phytoestrogen content. Men have told me they avoid these foods because they think it will take their testerone out of balance, and therefore, inhibit muscle growth and decrease fertility, or they avoid it because of other health concerns. As I probably mentioned before, I have come across a lot of women here too that completely avoid soy and think it is the root of many of our health problems (including AHDH, autism, diabetes, etc).
Here is what we know:
- Phytoestrogens (PE's) are compounds (including isoflavones, lignans, and coumestans) which are structurally similar to the hormone estrogen in human beings. These are found in grains, beans, seeds, berries, fruit, vegetables, and root crops (so if you are looking to avoid them, you are cutting out the foundation of a healthy diet). Another fun fact: they are found in trans-resveratrol in red wine which has been shown to be protective for cardiac health.
- Studies are not definitive, but many suggest that soy protein intake may help prevent breast cancer. In the Shanghai Breast Cancer Survival Study, the authors concluded: "Among women with breast cancer, soy food consumption was significantly associated with decreased risk of death and recurrence" (2). However, the findings of different studies are mixed, with the strongest trend showing that soy intake during adolescence may be protective against developing breast cancer later in life.
- PE's help to regulate blood-sugar balance, which is involved in insulin metabolism and weight control
- Only when PE's are isolated and concentrated (as in supplement form) do they actually promote some types of cancer growth
- Only a few studies have shown that in rats with high PE intakes their fertility decreases. However, most of these studies did not take into account other factors such as oxidative stress, so they are inconclusive.
- More research is still needed on PEs, but overall, the studies show no, or possibly, a favorable effect of eating a high PE diet (through food sources!). The message is that the studies are inconclusive.
- In order to get the most benefit, you need to eat PE's in natural food form, and DO NOT use supplements or concentrated doses. If you are a women with breast cancer or without ovaries, consult with your doctor before adopting a high PE diet (PE's act differently on these types of women).
My recommendation: Eat lots of beans, whole grains, fruits, vegetables, and yes... even soy and flax!
1. Feminist Women's Health Center Website: www.fwhc.org/health/phytoestrogens.htm
2. Boyapati, S. M., et al. (2005). Soyfood intake and breast cancer survival: a followup of the Shanghai Breast Cancer Study. Breast Cancer Research Treatment. 92, 11-17.
3. The World's Healthiest Foods Website. "Do phytoestrogens, like those found in flaxseed, have an effect on male hormone balance?" http://whfoods.org/genpage.php?tname=dailytip&dbid=144&utm_source=rss_reader&utm_medium=rss&utm_campaign=rss_feed
4. Linus Pauling Micronutrient Information Center. http://lpi.oregonstate.edu/infocenter/phytochemicals/soyiso/