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Copyright 2013 Natural Standard (
January 2012

Isoflavones May Reduce BPH Symptoms

Soy isoflavones may help reduce urinary tract symptoms associated with benign prostate hyperplasia (BPH), according to a recent study.

Isoflavones are a class of phytoestrogens; other classes include flavonoids, coumestans, and lignans. Phytoestrogens are naturally occurring chemicals in plants with estrogenic properties (ability to bind to estrogen receptors). Dietary isoflavones may be found in soybeans (Glycine max) or soy-derived foods (soy milk, soy flour, tempeh, soy nuts, tofu), as well as in smaller amounts in other legumes (peas, peanuts, navy beans, chick peas). The amounts in foods and crops vary depending on growth conditions and processing. Isoflavones may also be purchased in purified form, most often derived from soy or red clover.

In general, the actions of isoflavones are thought to be due to their estrogenic or antiestrogenic properties and their antioxidant action. Intakes of dietary isoflavones are low in the West due to low levels of consumed soy-derived foods. Natural intakes are higher (approximately 1-2 servings of soy, or 25-50 milligrams of isoflavones daily) in traditional diets from countries where soy-derived foods are commonly consumed. Also, due to purported health benefits, soy-derived foods are increasing in popularity in the West.

Researchers recruited 176 patients who had been diagnosed with BPH and had urinary tract symptoms. The team assigned participants to receive either soy isoflavones or a placebo for 12 months. Scientists collected data on urine flow and volume, as well as testosterone levels, quality of life and diet.

The results revealed that the soy isoflavones resulted in only slightly better reduction of symptoms, compared to placebo. The participants tolerated the isoflavones well.

The researchers concluded that consuming soy isoflavones may reduce urinary tract symptoms associated with BPH. However, more evidence is needed to confirm these findings.

The prostate is part of a man's reproductive (genitourinary) system and is located in front of the rectum and under the bladder. It surrounds the urethra, the tube through which urine flows. A healthy prostate is about the size of a walnut. Male hormones (androgens, particularly testosterone) normally produced by the body stimulate the growth of the prostate. The testicles are the main source of male hormones, including testosterone. The prostate changes size very little from birth until puberty, but at puberty it increases in weight and doubles in size. In general, the size of the prostate remains constant after puberty for the next 30 or more years. In some men, in fact, the prostate never again increases in size. Unfortunately, however, this is not the case for most men, who will develop some form of non-cancerous enlargement of the prostate, medically known as benign prostatic hyperplasia or BPH. Half of all men in their 50s and 80 percent of men in their 80s have some symptoms of BPH.

For more information about isoflavones, please visit Natural Standard's Foods, Herbs & Supplements Database.


  1. Natural Standard: The Authority on Integrative Medicine.
  2. Wong WC, Wong EL, Li H, et al. Isoflavones in treating watchful waiting benign prostate hyperplasia: a double-blinded, randomized controlled trial. J Altern Complement Med. 2012 Jan;18(1):54-60. View Abstract
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