The associations of age, lifestyle factors and chronic disease with testosterone in men: the Tromso Study

Abstract

Objective: To study whether lifestyle factors and/or chronic disease are associated with the age-related decline of total and free testosterone in men, or if these factors might be associated with the variation of total and free testosterone but not with their age-related decline. Design: A population-based, cross-sectional study was used. Methods: Total testosterone and sex hormone binding globulin (SHBG) levels were analyzed and free testosterone levels were calculated in 1563 men participating in the Tromsø study in 1994/1995. Anthropometric characteristics were also measured and two standardized questionnaires completed, including lifestyle factors and medical history. The data were analyzed with multiple linear regression analysis of covariance, and logistic regression. Results: Total and free testosterone were inversely associated (P ¼ 0.001 and P , 0.001), while SHBG was positively associated (P , 0.001) with age. Body mass index (BMI) was inversely associated with total (P , 0.001) and free (P ¼ 0.016) testosterone and SHBG (P , 0.001). Both total and free testosterone were positively associated with tobacco consumption (P , 0.001 and P ¼ 0.004) and total testosterone was positively associated with coffee consumption (P , 0.001). SHBG was positively associated with smoking (P ¼ 0.004) and coffee consumption (P , 0.001). Men who reported having had a stroke or having a cancer diagnosis had lower levels of total testosterone (P , 0.001 and P , 0.01) and free testosterone (P , 0.01). Conclusions: BMI and smoking are independent contributors to the variation of total and free testosterone and SHBG levels, and coffee consumption to the variation of total testosterone and SHBG. Thus, lifestyle factors can have a direct effect on circulating levels of free endogenous sex hormones and to total levels due to the effect on SHBG levels.

Are declining testosterone levels a major risk factor for ill-health in aging men?

“…Higher BMI and waist circumference are associated with lower total, bioavailable or free testosterone and SHBG. 6,7,[144][145][146] The association between higher BMI and lower total testosterone appears more consistent that between BMI and free testosterone. 146,147 Smoking, lower alcohol intake and physical activity or vigorous exercise are factors associated with higher total testosterone and SHBG levels.…”

“…146,147 Smoking, lower alcohol intake and physical activity or vigorous exercise are factors associated with higher total testosterone and SHBG levels. 6,7,147 However, other studies have not confirmed these associations. 148,149 It is important to note the severe damaging effects of smoking on cardiovascular and respiratory health far outweigh any possible benefit it may confer on testosterone levels.…”

“…In cross-sectional and longitudinal studies of men aged 30 or 40 years and above, total, bioavailable and free testosterone concentrations fall with increasing age with a steeper decline in bioavailable and free compared with total testosterone concentrations. [5][6][7][8][9][10][11][12] It is noteworthy that the falls in total and bioavailable or free testosterone levels are consistently greater in longitudinal studies than in cross-sectional analyses. 11,12 Thus, in the Massachusetts Male Aging Study of 1709 men aged 40-70 years at baseline, total testosterone declined cross-sectionally by 0.8% per year of age compared with a 2% decline in free and bioavailable testosterone, whereas the longitudinal declines within participating men were 1.6 and 2-3% per year of age, respectively.…”

Impact of Aging on Steroid Hormone Biosynthesis and Secretion

“…As early as 50-60 years ago it was realized that aging is accompanied by significant reduction in testosterone levels [97,98]. Although some follow-up studies failed to detect age-related decline in plasma testosterone levels in older men [99][100][101][102][103][104], subsequent population-based cross-sectional and longitudinal studies have confirmed progressive loss of testosterone with aging in healthy men [96,[105][106][107][108][109][110][111][112][113][114][115][116][117][118][119][120][121][122]. Mirroring this decline in plasma testosterone concentration is an age associated increase in sex-hormonebinding globulin (SHBG) level [117], a major plasma carrier of testosterone, resulting in even more dramatic decreases in unbound free testosterone [110,[123][124][125], and weakly bound bioavailable testosterone [126,127].…”

Testosterone Replacement Therapy in Reversing “Andropause”: What Is the Proof-of-Principle?

“…161 However, many studies have evaluated the effect of cigarette smoking on levels of male reproductive hormones, and findings still remain controversial. [161][162][163][164] Coffee consumption and physical exercise increased levels of TT and SHBG. 154,160 Interestingly, with the aim to determine whether greater participation in healthier behaviors, (i.e., refraining from smoking, maintaining physical activity, avoiding excessive alcohol consumption, eating more fish and less meat, avoiding adding salt to food, having a BMI] < 25 kg/m 2 , and consuming reduced-fat milk or skimmed milk) predicted reduced risk of subsequent lower circulating T in older men, Yeap et al conducted a crosssectional analysis of a population-based follow-up study concerning 3,453 men aged 65-83 years.…”