Lignans: Men’s Health
Flax lignans have many potential benefits for men, specifically in areas related to prostate health. Because of the growing health problem a great deal of attention is being focused on benign prostatic hyperplasia (BPH). The American Urological Association estimates that BPH affects 50 percent of men aged 50 to 60 and up to 90 percent of men over the age of 80.
This condition can be a problem because the urethra, the tube carrying urine from the bladder to outside the body, runs through the prostate (see illustrations). A growing prostate can pinch off the urethra and cause uncomfortable symptoms, like a frequent and overwhelming urge to urinate and painful urination. The exact cause of BPH is unknown but male hormones seem to play a role. Hormones also play a role in another prostate condition— prostate cancer, the second leading cause of cancer death among men. Estimates indicate over 350,000 American men will be diagnosed with prostate cancer and 42,000 will die of it this year. Once considered a disease of the elderly, prostate cancer is being diagnosed increasingly in men in their 40s and 50s. Fifty-nine percent of all men will experience some degree of prostate cancer in their lifetime.
In the body, testosterone is converted to a more potent form called dihydrotestosterone or DHT. Normal, healthy prostate cells require DHT for growth. However, it is thought that too much of the hormone can cause abnormal growth— leading to an enlarged prostate (BPH) or causing prostate cancer cells to divide. Therefore, prostate health depends on balanced levels of these hormones.
Medical treatment for BPH is readily available but the use of dietary supplements to manage prostate health is becoming increasingly common. Flax lignans are an example of one nutritional ingredient that can contribute to prostate health, naturally. Researchers have found that concentrations of lignans are higher in the urine and prostate fluid of populations that have a lower risk of prostate cancer. This indicates that people who eat more foods containing lignans have lower risk of prostate cancer.
Lignans are phytoestrogens and therefore may play a valuable role in influencing hormone metabolism, including testosterone. Because testosterone and its metabolites are important in the development of BPH and prostate cancer, lignans may help maintain a healthy prostate by influencing the metabolism of these hor-mones. In one study lignans were shown to block the action of the enzyme (5 alphareductase) that converts testosterone into the more potent form (DHT). Additionally, lignans have also been shown to inhibit other enzymes, which are essential for the synthesis of testosterone and estrogen. Lignans may also potentially reduce the amount of testosterone available for the body to use. In the average male, only a small amount of testosterone roams free in the blood. Most testosterone is bound to protein called sex hormone binding globulin (SHBG). An increase in SHBG would theoretically leave less testosterone available to stimulate prostate cell growth. Lignans have been shown to increase SHBG production in test tube studies and research also demonstrates that people consuming large amounts of lignans exhibit increased blood levels of SHBG.
Recently researchers at Duke