Does boron supplementation increase testosterone?
Weak EvidenceIT DEPENDS
Weak evidence suggests boron supplementation may modestly increase free testosterone, primarily by reducing sex hormone-binding globulin (SHBG). The effect size is small, study quality is low, and only a handful of trials exist with significant methodological limitations.
The Verdict
Weak evidence suggests boron supplementation may modestly increase free testosterone, primarily by reducing sex hormone-binding globulin (SHBG). The effect size is small, study quality is low, and only a handful of trials exist with significant methodological limitations.
What the Evidence Shows
Boron is a trace mineral found in fruits, vegetables, and nuts that has been proposed to influence steroid hormone metabolism. The most cited evidence comes from a 2011 study where 6mg boron daily for one week increased free testosterone by 28% and decreased estradiol by 39% in 8 healthy men. This study, while frequently referenced in supplement marketing, had only 8 participants, no control group, and has not been independently replicated at scale. The proposed mechanism involves boron's effect on SHBG metabolism and its role in hydroxylation reactions that influence steroid hormone synthesis and clearance. A 2015 review of boron's biological effects noted its involvement in vitamin D metabolism and inflammatory modulation, both of which could indirectly influence testosterone. However, the direct testosterone evidence is extremely limited. Two additional small studies found modest effects: one in bodybuilders showing no significant testosterone change after 7 weeks of 2.5mg/day boron, and another in postmenopausal women showing altered estrogen metabolism but not testosterone. Population-level data shows that dietary boron intake correlates poorly with testosterone levels when controlling for other nutritional factors. The supplement industry has disproportionately amplified results from a single weak study. Average dietary boron intake is 1-3mg/day, and supplemental doses in studies range from 3-10mg/day. Clinical significance of any testosterone increase from boron remains unestablished—no studies have linked boron to improved strength, body composition, or sexual function.
Evidence Quality
0
Meta-Analyses
3
RCTs
4
Observational
Important Caveats
- ⚠️ Primary evidence comes from a single uncontrolled study with 8 participants
- ⚠️ Independent replication at scale has not occurred
- ⚠️ Clinical significance (strength, body composition) has not been demonstrated
- ⚠️ Supplement industry claims far exceed the quality of available evidence
Population Studied
Healthy young men, bodybuilders, and postmenopausal women; all studies had very small sample sizes (n=8-19)
Dosage
6-10mg elemental boron per day in most studies; dietary intake averages 1-3mg/day; upper tolerable limit is 20mg/day for adults
Duration
The most cited study used only 7 days of supplementation; longer studies (7 weeks) showed less impressive results
Supporting Studies (2)
Comparative effects of daily and weekly boron supplementation on plasma steroid hormones and proinflammatory cytokines
RCTNaghii MR, Mofid M, Asgari AR, et al. · Journal of Trace Elements in Medicine and Biology (2011)
In 8 healthy male volunteers, 6mg/day boron supplementation for 1 week significantly increased free testosterone (28.3%), decreased estradiol (39%), and reduced inflammatory markers (IL-6, TNF-alpha, CRP).
View paper (DOI) →Nothing boring about boron: a review of its role in human biology
ObservationalPizzorno L. · Integrative Medicine (2015)
Comprehensive review identified boron's roles in steroid hormone metabolism, vitamin D activation, and SHBG modulation, suggesting plausible mechanisms for testosterone influence though clinical evidence remains preliminary.
View paper (DOI) →Contradicting Studies (1)
The effect of boron supplementation on lean body mass, plasma testosterone, and strength in bodybuilders
RCTFerrando AA, Green NR. · International Journal of Sport Nutrition (1993)
In 19 male bodybuilders, 2.5mg/day boron supplementation for 7 weeks produced no significant changes in total testosterone, lean body mass, or strength compared to placebo.
Why this disagrees:
Longer-duration supplementation at a lower dose failed to replicate acute hormonal changes. The brief spike seen in the 7-day study may represent a transient response that normalizes over time, or may be an artifact of the small uncontrolled design.
Related Claims
Does creatine supplementation improve cognitive function?
Moderate EvidenceModerate evidence suggests creatine may improve short-term memory and reasoning ability, particularly under conditions of sleep deprivation or cognitive stress. Effects in well-rested, healthy adults are smaller and less consistent.
Does sunlight exposure boost testosterone?
Moderate EvidenceModerate evidence links sunlight exposure to testosterone levels, primarily through vitamin D synthesis. Seasonal variation in testosterone is well-documented, and vitamin D supplementation in deficient men raises testosterone. Direct UV-to-testosterone pathways remain speculative.