There appears to be a great deal of controversy surrounding soy foods, mostly due to their isoflavones which can bind to estrogen receptors and affect thyroid hormone.
To help set the record straight, here are some important things to know about soy foods:
• A number of studies (1,2, 3) have shown that consumption of soy foods decreases the risk of heart disease. • Ingestion of soy isoflavones has been shown to significantly reduce the frequency and severity of hot flashes. • Soy may both reduce the risk of breast cancer and be associated with better breast cancer survival. • Soy consumption is associated with a decreased risk of prostate cancer. • Some evidence suggests that soy foods may increase the dose of thyroid hormone required by hypothyroid patients. However, hypothyroid adults need not avoid soy foods. It is important for soy food consumers to make sure their intake of iodine is adequate. • Soy allergies are rare. They occur mainly in young children with atopic dermatitis, who often outgrow the allergy after 1-2 years of dietary elimination. Allergic reactions in adults are less frequent. • Soy is not associated with male feminization. The results of a meta-analysis of more than 30 clinical studies suggest that neither soy foods nor isoflavone supplements alter measures of bioavailable testosterone concentrations in men.