Archive for Soy isoflavones
Lack of significant genotoxicity of purified soy isoflavones (genistein, daidzein, and glycitein) in 20 patients with prostate cancer.
This article is interesting given the fact that men with history of prostate cancer and women with history of breast cancer are told to avoid soy products. However, the evidence seems to support the fact that soy compounds are not only non-harmful, but possibly show a benefit.
AJCN — Abstracts: Miltyk et al. 77 (4): 875
Importance of Equol—A Clue to Effectiveness of Soy Isoflavones
We see a familiar concept here. Soy isolflavones need to be acted on by beneficial bacteria in the gut to produce equol–a nonsteroidal estrogen-like compound that is believed to be one of the most potent antioxidants in this class. This may explain some of the discrepancies in soy benefit studies and is further proof for a holistic approach to health that would include lifestyle changes to support healthy bacterial flora. We see this same concept with soluble fiber and colon cancer–the fiber needs to be acted on by beneficial bacteria to produce butyrate to protect the colonocytes.
Nutrition.org — Abstracts: Setchell et al. 132 (12): 3577
Adrenocortical Effects of Oral Estrogens and Soy Isoflavones
Just in case this email gets to an ob/gyn and they think I don’t know what I’m talking about… This article (which is a monkey study) finds that both oral contraceptive and conjugated equine estrogens (i.e. Premarin) mess with the adrenal glands in a negative way, producing too much cortisol and not enough DHEA. And, since this imbalance is well known to contribute to insulin resistance, do I need say any more?
JCEM — Abstracts: Wood et al. 89 (5): 2319 -
Soy isoflavones improve lipids in normal & mildly hypercholesterolemia
Soy is believed to act through several mechanisms (most centered on the liver) to lower cholesterol levels. The effect in this study was mild, but, as with any functional approach, with added exercise, lowering of refined carbs (high insulin will stimulate HMG-CoA reductase..the enzyme that makes cholesterol), nutrients designed to stimulate healthy liver and gall bladder function (to aid in the elimination of cholesterol through the feces) and avoidance of saturated fat and I’m the effect is no longer mild.
AJCN — Abstracts: Wangen et al. 73 (2): 225 http://www.ajcn.org/cgi/content/abstract/73/2/225
The Effect of Soy Consumption on 2:16-Hydroxyestrone Ratio in Postmenopausal Women Depends on Equol Production Status but is not influenced by Probiotic Consumption
Here’s some background…the body metabolizes estrogens down several pathways. The “2″ pathway is considered protective for certain types of cancer while the “16″ pathway is damaging. It is known that equols, compounds produced by bacterial conversion of soy isoflavones in the gut, shift the metabolization of estrogen to the 2 pathway (so does indole-3-carbonol from cruciferous veggies).
So, the idea in this study was to give probiotics with soy to see how much of an effect on equol levels was seen. There seems to be a subset of women that respond positively to this approach, but the researchers were not able to identify specifics. I do have a question for the more research-minded readers out there…
This study used a 2 week washout period. How can you get a washout period using probiotics? All things being healthy–the probiotics should maintain in the GI tract. I wonder how much this influenced the results?