Beer and hops have direct pro-estrogenic effects.
"drinking beer, beer and hops are directly pro-estrogenic. Men listening, [laughter] if you're a beer drinker, you're literally drinking an estrogen tincture." (said at 0:37:32)
Hops contain prenylflavonoids, notably 8-prenylnaringenin (8-PN), which is recognized in laboratory studies as a potent phytoestrogen that directly binds human estrogen receptors. Additionally, intestinal microbiota can metabolize isoxanthohumol found in hops into 8-PN. However, describing beer as 'literally drinking an estrogen tincture' with direct pro-estrogenic physiological effects in human drinkers significantly overstates the evidence. Concentrations of 8-PN in commercial beers are very low, animal models have shown that estrogenic tissue stimulation requires concentrations roughly 500-fold higher than those found in beer, and controlled human intervention trials measuring moderate beer consumption show no significant change in plasma estradiol levels.
- supports: The endocrine activities of 8-prenylnaringenin and related hop (Humulus lupulus L.) flavon… (The Journal of clinical endocrinology and metabolism 2000)
"8-Prenylnaringenin alone competed strongly with 17ss-estradiol for binding to both the alpha- and ss-estrogen receptors." (abstract, results, passage verified)
pubmedfull study (doi) - context: Oestrogenic activity of the hop phyto-oestrogen, 8-prenylnaringenin. (Reproduction (Cambridge, England) 2002)
"When the compound was given to ovariectomized mice in their drinking water, oestrogenic stimulation of the vaginal epithelium required concentrations of 100 mug ml(-1) (about 500-fold greater than can be found in any beer)." (abstract, results, passage verified)
pubmed - contradicts: Effect of moderate alcohol consumption on plasma dehydroepiandrosterone sulfate, testoster… (Alcoholism, clinical and experimental research 2004)
"Plasma testosterone level decreased in men by 6.8% (95% confidence interval, -1.0- -12.5), but no effect was found in women. Plasma estradiol level was not affected." (abstract, results, passage verified)
pubmedfull study (doi)