Boron Supplements: Their Role in Hormones and Bone Health, Backed by Evidence

Boron is a trace mineral found in plant foods, and it is credited with two main benefits: helping keep calcium in the bones and influencing sex hormones, including testosterone. Early studies do point in that direction, but they are small, dated and involve only a handful of people. In Canada, a licensed boron supplement can't promise much more than support for calcium metabolism. Here is what the research actually supports, and what to know before you buy.

Boron, a quiet trace mineral that still matters

Boron is essential for plant growth. In humans, its status is less clear. In a 2007 document on boron, Health Canada noted that no specific biochemical function had yet been identified in humans and that the U.S. Institute of Medicine had been unable to establish a nutritional requirement. No natural deficiency had been reported in North America either.

In practical terms, there is no recommended intake for boron, unlike calcium or magnesium. There are only upper limits:

• 20 mg per day for adults, according to the Institute of Medicine (2001);

• 10 mg per day for adults, according to the European Food Safety Authority (2004).

The same Health Canada document estimated the average natural intake of a Canadian adult at about 3.4 mg per day, combining food and drinking water. A diet rich in fruits and vegetables therefore already provides a meaningful amount.

Boron and calcium: the bone connection

This is the most common argument for boron, and it rests mainly on an American study published in 1987. Twelve postmenopausal women aged 48 to 82 were followed in a metabolic unit. For 119 days, they ate a diet very low in boron (about 0.25 mg per day). Researchers then gave them 3 mg of boron per day.

The result: participants excreted noticeably less calcium and magnesium in their urine. The effect appeared stronger in women whose diet was low in magnesium. The authors saw this as consistent with preventing calcium loss and bone demineralization.

Three nuances change how this study should be read:

1. The starting point was artificially low. The women were coming off four months of a diet almost free of boron, well below what a typical Canadian diet provides.

2. The dose tested matches what's on your plate. The authors themselves note that 3 mg per day is the amount commonly found in a diet rich in fruits and vegetables.

3. Urine was measured, not bone. Losing less calcium in urine does not demonstrate better bone density or fewer fractures.

Health Canada summarized the situation cautiously in 2007: boron interacts with calcium, magnesium, vitamin D and estrogen, which suggests a protective role against osteoporosis, but the benefits observed were mainly in animals and in people deficient in boron or related nutrients. The agency added that a claim about bone mineralization would require supporting evidence.

For bone strength, the best documented nutrients remain calcium, vitamin D and, to a lesser extent, vitamin K. Our article Support bone health with vitamins K and D covers their role. And since boron seems to have more effect when magnesium is lacking, checking your magnesium intake first makes sense: magnesium deficiency affects a large share of the population, according to another article on our blog.

Testosterone and estrogen: a closer look at the studies

Boron's "hormonal" reputation was built on three small studies, and they don't all say the same thing.

In postmenopausal women

In the 1987 study described above, adding 3 mg of boron markedly raised blood levels of estradiol (an estrogen) and testosterone. Once again, the effect was clearer in women low in magnesium, and it occurred after a period of boron deprivation. No one checked whether the effect lasted over time or whether it had any clinical significance.

In healthy men

In 2011, an Iranian team gave 10 mg of boron per day to eight healthy men for one week. Their free testosterone increased, their estradiol decreased, and so did some markers of inflammation. Eight participants, seven days, no separate control group: it's an interesting signal, not proof. Note also that 10 mg per day is the upper limit set in Europe.

In bodybuilders

The study closest to real-world use found the opposite. In 1993, 19 bodybuilders aged 20 to 27 received either 2.5 mg of boron per day or a placebo during seven weeks of training. Both groups gained total testosterone, lean mass and strength. Boron made no difference on any of these measures.

In short: it is plausible that boron influences sex hormone metabolism, especially when intake is low. Nothing supports the idea that a supplement raises testosterone in a man who already eats fruits and vegetables, or that it improves muscle mass. Even a highly favourable 2015 review suggests no more than 3 mg per day, mainly for people whose diet lacks fruits and vegetables or who are at risk for bone loss.

What Health Canada actually regulates

In Canada, boron is found in two types of products, regulated differently.

Product type	What the regulations provide
Multivitamins and minerals	According to Health Canada's monograph (version of June 26, 2026), boron is a "complementary" ingredient: maximum of 700 µg per day, for adults 19 and older only, and no claim can be based on it.
Boron-only supplements, often 3 mg	These are assessed product by product. The 2007 document set the maximum dose at 3.36 mg per day from natural health products. A licensed 3 mg boron citrate product reviewed in Health Canada's database carries the claim "helps maintain healthy calcium metabolism."

You'll notice that no official claim covers testosterone, libido or menopause. If a label or ad goes further, that's a reason to be extra cautious. The first step is still to check for a Natural Product Number (NPN), which confirms the product has been authorized by Health Canada.

Who should avoid boron or seek advice

The warnings associated with boron are few, but they matter. Based on the Health Canada document and the licensing conditions reviewed:

• Pregnancy and breastfeeding: the 2007 document contraindicates boron products in these situations.

• Children: boron products are for adults only.

• Hormone-dependent cancer: people diagnosed with an estrogen-dependent cancer should consult a health care practitioner before use. Health Canada specifies that this is a precaution, as no risk has been confirmed, but the logic is simple: avoid adding a product that could affect estrogen.

