In a recent study by Jang et.al. (Jang. 2010) taurine has been shown to protect the rat testis from oxidant damage. Their study done on isolated rat leydig cells and living laboratory rats also revealed that the positive effect of taurine on testicular testosterone production is dose-dependend and bi-phasic, i.e.
low concentrations of taurine (0.1–100 lg/ml) could stimulate testosterone secretion, whereas high concentration of taurine (400 lg/ml) could inhibit testosterone secretion.It is however relatively unlikely that levels >400lg/ml and thus negative effects will be achieved by orally administered doses of taurine. This hypothesis is validated by the results of the study (cf. Jang. 2010 Figure 5; below) which clearly illustrate that levels >1.5% taurine in drinking water did not significantly increase taurine levels in the rat testes above the levels achieved with 1.0%.
With a normal laboraty rat consuming roughly 50ml/day water (Warrington. 2001), the reported intake of 0.5-1.5% taurine via drinking water would amount to 0.25-0.75 mg of taurine per day.
The effects on hormone secretion are all the more remarkable (cf. Jang. 2010 Figure 4; below):
ergo-log.com claim, the HED, i.e. the human equivalence dose, is also way the amount of taurine that has been suggested to be effective in other contexts (such as weight-loss, insulin resistance, etc.). Assuming that an average laboratory rat weighs 400g, the BSA formula (Reagan-Shaw. 2008), which sets body weight and body surface into relation would deliver a HED of 1.25mg/kg * Km(rat) / Km(adult) = 0.2g/kg, i.e. ca. 16g taurine for an adult weighing 80kg.
Edit: I made a mistake with the units initially, its in fact 16g (corrected that from mg) - so supplementing huge amounts of taurine to increase test, could in fact be a better idea than I previously thought!