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I've heard that drinking beer lowers sexual desire and potency, and that's the physiological effect of hops.

Is it true? Does drinking a lot of beer have negative long-term effects on sexual desire or potency? Or is it just an urban myth, based on negative impacts of drinking too much?

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    This question appears to be off-topic because it seems to belong on skeptics (if the claim is notable) – wax eagle Jan 21 '14 at 21:44
  • @waxeagle well, it could be. I have a bit of links, unfortunatelly all in Polish. – Danubian Sailor Jan 21 '14 at 21:47
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    @waxeagle — but, as with Homebrewing questions, this might simply be a question with overlapping audiences. The question is certainly about beer, and it's an important question I've frequently heard asked by athletes and health-conscious people in general. Any definitive answer to this question (although I suspect there is none) would certainly affect my consumption / enjoyment of beer. I think it's a good question, and not only because I answered it. – Andrew Cheong Jan 22 '14 at 8:00
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    I'd say this falls pretty squarely in the beer category of questions. A popular (perhaps even notable) claim about beer falls right in scope for this site, just like a popular (perhaps even notable) claim about rubber used in bicycle tires falls square in the realm for bicycles. – Tim Post Jan 22 '14 at 14:05
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tl;dr—We don't know (via science, at least).

Letting alone ethanol, which triggers innumerable biochemical pathways in our bodies, hops itself may affect potency and sexual desire, in males at least, but there appears to be few clinical studies supporting this claim directly. Many articles online appear to have chained together several studies (or played news-telephone) to publish indirect conclusions, many of which oversimplify the effects of estrogen. For example, contrary to popular belief, it isn't testosterone (alone) which masculinizes the male brain and behavior, but rather its interaction with estrogen, produced from testosterone through a process known as aromatization.1 So it's not as simple as more-estrogen-less-sex-drive.

I'm certainly not qualified to deliver conclusions myself, but I can at least point to some of the important studies from which current (mis)conceptions have derived.

1: Wu, M. V. et al. Estrogen Masculinizes Neural Pathways and Sex-Specific Behaviors. 2009. [PDF]

Why some claim that hops decreases sex drive...

Hops contains phytoestrogens,

substances that promote estrogenic actions in mammals and structurally are similar to mammalian estrogen 17β-estradiol (E2) [...]

Ososki, A. L. and Kennelly, E. J. Phytoestrogens: a Review of the Present State of Research. 2003. [PDF]

Specifically,

a recurring suggestion has been that hops have a powerful estrogenic activity and that beer may also be estrogenic. [...] We have identified a potent phytoestrogen in hops, 8-prenylnaringenin, which has an activity greater than other established plant estrogens.

Milligan, S. R. et al. Identification of a potent phytoestrogen in hops (Humulus lupulus L.) and beer. 1999. [PDF]

However, it's worth noting that the same paper concludes,

[...] despite the high estrogenic activity of 8-prenylnarigenin, the total estrogenic activity of beer made using whole hops is still low [...] and no detrimental health effects due to "estrogens in beer" are to be expected.

Anyway, another study led by the same researcher delved into the mechanism of action:

8-Prenylnaringenin alone competed strongly with 17β-estradiol for binding to both the α- and β-estrogen receptors.

Milligan, S. R. et al. The endocrine activities of 8-prenylnargingenin and related hop (Humulus lupulus L.) flavonoids. 2000. [PDF]

(In case one is unfamiliar with how receptors work, receptors "catch" freestanding compounds in a medium such as the bloodstream, thereby reducing their effects. The phytoestrogen in hops appears to get itself "caught" by estrogen receptors, thereby blocking those receptors from catching estrogen it'd normally catch, thereby leaving higher levels of estrogen in the bloodstream.)

...but it's not that simple!

Again, from these findings alone, conclusions about male potency and sex drive can't be so easily drawn. Hormone interactions are sufficiently complex that researchers are still trying to untangle, isolate, and explain ever-more-specific biochemical pathways. Certainly the average Joe (or journalist) wouldn't be capable of appreciating the magnitude (or triviality) of the effects of biochemical pathways described in researchers' findings, much less draw definitive conclusions about physiological effects like "potency," "sex drive," and how it all affects, say, muscle-building. Not to mention all the other chemicals in play!

As a very example of the latter, one site [link] (which, unfortunately, ranks high among Google search results) is clearly biased, grasping for evidence to "prove" that beer has detrimental effects on testosterone activity. I'm not saying beer doesn't, but their article states that Xanthohumol, another compound found in hops, "blocks testosterone," when in fact the very paper it cites says (in its abstract nonetheless),

Although hops is commonly linked with phytoestrogenic effects, we identified XN [Xanthohumol] as a pure estrogen antogonist. Interestingly, XN may also reduce the generation of estrogens by inhibition of the enzymatic activity of aromatase, which converts testosterone to estrogen. Anti-estrogenic effects of XN [...] were confirmed in vivo in an uterotrophy assay with prepubertal rats.

Strathmann, J. et al. Xanthohumol from Hops Prevents Hormone-Dependent Tumourigenesis In Vitro and In Vivo. 2008. [PDF]

On top of all this, ethanol affects so many parts of the brain via so many chemical pathways—what's even the significance of 8-prenylnarigenin or Xanthohumol when stacked against ethanol? Do you know?—I sure don't—and probably no one does—else it'd have been stated by researchers themselves, without the "help" of attention-seeking bloggers and headline-hunting journalists.