• Kidney disorder: boron is eliminated by the kidneys, and a licensed product asks users to consult a practitioner if they have a kidney disorder.

• Ongoing hormone therapy: if you're on hormone treatment, talk to your doctor or pharmacist before adding a product marketed as "hormonal."

Eat your boron rather than swallow it

Since the positive studies were done in people deprived of boron, the simplest way to avoid low intake is through your plate. Boron is concentrated in plants: a diet with plenty of fruits, vegetables, legumes and nuts naturally provides it.

A few situations may justify a closer look:

• a diet low in fruits and vegetables over a long period;

• low magnesium intake, since boron's effects seemed stronger in that context;

• concerns about bone health after menopause, to discuss with a health professional along with calcium, vitamin D and physical activity.

If a supplement seems right for you, you'll find boron on its own and bone formulas in our vitamins, minerals and amino acids section. Check the amount of boron per dose, especially if you already take a multivitamin that contains it: the amounts add up.

Your questions about boron

Does boron really increase testosterone?

One small study found a rise in free testosterone in eight men after one week at 10 mg per day. Another, in bodybuilders, found no effect at 2.5 mg per day over seven weeks. The data are too thin to make any promise, and Health Canada does not authorize any claim to that effect.

Can boron replace osteoporosis treatment?

No. The data on boron concern urinary calcium excretion in boron-deprived women, not bone density or fractures. If you have been diagnosed with osteoporosis or osteopenia, your plan should be set with your doctor.

Is boron helpful during menopause?

The 1987 study was conducted in postmenopausal women, hence the interest in this stage of life. However, it does not support any effect on hot flashes or other symptoms, and women with a history of hormone-dependent cancer should consult before taking it.

Is there a risk in exceeding the dose?

Upper limits are set at 20 mg per day in the United States and 10 mg per day in Europe for adults. A 3 mg product taken as directed stays well below these thresholds, but you need to add up all the products you take, including your multivitamin.

Boron: the key takeaways

Boron is neither a myth nor a cure. Studies suggest it plays a part in calcium and sex hormone metabolism, especially when dietary intake is low, but they remain small and show neither an effect on fractures nor a reliable rise in testosterone. In Canada, the only claim reviewed for a boron-only supplement concerns calcium metabolism. Start with your plate and your magnesium intake, choose a product with an NPN if you go further, and avoid it during pregnancy or with a hormone-dependent cancer without medical advice.

Not sure whether to choose a boron supplement, a bone formula or a simple change in your diet? Our certified naturopaths can help you sort it out during a personalized consultation at one of our four Gatineau locations, or call 819-771-3000 to book an appointment.

References

1. Boron as a Medicinal Ingredient in Oral Natural Health Products (archived). Health Canada. 2007. https://www.canada.ca/en/health-canada/services/drugs-health-products/reports-publications/natural-health-products/boron-medicinal-ingredient-oral-natural-health-products-natural-health-products-directorate-heath-canada-2007.html

2. Boron, Fact Sheet for Health Professionals. Office of Dietary Supplements, National Institutes of Health (NIH). 2022. https://ods.od.nih.gov/factsheets/boron-HealthProfessional/

3. Effect of dietary boron on mineral, estrogen, and testosterone metabolism in postmenopausal women. Nielsen FH et al. FASEB Journal. 1987. https://pubmed.ncbi.nlm.nih.gov/3678698/

4. Calcium and Vitamin D supplements. Osteoporosis Canada. 2026. https://osteoporosis.ca/position-statements/calcium-and-vitamin-d-supplements/

5. Support bone health with vitamins K and D. La Boîte à Grains. https://laboiteigrains.com/en/blogs/sante-globale/soutenez-la-sante-des-os-avec-les-vitamines-k-et-d

6. Magnesium and its benefits. La Boîte à Grains. https://laboiteigrains.com/en/blogs/supplements-naturels/82-de-la-population-presente-une-carence-en-magnesium

7. Comparative effects of daily and weekly boron supplementation on plasma steroid hormones and proinflammatory cytokines. Naghii MR et al. Journal of Trace Elements in Medicine and Biology. 2011. https://pubmed.ncbi.nlm.nih.gov/21129941/

8. The effect of boron supplementation on lean body mass, plasma testosterone levels, and strength in male bodybuilders. Ferrando AA, Green NR. International Journal of Sport Nutrition. 1993. https://pubmed.ncbi.nlm.nih.gov/8508192/

9. Nothing Boring About Boron. Pizzorno L. Integrative Medicine: A Clinician's Journal. 2015. https://pubmed.ncbi.nlm.nih.gov/26770156/

10. Multi-Vitamin/Mineral Supplements monograph. Natural Health Products Ingredients Database, Health Canada. https://webprod.hc-sc.gc.ca/nhpid-bdipsn/

11. Product information, NPN 80044094 (boron 3 mg). Licensed Natural Health Products Database, Health Canada. https://health-products.canada.ca/lnhpd-bdpsnh/info?licence=80044094

12. What is a Natural Product Number (NPN)? La Boîte à Grains. https://laboiteigrains.com/en/blogs/nutrition/quest-ce-que-le-numero-de-produit-naturel-npn