Jackie’s Wellness Coaching Wednesday Weigh In- May 5th, 2010

On Soy, estrogen and why tofu is good for you! I have to say, I hear the most amazing things – food fiction and nutrition myths abound. But this one really floored me – a personal trainer telling a male client not to eat tofu or soy because it would give him too much estrogen…

Well, here are some FACTS about soy foods that you should know:

Soyfoods do not contain estrogens. Soyfoods contain complex mixtures of proteins, fats, carbohydrates, and bio-active compounds including soy isoflavones. Although isoflavones naturally found in soy are plant “phytoestrogens” that look similar in chemical structure to estrogens, they act differently in the human body and should not be confused with the human hormone estrogen. Isoflavones are bioactive compounds that may improve the health of arteries, prevent certain cancers, and reduce bone loss.

Numerous human studies have found that men and women consuming 40-70 mg/day of soy isoflavones from soyfoods or soy supplements had no significant changes in testosterone levels or estrogen levels compared to control groups.

Some animal studies that are looking for effects inject or feed a very high dose of a concentrated source of a single isoflavone, such as genistein, which is very different from the way isoflavones are consumed in food. Problems seen in some animals but not humans are believed to be due to differences in the way soy isoflavones are metabolized by humans and animals.

Still have questions? Check out these sources.
1. American Cancer Society. Soy and Breast Cancer. Accessed on January 3, 2007 at cancer.org/docroot/NWS/content/NWS_1_1x_Soy_and_Breast_Cancer.asp.
2. Colacurci N, Chiantera A, Fornaro F, de Novellis V, Manzella D, Arciello A, Chiantera V, Improta L, Paolisso G. Effects of soy isoflavones on endothelial function in healthy postmenopausal women. Menopause 2005;12:299-307.
3. Messina M. Emerging evidence on the role of soy in reducing prostate cancer risk. Nutr Rev 2003;61:117-131.
4. Korde L FT, Wu A, et al. Adolescent and childhood soy intake and breast cancer risk in Asian-American women. Breast Cancer Res Treat 2005;88:S149.
5. Messina M, Ho S, Alekel DL. Skeletal benefits of soy isoflavones: a review of the clinical trial and epidemiologic data. Curr Opin Clin Nutr Metab Care 2004;7:649-658.
6. DiSilvestro RA, Mattern C, Wood N, Devor ST (2006) Soy protein intake by active young adult men raises plasma antioxidant capacity without altering plasma testosterone. Nutr Res 26:92-95.