Women definitely know why they want a macho: because they live longer!

A new research suggests that men with low levels of testosterone are 33 % more predisposed to a premature death than men with high levels of the male sex hormone.
It seems that "testosterone replacement therapy", the male equivalent of hormone replacement therapy in women, is effective.

"We are very excited by 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. We're not ready to take this to the prescribing pharmacist. It's very possible that lifestyle determines what level of testosterone a patient has. It may be possible to alter the testosterone level by lowering obesity." said lead researcher Dr Elizabeth Barrett-Connor, at the University of California's San Diego School of Medicine.

Testosterone is synthesized mainly in the testes and its levels boom at the puberty, linked to sexual development and sex drive emergence. But individual levels largely vary from man to man, depending on the age and even fatherhood.

Low testosterone levels induce lower sex drive, mood swings, weaker muscle power and tonus and higher occurrence of osteoporosis. This is normal in the "andropause" or "male menopause": 50 % of 50-year-old men will experience it and in the case of those being 70 years old the percentage grows to 70 %.

A treatment for middle-aged men in andropause are considered the testosterone patches, which boost their libido and eliminate mood swings, but there is some skepticism as long-term effects of this therapy are not known.

The research team focused on the medical records of 800 men, aged 50 to 91, over 20 years. At the beginning of the survey in the 1980s, about 35 % of the men had decreased testosterone levels for their age. This category proved to present a 33 % higher risk of dying during the following 18 years than male with high testosterone values, even when factors like smoking, drinking, physical activity or pre-existing illnesses (like heart disease and diabetes) were considered.

"This is only the second report linking deficiency of this sex hormone with increased death from all causes, over time, and the first to do so in relatively healthy men who are living in the community. This study did show there may be an association between low testosterone levels and higher mortality. It did not show that higher levels of testosterone are associated with decreased mortality." said co-author Dr Gail Laughlin.

The precise reasons are unknown, but men with the lowest levels of male's sex hormone were more likely to be obese and present high blood pressure and increased amounts of "bad" cholesterol.