D
Deleted member 23391
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Stop listening to broscience from idiot gymcels. Cholesterol is NOT the rate-limiting factor of steroidogenesis. In men without damage to the testicles, the reason for lower testosterone is SECONDARY (having to do with the hypothalamus or pituitary not sending enough of a signal to the testicles). Not insufficient cholesterol or fat. That is to say that testosterone levels are regulated by brain signaling. The endogenous cholesterol production is more than enough to supply substrate for testosterone synthesis, hence why vegans have similar levels of testosterone to meat eaters despite eating little to no cholesterol.
Vegans have equal or higher testosterone levels:
https://pubmed.ncbi.nlm.nih.gov/32332862/
https://pubmed.ncbi.nlm.nih.gov/33599941/
For testosterone synthesis cholesterol requirements, healthy adult males produce ~14-42 micromoles testosterone per day:
https://www.ncbi.nlm.nih.gov/pubmed/14083165
One molecule of testosterone requires one molecule of cholesterol. Under gonadotropin stimulation, 700 million Leydig cells (however, adults can have up to 1573 million so this is a conservative estimate - pubmed.gov/3779804) synthesize ~13.2 micromoles per day when external sources are not provided:
https://www.ncbi.nlm.nih.gov/pubmed/736271
https://www.ncbi.nlm.nih.gov/pubmed/2226298
Meaning some plasma import is theoretically required. In humans, LDLR is the primary pathway for this, while SRB1 functions as a backup:
https://www.ncbi.nlm.nih.gov/pubmed/20515451
LDLR kinetics saturate at ~25mg/dL plasma LDL-C:
https://www.ncbi.nlm.nih.gov/pubmed/198627
whereas SRB1 kinetics saturate at ~30 mg/dL plasma HDL-C:
https://www.ncbi.nlm.nih.gov/pubmed/10872459
What that means is testosterone production is not substrate-limited unless there is extremely low blood cholesterol levels, achievable only with drugs and/or rare genetic disorders, not dietary cholesterol restriction. The human liver alone (the intestine being the other source of LDL and HDL) is capable of endogenously synthesizing ~2.6 micromoles of cholesterol per kg bodyweight per day, more than enough when considering ~70% circulating LDL-C remains unused and is simply taken up by the liver again for recycling:
https://www.ncbi.nlm.nih.gov/pubmed/8245716
Testosterone production in adult males is 4-12 mg/day, while endogenous cholesterol synthesis in humans is 12-13 mg/kg a day. The receptors responsible for delivering cholesterol to Leydig cells are saturated at 50 mg/dL and 30 mg/dL blood LDL-C and HDL-C, respectively. You have more than enough:
http://science.sciencemag.org/content/232/4746/34
http://science.sciencemag.org/content/271/5248/518
Over and above this is actually bad, for the cells can become overloaded with cholesterol or it can start to oxidize, both of which are toxic and impair production:
http://www.sciencedirect.com/science/article/pii/S002191509900310X
http://www.jbc.org/content/288/16/11509.short
Not to mention carbs are critical to have high testosterone because of SHBG, this is a protein that binds to testosterone and renders it inert. Eating carbohydrate blocks SHBG synthesis in the liver because of the increases in insulin which increases free testosterone. The more insulin you have over the course of the day, the lower the SHBG. Also, ketosis increases cortisol which reduces testosterone biosynthesis.
High SHBG is a common problem among carnivore diet practitioners. Their terrible blood work is a lot of the reason many such as Paul Saladino have started to embrace eating carbs. Also low insulin -> low IGF-1 -> stunted growth (teencels take note) @BrahminBoss
Vegans have equal or higher testosterone levels:
https://pubmed.ncbi.nlm.nih.gov/32332862/
https://pubmed.ncbi.nlm.nih.gov/33599941/
For testosterone synthesis cholesterol requirements, healthy adult males produce ~14-42 micromoles testosterone per day:
https://www.ncbi.nlm.nih.gov/pubmed/14083165
One molecule of testosterone requires one molecule of cholesterol. Under gonadotropin stimulation, 700 million Leydig cells (however, adults can have up to 1573 million so this is a conservative estimate - pubmed.gov/3779804) synthesize ~13.2 micromoles per day when external sources are not provided:
https://www.ncbi.nlm.nih.gov/pubmed/736271
https://www.ncbi.nlm.nih.gov/pubmed/2226298
Meaning some plasma import is theoretically required. In humans, LDLR is the primary pathway for this, while SRB1 functions as a backup:
https://www.ncbi.nlm.nih.gov/pubmed/20515451
LDLR kinetics saturate at ~25mg/dL plasma LDL-C:
https://www.ncbi.nlm.nih.gov/pubmed/198627
whereas SRB1 kinetics saturate at ~30 mg/dL plasma HDL-C:
https://www.ncbi.nlm.nih.gov/pubmed/10872459
What that means is testosterone production is not substrate-limited unless there is extremely low blood cholesterol levels, achievable only with drugs and/or rare genetic disorders, not dietary cholesterol restriction. The human liver alone (the intestine being the other source of LDL and HDL) is capable of endogenously synthesizing ~2.6 micromoles of cholesterol per kg bodyweight per day, more than enough when considering ~70% circulating LDL-C remains unused and is simply taken up by the liver again for recycling:
https://www.ncbi.nlm.nih.gov/pubmed/8245716
Testosterone production in adult males is 4-12 mg/day, while endogenous cholesterol synthesis in humans is 12-13 mg/kg a day. The receptors responsible for delivering cholesterol to Leydig cells are saturated at 50 mg/dL and 30 mg/dL blood LDL-C and HDL-C, respectively. You have more than enough:
http://science.sciencemag.org/content/232/4746/34
http://science.sciencemag.org/content/271/5248/518
Over and above this is actually bad, for the cells can become overloaded with cholesterol or it can start to oxidize, both of which are toxic and impair production:
http://www.sciencedirect.com/science/article/pii/S002191509900310X
http://www.jbc.org/content/288/16/11509.short
Not to mention carbs are critical to have high testosterone because of SHBG, this is a protein that binds to testosterone and renders it inert. Eating carbohydrate blocks SHBG synthesis in the liver because of the increases in insulin which increases free testosterone. The more insulin you have over the course of the day, the lower the SHBG. Also, ketosis increases cortisol which reduces testosterone biosynthesis.
High SHBG is a common problem among carnivore diet practitioners. Their terrible blood work is a lot of the reason many such as Paul Saladino have started to embrace eating carbs. Also low insulin -> low IGF-1 -> stunted growth (teencels take note) @BrahminBoss
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