TimT said:
Do hop oestrogens have a cumulative effect though? Is it prolonged exposure to them that might have an effect on a person?
The phytoestrogens in hops, black cohosh, etc are estimated to be roughly 1/100th the strength of endogenous oestrogen's.
They very weakly competitively inhibit endogenous oestrogen's - so herbalists use them to blunt the effects of very high levels of endogenous oestrogen's.
Conversely, if a girl has very low levels of oestrogen's, the phytoestrogens are intended to very weakly contribute to the overall oestrogen effect.
Men have different levels of oestrogen receptors and essentially don't have the various tissues that are particularly sensitive to oestrogen. So basically that's saying what Dave70 et al said - the very weak oestrogenic effect of hops in IPAs etc is going to be negligible, at least in men. The man boobs are from being a fat *******, not a big girl.
FWIW, alcohol has the effect of increasing endogenous oestrogen levels by reducing the kidney's clearance of excess oestrogen's in the body. So given the comparative strength of endogenous oestrogens, the alcohol itself is likely to have a much greater impact on overall oestrogenic effects within the body, compared to phytoestrogens from hops. So the man boobs are from being an alcoholic fat ******* ...
2c
PS: i'd suggest the negative health effect of the alcohol far outweighs any real health benefit of the herbal components in the beer. It might help a fraction more than not having them in there, but i'd say if you're that worried about your health then drink less booze. And if you prefer the succulent nectar of an IPA, then just enjoy 1 really good one - quality rather than quantity.