Boron Raised Free Testosterone in Eight Men in One Week, With No Placebo Group. In 19 Bodybuilders Given a Placebo Arm, It Did Nothing.
Does boron raise testosterone in men? The evidence is thin and it points both ways. Boron and testosterone became linked through a single study design: give a small group of people boron, measure their hormones before and after, and compare. In 2011, eight healthy men in Tehran took 10 mg of boron a day for a week, and their mean free testosterone went up while their estradiol went down. Those eight men had no separate placebo group. Eighteen years earlier, a trial in 19 male bodybuilders did have one, and 2.5 mg of boron a day for 7 weeks had no effect on total testosterone, free testosterone, lean mass or strength. The rest of the human data comes from postmenopausal women, a handful of men over 45 in a metabolic ward, and factory workers exposed to boron dust. This article goes through each study, what it measured, and where the testosterone claim outruns it.
Key Takeaways: Boron and Testosterone
In 2011, eight healthy men took 10 mg of boron daily for one week, and their mean plasma free testosterone increased while estradiol decreased; the study had no separate placebo group (Naghii and colleagues, Journal of Trace Elements in Medicine and Biology). In a placebo-controlled trial of 19 male bodybuilders aged 20 to 27, 2.5 mg of boron a day for 7 weeks had no significant effect on total or free testosterone, lean body mass or strength (Ferrando and Green, International Journal of Sport Nutrition, 1993). In a 1997 study of healthy men, 10 mg of boron a day for 4 weeks raised plasma estradiol from 51.9 to 73.9 pmol/L, with only a trend toward higher testosterone (Naghii and Samman, Biological Trace Element Research). The boron and testosterone idea traces back to a 1987 metabolic ward study of 12 postmenopausal women, in whom 3 mg of boron a day markedly raised serum testosterone and estradiol after months on a low-boron diet (Nielsen and colleagues, FASEB Journal). Boron workers in Turkey with a mean exposure of 47.17 mg a day showed no adverse effect on total testosterone, LH, FSH or semen quality (Duydu and colleagues, Archives of Toxicology, 2018). The US upper intake level for adults is 20 mg a day.
Does boron increase testosterone in men?
Boron has not been shown to raise total testosterone in men. One uncontrolled study found a rise in free testosterone after a week, and the one placebo-controlled trial in men found no change in either total or free testosterone. The human boron and testosterone literature is small enough to list in a sentence. There is a 1987 study of 12 postmenopausal women, a follow-up depletion study that included five men over 45, a 1993 placebo-controlled trial in 19 bodybuilders, a 1997 four-week study in healthy men, and the 2011 one-week study in eight men. No meta-analysis pools them, because there is almost nothing to pool. The studies also did not test the same thing. The women's studies took people who had eaten a very low-boron diet for months and gave them back a normal dietary amount. The 2011 study gave healthy men 10 mg a day, which is several times what a typical diet provides. The bodybuilder trial used 2.5 mg. A result in one design says little about the others. The honest summary is that boron supplementation produced hormone changes in some small studies, that the direction of the estrogen change differed between two studies in men, and that the only trial with a separate placebo group found boron added nothing to testosterone in young men who were training.
The Whole Human Boron and Hormone Evidence Fits in One Small Room
Participants per study. Sources: Nielsen and colleagues, FASEB Journal, 1987; Nielsen, Environmental Health Perspectives, 1994; Naghii and colleagues, Journal of Trace Elements in Medicine and Biology, 2011; Ferrando and Green, International Journal of Sport Nutrition, 1993.
Where did the claim that boron boosts testosterone come from?
The claim started with a 1987 study in postmenopausal women, not men. Forrest Nielsen and colleagues at the US Department of Agriculture's Grand Forks Human Nutrition Research Center housed 12 women aged 48 to 82 in a metabolic unit and fed them a diet supplying about 0.25 mg of boron a day for 119 days. The researchers then added 3 mg of boron a day. Boron supplementation markedly elevated serum 17 beta-estradiol and testosterone, and the rise seemed larger when dietary magnesium was low, according to the paper in the FASEB Journal. The authors framed the finding around bone: less calcium and magnesium were lost in urine, which they described as consistent with preventing bone demineralization. In a 1994 review in Environmental Health Perspectives, Nielsen described the follow-up design. Five men over 45, four postmenopausal women and five women on estrogen therapy ate a boron-low diet of 0.23 mg per 2000 kcal for 63 days, then took 3 mg of boron a day for 49 days. That abstract reports changes in copper status and antioxidant enzymes; it does not report a testosterone result for the men. A second group tried to repeat the women's finding. Beattie and Peace at the Rowett Research Institute raised boron intake in postmenopausal women from 0.33 to 3.33 mg a day after 3 weeks on a low-boron diet and found no effect on minerals or sex steroids (British Journal of Nutrition, 1993). They suggested the low-boron diet itself may have obscured any effect. Supplement marketing took the 1987 testosterone line and applied it to men. Green and Ferrando opened their 1994 paper by noting a proliferation of athletic supplements touting boron as a testosterone booster, which is why they ran the bodybuilder trial.
