Boron

Also known as: Boric acid, Boron citrate, Calcium fructoborate, Sodium borate

The bone-and-joint trace mineral — small trials, a calcium-magnesium-vitamin D partnership, and a 20 mg upper limit.

Editorial review by the IngredientWiki Editorial Team
Updated 2026-09-26
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2 min read
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Mineral specimens, neutral tablets, and a measuring spoon — Editorial illustration

Boron affects mineral metabolism, but human evidence for bone, osteoarthritis, or hormone outcomes is limited and there is no established U.S. recommended intake. Small calcium-fructoborate trials should not be generalized to every boron supplement.^{1, 2}

Trace mineral found in plant foods, soil, and water^{1, 2}
Helps the body use calcium, magnesium, and vitamin D^{1, 2}
Calcium fructoborate studied for osteoarthritis symptoms^{1, 2}
No RDA; adult upper limit is 20 mg per day^{1, 2}

What is Boron?

Boron never gets headline treatment, and perhaps that is fitting for a mineral whose job is mostly behind the scenes. It is not a structural building block like calcium; instead it nudges the metabolism of the minerals and hormones that are. The interesting human data centers on two areas: bone metabolism, where boron appears to reduce calcium and magnesium losses, and osteoarthritis, where a specific boron-carbohydrate compound — calcium fructoborate — has reduced pain and stiffness in several small trials.¹

Where it comes from

Natural sources

Widely distributed in plant foods: raisins, prunes, avocados, nuts, and legumes
Present in soil and drinking water at varying levels
Average adult intake estimated around 1 mg per day from food

How it's made

Supplements use boron citrate, glycinate, or calcium fructoborate forms.

What it does in products

Benefits

Bone health support

limited evidence

Small studies show boron reduces urinary calcium and magnesium losses and raises vitamin D utilization — suggestive support for bone density, though long-term fracture data are lacking.^{1, 2}

Boron influences mineral metabolism, but long-term human bone-density and fracture evidence is insufficient.

Osteoarthritis symptoms

limited evidence

Small short-term trials of calcium fructoborate report changes in knee symptoms or inflammatory markers, but they do not establish boron as an osteoarthritis treatment.^{3, 4, 1}

The studied compound is not interchangeable with every boron supplement, and the trials are too small for a confident effect estimate.

Hormone metabolism

insufficient evidence

Boron influences metabolism of steroid hormones, including vitamin D and estrogen; meaningful clinical benefits in healthy adults are not established.^{1, 2}

Short metabolic studies do not establish a meaningful testosterone, estrogen, or performance benefit in healthy adults.

Evidence scope and limitations

The review covers dietary boron, general boron supplements, and calcium fructoborate trials as distinct exposures.

Boron has no established U.S. recommended dietary allowance and no clear clinical deficiency syndrome in humans.
Most intervention studies are small, short, and use compounds that should not be treated as interchangeable.

Evidence last checked: 2026-09-26

Side effects & safety

Nausea and stomach upset (uncommon)Usually at high supplemental doses; take with food.

Diarrhea (uncommon)Dose-related; resolves when intake is reduced.

Safety considerations

Boron supplements are not recommended in pregnancy; stick to food sources. High-dose boric acid ingestion is toxic and particularly dangerous for infants.
None well documented at typical supplemental doses.
Not for: Kidney disease (boron is cleared by the kidneys)
Not for: High-dose boric acid products should never be ingested

Amounts studied & product use

These figures describe research or common product use, not a personal dose or treatment recommendation.

In supplement studies and products

Small studies use different boron compounds and commonly supply roughly 3–6 mg elemental boron daily; calcium fructoborate trials report the compound mass separately. The U.S. adult upper limit is 20 mg daily, but no RDA or established treatment dose exists.

^{1, 3, 4}

Regulatory status

Dietary supplement under DSHEA. Boric acid and sodium borate are restricted as food additives; supplement forms (citrate, glycinate, fructoborate) are the standard.

⁵

Why boron appears in bone supplements

Boron's bone story is about retention, not construction. Human depletion studies found that a low-boron diet increased urinary losses of calcium and magnesium and reduced vitamin D levels — and that adding back just 3 mg per day reversed the effect. That mechanism makes boron a plausible supporting cast member alongside calcium, magnesium, and vitamin D, which is exactly how supplement makers position it. What is still missing is long-term evidence that boron itself reduces fracture risk, so treat it as a helper nutrient rather than a primary bone treatment.

Frequently asked questions

How much boron do I need per day?

There is no official recommended dietary allowance for boron. Food intake averages about 1 mg daily; supplements typically provide 3–6 mg. The adult upper limit is 20 mg per day — staying under it is important because high doses are toxic.^{1, 2}

Does boron help arthritis?

Possibly, in a specific form. Calcium fructoborate has shown reduced knee pain and stiffness in several small, short-term osteoarthritis trials. The research is encouraging but not yet large enough for it to be considered a standard treatment.^{1, 2}

Which foods contain boron?

Raisins, prunes, avocados, nuts (especially almonds and peanuts), legumes, and some fruits and vegetables are good sources. Coffee, wine, and drinking water also contribute depending on local soil boron levels.^{1, 2}

The bottom line

Boron is biologically interesting but clinically under-established. Current evidence supports cautious language, not hormone or bone-treatment promises.

References

Boron: Health Professional Fact Sheet. NIH Office of Dietary Supplements (2025) · government guidance
Relationship between boron and magnesium status and bone mineral density: a review. Magnesium Research (1993) · other · PMID 8292503
Calcium fructoborate and inflammation markers in adults with osteoarthritis: a pilot trial. Biological Trace Element Research (2011) · randomized trial · PMID 21607703
Short-term efficacy of calcium fructoborate in adults with knee discomfort. Clinical Interventions in Aging (2014) · randomized trial · PMID 24940052
Dietary Supplements. U.S. Food and Drug Administration (2025) · government guidance

Revision history

2026-09-26Replaced search-result citations with exact sources, mapped claims to evidence, and reassessed evidence strength.