Boron is required in only milligram quantities but plays a disproportionate role in hormone metabolism — small human trials show it can lower SHBG (sex hormone binding globulin), the protein that binds testosterone and keeps it biologically inactive, effectively raising the free, usable fraction without raising total testosterone. It also supports vitamin D activation and bone mineral density, giving it overlapping relevance for both hormonal and skeletal health stacks. It is one of the cheapest, most evidence-grounded entries in the testosterone-support category relative to flashier botanicals.