What did the 10 mg boron study in eight men actually find?
The 2011 study found that eight healthy men had higher mean free testosterone and lower mean estradiol after taking 10 mg of boron daily for one week. It is the study behind most boron testosterone marketing, and its design is weaker than the claims built on it. Naghii and colleagues at Baqiyatallah University of Medical Sciences in Tehran brought the men into the lab on day 0, day 1 and day 7. On day 0 they took a placebo with breakfast. On day 1 they took a 10 mg boron capsule. They then took 10 mg every morning, and blood drawn at 8 a.m. on day 7 was compared with the earlier samples. Six hours after the first dose, sex hormone binding globulin (SHBG), high-sensitivity CRP and TNF-alpha had dropped. After a week, mean free testosterone had increased and mean estradiol had decreased. Dihydrotestosterone, cortisol and vitamin D were elevated. The authors described it as the first human study to report higher free testosterone after boron. The limits are in the methods. Eight men is a very small sample. The placebo was a single day in the same men, not a parallel group, so a week of lab visits, time of year or regression to the mean cannot be separated from the boron. The study lasted seven days, which says nothing about whether any change holds. The abstract reports free testosterone, not total testosterone, and a fall in SHBG can shift the free fraction without the testes making more hormone. None of this means the result is wrong. It means one week in eight men without a control group is a starting point for a trial, and that trial has not been published since.
What happened when bodybuilders took boron against a placebo?
When bodybuilders took boron against a placebo, boron made no difference to testosterone, lean mass or strength. Ferrando and Green randomized 19 male bodybuilders aged 20 to 27: 10 took 2.5 mg of boron a day and 9 took a placebo for 7 weeks (International Journal of Sport Nutrition, 1993). The boron did reach the blood. Mean plasma boron in the supplement group went from 20.1 ppb to 32.6 ppb, while the placebo group went from 15.1 ppb to 6.3 ppb. In a companion report in Environmental Health Perspectives, the same researchers noted that only 6 of the 10 men given boron had a rise in plasma boron at all. Analysis of variance found no significant effect of boron on any outcome: total testosterone, free testosterone, lean body mass, 1-RM squat or 1-RM bench press. Both groups gained total testosterone, lean mass and strength. The authors concluded that 7 weeks of bodybuilding raised these measures in lesser-trained lifters, and boron added nothing. This trial has its own limits. It is small, and 2.5 mg is a lower dose than the 10 mg used in 2011. A supporter of boron could argue the dose was too low. That argument cuts the other way too: the strongest positive evidence comes from a higher dose without a placebo group, and the evidence with a placebo group used a lower dose. Nobody has yet run 10 mg against placebo in men for longer than a week.
Boron Reached the Blood. Testosterone Did Not Move.
Mean plasma boron, ppb, day 1 and day 49. Total and free testosterone, lean mass and strength showed no boron effect. Source: Ferrando and Green, International Journal of Sport Nutrition, 1993.
- Start
- 7 weeks
Does boron raise estrogen in men?
Boron raised estradiol in one study of men and lowered it in another, so the effect on estrogen in men is not settled. The conflicting results both come from the same lead researcher using the same 10 mg daily dose. In 1997, Naghii and Samman at the University of Sydney gave healthy men 10 mg of boron a day for 4 weeks. Plasma estradiol rose significantly, from 51.9 to 73.9 pmol/L, and testosterone showed only a trend toward an increase (Biological Trace Element Research). The authors read the estrogen rise as a possible benefit for the arteries. In 2011, the same 10 mg dose for one week in eight men lowered mean estradiol and raised free testosterone, as described above. Supplement sellers often cite the 2011 result as proof that boron lowers estrogen in men, but leave out the 1997 study that found the opposite after four weeks. The two studies differed in length, setting and sample, and neither had a parallel placebo group, so there is no way to say which reflects a real effect. For a man worried about estradiol, the only fair reading is that boron's effect on estrogen is unpredictable in the small data that exist. The postmenopausal women in 1987 also saw estradiol rise with boron, which fits the 1997 result better than the 2011 one.