In conclusion,

I'm not saying these blogs, articles, and threads are necessarily wrong—they might be right, whether right-by-chance, or right-by-empiricism (observation). What I am saying is that they can't be right-by-science, as currently available research seems extremely domain-specific, incomplete in larger perspectives, and therefore not generalizable.


Addendum

The study by Ososki and Kennelly also states

As potential endocrine disrupters, phytoestrogens may act as antiestrogens and harm the reproductive health of males (Sharpe and Skakkebaek, 1993; Santti et al., 1998). Reduced sperm quality, undescended testes and urogenital tract abnormalities were increased in the sons of mothers taking DES compared with those who did not take the miscarriage preventative drug [...]

This statement is initially misleading as it says "males" instead of "developing males"—a fact not made clear until the following sentence. From the studies it cites (emphasis mine),

We argue that the increasing incidence of reproductive abnormalities in the human male may be related to increased oestrogen exposure in utero, and identify mechanisms by which this exposure could occur.

Sharpe, R. M. and Skakkebaek, N. E. Are oestrogens involved in falling sperm counts and disorders of the male reproductive tract? 1993. [URL]

Exposure to diethylstilbestrol (DES) induces persistent structural and functional alterations in the developing reproductive tract of males.

Santti R. et al. Phytoestrogens: Potential Endocrine Disruptors in Males. [URL]

So, more potential sources of misunderstanding and misreporting.

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I guess there are 2 important think to point out:

Beer is also alcohol

That is directly from wikipedia:

Men's sexual behaviors can be affected dramatically by alcohol. Both chronic and acute alcohol consumption have been shown in most (but not all) studies to inhibit testosterone production in the testes. This is believed to be caused by the metabolism of alcohol reducing the NAD+/NADH ratio both in the liver and the testes; since the synthesis of testosterone requires NAD+, this tends to reduce testosterone production.

As testosterone is critical for libido and physical arousal, alcohol tends to have deleterious effects on male sexual performance. Studies have been conducted that indicate increasing levels of alcohol intoxication produce a significant degradation in male masturbatory effectiveness (MME). This degradation was measured by measuring blood alcohol concentration (BAC) and ejaculation latency. Alcohol intoxication can decrease sexual arousal, decrease pleasureability and intensity of orgasm, and increase difficulty in attaining orgasm.

Since wikipedia show related soruce of that info and most of them are clinical research, we can say that alcohol have a negative effect on men.

In many women, alcohol increases sexual arousal and desire, although it does lower the physiological signs of arousal. Women have a different response to alcohol intoxication. Studies have shown that acute alcohol consumption tends to cause increased levels of testosterone and estradiol. Since testosterone controls in part the strength of libido in women, this tends to cause an increase in interest in sex. Also, because women have a higher percentage of body fat and less water in their bodies, alcohol can have a quicker, more severe impact. Women’s bodies take longer to process alcohol; more precisely, a woman's body often takes one-third longer to eliminate the substance.

Sexual behavior in women under the influence of alcohol is also different from men. Studies have shown that increased BAC is associated with longer orgasmic latencies and decreased intensity of orgasm. Some women report a greater sexual arousal with increased alcohol consumption as well as increased sensations of pleasure during orgasm. Because ejaculatory response is visual and can more easily be measured in males, orgasmic response must be measured more intimately. In studies of the female orgasm under the influence of alcohol, orgasmic latencies were measured using a vaginal photoplethysmograph, which essentially measures vaginal blood volume.

Different from men, we can say alcohol have more pros beside few cons for women.

Beer and couples

Men

Beer is probably the least powerful aphrodisiac alcoholic drink. The alcohol percentage in beer is low, meaning that more liquid has to be consumed to raise men's testosterone levels to hit that "comfortable" level. Most beers are very nourishing and filling, and when too many of them are consumed, they can create an unpleasant stomachache. Drinking too much beer will make men go to the washroom more often, as well as create a bloating sensation. The effects of being bloated surely don't entice sexual encounters and won't lead men to seek out sexual opportunities. Yet, some special beers have a local reputation for increasing libido, but even with that, beer is not the best choice for men.

Women

While hops in beer will have a negative impact on men’s hormonal balance, it may actually be positive for women. Hops has aphrodisiac-like qualities for women, as because of the phytoestrogen it contains, which mimic natural estrogen. Low sex drive in women is often cause by low levels of estrogen.

Consuming beer, especially hop-rich varieties like IPA, could actually help restore hormonal balance and help with libido and also alleviate menopausal symptoms of fatigue, irritability and hot flashes

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Without getting technical, I think it really depends on the individual person just as much as the science behind it, hence the articles from previous posts. I have known females that will get extremely aroused just by drinking one or two sips of alcohol, this is due to the fact that these individuals actually had a very satisfying encounter with alcohol and sex, others may be put off if the experience was bad. I think quantity is key to sex and alcohol. Drinking alcohol impairs judgement and can make a person more out going and take more risk too much drinking can lead to passing out or getting the o' limp noodle despite the fact that you want to have intercourse. I guess there is not an exact scientific answer.

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