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Boron — The Complete Supplement Guide

Not officially essential, but with intriguing effects on bone, magnesium/vitamin D and hormones — here's the honest state of the evidence and the safe limit.

Reviewed by Bodil Isaksson, Licensed Biomedical Scientist (Sweden)Last reviewed July 2026Supplement guide

SupplementsMineralsBoron

Boron is an ultratrace element that is not classified as essential for humans, yet influences how the body handles calcium, magnesium, vitamin D and steroid hormones. For the short dietary version, see the Minerals page.

Read first. Boron is not an established essential nutrient and most people need no supplement. Studied doses are low (a few mg); higher intakes have a real upper limit and reproductive toxicity in animal studies. Information, not a prescription.

Key takeaways

  • Not classed as essential, but influences calcium, magnesium, vitamin D and hormones.
  • No official requirement; typical diet 1–3 mg/day (studied at 3–10 mg).
  • Upper limit 10 mg/day (EFSA).

Function

Boron is not classed as essential, but appears to modulate several systems:

  • Bone & mineral metabolism: influences how the body uses calcium, magnesium and vitamin D, and may support bone strength.
  • Hormones: small studies suggest it can raise free testosterone and oestrogen and lower inflammatory markers.
  • Vitamin D: may help maintain higher active vitamin D levels.
  • Joints & cognition: preliminary links to joint comfort and cognitive performance — all early-stage.

Different forms — and which to choose

Boron citrate / glycinate / aspartateCommon chelated supplement forms.
Sodium borate (borax)A simple source; low doses only.
Food & waterFruit, vegetables, nuts and drinking water are the natural sources.

Absorption in the body

How muchVery well absorbed (>90%) and rapidly excreted in urine, so it does not accumulate at normal intakes.

Deficiency symptoms

SymptomsNo defined deficiency disease in humans, since boron is not established as essential.
NoteLow intakes may sub-optimally affect bone/mineral handling, but this is not a recognised clinical deficiency.

Recommended intake

No official requirement · typical diet 1–3 mg

No reference intake is set. Typical Western diets provide about 1–3 mg/day.

Best sources: fruit (apples, pears, raisins, prunes), nuts, legumes, leafy vegetables and avocado.12

Therapeutic use

Bone & hormonesSmall trials use ~3–10 mg/day for bone density, joint comfort and modest testosterone/vitamin-D effects — preliminary, not established.
Keep it modestThere's no case for high-dose boron; benefits (if real) appear at low doses.

Therapeutic doses

Studied: 3–10 mg/day
If triedMost studies use 3 mg/day; higher doses add risk without clear benefit.
Stay well under the ULSee below.

Toxicity & upper limit

UL: 10 mg/day (EFSA adult)
Upper limitEFSA set an adult UL of about 10 mg/day (US UL 20 mg).2
ExcessHigh intakes cause nausea and GI upset; very high doses are toxic, and animal studies show reproductive/developmental harm — avoid in pregnancy beyond food levels.

Bottom line: boron isn't officially essential and a fruit-and-nut-rich diet supplies it. A low-dose (~3 mg) supplement is a reasonable experiment for bone/joint support, but keep well under the 10 mg limit and don't megadose — especially in pregnancy.

← All supplementsShort dietary version

References

Reference and upper-limit values are general adult figures from official bodies; individual needs vary. Therapeutic doses describe clinical/research use, not prescriptions.

  1. Pizzorno L. Nothing Boring About Boron. Integrative Medicine (Encinitas) 2015;14(4):35–48 (review of boron's roles in bone, hormones and inflammation). ncbi.nlm.nih.gov (PMC)
  2. EFSA. Tolerable Upper Intake Level of boron (10 mg/day for adults). EFSA / SCF Tolerable Upper Intake Levels summary. efsa.europa.eu

This article summarizes nutrition science from official health authorities and peer-reviewed sources for education. It is not a substitute for individual medical advice, and the doses given are not prescriptions — always consult a professional before therapeutic supplement use, in pregnancy, in kidney disease, or alongside medication.

✓
Bodil Isaksson, Licensed Biomedical Scientist (Sweden)

At Food Health Lab we explain what the science says in plain language, and we cite our sources so you can check for yourself.

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