Scientists used to think drops in the male sex hormone were simply a normal part of the aging process. Now they're rethinking that hypothesis.
We know this much: that as men age, their testosterone levels tend to drop. We've largely taken the observation to mean that aging leads to a natural decline in the sex hormone. Yet there's little evidence to prove anything beyond a coincidental relationship between age and testosterone loss. It's a hypothesis the medical establishment merely accepted as truth over time.
Now, new research suggests a decline in testosterone levels doesn't have to be a fact of life. Instead, it may be the product of lifestyle choices you make as an adult.
In a study of 1,382 men, Australian researchers discovered that individuals with certain traits and habits wound up with lower testosterone levels than their peers. Those with chronic health problems in particular were more likely to see greater declines in the hormone. Participating men in the study ranged from 35 to 80 years of age, and the average age was 54.
The study subjects were tested for blood testosterone at the beginning and at the end of a five-year study period. The passage of time evidently had very little effect on the sample population in the aggregate; on average, testosterone levels declined about one percent per year. But when the researchers examined test subjects in groups, they found greater declines among those who, at either end of the study, had been obese, depressed, or had quit smoking. What this suggests is that the aging process may have only a marginal role to play in the testosterone decline observed in older men.