You’ve probably heard about the health benefits of soy, but do you know specifically what makes this legume so good for you? Soybeans and foods made from them are packed with nutrients and plant compounds that do a body good. Getting your fill can help lower your cholesterol, keep your heart healthy, and ease hot flashes. Here’s your primer on reaping soy’s perks.
What Exactly Is Soy?
Soybeans are legumes, like peas and lentils. But unlike other beans, soy is one of just a few plants that provide all nine essential amino acids, making them a complete protein. Soybeans are also jam-packed with fiber, vitamins, and minerals like potassium, iron, and calcium.
You can eat soybeans fresh or dried. More commonly in the American diet, you’ll find soy in these forms:
Tofu and tempeh: Made from curdled soy milk, tofu soaks up flavors well while tempeh has a firmer, nuttier, more fiber-rich texture.
Soy milk: Made by soaking dried soybeans, then grinding them with water. It has a mild, nutty flavor.
Edamame: Immature green soybeans that are steamed or boiled while still in the pod. They make a healthy snack thanks to protein, folate, and fiber.
Soy sauce: Adds a salty flavor in cooking. Be sure to stick to fermented varieties like tamari over ones high in sodium.
Soybean oil: Versatile for baking and frying. Opt for unhydrogenated versions high in better-for-you monounsaturated and polyunsaturated fats.
TVP and soy protein powder: Textured vegetable protein (TVP) made from defatted soy flour is a versatile meat substitute when hydrated, while soy protein powder is popular for smoothies and shakes.
Miso: This fermented soybean paste makes flavorful soups.
The Perks of Soy
Heart Helper
The FDA allows products that contain at least 6.25 grams of soy protein per serving to sport a heart-healthy claim. Why? Soy can lower LDL or “bad” cholesterol. In 1999, the FDA decided that “25 grams of soy protein a day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease.”
Research shows swapping soy protein for animal protein has a favorable effect. One study found that eating soy protein regularly can lower LDL 8% to 11%.
Exactly how soy works its magic isn’t completely understood. Experts think isoflavones – a type of plant compound abundant in soy – may improve blood vessel function. The amino acid makeup may also play a role. Replacing meat with soy also reduces your intake of artery-clogging saturated fats found in beef, pork, and chicken.
Cancer Crusader
You’ll often spot headlines linking soy consumption to a drop in cancer risk, especially premenopausal breast cancer risk. This may be due to soy’s isoflavones, which are called phytoestrogens. These plant estrogens mimic the effects of estrogen in the body by binding to estrogen receptors. For this reason, they’re thought to protect against estrogen-dependent breast cancers.
Research is mixed. A few studies show eating 10 mg or more soy isoflavones daily curbs breast cancer risk. But an analysis of 35 studies concluded “the data are not sufficiently robust to conclude that soy foods consumption has significant potential for primary prevention of breast cancer.”
Soy intake earlier in life may be key. One study found women who consumed soy during childhood were 58% less likely to develop breast cancer later in adulthood compared to non-soy eaters. Childhood soy consumption may offset the cancer-stoking effects of meat cooked at high temperatures.
Menopause Must-Have
During perimenopause and menopause, soy isoflavones may provide relief from hot flashes by mimicking estrogen’s effects. In one study of more than 100 women, eating soy protein with phytoestrogens daily was as effective as a low-dose hormone replacement therapy at cooling hot flashes. Miso soup is an easy way to work in soy first thing.
In another study, when women swapped one to two servings of meat with soy daily their hot flash frequency plummeted 20-45%. Soy may also fend off heart disease risk during menopause. Research shows that for women transitioning into menopause, soy protein lowers LDL and triglycerides while boosting protective HDL.
Downside of Soy
Soy is safe for most healthy adults. But before upping your soy intake substantially, do a gut check. Concern exists about potential effects of soy phytoestrogens for:
Breast cancer survivors: Don’t nosh on large amounts of soy foods over extended time frames until more is known, experts advise.
Those with estrogen receptor positive breast cancer: Check with your oncologist about eating soy in moderation during treatment.
Those taking tamoxifen: This breast cancer drug can be less effective when paired with high soy intake. But moderate amounts (less than two to three servings daily) are likely safe.
Children: Soy formula given at very high volumes may theoretically affect development. Babies seem to do fine with average consumption. Check with your pediatrician.
Men with prostate cancer: Experts used to advise avoiding soy out of concern about testosterone effects. But newer evidence finds neither soy foods nor isoflavone supplements affect prostate cancer progression or testosterone levels. Still, it’s smart to keep soy intake moderate and choose whole foods over supplements.
Those with thyroid issues: Very high soy intake may affect thyroid function though evidence isn’t definitive. Check with your doctor about your personal risk if you have hypothyroidism.
Soy’s Bottom Line
Current research suggests consuming a moderate amount of whole soy foods – about 1 to 2 servings daily – is safe for most healthy adults. This amount supplies beneficial plant protein, fiber, vitamins, minerals, and antioxidants. Replacing some meat with soy is smart for better cardiovascular health, while enjoying soy foods may ease menopause symptoms. Be sure to pair soy with plenty of fruits, veggies, and whole grains too as part of an overall balanced diet. With soy in your corner, you’ll feel on top of your health game.
The Best Sources of Soy
Want to eat more soy but aren’t quite sure where to start? Here’s your cheat sheet of foods packed with soy protein, fiber, vitamins, and health-boosting compounds like isoflavones:
Edamame: One cup of this fun finger food in the pod packs a whopping 18 grams of soy protein. Boil or steam these immature green soybeans. Sprinkle with a pinch of sea salt and squeeze fresh lemon for one of the easiest appetizers ever.
Tofu: With about 10 grams of soy protein in a 3-ounce serving, tofu makes an ideal canvas for stir-fries, lettuce wraps, grain bowls, smoothies, and more. Opt for firm or extra firm tofu to get an even bigger protein boost. And be sure to press water out before marinating to infuse flavor.
Tempeh: This cake of fermented cooked soybeans wields 15 grams of soy protein per 3-ounce serving. Its extra firm texture stands up well to crisping and caramelizing. Try marinated baked tempeh strips for protein-rich snacks and meals.
Soy nuts: To make these crunchy, roasted soybeans, dried soybeans are soaked then baked. A quarter cup of unsalted dry-roasted soy nuts supplies 11 grams of protein. Toss them into trail mixes or eat by the handful.
Soy milk: With a mild, nutty flavor (and usually vitamin D, calcium, and vitamin B12 pumped in), soy milk makes mornings brighter. An 8-ounce glass typically wields about 7 to 10 grams of protein. Use it on cereal, in smoothies, or heat up with cinnamon for a comforting nightcap.
Miso paste: This salty, fermented soybean paste can transform soups, dressings, marinades, stir-fries, and more. Red miso packs the most protein, while mellower white miso works when you want a delicate flavor. Even just a tablespoon lends 4 grams of protein.
Soy protein powder: Add 2 scoops of powder to smoothies or shakes and you’ll get about 25 grams of soy protein. Choose unsweetened soy protein isolate powder for the most protein, the fewest carbs, and hardly any soybean flavor.
With all these tasty ways to enjoy hearty, healthy soy, there’s no reason not to give this wholesome bean a prime spot on your plate. One bite and you’ll quickly become an edamame addict!