Woke up from my insomnia and just found this on /r/HumanMicrobiome/ and only skimmed it.
https://sci-hub.tw/https://www.physiology.org/doi/abs/10.1152/ajpendo.00338.2019
Figure 10. Comparison of unconjugated androgen levels in feces and serum of young adult
men. Unconjugated (free) dihydrotestosterone (DHT) and testosterone (T) levels were measured
by gas chromatography-tandem mass spectrometry. Grey bars: serum, white bars: feces. Values
are shown as mean SEM, n = 8. * p = 0.016 according to Student’s two-tailed paired t-test
WTF
The finding of very high free DHT levels in the distal intestinal content of mice with a normal
GM composition and men was unexpected, and the physiological and pathophysiological
roles of DHT within the distal intestine are mainly unknown. DHT has been reported to
increase smooth muscle contractility in colon, an action dependent on the androgen receptor
(22, 23). Furthermore, androgens can influence intestinal endothelial function (5). It is, thus,
justified to hypothesize that the high levels of DHT, being the most potent androgen, could
have a role in the regulation of the contractility and permeability of the distal intestinal wall.
Our novel finding of high free DHT levels in the distal intestinal content of mice and men
may have implications also for the pathophysiology of intestinal diseases. In humans, the age adjusted incidence of colon cancer is higher in men than in women (1, 18) and a study in rats
has shown that orchidectomy decreases the risk of colonic adenomas, while T treatment of
orchiectomized rats increases this risk (3). In addition, irritable bowel syndrome (IBS) has
been reported to be more common in women than in men (31) and it has been suggested that
androgens protect against IBS (27). Furthermore, male patients with IBS show a different
symptomatology than women, with more men reporting diarrhea, whereas constipation is
more common in females (11, 36). One may speculate that pharmacological or nutritional
treatments affecting the GM composition may change the free DHT levels in the distal
intestine, and thus have an impact on the risk and pathophysiology of intestinal diseases
having a link to androgens, such as colon cancer or IBS.
In conclusion, the findings in the present study demonstrate that the GM in the cecum
deglucuronidates high levels of glucuronidated DHT and T found in the small intestinal
content. This results in remarkably high free levels of the potent androgen DHT in the distal
intestinal content of healthy young mice of both sexes and men. We propose that treatments
with probiotics or changes in the diet affecting the GM composition might modulate intestinal
androgen metabolism and, thereby, affect the risk of androgen-related diseases mainly in the
distal intestine, but potentially also at extra-intestinal locations. Further studies are needed to
evaluate the physiological and pathophysiological roles of the high levels of free DHT in the
distal intestine.