Made from high protein soybeans, soy contains isoflavones, saponins and phytosterols, and is cholesterol-free and low in fat. Soy is found in whole soybeans, soy nuts, edamame, tempeh, tofu, soy milk, supplements, soy flour and meat substitutes. A nutritional food source, soy has many benefits and few dangers.
The University of Maryland Medical Center reports that in 1999 the Food and Drug Administration first allowed products containing soy to carry a heart-healthy label stating that soy may reduce cholesterol when eaten in conjunction with a healthy diet. A soy product must contain at least 6.25 grams of soy protein per serving for this labeling. Eating a diet of at least 20 grams of soy protein per day in addition to a diet low in cholesterol and saturated fat may lower blood fat levels.
People in Asian countries who routinely eat up to 55 grams of soy protein per dayhave lower rates of heart disease than people who eat a Western diet of less than 5 grams of soy per day, according to University of Michigan Health System. Soy protein and the isoflavones contained in soy may improve the lining of blood vessels and inhibit the effects of low density lipoproteins, or LDL cholesterol, causing less damage to arteries.
Soy foods may help prevent osteoporosis by increasing bone mineral density. Women who eat a diet rich in soy protein are more likely to boost bone mineral density. Vanderbilt University states that there may be a link between a high intake of isoflavones found in soy and stronger bones, and a diet high in soy protein is favorable to bone density.
A small percentage of people have allergies to soybeans. Since soybeans are legumes, allergies to other legumes and beans are usually present in people with soy allergies, according to the Children’s Hospital of Philadelphia.
Lowered Thyroid Function
Soy isoflavones may lower the levels of iodine in the body, leading to hypothyroidism or an underfunctioning thyroid. According to University of Michigan Health System, a preliminary study of soy supplementation among healthy Japanese subjects found that adding about an ounce of soybeans to the diet per day for three months led to a small reduction in the thyroid-stimulating hormone. The Japanese participants complained of tiredness, constipation and goiter; these symptoms stopped a month after ceasing soy supplementation.
Breast Cancer Benefit and Danger
According to UMMC, soy is thought to reduce the overall risk of breast cancer, but if you have already had breast cancer, soy may not be safe and may stimulate the growth of breast cancer cells. If you or your family has a history of breast cancer, talk to your physician prior to supplementing your diet with extra soy or soy products.