Boron is a trace mineral found in plant foods, and a boron supplement provides it in concentrated form. The evidence for benefits is limited: small studies have looked at bone minerals, osteoarthritis symptoms, and hormones, but none shows that boron prevents disease, and the testosterone claims are not well supported. Most adults get roughly 1 mg a day from food (reference 1). The U.S. upper limit for adults is 20 mg a day from all sources combined (reference 2), and supplements are not needed to meet any established requirement, because no recommended intake has been set.
This guide covers what boron is, what the research does and does not show, dietary sources, how much is used in studies and where the safety ceiling sits, side effects, and who should be cautious.
At a Glance
- What it is: A trace mineral. Beverages, especially instant coffee, are the largest dietary source for adults (reference 1), alongside fruits, nuts, legumes, and potatoes.
- Typical intake: About 1.0 to 1.5 mg a day from food and supplements combined for adults (reference 1). Common supplement amounts range from 0.15 to 6 mg (reference 1).
- Upper limit: 20 mg a day for adults from food, drinks, and supplements together, and lower for children and teens (reference 2).
- Best-supported use: None is firmly established. Evidence is early and based on small studies.
- Never swallow: Boric acid or borax. These household chemicals are poisonous and are not supplements.
What the Research Shows
Most boron studies are small, short, and run on specific products, so they raise questions rather than answer them. The table summarizes the main areas and their limits.
| Area | What was found | Limits |
|---|---|---|
| Bone and minerals | A 1987 study in 12 postmenopausal women reported that 3 mg a day reduced urinary calcium and magnesium loss (reference 5). | Tiny study of a mineral marker, not fractures or bone density. Details were not verified against the original paper. |
| Osteoarthritis | A pilot study of 20 people with 6 mg a day for 8 weeks found reduced symptoms compared with placebo (reference 1). | Very small and short. Calcium fructoborate trials are also small and product-specific. |
| Testosterone (men) | An 8-man trial using 10 mg a day for one week reported higher free testosterone (reference 4). A 7-week randomized trial in 19 bodybuilders using 2.5 mg a day found no effect on testosterone, muscle mass, or strength (reference 3). | Results conflict, doses differ, and neither study shows a lasting or clinically meaningful change. |
Does boron raise testosterone or build muscle?
There is no solid evidence that it does. The one-week trial that reported a rise was very small and used untrained men. The longer controlled trial in trained lifters found that testosterone, lean mass, and strength rose in both groups, with or without boron, which the authors attributed to the training itself (reference 3). Resistance training and adequate protein have far better evidence for muscle growth. If you are worried about low testosterone, a blood test and a clinician are the right next step, not a supplement.
Boron From Food vs. Supplements
Plant foods supply most dietary boron, including fruits, nuts, legumes, and potatoes. Beverages, especially instant coffee, are the largest source for adults, while milk and cheese matter more for adolescents (reference 1). Boron content varies with soil and preparation, so food labels rarely list it.
The World Health Organization has described an acceptable safe range of 1 to 13 mg a day for adults (reference 1). Eating a varied, plant-rich diet is the simplest way to stay inside that range, and it also provides fiber, protein, and other nutrients a capsule does not.
Boron Dosage
There is no recommended daily amount, so there is no dose you need to hit. What exists is a ceiling and a range of amounts used in studies.
| Reference point | Amount (elemental boron) |
|---|---|
| Typical total intake, adults | About 1.0 to 1.5 mg a day (reference 1) |
| Common supplement amounts | 0.15 to 6 mg (reference 1) |
| Amounts used in studies above | 2.5 to 10 mg a day |
| Upper limit, adults (including pregnant and breastfeeding adults) | 20 mg a day from all sources (reference 2) |
| Upper limit, children | 3 mg (ages 1 to 3), 6 mg (4 to 8), 11 mg (9 to 13), 17 mg (14 to 18) (reference 2) |
How to read a label: Check the milligrams of elemental boron, not just the weight of the compound. Calcium fructoborate and similar products often list the compound weight, which is larger than the boron it contains. Add every product you take, since multi-mineral and "bone" formulas can also contain boron.
No evidence shows a best time of day. If you take it, take it consistently and with food if that is more comfortable. Higher amounts are not shown to work better, so staying well under the upper limit makes sense.
Side Effects and Safety
At typical supplement amounts, serious side effects are not well documented, but long-term safety data are limited. Very high intakes, most often from swallowing boric acid, borax, or pesticide products, cause nausea, vomiting, and diarrhea, and can damage the kidneys. Because the kidneys clear boron from the body, people with kidney disease should ask a clinician before using it.
Boric acid and borax
Boric acid appears in some pesticides, and borax (sodium borate) is used in cleaning products. They are not interchangeable with supplement forms such as boron citrate, glycinate, aspartate, or calcium fructoborate. If a child swallows a boric product, contact poison control or emergency services right away. Keep these products away from children.
Interactions and quality
NIH states that boron is not known to interact with medicines or other supplements (reference 2). Some drug-reference databases list a mild possible interaction with estrogen medicines, so tell your pharmacist if you take hormone therapy. The FDA does not approve supplements before they are sold, so look for independent testing seals such as USP or NSF, which check that a product contains what the label says.
Who should be cautious
Ask a clinician before using boron if you are pregnant, planning pregnancy, or breastfeeding, if you have kidney disease, or if you take prescription medicines. Do not give boron supplements to children unless a pediatrician recommends them.
Frequently Asked Questions
Is boron an essential nutrient?
No recommended intake has been established, so it is not classified as essential for humans. Researchers are still studying whether it has a role in bone and mineral metabolism.
Will boron help my joints or bones?
Possibly, but the evidence is early. A small pilot reported fewer osteoarthritis symptoms, and a small older study found changes in calcium and magnesium handling. Neither shows it prevents fractures or replaces standard care. Calcium and vitamin D remain the better-established bone nutrients.
Can I get enough from food?
Because no requirement exists, there is no deficiency to fix. Food provides roughly 1 mg a day for most adults, and eating more plant foods and beverages like coffee raises that naturally.
What is the safest way to stay within limits?
Add up boron from all supplements, assume food provides around 1 to 3 mg, and stay well below 20 mg a day total. Choose a single clearly labeled product rather than stacking several.
References
- National Institutes of Health, Office of Dietary Supplements. Boron: Fact Sheet for Health Professionals. ods.od.nih.gov/factsheets/boron-healthprofessional
- National Institutes of Health, Office of Dietary Supplements. Boron: Fact Sheet for Consumers (updated January 15, 2021). ods.od.nih.gov/factsheets/Boron-Consumer
- Ferrando AA, Green NR. The effect of boron supplementation on lean body mass, plasma testosterone levels, and strength in male bodybuilders. International Journal of Sport Nutrition, 1993. ntrs.nasa.gov/citations/20040199486
- Naghii MR, Mofid M, Asgari AR, Hedayati M, Daneshpour MS. Comparative effects of daily and weekly boron supplementation on plasma steroid hormones and proinflammatory cytokines. Journal of Trace Elements in Medicine and Biology, 2011;25(1):54-58. pubmed.ncbi.nlm.nih.gov/21129941
- Nielsen FH, et al. Effect of dietary boron on mineral, estrogen, and testosterone metabolism in postmenopausal women. FASEB Journal, 1987.
