The Soy Controversy: Is It Good for Your Heart?
Can soy be part of a heart-healthy diet? Our resident dietitian breaks down the latest news.
Recently, the Food and Drug Administration announced a proposal to revoke its claim that soy protein reduces the risk of heart disease. This is the first time the FDA has considered revoking one of its 12 approved health claims. The organization says that numerous studies published since 1999 have presented inconsistent findings regarding the relationship between soy protein and heart disease. As such, the looming question still remains: can soy and soy-based foods be part of a heart-healthy diet?
Soy Nutrition 101
Soybeans can be found in many forms. You’ve probably munched on baby soybeans in or out of their pod, also called edamame. Soy can also be made into soy nuts, soy milk, soy sauce, tofu, miso paste (a fermented soy product used in soups and dressings), and tempeh (made from compressed soy beans).
One cup of in-shell edamame provides 189 calories, 16 grams of carbs, 8 grams each of total fat and fiber, and 17 grams of protein. The fat found in soy is mostly healthy unsaturated fat, while the protein is complete, meaning it provides all the essential nutrients the body needs.
Soy and Heart Health
"The FDA isn’t claiming soy protein doesn’t lower blood cholesterol levels," says Mark Messina, PhD, MS, Executive Director of the Soy Nutrition Institute. "It has tentatively concluded that the evidence in support of a cholesterol-lowering effect of soy protein isn’t as consistent as it once was. Bear in mind that the studies show soy protein either lowers cholesterol levels or has no effect. None of the studies show soy protein raises blood cholesterol levels."
There have been many studies that show that soy can reduce cholesterol levels and lower heart disease risk. But the possible benefits don’t stop there. "Soy has also been shown to have cancer-protective benefits, and even protect the bones. Some studies show that it can help prevent hot flashes in women during menopause," says Sharon Palmer, RDN, The Plant-Powered Dietitian, author of Plant-Powered for Life, SharonPalmer.com.
However, some men feel that eating soy can have negative or feminizing effects on their body. According to Messina, "clinical studies show even large amounts of soy foods (over four servings per day) don’t lower testosterone levels or raise estrogen levels in men and don’t adversely affects sperm or semen." For all the men out there, you can enjoy soy and the protein and possible health benefits it provides without worrying about any negative effects.
There are no official recommendations to the amount of soy that should be consumed. "For a variety of health outcomes, most studies suggest two servings per day are sufficient to derive benefits such as the alleviation of menopausal symptoms or improvement in arterial health," says Messina. The FDA has set a threshold of 25 grams per day of soy protein in order to help lower cholesterol. As most Americans don’t even come close to this amount, getting 1 to 2 servings per day is a good way to get started. One serving is equivalent to 1/2 cup of tofu or edamame, 1 ounce of soy nuts, or 1 cup of soymilk.
Bottom Line: There is evidence linking soy to heart health, perhaps not as substantial as the FDA would like. However, you can enjoy a variety of soy foods as part of a heart healthy diet plus reap the multitude of other health benefits that soy may provide.
Toby Amidor, MS, RD, CDN, is a registered dietitian and consultant who specializes in food safety and culinary nutrition. She is the author of The Greek Yogurt Kitchen: More Than 130 Delicious, Healthy Recipes for Every Meal of the Day.