Why is too much tofu bad for you

With more and more Americans exploring a plant-based diet for the benefit of both their own health and the planet, soy-based foods such as tofu, soy milk, miso, tempeh and edamame are no longer relegated to quirky health-food stores. They're prominently displayed in supermarkets, available to pour into your latte at the local coffee bar, and on restaurant menus in many different forms. For vegans, vegetarians and those who just are just veg-curious, they are a protein-packed way to replace meat and dairy. But with a lot of contradictory and confusing info out there, you might wonder, is soy actually good for for you or bad for you?

Let's sit back with a nice glass of soy milk and a slice of tofu-based peanut-butter pie, and discuss.

How nutritious is soy?

For the most part, you can dig in to your stir-fried tofu and sip that soy latte without a worry. "Soy is an excellent source of plant-based protein and fiber. Its low in saturated fat and can provide a more economical way to eat a balanced diet," says Amy K. Fischer, RDN, a registered dietitian with the Good Housekeeping Institute. "It's a complete protein, containing all nine essential amino acids, and is a rich source of B vitamins, fiber, potassium and magnesium, among others."

"Soybeans provide a slew of vitamins and minerals crucial for reducing risk of chronic disease; and fiber that helps you fill up and feel satisfied," adds Jaclyn London, MS, RD, CDN.

Here's the facts for four of the most popular ways to eat soy:

• Tofu: A half-cup of raw, firm tofu has 94 calories, a little over 10g protein, 5g of fat and 227 mg of calcium.
• Tempeh: A half-cup has about 110 calories, about 15 g protein and 9g of fat, depending on brand.
• Soy milk: One cup has 110 calories, 8g protein and hardly any fat (though it often contains added sugar).
• Miso: A paste made from fermented soybeans, miso has (per tablespoon) about 33 calories, 2.2g protein and just 1g of fat.

Of course, one thing to remember when you're choosing which type of soy to try is that whole foods are always better. Many of the inflammatory articles about the "risks" of eating soy are based on eating products made from soy protein isolates (think supplements, protein bars and "fake" meats). "Soy protein isolates, where the protein has been isolated from the soybean, does not have the same benefits that unprocessed or whole soy does," Fischer explains. "During processing, valuable vitamins and minerals get stripped away. In addition, things you dont want in your body, such as chemicals, could potentially be introduced."

Why soy is controversial?

Lets take a trip back to the 1990s, when soy foods first started really hitting it big. At the time, many experts believed that soy had the power to fight problems like obesity, heart disease and even cancer. After all, people in Asia eat a ton of soy, and studies showed that these populations had significantly lower rates of obesity, heart disease and breast cancer compared to people in the U.S. Clearly, soy was the miracle food, right?

Not necessarily. Those studies only looked at associations, not causation. Just because people who consume a lot of soy also happen to be healthier than people who dont eat soy doesnt automatically mean that soy is the key to their superior state. Countless other factors including genetics, lifestyle and the rest of their diet could also play a role.

When researchers began taking a closer look to find out what made soy so healthy, they ran into some surprises. Soy, it turned out, contains estrogen-like compounds called isoflavones. And some findings suggested that these compounds could promote the growth of some cancer cells, impair female fertility and mess with thyroid function. Some health experts also trash-talk soy because of its potential to be an endocrine disrupter meaning it can mimic estrogen in the body, which may lead to a hormone overload.

At the same time, other studies were still showing that soy consumption could cure high cholesterol and help women cope with the symptoms of menopause. And Dawn Jackson Blatner, RDN, a Chicago-based dietitian, says that while whole soy does contain natural plant estrogens, they're much weaker than actual human hormones, and shouldn't case you worry. Add it all up, and you can see how this little green bean became a source of mass dietary confusion.

What we know today:

As with all foods, experts still dont know everything there is to know about soy. But research in recent years suggests that moderate consumption of minimally processed soy foods (more on what those are later) not only isnt bad for you, it probably has some benefits. Heres what we can say about soy today:

Soy may decrease your risk of certain cancers, among other chronic diseases.

How did soy even get linked to cancer risk in the first place? Stephanie Clarke, RDN, a dietitian based in Washington, D.C., says it has to do with processed grocery products. Soy protein isolates may contain more soy isoflavones, which are organic compounds that can also be considered endocrine disruptors in high amounts. Elevated levels of this kind of soy may lead to unbalanced hormone levels, which can play a factor in cancer risk.

