Boron
Summary
Boron is a trace element in plant foods that is not classed as an essential nutrient. Small trials suggest less menstrual pain and possible effects on osteoarthritis symptoms and sex hormones, but evidence is thin. The adult upper limit is 20 mg/day, and very large doses are toxic. ODS lists no known medicine interactions.
Key facts
- No RDA or AI; boron is not classed as essential because no clear biological function has been identified[1]
- 20 mg/day for adults, including pregnancy and lactation; WHO estimates a safe range of 1–13 mg/day[1]
- Prune juice (1.43 mg per cup), avocado (1.07 mg per ½ cup), raisins and peaches; coffee, milk and apples are main US sources[1]
- Two small 8-week studies of 20 people each reported fewer symptoms at 6 mg/day (12 mg/day for severe disease in one, which was not blinded or placebo-controlled); ODS says confirmation is needed[1]
- About 85–90% of ingested boron is absorbed; it concentrates in bone, nails and hair[1]
- 2 graded human outcomes on this page
- October 11, 2026
How it works
ProposedBoron may influence bone formation, inflammation and steroid hormones including vitamin D and estrogen, but a clear biological role in humans has not been identified.[1]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Menstrual pain | Grade C | Improved | RCT · n = 113 · 2015 | 1 row |
| Hormones | Grade D | Mixed | Open-label · n = 8 · 2011 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Menstrual pain severity and duration | Improved | Grade C | RCT · n = 113 · 2015 University students with primary dysmenorrhea Form: Boron capsules · Dose: 10 mg/day from 2 days before to day 3 of menstruation · Duration: 2 menstrual cycles Pain severity and duration were lower than with placebo after the intervention. | 25906949 (opens PubMed)Source [2] |
| Sex hormones and inflammation markers | Mixed | Grade D | Open-label trial · n = 8 · 2011 Healthy men Form: Boron capsules · Dose: 10 mg/day · Duration: 1 week Free testosterone rose and estradiol fell after a week, and SHBG, hsCRP and TNF-α fell within hours; there was no placebo group and only 8 participants. | 21129941 (opens PubMed)Source [3] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Calcium fructoborate | Varies | Most ingested boron, whatever the form, is converted to boric acid in the gut and 85–90% is absorbed.[1] | No form-specific tolerance data in the sources cited here. | Osteoarthritis pilot studies |
| Boron citrate, glycinate or aspartate | Varies | No head-to-head human data comparing forms in the sources cited here. | No form-specific tolerance data in the sources cited here. | General supplements |
Studied doses
Doses studied in human trials ranged from 1.5–6 mg of boron per day for 2 weeks (calcium fructoborate) and 3 mg per day for 10 months (bone markers) to 6–12 mg per day in 8-week osteoarthritis studies and 10 mg per day in hormone and menstrual-pain studies; the adult UL is 20 mg per day.[1][2][3]
Intake reference: No RDA, AI or EAR. Tolerable Upper Intake Level: 20 mg/day for adults 19 and older (including pregnancy and lactation); 17 mg/day at 14–18 years.[1] ULs for children are lower (3 mg at 1–3 years, 6 mg at 4–8 years, 11 mg at 9–13 years); infants should get boron only from breast milk, formula and food. NIH ODS fact sheet (updated June 9, 2022).
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
None found in our sources.
Who should be careful
- High doses
- Boric acid or borax poisoning causes nausea, vomiting, diarrhea, rash and convulsions; 15,000–20,000 mg can be fatal in adults. Supplements should stay under the 20 mg/day UL.[1]
- Children
- ULs are much lower for children (3–11 mg/day), and infants should get boron only from food, breast milk or formula.[1]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Food sources
| Food | Serving | Amount |
|---|---|---|
| Prune juice | 1 cup | 1.43 mg[1] |
| Avocado, raw, cubed | ½ cup | 1.07 mg[1] |
| Raisins | 1.5 ounces | 0.95 mg[1] |
| Peach | 1 medium | 0.8 mg[1] |
| Apple | 1 medium | 0.66 mg[1] |
- Prune juice1.4 mg
- Avocado, raw, cubed1.1 mg
- Raisins1 mg
- Peach0.8 mg
- Apple0.7 mg
Frequently asked questions
Is boron an essential nutrient?
No. There is no RDA because a clear biological function in humans has not been identified.[1]
How much boron is too much?
The adult upper limit is 20 mg/day; very large accidental doses of boric acid are toxic and can be fatal.[1]
Does boron raise testosterone?
In 8 healthy men, 10 mg/day for a week raised free testosterone and lowered estradiol, but there was no placebo group.[3]
Does boron help joint pain?
Two small 8-week studies of 20 people each reported improvements at 6 mg/day, one without a placebo group; short calcium fructoborate trials also eased knee discomfort, but ODS says confirmation is needed.[1]
Does boron interact with medicines?
ODS lists no known clinically relevant interactions with medications.[1]
Sources
- [1]Boron: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements, 2022. fact-sheet
- [2]Effects of boron supplementation on the severity and duration of pain in primary dysmenorrhea. Complement Ther Clin Pract, 2015. RCT
- [3]Comparative effects of daily and weekly boron supplementation on plasma steroid hormones and proinflammatory cytokines. J Trace Elem Med Biol, 2011. open-label
What changed
- New monograph. Every PMID checked against NCBI E-utilities (title, journal and year from the PubMed record); each evidence row written from its abstract; intake and safety facts from the cited fact sheets.
- Review: osteoarthritis lines now state that one pilot was unblinded with no placebo, matching the ODS fact sheet; dose range widened to the 1.5 mg/day trial ODS describes.