Are Men Becoming Less Manly?

[Angel]

A recent collaboration of studies documents the gradual decline of testosterone amongst American men over the last two decades.

Testosterone: the male sex hormone - is important for maintaining bone and muscle mass. A drop in testosterone levels can lead to a lower libido and a higher risk of diabetes. Testosterone levels in men peak around their late 20s and then begin a gradual decline from age 30 onward. So it is evident that men as individuals lose testosterone as they age, but what about men the same age from different periods?

Researchers from the New England Research Institutes (NERI) in Watertown, Mass., based their findings on data from the Massachusetts Male Aging Study (MMAS). This study collected blood from 1,500 randomly selected men in the greater Boston area over 17 years.

Researchers say that the blood samples of 50-year-old men, taken in 1988, had higher levels of testosterone when compared to blood samples from 50 year old men taken in 1996. So the drop in testosterone cannot be attributed to individual aging, ruling out age as a factor.

Because hormone concentrations in the blood often fluctuate from day to day, two samples were obtained at each patient visit and were always taken at the same time - early in the morning - when testosterone levels are at their highest.

Over a span of the last 20 years, there has been about a 15-percent decrease between different groups of same-aged people, according to lead author Thomas G. Travison, Ph.D. "It could be an alarming trend that indicates other factors that are changing over time that we don't yet have a complete handle on," Dr. Travison told Ivanhoe.

The reasons for this decline are unclear; the study suggests neither aging nor changes in certain health factors, such as body weight/BMI, or smoking, can completely explain the phenomenon.

"There may be health-related or environmental effects we didn't measure," Dr. Travison said. "Gradual trends at the population level can presage dramatic trends at the individual level."

While testosterone is present in females, the level trend for women has yet to be studied.