Boron
Evidence Fact Sheet
Boron is a dietary trace mineral (studied as boric acid, borate, or calcium fructoborate) linked to steroid-hormone, calcium-magnesium-vitamin-D, and inflammatory signaling. Human evidence is limited to small trials; typical intake 1-3 mg/day, supplements studied at 3-10 mg/day, UL 20 mg/day. No EFSA-authorized health claim.
Also known as: B · Boron (elemental trace mineral) · Sodium tetraborate / boric acid (forms studied) · Calcium fructoborate (organic boron form)
Overview
Boron is a non-essential dietary trace mineral consumed mainly from fruits, vegetables, legumes and water, and studied in supplement form as boric acid, sodium tetraborate/borate, or the organic form calcium fructoborate. Proposed mechanisms include modulation of steroid-hormone metabolism (free testosterone, 17-beta-estradiol, SHBG), influence on calcium, magnesium and vitamin-D homeostasis, and down-regulation of NF-kB-driven inflammatory signaling. Typical dietary intake is about 1-3 mg/day, supplemental boron has been studied at roughly 3-10 mg/day, there is no established RDA/AI, and the US tolerable upper intake level is 20 mg/day for adults. It is lawful as a dietary supplement under DSHEA (structure/function claims only); EFSA has authorized no health claims, and its status in China and Brazil is pending. This is an educational evidence summary, not a dosing or treatment recommendation.
Mechanism of Action
Modulation of steroid-hormone metabolism (reported shifts in free testosterone, 17-beta-estradiol, and SHBG in small human trials) · Influence on calcium, magnesium and vitamin-D homeostasis (reduced urinary Ca/Mg excretion in depletion-repletion studies) · NF-kB pathway down-regulation and reduction of inflammatory markers (hsCRP, TNF-alpha) in mechanistic/early human work · Putative role in bone mineralization and mineral-metabolism enzymatic activity
Body systems: Musculoskeletal · Endocrine & Metabolic · Reproductive · Immune System
Evidence-Based Benefits
Each benefit below is anchored to a specific PubMed-indexed study. Effect sizes, sample sizes, and p-values are reported as published; no values are inferred. Honest negatives and null results are kept alongside the positive findings, and disease-research populations are described as such — Boron is not characterized as a treatment for any disease.
Steroid-Hormone Markers (Testosterone / Estradiol / SHBG)
RCT supported- 8healthy male volunteers
- 6 hacute SHBG/hsCRP/TNF-α drop
In a small crossover study of eight healthy men, one week of 10 mg/day boron was reported to significantly increase mean plasma free testosterone and decrease estradiol, with acute six-hour decreases in SHBG, hsCRP and TNF-α. The abstract states direction and significance only; no numeric effect sizes were reported, so effect size was not extracted.
Effect size: this study reports the direction of the finding but does not state a specific numeric effect size, so none is given here rather than estimated.
“Six hours supplementation showed a significant decrease on sex hormone binding globulin (SHBG), high sensitive CRP (hsCRP) and TNF-α level. After one week (in samples taken at 8.00 A.M, only), the mean plasma free testosterone increased and the mean plasma estradiol decreased significantly.”
Source: PMID 21129941 · Naghii 2011 · J Trace Elem Med Biol
Testosterone, Lean Body Mass & Strength (Resistance-Trained Men)
Null / no benefit RCT supported- no significant effecton any variable
In a 7-week double-blind RCT of 19 male bodybuilders (10 boron, 9 placebo), 2.5 mg/day boron significantly raised plasma boron (20.1 to 32.6 ppb) but had no significant effect on testosterone, lean body mass or strength. Both groups gained from training alone, indicating the improvements were due to training, not boron. This is an honest negative finding.
Reported effect: Plasma boron rose from 20.1 ± 7.7 ppb to 32.6 ± 27.6 ppb (p < 0.05); no significant effect of boron on testosterone, lean body mass, or strength
“Plasma boron values were significantly (p < 0.05) different as the experimental group increased from (+/- SD) 20.1 +/- 7.7 ppb pretest to 32.6 +/- 27.6 ppb posttest... Analysis of variance indicated no significant effect of boron supplementation on any of the dependent variables... boron supplementation had no effect on these measures.”
Source: PMID 8508192 · Ferrando 1993 · Int J Sport Nutr
Calcium / Magnesium & Bone Mineral Metabolism (Postmenopausal Women)
RCT supportedIn a metabolic-unit depletion-repletion study of 12 postmenopausal women, supplementing a low-boron diet with 3 mg/day boron markedly reduced urinary calcium and magnesium excretion and markedly elevated serum 17-beta-estradiol and testosterone, effects more marked under low dietary magnesium. The abstract reports direction ("markedly") but no numeric effect sizes, so effect size was not extracted.
Effect size: this study reports the direction of the finding but does not state a specific numeric effect size, so none is given here rather than estimated.
“Boron supplementation markedly reduced the urinary excretion of calcium and magnesium; the depression seemed more marked when dietary magnesium was low... Boron supplementation markedly elevated the serum concentrations of 17 beta-estradiol and testosterone.”
