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Testosterone: Difference between revisions
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There has been a secular decline in male T levels in Western countries that is independent of factors such as population aging and increased obesity,<ref>https://academic.oup.com/jcem/article/92/1/196/2598434?login=true</ref> leading to sensationalist headlines regarding rampant [[soyboy|feminization]] of men being driven by this factor alone. However, other longitudinal studies have found concurrent evidence that sex-hormone-binding globulin (SHBG), a protein that binds to testosterone and makes it inert in the body, has also been decreasing on a population and cohort level.<ref>https://academic.oup.com/jcem/article/92/12/4696/2597312?login=true</ref> | There has been a secular decline in male T levels in Western countries that is independent of factors such as population aging and increased obesity,<ref>https://academic.oup.com/jcem/article/92/1/196/2598434?login=true</ref> leading to sensationalist headlines regarding rampant [[soyboy|feminization]] of men being driven by this factor alone. However, other longitudinal studies have found concurrent evidence that sex-hormone-binding globulin (SHBG), a protein that binds to testosterone and makes it inert in the body, has also been decreasing on a population and cohort level.<ref>https://academic.oup.com/jcem/article/92/12/4696/2597312?login=true</ref> | ||
If this finding proves robust, this reduction in SHBG would result in less negative feedback being exerted on men's hypothalamic-pituitary-gonadal axis (HPG axis), which would lead to the body downregulating T production as it essentially needs less to produce the desired effects. Meaning the secular decrease in T wouldn't be particularly relevant in driving any practical differences in population level masculinization. SHBG is likely lowering due to increasing obesity, meaning that obese men would often have lower T levels (due to higher aromatization of T to estrogen, as the fat cells contain the aromatase enzyme<ref>https://pubmed.ncbi.nlm.nih.gov/11399122/</ref>) but would also be more sensitive to the testosterone they do produce. | If this finding proves robust, this reduction in SHBG would result in less negative feedback being exerted on men's hypothalamic-pituitary-gonadal axis (HPG axis), which would lead to the body downregulating T production as it essentially needs less to produce the desired effects. Meaning the secular decrease in T wouldn't be particularly relevant in driving any practical differences in population level masculinization. SHBG is likely lowering due to increasing obesity, meaning that obese men would often have lower T levels (due to higher aromatization of T to estrogen, as the fat cells contain the aromatase enzyme<ref>https://pubmed.ncbi.nlm.nih.gov/11399122/</ref>) but would also be more sensitive to the testosterone they do produce. | ||
Serum testosterone levels are far less clinically relevant than levels of unbound (free) testosterone, so what is important to establish a real decline in T levels would be to prove that levels of free-testosterone are falling. | |||
Another flaw with many of these studies is that they do not control for the fact that smoking has massively decreased in Western countries,<ref>https://ncci.canceraustralia.gov.au/prevention/smoking-prevelance/smoking-prevalence-adults</ref> with cigarette consumption peaking in the 1950s and falling to low levels in the modern era.<ref>https://ourworldindata.org/smoking</ref> | Another flaw with many of these studies is that they do not control for the fact that smoking has massively decreased in Western countries,<ref>https://ncci.canceraustralia.gov.au/prevention/smoking-prevelance/smoking-prevalence-adults</ref> with cigarette consumption peaking in the 1950s and falling to low levels in the modern era.<ref>https://ourworldindata.org/smoking</ref> | ||