Estrogen—which is not just one hormone but several related compounds with very similar biological activity—only recently was discovered to be important in many physiological functions in men, including maintenance of bone mass and cognitive function.
While some estrogen is essential to men’s health, too much of it can be quite harmful, especially when in the form of 16-alpha-hydroxyestone. This chemical has been implicated for its carcinogenic activity.
Total testosterone levels peak in a man at approximately age 30. By age 40, 5% of men are thought have low testosterone levels, and by age 70, that figure goes up to at least 40-50%.
Testosterone is vitally important for both its anabolic properties, including effects on maintaining healthy cholesterol levels, protein synthesis, muscle mass and bone density, and its androgenic effects, including the development and maintenance of male secondary sex characteristics (deep voice, increase in facial and body hair, muscle development) and sexual functions such as libido and erectile capability.
As men age and testosterone levels decrease, classic signs of testosterone deficiency—andropause—frequently appear. These signs include thinning hair, decreasing libido, increasing fat mass and declining muscle mass, and even depression.
Institute of Medicine Report:
A Fair Examination?
Because of both the large increase in testosterone use among men and the aging of the estimated 50-70 million members of the baby-boom generation, in 2002, the National Institute on Aging and the National Cancer Institute directed the Institute of Medicine to assess the benefits and risks of testosterone supplementation among older men. The result was a 217-page book released in November 2003.
The section of the book, “Testosterone and Health Outcomes,” cites various studies showing that testosterone supplementation can play a significant role in alleviating many symptoms of andropause, including the loss of bone and muscle mass, depression, loss of sexual functioning, and heart disease.
One study which, surprisingly, is not cited by the Institute of Medicine, shows conclusively that testosterone levels are vitally important for overall physical function in aging men. Published in the Journal of Endocrinology and Metabolism, this study of 403 healthy men, aged 73 to 94 years, examined decreases in muscle strength, bone mass, and body composition seen in aging males and their relationship to falling testosterone levels. The researchers measured the men’s hormonal levels and ran multiple tests to gauge their body composition, muscle strength, and bone mass. Their findings were not surprising, at least to physicians well versed in anti-aging medicine—muscle strength and bone mass were at optimal levels in men with the highest levels of free testosterone.
Low Testerone Tied to Health Disorders
While optimal testosterone levels are needed to maintain muscle mass and bone strength, testosterone also is needed for cognition, sexual functioning, and even heart health. Multiple studies have confirmed that men who maintain optimal testosterone levels as they age have significantly fewer symptoms of mental senility when compared to men with low levels of testosterone.
The Institute of Medicine book confirms this and cites three widely publicized, randomized, placebo-controlled studies showing that testosterone supplementation improves verbal memory, working memory, and visuospatial performance in elderly men. Unfortunately, the Institute of Medicine also omits a landmark study published in 2002 in which 407 men, aged 50-91, were followed for 10 years and had multiple tests to determine their testosterone levels and cognitive functioning.
A third recent study, also overlooked by the Institute of Medicine, shows that elderly men who suffered from Alzheimer’s disease had lower-than-expected levels of testosterone, which the authors hypothesize may be due to brain degeneration seen in Alzheimer’s sufferers. The study authors are now investigating whether low testosterone levels precede cognitive dysfunction in men at risk for Alzheimer’s. If they do, then testosterone replacement therapy could be warranted for men with lower-than-normal testosterone levels to potentially ward off Alzheimer’s disease.
Testosterone supplementation has been shown in multiple studies to improve libido and erectile capability when administered to aging men. Given basic scientific knowledge of how testosterone plays a key role in men’s sexual development during puberty and functioning during adulthood, results such as this should come as no surprise.
With cardiovascular disease being the number-one killer of men in the US and most Western industrialized nations, it is surprising that the Institute of Medicine does not give this very important topic more consideration. As in other sections of the book, the authors overlook studies showing the beneficial effects of testosterone on heart disease, such as the Rotterdam Study, in which researchers examined Testosterone levels and cardiac health among 504 men aged 67 to 75. The researchers conclusively showed that men with higher levels of testosterone had lower levels of coronary artery disease.
Does Testosterone Cause Prostate Cancer?
Mainstream medical practitioners often have stated that prostate cancer, which in 2003 was responsible for the deaths of more than 29,000 men in the US, is caused by testosterone. Fortunately, the Institute of Medicine includes some data showing that optimal levels of testosterone do not cause prostate cancer, and in fact may protect against this major killer of elderly men.
Estrogen’s Role in Prostate Cancer
Unfortunately, while the Institute of Medicine spends 11 pages (pp. 87-98) detailing testosterone’s effect on the prostate, it offers no discussion of the possible effects of estrogen on the prostate and its role in prostate cancer. The belief that estrogen, rather than testosterone, is one of the prime hormonal initiators of prostate cancer is based on the fact that while testosterone levels are highest in young men, prostate cancer essentially is never seen in this population. It is only in older men, who have lower levels of testosterone (but higher levels of estrogen and its breakdown products), that prostate cancer is a significant health threat.
Animal studies have shown that male rats treated with testosterone alone showed significantly less prostate growth compared to animals treated with both testosterone and estrogen. A 1993 study showed that men treated with DHT (which cannot convert to estrogen) saw a reduction in the size of their prostate with no sign of prostate cancer.
The Institute of Medicine’s Recommendations
With all the positive studies cited by the Institute of Medicine, it would be reasonable to expect the authors to conclude that testosterone supplementation, to even the most conservative-minded researcher, has been shown to be efficacious for a variety of andropause-related symptoms. Unfortunately, that is not the case. In fact, the authors do not even acknowledge that low testosterone contributes to andropause in any way, shape, or form.
It is puzzling, at the very least, why the Institute of Medicine fails to even mention the significant effect of rising estrogen levels on the prostate cancer when a substantial amount of well-researched literature has been published on this very subject.
In fact, the authors cast a derisive eye on many reports showing the effectiveness of testosterone supplementation.
Apparently, at the cost of the health and possibly lives of many thousands of middle-aged and elderly men, the Institute of Medicine committee had decided that yet another trial of testosterone supplements should be conducted, a trial that will take years (and be funded by taxpayers), while those very same taxpayers are suffering from the very real, and often very debilitating symptoms, of andropuse-induced testosterone deficiency.
Instead of reading the Institute of Medicine’s book, the media instead chose to malign the multiple benefits of testosterone replacement and exaggerate its potential side effects. Testosterone and Aging cites numerous clinical studies showing significant anti-aging effects, but the media reported only the disparaging conclusions made by certain committee members that had little or no basis in fact.
Excerpted from a review by Edward R. Rosick, MD