Minerals

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.

By IngredientWiki Editorial Team
Fact-checked by IngredientWiki Editorial Team
Updated 2026-09-26
2 min read

In short

Boron is a trace mineral found in soil, groundwater, and plant foods — raisins, avocados, nuts, and prunes — that the body uses in small but important ways. Its best-supported role is metabolic: it appears to help the body retain and use calcium, magnesium, and vitamin D, which is why it shows up in bone-health supplements. Some studies also report less osteoarthritis pain with boron compounds like calcium fructoborate. There is no official recommended daily intake, and 20 mg per day is the adult upper limit.

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

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.

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

emerging 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.

Osteoarthritis symptoms

moderate evidence

Several small trials of calcium fructoborate report reduced knee pain and stiffness and lower inflammatory markers, but the evidence base remains small and short-term.

Hormone metabolism

emerging evidence

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

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

How it's used

In supplements

Typical supplements provide 3–6 mg per day, sometimes up to 10 mg. The adult upper limit (UL) is 20 mg per day from all sources. Bone and joint trials most often used calcium fructoborate at 110–220 mg daily.

Regulatory status

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

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.

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.

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.

The bottom line

Boron is a genuine but secondary player: it helps your body hold onto calcium, magnesium, and vitamin D, and a specific form shows modest osteoarthritis benefit. A 3–6 mg supplement is reasonable for bone-support stacking; skip it in pregnancy and stay far below the 20 mg upper limit.

References

Boron fact sheet for health professionals. NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Boron-HealthProfessional/
Boron and bone health — literature search. PubMed (National Library of Medicine). https://pubmed.ncbi.nlm.nih.gov/?term=boron+bone+calcium+magnesium
Calcium fructoborate and osteoarthritis — literature search. PubMed (National Library of Medicine). https://pubmed.ncbi.nlm.nih.gov/?term=calcium+fructoborate+osteoarthritis
Boron compound records. PubChem (National Library of Medicine). https://pubchem.ncbi.nlm.nih.gov/#query=boron