, you'll want to discuss with your doctor or a healthcare professional about soy's role in your diet since it might be different for everyone.

Below, take a look at a few soy products that might be worth adding to your diet.