6,353
edits
Testosterone: Difference between revisions
Jump to navigation
Jump to search
m
→Secular decline in T-levels of Western men
| Line 14: | Line 14: | ||
==Secular decline in T-levels of Western men== | ==Secular decline in T-levels of Western men== | ||
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. | 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. | ||
Many men have high serum T levels because their level of SHBG is high, which means most of the T they produce is effectively useless. Cross-national and cross-temporal difference in diet and general lifestyle also likely play much of a role in determining the hormonal profile of men from said countries and periods. For example, intakes of dietary protein in wealthy Western countries generally higher than in developing countries,<ref>https://www.wri.org/data/people-are-eating-more-protein-they-need-especially-wealthy-regions</ref> which together with dietary fibre intake also being negatively correlated with country level economic development,<ref>https://www.robertbarrington.net/fibre-intake-various-countries/</ref> generally results in lower levels of SHBG in the bloodstream, which would again lead to the bodies of Western individuals being generally more sensitive to the effects of T compared to people in developing countries. <ref>https://academic.oup.com/jcem/article/85/1/293/2854619?login=true</ref> | Many men have high serum T levels because their level of SHBG is high, which means most of the T they produce is effectively useless. Generally the body tries to maintain strong homeostasis when it comes to hormones. Cross-national and cross-temporal difference in diet and general lifestyle also likely play much of a role in determining the hormonal profile of men from said countries and periods. For example, intakes of dietary protein in wealthy Western countries generally higher than in developing countries,<ref>https://www.wri.org/data/people-are-eating-more-protein-they-need-especially-wealthy-regions</ref> which together with dietary fibre intake also being negatively correlated with country level economic development,<ref>https://www.robertbarrington.net/fibre-intake-various-countries/</ref> generally results in lower levels of SHBG in the bloodstream, which would again lead to the bodies of Western individuals being generally more sensitive to the effects of T compared to people in developing countries. <ref>https://academic.oup.com/jcem/article/85/1/293/2854619?login=true</ref> | ||
These are all factors that need to be taken into account when trying to examine cohort level differences in hormonal profiles. | These are all factors that need to be taken into account when trying to examine cohort level differences in hormonal profiles. | ||