Three updates this week:
D-Aspartic Acid (another testosterone booster)
Minoxidil (aka Rogaine) for hair regeneration.
D-Aspartic Acid has been shown to boost testosterone in humans, but it is overhyped. There was a statistically significant boost that may benefit cognition, but is unlikely to be a determining factor in muscle building; it was only conducted with one research group and the research parameters could definitely be expanded upon (eg. a higher dose, a longer duration period, synergistic compounds, etc.)
D-Aspartic Acid would best be viewed as a compound that might make the basis of a testosterone boosting or pro-aphrodisia 'stack', but gives a minor boost on its own.
Tribulus Terrestris received an update, and its effects on testosterone appear to have shifted from 'ineffective' to 'probably ineffective'. It still does not have human evidence for a testosterone increase when Tribulus is used in isolation up to 450mg for up to 8 weeks, but at least two studies in non-castrated rats (these usually extrapolate to humans) indicate doses equivalent to 750mg increase testosterone. Of course, the hypothesis that testosterone spikes are only observed in animals cannot yet be refuted either so there is some ambiguity as to whether tribulus can work or not.
It is fairly healthy though, protecting the liver from some mineral-induced oxidation and lowering blood pressure in those with hypertension. Also does appear to be a potent aphrodisiac in animals.
Finally, Minoxidil is Rogaine. It works via extending the amount of time a hair follicle spends in its growth phase (Anagen). It works best in hair loss that is not mediated by androgens (so, bald patches) and although it does work to a degree in androgenic hair loss (receding hair line), its reliability is lower. For androgenic hair loss, it would best be paired with an anti-androgen such as ketoconazole.