San Diego: Men with higher levels of the hormone testosterone may live longer, according to a new study.
Men with low testosterone levels tend to have fatter waists, high blood pressure and higher blood sugar levels, researchers found.
Those with high levels of the male sex hormone tended to have a lower risk of heart disease and diabetes in later life.
The study – the first of its kind to look at normal, relatively fit males – could lead to men with low levels taking supplements.
The survey followed the lives of 800 men aged over 51 since the 1970s. It found that those with low testosterone levels were a third more likely to die over an 18-year period than those with high testosterone levels.
The results cast doubt on the popular wisdom that the female hormone, oestrogen, is “good” for health in later life and testosterone is ‘bad’. According to the research team at the San Diego School of Medicine, the discrepancy could not be explained by pre-existing diseases such as diabetes or heart disease.
Dr Gail Laughlin, from the school’s Department of Family and Preventative Medicine, said: “We have followed these men for an average of 18 years and our study strongly suggests that the association between testosterone levels and death is not simply due to some acute illness. The study did show there may be an association between low testosterone levels and higher mortality.”
She cautioned that the study did not directly show that higher testosterone levels protected against diseases.
Testosterone declines slowly with age. However, there is a wide natural variation in the amount that different men produce.
The researchers said that besides tending to have larger waists and higher blood pressure, men low in testosterone had higher levels of inflammatory cytokines, proteins that contribute to the development of many diseases.
The San Diego School of Medicine is now considering trials of testosterone supplements to see if they have a preventative effect.
However, Dr Elizabeth Barrett-Connor, of the San Diego School of Medicine’s Division of Epidemiology, said the prospect of men popping testosterone pills to protect against diseases was a long way off.
She said: “We are very excited about these findings, which have important implications, but we are not ready to say that men should go out and get testosterone to prolong their lives.
She also said that low testosterone levels could be a by-product of obesity and suggested it may be possible to alter testosterone levels by lowering obesity.