Source: PMID 3678698 · Nielsen 1987 · FASEB J
Joint / Inflammatory Markers (Rheumatoid Arthritis Adjuvant)
RCT supported- 6 mgelemental boron/day
In a 60-day double-blind RCT, 80 rheumatoid-arthritis patients on etanercept were randomized to calcium fructoborate (220 mg/day), sodium tetraborate (55 mg/day; ~6 mg elemental boron) or placebo; 72 completed. Both boron forms significantly improved clinical scores and lowered ESR, hsCRP, IL-1α, IL-6 and TNF-α versus baseline and placebo, with calcium fructoborate superior. The abstract reports direction and significance only; no numeric effect sizes were given, so effect size was not extracted.
Effect size: this study reports the direction of the finding but does not state a specific numeric effect size, so none is given here rather than estimated.
“After 60 days, both types of boron significantly improve the clinical scores, in association with significant decrease in the serum levels of ESR, hsCRP, IL-1α, IL-6, and TNF-α with remarkable superiority for calcium fructoborate (CFB) over sodium tetraborate (NTB), compared to baseline and placebo-treated group.”
Source: PMID 28163961 · Hussain 2016 · J Intercult Ethnopharmacol
Dosage (research context · not a recommendation)
Typical dietary intake 1-3 mg/day; supplemental boron studied at ~3-10 mg/day in human trials; no established RDA/AI; tolerable upper intake level (UL) 20 mg/day for adults (US FNB). Educational reference, not a dosing recommendation.
Regulatory Status · 4 Markets
- US · FDA
- Lawful as a dietary supplement under DSHEA; no independent GRAS notice (GRN) for elemental boron; structure/function claims permitted (no disease claims).
- EU · EFSA
- 0 authorized health claims / 8 non-authorised opinions (bone, joint, cognitive and other directions all returned unfavourable, incl. EFSA J.1261 2009 and J.2209 2011); marketable but no permitted health claim in the EU.
- CN · China
- Not an established positive-list entry: boron is not a GB 14880 nutritional fortification substance and has no clear SAMR health-food raw-material pathway (non-traditional mineral, status to be confirmed); regulatory status pending in China
- BR · ANVISA
- Not a default entry on the IN 28/2018 positive list; requires case-by-case (caso-a-caso) assessment for use in supplements in Brazil.
Safety
Generally well tolerated at typical dietary and low-supplemental intakes; UL is 20 mg/day for adults (do not exceed). High intakes can cause GI upset; very high acute doses of boric acid/borate are toxic. Reproductive/developmental toxicity reported in animals at high doses, so caution in pregnancy/lactation (inadequate human data). Educational information, not medical advice.
Related
Goals: joint-bone · reproductive-health
Lifestyles: senior-60-plus
References
PubMed-indexed citations anchoring the benefit findings above. Effect sizes are reported as published.
- PMID 21129941 · Naghii 2011 · J Trace Elem Med Biol — Steroid-Hormone Markers (Testosterone / Estradiol / SHBG)
- PMID 8508192 · Ferrando 1993 · Int J Sport Nutr — Testosterone, Lean Body Mass & Strength (Resistance-Trained Men)
- PMID 3678698 · Nielsen 1987 · FASEB J — Calcium / Magnesium & Bone Mineral Metabolism (Postmenopausal Women)
- PMID 28163961 · Hussain 2016 · J Intercult Ethnopharmacol — Joint / Inflammatory Markers (Rheumatoid Arthritis Adjuvant)
Frequently Asked Questions
1. Does boron raise testosterone?
The evidence is mixed and limited to very small studies. A 1-week crossover study of 8 healthy men (10 mg/day) reported a significant increase in free testosterone, and a depletion-repletion study of 12 postmenopausal women (3 mg/day) reported elevated serum testosterone and estradiol — but neither abstract gave numeric effect sizes. In contrast, a 7-week double-blind RCT of 19 male bodybuilders (2.5 mg/day) found no significant effect on testosterone despite raising plasma boron. So claims of a reliable testosterone boost are not supported by controlled data.
2. What forms and doses of boron have been studied?
Human trials have used boric acid, sodium tetraborate/borate, and the organic form calcium fructoborate. Typical dietary intake is about 1-3 mg/day, and supplements have been studied at roughly 3-10 mg/day (for example 3 mg/day in postmenopausal women, 10 mg/day in the hormone-marker study, and ~6 mg elemental boron in the rheumatoid-arthritis trial). The US tolerable upper intake level is 20 mg/day for adults. These are research doses, not a dosing recommendation.
3. Is there strong evidence for boron and joint health?
Only preliminary. A 60-day double-blind RCT in 80 rheumatoid-arthritis patients (72 completed) found calcium fructoborate and sodium tetraborate significantly improved clinical scores and lowered inflammatory markers (ESR, hsCRP, IL-1α, IL-6, TNF-α) as an add-on to etanercept. This is a single small adjuvant trial reporting direction without numeric effect sizes, so it is suggestive rather than conclusive, and is not a treatment recommendation.
4. Are there authorized health claims for boron?
No. There is no human meta-analysis of boron monotherapy, and EFSA has authorized zero health claims for boron (with several unfavourable opinions across bone, joint and cognitive directions). In the US it is lawful as a dietary supplement under DSHEA with structure/function claims only; its regulatory status in China and Brazil is pending. This page summarizes research findings and is not medical or dosing advice.
Last evidence review: 2026-06-13