Grapefruit juice and increased estrogen; MS comments?

[wilson6]

MS,

I was just reading some unrelated material on estrogens and found some evidence that grapefruit juice or extracts impair hepatic clearance of estrogen, resulting in increased circulating E particularly those taking E.

Related to the earlier diet thread on grapefruit extract, this doesn't sound like something that would help with fat loss.

Comments,

W6

 

[MS]

Yes, grapefruit can inhibit the hepatic metabolism of many steroids (via CYP3A4 inhibition). The nett effect of this is unknown to me. At low circulating E2 concentrations it doesn't seem to matter much, and 17beta-hydroxy dehydrogenation of E2 predominates and CYP1A2 can pick up the slack from the inhibited CYP3A4 (CYP3A4 and 1A2 are required to produce the 2-OH estrogen metabolite). But at high concentrations of E2 the loss of CYP3A4 (through grapefruit, other drugs or mutation) becomes limiting so that more of the E2 continues to go down the 17beta-hydroxy dehydrogenation pathway than would normally occur if you didn't drink the grapefruit juice.

The sound bite of this is that you get less "good" estrogen and more "bad" estrogen from too much grapefruit. But it may only be relevant if you've already got high estrogen levels to begin with (such as women on OC's).

Of course the same applies for many other 'drugs'.