© 2010 Roy Benaroch, MD
From LeeAnn: “Are soybeans (edamame) safe for my 11 year old daughter to eat? I have heard that they can ‘mess with’ her hormones?”
You want to see a freakshow? Try googling this topic. I found one essay, on a “news” site, that blamed soy products for everything from stroke to vision loss to homosexuality. On the other hand, other authors love soy: it will apparently prevent heart attacks, improve the symptoms of menopause, and help flush the toxins out of your body while improving your sex drive (women) and fracture healing (men.) On one site, in two adjacent paragraphs, I found a breathless author worrying that soy could cause breast cancer, followed by a second paragraph extolling its virtues in preventing breast cancer.
Soybeans contain a group of chemicals called “phytoestrogens” (sometimes called “isoflavones”) that are chemically somewhat similar to human estrogen hormones. In the 1970’s and 1980’s, some research showed that in the laboratory, these compounds could activate human estrogen receptors, presumably causing estrogen-like effects. So that’s the germ of truth.
But these phytoestrogens activate human estrogen receptors very, very weakly. They’re also easily broken down by cooking and processing, and by enzymes in the human body. It would take a tremendous amount of soy, eaten every day, to have anything close to a genuine hormonal effect. No human study has shown anything close to a measurable effect of consuming soy, at least not in ordinary amounts.
So: enjoy your edamame, tofu, and soy burgers. Dip your sushi in a little soy sauce, and try this tasty recipe from Alton Brown. If you want to be super-careful, just don’t do all of this on the same day.