Men’s Health

Isoflavones, having a structure similar to the female hormone estrogen, have beneficial effects on women but what about their influence on men? On the internet you can find many stories about the possible feminizing effects of isoflavones on men: they may cause men to grow breasts and even to lactate and may be bad for their reproductive health. No scientific studies exist to substantiate these claims. To the contrary, studies show that isoflavones have no effect on male fertility and can even improve male’s health. Isoflavones are antioxidants which protects cells from oxidative damage and more specifically they may reduce the risk of prostate cancer.

Prostate cancer and isoflavones

At a later age, men’s health is much related with prostate health. In Japan and other Asian countries where a lot of soy is consumed, prostate cancer is 5 times rarer than in Western countries where a very little amount of isoflavones is consumed. It appears that isoflavones have a positive effect on male hormone-related cancers. Prostate cancer is linked to testosterone levels and is often treated by reducing the level of testosteron. Clinical studies on males show the beneficial role of soy in reducing hormonal levels. The male hormone, testosterone, has is needed for the development of typical male characteristics but if a man develops prostate cancer, testosterone will hasten its progression. Studies indicate that soy isoflavones might inhibit human prostate cancer development by the inhibition of growth of prostate cells.

A recent Japanese study published in the August 2007 edition of the Journal of Nutrition concluded that the intake of soy isoflavones may reduce the risk of prostate cancer by 58 per cent. In this case-control study the dietary intakes of 200 men with different stages of prostate cancer were those of 200 healthy male controls. The researchers found that an increased intake of the soy isoflavones was significantly associated with a decreased risk of prostate cancer.


Geller J et al. Genistein inhibits the growth of human-patient BPH and prostate cancer in histoculture. Prostate Feb 2000.

Effect of a phytoestrogen food supplement on reproductive health in normal males. Clin Sci (Lond). 2001 Jun;100(6):613-8

Soy isoflavone supplementation in healthy men prevents NF-kappaB activation by TNF-alpha in blood lymphocytes. Free Radic Biol Med 2001;30:1293-1302

Prevention of spontaneous prostate-related cancer in Lobund-Wistar rats by a soy protein isolate – isoflavone diet. Prostate 2000 Oct 1;45(2):101-5

Soy isoflavones in the treatment of prostate cancer. Nutr Cancer 2003;47(2):111-7