Soy and soy foods are rich in protein, fiber, phytochemicals and other nutrients. Soy and soy foods are popular in the United States, however there are some myths that effect consumers' opinion of soy. I asked Dr. Mark Messina, adjunct associate professor of nutrition at Loma Linda University and an expert on soy and nutrition, to help me dispel the myths surrounding soy.
Myth: Soy Is Bad for Boys Because It's Estrogenic
Some people claim the phytoestrogens in soy foods, and especially soy formulas, are bad for boys because they negatively effect male hormones. Some fear-mongers go so far as to claim soy infant formula will cause boys to become homosexual and more feminine in nature. Messina assures that's not the case. "The isoflavones in soy foods, which are classified as phytoestrogens, have raised concerns about feminization. However, isoflavones are different from the hormone estrogen. Studies show quite clearly that the two molecules - isoflavones and estrogen - exert different physiological effects. For example, estrogen raises levels of triglycerides, which increases risk of heart disease, and raises levels of HDL-cholesterol, which lowers risk. In contrast, isoflavones have no effect on triglycerides or HDL."Nor do isoflavones have any detrimental effects on male hormones. Dr. Messina explains, "A meta-analysis examined the relationship between soy/isoflavone intake and reproductive hormone levels in men. The study included 36 treatment groups and found no effects on total and free testosterone levels. By the way, three clinical studies also show no effects on sperm or semen."
There isn't a lot of research on children and soy. However, Messina describes one study. "One study did examine whether isoflavones might raise HDL levels in boys. When boys reach puberty, HDL levels decrease whereas in girls they remain high. The authors speculated that isoflavones might exert an estrogenic effect and keep HDL elevated, but they found no such effects. Of course, Asian children have consumed soy for centuries without apparent adverse effects."
Messina also goes on to point out that soy formula produces normal growth and development. "Since the early 1960s, about 20 million infants have used soy formula for various lengths of time. The American Academy of Pediatrics just published their updated position paper on soy formula and concluded, 'In term infants, although isolated soy protein-based formulas may be used to provide nutrition for normal growth and development, there are few indications for their use in place of cow milk-based formula" and '… there is no conclusive evidence from animal, adult human, or infant populations that dietary soy isoflavones may adversely affect human development, reproduction, or endocrine function.'"
Mark Messina, Ph.D. is a Health and Wellness Expert for The United Soybean Board.
Source:
Email interview with Mark Messina, PhD. April 2009. The Soy Connection.
