Secular decline in testosterone levels

A Population-Level Decline in Serum Testosterone Levels in American Men

Context: Age-specific estimates of mean testosterone (T) concentrations appear to vary by year of observation and by birth cohort, and estimates of longitudinal declines in T typically outstrip cross-sectional decreases. These observations motivate a hypothesis of a population-level decrease in T over calendar time, independent of chronological aging.

Objective: The goal of this study was to establish the magnitude of population-level changes in serum T concentrations and the degree to which they are explained by secular changes in relative weight and other factors.

Design: We describe a prospective cohort study of health and endocrine functioning in randomly selected men of age 45–79 yr. We provide three data collection waves: baseline (T1: 1987–1999) and two follow-ups (T2: 1995–1997, T3: 2002–2004).

Setting: This was an observational study of randomly selected men residing in greater Boston, Massachusetts.

Participants: Data obtained from 1374, 906, and 489 men at T1, T2, and T3, respectively, totaling 2769 observations taken on 1532 men.

Main Outcome Measures: The main outcome measures were serum total T and calculated bioavailable T.

Results: We observe a substantial age-independent decline in T that does not appear to be attributable to observed changes in explanatory factors, including health and lifestyle characteristics such as smoking and obesity. The estimated population-level declines are greater in magnitude than the cross-sectional declines in T typically associated with age.

Conclusions: These results indicate that recent years have seen a substantial, and as yet unrecognized, age-independent population-level decrease in T in American men, potentially attributable to birth cohort differences or to health or environmental effects not captured in observed data.

What’s behind this, if true? The authors say that smoking and obesity have been factored out. Some other possibilities: xenoestrogens, for instance in soy: use of pornography; endocrine disruptors in plastics; perhaps even feminism with the displacement of men in the workplace. It’s been shown that diets high in saturated fat are better for T levels, so maybe the urging to eat less sat fat has had an effect.

For what it’s worth, at least one urologist believes that declining sperm counts are a myth. Not the same as T levels of course, but how certain is our knowledge of declining T levels?

image_pdfimage_print

Leave a Comment:

7 comments
Steve Parker, M.D. says April 1, 2014

You gotta wonder about environmental endocrine disrupting chemicals (sometimes called persistent organic pollutants).

-Steve

Reply
J says April 1, 2014

Female bosses and bossy females sure depress ME.

Reply
Noah Saenger says April 2, 2014

And if you want to increase your testosterone, you’re suddenly looked upon with suspicion. See also:
http://andro-plus.com/6_Surprising_Things_Causing_Low_Testosterone_Worldwide

Reply
Anonymous says April 6, 2014

I’d say it’s the new diapers/nappies and the overheating of infant boys testes they cause.

Reply
My experience with an aromatase inhibitor - Rogue Health and Fitness says March 3, 2015

[…] been a generational, secular decline in testosterone levels, which may be caused by environmental pollutants, endocrine disruptors, or obesity, or all of them […]

Reply
Best aromatase inhibitor and my experience with it - Rogue Health and Fitness says September 16, 2015

[…] been a generational, secular decline in testosterone levels, which may be caused by environmental pollutants, endocrine disruptors, or obesity, or all of them […]

Reply
Natural Testosterone Boosters - Rogue Health and Fitness says December 5, 2016

[…] therapy) has become a hot topic among men in general and readers on this site, understandably given the secular decline in testosterone levels. The causes of this secular decline are unknown, but speculation centers on obesity and […]

Reply
Add Your Reply