Men, listen, soy is not your friend.

Sex and the Soybean: A Cautionary Tale

Dr. Kaayla Daniel
Recovery from Modern Diets
2011 October 13

Can soy be used as an aid to celibacy?    Is it true that Zen monks eat soy because naughty behavior goes down when tofu consumption goes up?  Do Japanese wives feed unfaithful husbands extra helpings of soy?    Could politicians with the “zipper problem” better control their errant behavior if they consumed enough soy?

Anecdotally, the answer is, yes, and a fair amount of science backs it up.  To date, many studies show that soy’s estrogenic isoflavones interfere with the production and usage of testosterone in the body.   Some evidence points to soy as a feminizing influence that can lead to  gynecomastia (man breasts).   And there’s massive evidence of reproductive toxicity.

The latest news is a case study in the journal Nutrition.  The subject is a 19-year-old heterosexual man who become vegan, began consuming a lot of soy,  and, soon after, experienced loss of libido and erectile dysfunction.   Prior to adopting veganism, he had an active sex life with no reported problems.

Lab assessment revealed low levels of free and total testosterone with increased levels of DHEA.   During the year prior to this workup, the young man’s diet had packed a whopping punch of soy isoflavones, averaging 360 mg per day, from soy milk, soy crisps, tofu, soy sauce, soy nuts and edamame.   This level of soy consumption is far above average, yet increasingly common these days as people quit meat and dairy products for soy substitutes.   Prior to becoming vegan, the man had been on a Standard American Diet (SAD).  After discontinuing his vegan diet and eliminating soy foods altogether, he noticed a gradual improvement in  sexual function over the course of a year and his lab tests revealed  gradual normalization of testosterone and DHEA levels.

The researchers conclude with the usual caveat “more studies are needed.”  Yes, indeed, and as soy consumption increases, doctors and other health practitioners will most likely report many such cases.   Let’s hope future studies focus on women as well as men, and include a study on the link between sex, soy and vulvodynia.   What to do now?   The science may not be entirely in, but the message is already clear:  “If you love and respect your naughty bits, Practice Safe Soy.”

To read the study:

Hypogonadism and erectile dysfunction associated with soy product consumption.Siepmann T, Roofeh J, Kiefer FW, Edelson DG.Nutrition. 2011 Jul-Aug;27(7-8):859-62. Epub 2011 Feb 25.

For more about soy and reproduction, including citations, read chapter 29 of  The Whole Soy Story: The Dark Side of America’s Favorite Health Food. For information on how much soy is safe to eat read “Soy Alert” articles and blogs on this website, and also visit:


Posted on 2011 November 1, in Health and tagged , , , , , , , , , . Bookmark the permalink. Leave a comment.

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