Despite concerns, soy probably safe for thyroid

Despite some concerns to the contrary, the soy-based dietary supplement genistein may not harm postmenopausal women's thyroid function, a new study finds.Genistein is a type of soy isoflavone, a plant chemical that is structurally similar to estrogen and may have certain estrogen-like effects in the human body. In a 2007 clinical trial, Italian researchers found that genistein supplements, along with calcium and vitamin D, appeared to help boost bone mass in postmenopausal women with thinning bones. In this latest study, the researchers evaluated data from the same clinical trial -- this time looking at whether the genistein supplements had any effects on the women's thyroid function. More...