The majority of recent, high-quality studies, however, have found that unprocessed soy doesnt increase breast cancer risk, and very high consumption could even offer some protection. In fact, an analysis of more than 30 studies showed that soy intake reduced the risk of breast cancer for both pre- and postmenopausal women in Asian countries, where people tend to start eating soy from a very young age.

Eating soy could help protect against other types of cancer, too. Findings show that soy consumption may slightly lower the risk for gastrointestinal cancers and have a protective effect in prostate cancer survivors. Eating a high-fiber diet is also tied to lower colon cancer rates, and soy foods like edamame and tempeh both have plenty of roughage.

The only instance in which you may wish to limit soy consumption? If you've previously been diagnosed with estrogen receptor-positive breast cancer, Clarke says. Your doctor may advise that it's best to skip soy altogether if estrogen is at play in this case.

Soy might improve fertility and help with hot flashes.

Soy appears to be beneficial for fertility, as long as you dont eat too much. Women undergoing in vitro fertilization who have environmental exposure to BPA are more likely to get pregnant if they also ate soy. Thats likely because soys isoflavones help neutralize the BPAs endocrine-disrupting effects, researchers say.

Just dont go overboard. Consuming over 100mg of soy isoflavones (the equivalent of 6-ounces uncooked tempeh or 16 cups soy milk) daily was linked to reduced ovarian function, found a Journal of Nutrition review. But moderate soy consumption didnt pose a problem.

As for soy solving those annoying and disruptive hot flashes that accompany menopause? It might help, but not for everyone. Among women whose bodies produce the soy metabolite equol, those who ate the most soy experienced significantly fewer hot flashes and night sweats compared to those who ate the least, found one Menopause study. (Between 20% and 50% of North American and European women produce equol. Some research centers can test for it in a urine sample, but theres an easier option: Try adding soy to your diet for four to six weeks and see what happens. If it helps, you produce equol. If it doesnt, you probably dont, the study authors say.)

Eating soy in place of meat will probably protect your heart.

Early research suggested that soy could help lower levels of bad cholesterol. But more recent findings have shown that might not be the case, and in 2008, the American Heart Association said that there wasnt enough evidence to say for sure that soy lowered the risk of heart disease. However, some interesting new research has suggested that fermented soy products such as natto may be protective against both cardiovascular disease and cancer. "I was recently introduced to natto, a staple in Japan that is lesser0known stateside," says Fischer. "It's a delicious form of fermented soybeans that is often served with rice."

One of the healthiest aspects of eating soy comes in what it replaces on your plate: Swapping out animal-based foods for plant foods like soy lowers saturated fat intake and ups fiber intake, both of which help your heart. In other words, skipping that steak and cooking or tofu or tempeh instead is a heart-smart move.

You should pay more attention to your soy intake if you have thyroid issues.

Soy foods dont affect thyroid function in people with healthy thyroids, found a Loma Linda University review of 14 studies. But if you have an underactive thyroid, you might want to watch how much soy you eat. Soy foods have been shown to interfere with the bodys absorption of thyroid medication but only if you overdo it, suggests a 2016 Nutrients review. The evidence is still far from conclusive, but experts still advise to wait at least four hours after consuming soy to take your thyroid medicine.

The best (and worst) types of soy to eat:

Diane LabombarbeGetty Images

All of soys potential benefits come with an important caveat: To reap them, you need to pick minimally processed forms of soy think tempeh, tofu, miso and edamame.

These foods serve up soys entire nutritional package without added sugar, unhealthy fats, sodium or preservatives that you usually find in highly processed foods. Fischer recommends using tempeh or tofu to replace the meat in tacos or chili, and to keep a bag of frozen edamame around to snack on when you crave a crunchy bite.

Soy frankenfoods like meat analogs, soy bars, soy yogurts, or protein powders usually only contain soy protein isolates, rather than nutrition from the whole soybean. "Just as other processed foods are lower in nutrient density, removing the protein from the other enzymes and bacteria needed for digestion affects the nutritional quality," says Taz Bhatia, MD, integrative health expert and author of What Doctors Eat.

As for how often you should eat soy? As with all foods, moderation is the way to go. Generally, three to five servings of minimally processed soy foods per week are perfectly fine, Bhatia says. If youre unsure, or you have an underlying health condition (like hypothyroidism), bring it up with your doctor the next time you discuss your diet. If you want to mix it up with other plant-based proteins, consider incorporating more legumes, such as lentils and chickpeas into your diet, as well as hemp seeds ad quinoa, Fischer suggest.

This content is created and maintained by a third party, and imported onto this page to help users provide their email addresses. You may be able to find more information about this and similar content at piano.io