Does boron increase your testosterone?
Boron may modestly raise free testosterone in some people, particularly those who are deficient, but for healthy men who already get enough the effect is small and uncertain. Do not expect any sports performance benefit from it; the existing studies are too small to draw conclusions on that.
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Boron increases free testosterone, as shown by a small study of 8 healthy men who took 10 mg per day: after seven days, free testosterone had risen significantly. A protein that binds testosterone and keeps it inactive (SHBG) dropped within just six hours. Less SHBG means that more testosterone is available to the body.
Similar effects have been seen in postmenopausal women and older men taking 3 mg per day, after they had first gone through a period of eating little boron. The effect was stronger when magnesium levels were also low. This suggests that boron does more for people who are not getting enough of it.
Caution is warranted, however. All studies are small, involving no more than 8 to 12 participants, and some come from the same research centre. A comprehensive review even described the evidence for boron as a testosterone booster in healthy men as 'reasonably negative', particularly as a bodybuilding supplement. How boron precisely affects hormones also remains unclear.
Boron influences other hormones as well. In women who took 10 mg per day, oestradiol (a female sex hormone) also rose. Boron therefore does not act purely on testosterone; it affects multiple hormone levels at the same time.
A study of more than 200 factory workers with an average daily exposure of 47 mg or more found no additional rise in testosterone and no reproductive harm. This sets an upper boundary on safety, but also makes clear that taking far more boron does not produce a proportional effect.
All studies are small (maximum 212 participants for safety, 8-12 for hormonal effect). Several positive studies come from the same research centre. One comprehensive review is negative about its use as a bodybuilding supplement. The mechanism has not been fully clarified.