The Story of Boron: How a Trace Mineral Became a Popular Supplement

Few supplements have had a career as unusual as boron. For most of the twentieth century it was known mainly to agronomists as a micronutrient for crops. Then a single human study in the late 1980s, and the marketing that followed, turned it into a fixture of "natural testosterone" formulas. Our editorial team traces that journey and separates the evidence from the enthusiasm.

From borax to biology

Boron compounds have been used by humans for centuries. Borax was traded along Asian routes for glazes and metalworking, and boric acid later became a common antiseptic and food preservative. In nineteenth-century Europe borates were added to milk, butter and meat to extend shelf life, a practice that was eventually curtailed because of concerns about toxicity at the levels used.

The biological story began in plants. In the 1920s researchers, notably Katherine Warington at Rothamsted Experimental Station in Hertfordshire, demonstrated that broad beans could not grow normally without traces of boron. This established it as an essential plant nutrient and gave farmers a reason to monitor boron in soils.

For animals and humans the picture remained vague for decades. Boron is present in fruit, vegetables, nuts, pulses, coffee and wine, so dietary intake is never zero, and no clear deficiency disease was ever described. That uncertainty persists today: boron is not formally classed as an essential nutrient for humans.

Interest grew in the 1980s when scientists at the United States Department of Agriculture's Grand Forks Human Nutrition Research Center, led by Forrest Nielsen, began feeding volunteers diets deliberately low or adequate in boron and measuring the effects on mineral metabolism.

The 1987 study that started the hype

In 1987 Nielsen and colleagues published a paper in the FASEB Journal describing twelve postmenopausal women who first ate a low-boron diet and then received 3 mg of boron per day. During supplementation, urinary calcium and magnesium losses fell, and serum concentrations of 17β-oestradiol and testosterone rose.

The finding was modest, the sample was small and the participants were older women on a carefully controlled diet. Nevertheless, the word "testosterone" was enough. By the early 1990s boron was being sold to bodybuilders as a natural anabolic, often in amounts of several milligrams per capsule.

The idea spread quickly through magazines and mail-order catalogues, which at the time rarely distinguished between a hormonal change in postmenopausal women and a meaningful effect on muscle growth in young trained men.

What later research found

The first direct test in athletes came in 1993, when Ferrando and Green gave male bodybuilders 2.5 mg of boron daily for seven weeks during training. Both the supplement and placebo groups gained lean mass and strength, and there was no difference in testosterone between them. For many researchers this settled the question of boron as an anabolic agent.

Interest revived in 2011 when Naghii and colleagues reported that 10 mg per day for one week in a small group of healthy men increased free testosterone and decreased oestradiol and some inflammatory markers. The study was short, uncontrolled in key respects and has not been replicated in large trials.

Reviews by Pizzorno (2015) and others have since described plausible roles for boron in bone metabolism, vitamin D and magnesium handling, and inflammation. However, the authors were careful to note that the clinical evidence is limited and mostly from small studies.

The table summarises the key human studies most often cited in marketing.

Why boron stayed popular

Boron survived its disappointing sports trial for several reasons. It is cheap, widely available and has a reassuring "mineral" image. It fits neatly into multi-ingredient formulas alongside zinc, magnesium and herbal extracts, where its individual contribution is impossible to judge.

Online communities also played a role. Anecdotal reports of improved wellbeing, often from people with low dietary intake, circulated widely. Because the effect on free testosterone reported in 2011 was short-term and small, it was easy to over-interpret.

Another factor is the broader interest in bone and joint health. Some people take boron for those reasons rather than performance, and the overlap in marketing helps keep it in the public eye.

• Plausible areas of interest: mineral balance, bone metabolism, inflammatory markers.
• Weak or absent evidence: muscle growth, strength gains, meaningful testosterone increases in healthy young men.
• Research gap: large, long-term randomised trials in athletes.

Safety and UK regulation

In the UK, boron is permitted in food supplements under retained food supplement law, in the forms listed in the regulations, such as boric acid and sodium borate. The Expert Group on Vitamins and Minerals (2003) set a safe upper level of 9.6 mg per day from supplements for adults. The European Food Safety Authority has proposed a tolerable upper intake of 10 mg per day from all sources.

Typical diets supply roughly 1–2 mg daily, more for those who eat plenty of plant foods. Supplements on the market commonly provide 3–10 mg. Staying at the lower end and checking for boron in multi-ingredient products helps avoid double dosing.

Boric acid and borates are classed as reproductive toxicants under chemical regulations, based on high-dose animal studies. This does not mean dietary amounts are dangerous, but it is a good reason to respect upper limits. Pregnant women and people with kidney disease should not take boron supplements without medical advice.

Signs of excess intake can include nausea, vomiting, diarrhoea and skin rashes. Acute poisoning from boric acid has historically occurred mainly through accidental ingestion of antiseptic preparations rather than supplements.

Conclusions of the editorial team

Boron's rise is a textbook example of how one small study can shape a supplement category for decades. The original 1987 findings concerned mineral metabolism in older women, not muscle building.

The one controlled trial in bodybuilders found no performance benefit, and the short-term hormonal changes seen later have not been confirmed by robust research. Boron may still have a role in a balanced diet, but it is not a meaningful anabolic agent.

If you choose to use it, keep within UK safe upper levels and look at the whole picture of your diet first.

For further reading, we suggest our articles on zinc and magnesium for active people, on how to evaluate "testosterone booster" claims and on vitamin D status in UK athletes.

References

1. Nielsen FH, Hunt CD, Mullen LM, Hunt JR. Effect of dietary boron on mineral, estrogen, and testosterone metabolism in postmenopausal women. FASEB J. 1987;1(5):394–397.
2. Ferrando AA, Green NR. The effect of boron supplementation on lean body mass, plasma testosterone levels, and strength in male bodybuilders. Int J Sport Nutr. 1993;3(2):140–149.
3. 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. J Trace Elem Med Biol. 2011;25(1):54–58.
4. Pizzorno L. Nothing boring about boron. Integr Med (Encinitas). 2015;14(4):35–48.
5. Warington K. The effect of boric acid and borax on the broad bean and certain other plants. Ann Bot. 1923;37(148):629–672.
6. Expert Group on Vitamins and Minerals. Safe Upper Levels for Vitamins and Minerals. London: Food Standards Agency; 2003.
7. https://testolabmilano.com/post-course-therapy/gonadotropin/