Let's face it: There is a lot of misunderstanding about the link between soy and women's health. Can it increase a woman's chance of getting cancer or does soy have a positive or protective effect? Carolyn Mitchell, RDN, CNSC, a registered dietitian nutritionist at Sharp Coronado Hospital, weighs in.
- What are the health benefits of soy?
Soy contains high-quality protein and necessary vitamins and minerals. Tofu is packed with calcium and omega-3 fatty acids. Tempeh contains B vitamins (thiamine, riboflavin, niacin) and is a rich source of magnesium, copper, iron, manganese and phosphorous. Tempeh provides healthy monounsaturated fats. Miso is rich in vitamin B-12, which is involved with fat and carbohydrate metabolism. Natto — a fermented soy product — is rich in the enzyme nattokinase, which emerging research shows has blood-thinning properties, which may reduce the risk of blood clots and help break up the plaque associated with Alzheimer's disease.
- How can I get soy into my diet?
Eating whole soy foods is best. Examples include tofu (soybean curd) and edamame (young green soybeans). Fermented forms of soy include tempeh (chunky, tender soybean cake), miso (smooth paste) and natto (sticky paste). Processed forms of soy, such as soy burgers, soy energy bars and the highly processed "frankensoy" products, are not good choices because the processing strips away the nutrients. Additionally, foods like these are also likely to have added sugars, fats and refined flours.
It is best to consume soy in moderation: One to two servings of whole and fermented soy foods a day is recommended. On average, a serving is a half-cup of tofu or 1 cup of soy milk.
- Is soy milk a good substitute for cow's milk?
Soybeans that are soaked, finely ground and strained produce a fluid called soy milk. Plain, unfortified soy milk is an excellent source of high-quality protein and B vitamins. However, many types of soy milk are processed and are not made with real soybeans. Also, be wary of a far-off expiration date. While it may seem like a good deal, the further out the expiration date, the more likely the soy milk will contain additives to extend its shelf life.
Check the label for hidden or added sugars. Look for brown rice syrup or evaporated cane juice — especially if either is one of the first ingredients listed. One cup of this kind of soy milk can easily wind up being 100 calories more than a cup of skim milk.
- What is the link between soy and breast cancer?
The American Institute for Cancer Research states that consuming three servings of soy foods a day is not associated with increased cancer risk. Additionally, the American Cancer Society concluded that breast cancer patients can safely consume up to three servings of traditional soy foods daily but advised against the use of more concentrated sources of isoflavones (compounds classified as phytoestrogens) such as powders and supplements.
Although adult soy intake does not appear to reduce breast cancer risk, evidence suggests that soy consumption during childhood and adolescence does. There may be a possible link between consuming soy foods and improved survival from breast cancer.
- Does eating soy lower my chance of having heart disease?
Soy contains isoflavones, which studies show reduce blood pressure particularly in African-Americans. Soy foods potentially offer protection against heart disease through several mechanisms. Soy foods are low in (inflammatory-promoting) saturated fat, and high in polyunsaturated fat. Soy protein also has cholesterol-lowering benefits. A recent study found that postmenopausal women who ate a soy protein diet had significantly improved insulin sensitivity and lower total and LDL cholesterol (factors in metabolic syndrome) compared to women who consumed an animal protein diet.
If you are concerned about the amount of soy in your diet or have additional questions about soy, talk with your doctor, who can best answer questions about how it may affect your personal health.