January 01, 2008
No Testosterone Performance Boost For Aged?

Pro baseball players might get a performance boost from testosterone supplements. But a study of some old guys in the Netherlands found testosterone supplements for low testosterone old guys didn't boost their performance.

Older men with low testosterone levels who received testosterone supplementation increased lean body mass and decreased body fat, but were no stronger and had no improvement in mobility or cognition compared with men who did not use the supplement, according to a study in the January 2 issue of JAMA.

I find it surprising the men had more lean muscle mass but weren't any stronger. However, a lot of guys would enjoy the decrease in body fat since they'd look better.

“Male aging is associated with a gradual but progressive decline in serum levels of testosterone, occurring to a greater extent in some men than in others. Decline in testosterone is associated with many symptoms and signs of aging such as a decrease in muscle mass and muscle strength, cognitive decline, a decrease in bone mass, and an increase in (abdominal) fat mass,” the authors write. Clinical trials examining whether testosterone supplementation provides benefits or adverse effects have yielded mixed findings.

Marielle H. Emmelot-Vonk, M.D., of University Medical Center Utrecht, the Netherlands, and colleagues conducted a randomized, placebo-controlled study to assess the effects of testosterone supplementation on functional mobility, cognition, bone mineral density, body composition, lipids, quality of life, and safety parameters in older men with testosterone levels less than 13.7 nmol/L (less than the average level in this age group) during a period of six months. The trial, conducted from January 2004 to April 2005, included 207 men between the ages of 60 and 80 years. Participants were randomly assigned to receive 80 mg of testosterone undecenoate or a matching placebo twice daily for six months.

The results were mixed. I think what is needed is a much longer term study so that differences in all cause mortality could become clear.

The researchers found that during the study, lean body mass increased and fat mass decreased in the testosterone group compared with the placebo group but these factors were not accompanied by an increase of functional mobility or muscle strength. Cognitive function and bone mineral density did not change. Insulin sensitivity improved but high-density lipoprotein cholesterol (the “good” cholesterol) decreased. By the end of the study, 47.8 percent in the testosterone group vs. 35.5 percent in the placebo group had the metabolic syndrome (a strong risk factor for cardiovascular disease and type 2 diabetes, a group of several metabolic components in one individual including obesity and dyslipidemia). This difference was not statistically significant.

Quality-of-life measures did not differ aside from hormone-related quality of life in the testosterone group. Adverse events were not significantly different in the two groups. Testosterone supplementation was associated with an increase in the concentrations of blood creatinine, a measure of kidney function, and hemoglobin and hematocrit, two red blood cell measures. No negative effects on prostate safety were detected (some reports have suggested that testosterone therapy could increase the risk of development or progression of prostate disease or cancer).

This is an important study because the differences in testosterone levels were caused by testosterone supplementation, not by naturally occurring differences between people. Other studies have found indications of possible benefit from having naturally occurring higher testosterone. See my posts Low Testosterone Men Die More Rapidly and Low Testosterone Men Die Sooner and Higher Testosterone Men Face Lower All Cause Mortality. But these studies on naturally occurring testosterone levels do not demonstrate the order of cause and effect. It could be that the men with higher testosterone have higher testosterone because they are more healthy. Maybe their genes cause them to age more slowly and age-adjusted relative youthfulness of their bodies allows their bodies to make more testosterone.

We need long term double blind controlled clinical studies of testosterone supplementation to find out if it is a net help or net harm. We simply do not know at this point. Personally, I'd rather have rejuvenated stem cell therapies, gene therapies, and nanomachine repair devices injected into me (at least as long as they won't take over my brain). I don't hold out big hopes for hormone supplementation therapies. We need to fix and replace what wears out. For that we need gene therapies and cell therapies.

Share |      Randall Parker, 2008 January 01 10:30 PM  Aging Treatment Studies


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