Soy Vey! Is It Time to Toss Your Tofu?
Superfood or diet villain? Researchers weigh in on the pros and cons of soy.
Some foods get all the glory—think kale, quinoa, blueberries. But others seem to go straight from superfood status one day to nutritional bad boy the next.
That seems to be the case with soy. Long celebrated as a health food staple, this ubiquitous legume has been facing serious health questions—such as whether eating soy foods can affect your hormones or even increase your chances of breast cancer. Those claims can be particularly scary for vegetarians and vegans who lean heavily on soy for protein in their diet.
So what’s the real scoop on soy? The short answer is that, while you may want to avoid highly concentrated soy-derived supplements, you can keep noshing on tofu and edamame. Researchers and nutritionists still consider soy foods safe and healthful.
“Soy is a good source of plant-based protein, which provides all your essential amino acids, plus a variety of vitamins and minerals like potassium, folate, and calcium that support health,” says dietitian Toby Smithson, a spokesperson for the Academy of Nutrition and Dietetics.
Soy packs a superstar fat profile (low in saturated fat, high in polyunsaturated fats with omega-3 fatty acids), so it can improve your heart health. “If you replace foods that are high in saturated fat with soy, you can reduce cholesterol levels by as much as 4 percent,” says Smithson. That may sound small, but it makes a difference—each 1 percent decrease in cholesterol lowers heart disease risk by 2 percent, she notes.
What’s more, soy is rich in isoflavones, which may improve the health of arteries by increasing the production of nitric oxide, a substance that makes blood vessels flexible. In a 2012 study, researchers at Columbia University found that young adults with a high intake of isoflavones lowered their systolic blood pressure by 5.5 points more than adults with a low intake.
But wait—what about those scary warnings linking soy and cancer? Those heart-healthy isoflavones belong in a class of compounds called phytoestrogens, which can mimic properties of the hormone estrogen. Some researchers have investigated whether a high intake of these compounds can increase the risk of hormonally sensitive cancers, like breast cancer. Many studies have tested the effects upon animals given high doses of soy-derived supplements, and the results have been mixed and inconclusive.
Meanwhile, studies on humans haven’t found that consuming soy foods is harmful. On the contrary, the research suggests that soy’s anti-inflammatory properties may actually be protective against cancer, says Smithson. Even breast cancer survivors can consume soy safely, concludes one recent study from Vanderbilt University.
The official recommendation from the Academy of Nutrition and Dietetics is that adults can eat up to three servings of soy foods per day (one serving might be a half cup of tofu, a cup of soy milk, or a half cup edamame). Fill up on whole-food sources of soy, like edamame and tofu, and limit your intake of heavily processed soy products, like soy chips or soy-based imitation meats, which are often higher in sodium and empty calories. (Eating foods like soy veggie burgers can be fine in moderation. When it comes to those products, Smithson recommends looking for brands with less than 300 milligrams of sodium per serving.)
And if the potential benefit of consuming tofu or miso hasn’t been on your radar until today, don’t worry: babies in Japan might be eating soy at six months of age—but it’s never too late to start!
Chew on This
Making soy a part of a healthful diet can provide big benefits. Here’s what to fill up on:
Edamame: A half cup of shelled beans packs eight grams of filling protein. It’s also a good source of iron, a mineral that plays a critical role in helping you maintain energy levels.
Tofu: For only 90 calories, a half-cup serving of tofu lends 25 percent of your daily calcium needs, nearly as much as a cup of skim milk. Plus, it also contains manganese, copper, and zinc. Taken together, those four minerals may help slow bone loss that can happen with age.
Soy milk: If you don’t drink cow’s milk, soy milk is going to be the closest nondairy option you can find. Both skim and soy milk contain around 80 calories per cup, and fortified brands deliver at least 30 percent of your daily value of calcium and a similar amount of protein (six grams in soy, eight in regular milk). Look for unsweetened varieties to save on calories and added sugar.
Roasted soy nuts: Snack on this crunchy legume and get a whopping 15 grams of protein and nearly eight grams of fiber per quarter cup, both of which can help keep energy levels steady throughout the day. One thing to remember: there are about 200 calories per serving, so keep portions in check.
Tempeh: Made from fermented cooked soybeans, there’s good reason to swap some of your plain Jane tofu for earthier-tasting tempeh. While tempeh does contain more calories than tofu (196 versus 91 in a 3.5-ounce serving), you’ll also get more protein in tempeh (18 grams) than in tofu (10 grams) to feel fuller, longer.