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Definition: "An ergogenic aid is any substance or phenomenon that enhances performance "

15.07.2009

Nolvadex best testosterone booster of the SERMS

You've just taken a course of steroids and are looking for something to normalise your testosterone level. You can't make up your mind between good old Nolvadex, alias tamoxifen, and its cousins raloxifene and toremifene. Greek researchers have published the results of a study in Fertility & Sterility which suggests that tamoxifen is the best choice.

Tamoxifen, raloxifene and toremifene are SERMs: they attach themselves to the receptor for estradiol but don't start up the processes that usually follow after estradiol has attached itself to its receptor. That's why doctors use SERMS against tumours whose growth is stimulated by female hormones.

Chemical athletes use SERMs because they raise the testosterone level. One of the ways that the body monitors its own production of sex hormones is by keeping an eye on the concentration of estradiol in the blood. If it gets too high then sex hormone production is reduced – including the production of testosterone. Because the control mechanisms make use of estradiol receptors, SERMs crank up testosterone production. That’s why chemical athletes use substances like tamoxifen after taking a course of steroids.

The Greek researchers did a trial with just under three hundred infertile men, whose sperm count was low and most of whom had low levels of testosterone production. The researchers gave the men either 20 mg tamoxifen, 60 mg toremifene or 60 mg raloxifene daily for three months. The table below shows what happened to the men's LH, FSH and testosterone levels.

Raloxifene has little effect on the testosterone level, so it's not an interesting candidate for a Post Cycle Therapy supplement. Toremifene is somewhat better, but doesn't perform as well as tamoxifen, and it loses its maximum effect after two months as well.

To complete the story we've added the table below, which shows the effect of the three on sperm cells. Once again, raloxifene performs less well than tamoxifen and toremifene.

The researchers suspect that the two more effective SERMs not only work through the body's hormonal thermostat, thereby inducing the pituitary gland to make more messenger hormones [which in turn get the testes to produce more testosterone]. They think that tamoxifen and toremifene also have a direct effect on the testosterone producing cells.

Source:
Fertil Steril. 2009 Apr;91(4 Suppl):1427-30.