Four Weeks of 10 mg Boron Raised Estradiol in Men
Mean plasma estradiol, pmol/L, healthy men. Testosterone showed only a trend toward an increase. Source: Naghii and Samman, Biological Trace Element Research, 1997.
How much boron do men already get from food?
Most men already take in roughly 0.35 to 3.53 mg of boron a day from food, judging by urinary excretion. In the 1997 Sydney study, urinary boron in 18 healthy men on their usual diets fell in that range, and when the men took 10 mg a day for 4 weeks, 84% of the supplemented dose came back out in the urine. That high recovery matters. It shows boron is absorbed efficiently and also cleared efficiently, so urinary boron tracks intake closely. It also means a 10 mg supplement multiplies a typical daily intake several times over. Boron in food comes mostly from plants. In a 2014 review in the Journal of Trace Elements in Medicine and Biology, Forrest Nielsen wrote that animal and human data indicate an intake under 1.0 mg a day inhibits boron's health benefits, and that such low intakes are not rare. His recommendation was a diet rich in fruits, vegetables, nuts and pulses. Nielsen's study in postmenopausal women supports the same idea from the other side. The hormone changes appeared when women who had eaten about 0.25 mg a day for 119 days were brought back up to about 3 mg, an amount the authors described as commonly found in diets high in fruits and vegetables. That is a correction of a deficit, not a boost above normal. A 2015 review by Pizzorno in Integrative Medicine noted that in the studies to date, boron's beneficial effects did not appear at intakes above 3 mg a day.
Is boron safe to take at supplement doses?
Boron at typical supplement doses of 3 to 10 mg a day sits below the US upper intake level of 20 mg a day for adults, and studies of heavily exposed workers have not found harm to male hormones. The caution comes from animal data at much higher doses. Boric acid and sodium borates are classified under the EU CLP regulation as toxic to reproduction, Category 1B, with hazard statement H360FD. That classification rests on animal studies. A multigeneration rat study set a no observed adverse effect level of 17.5 mg of boron per kg of body weight per day for male reproductive effects, according to Duydu and colleagues in Archives of Toxicology in 2011. Human worker studies have not found those effects. In boric acid plant workers in Bandirma, Turkey, the most exposed group averaged 14.45 mg of boron a day with no adverse changes in sperm concentration, motility, morphology, FSH, LH or total testosterone (Duydu and colleagues, 2011). A larger 2018 study of 212 workers included an extreme exposure group of 98 men averaging 47.17 mg a day, and still found no boron-associated effects on semen, FSH, LH or total testosterone. Those worker results also cut against the testosterone claim. Men taking in several times the 10 mg supplement dose every working day for years did not show higher total testosterone. Pizzorno's 2015 review notes that no estimated average requirement or dietary reference intake has been set for boron, only the upper intake level of 20 mg a day for adults 18 and over.
Where a 10 mg Capsule Sits on the Boron Scale
Boron, mg per day. Workers at both exposure levels showed no adverse effect on total testosterone, LH, FSH or semen. Sources: Nielsen and colleagues, 1987; Naghii and Samman, 1997; Pizzorno, Integrative Medicine, 2015; Duydu and colleagues, Archives of Toxicology, 2011 and 2018.
Does boron lower prostate cancer risk?
Boron has not been shown to lower prostate cancer risk. One cross-sectional analysis found an association, and its own authors urged caution. Cui and colleagues at UCLA compared dietary boron intake in 95 men with prostate cancer and 8,720 male controls in the third National Health and Nutrition Examination Survey (Oncology Reports, 2004). After adjusting for age, race, education, smoking, body mass index, calories and alcohol, men in the highest quartile of boron intake had an odds ratio of 0.46 compared with the lowest quartile. The confidence interval ran from 0.21 to 0.98, and the P for trend was 0.0525. The authors flagged the small number of cases and the cross-sectional design. Men who eat more boron are men who eat more fruits, vegetables, nuts and pulses, and that diet travels with other habits. An association of this kind cannot show that boron, or a boron capsule, changes cancer risk. No randomized trial has tested it.
Should men over 40 take boron to raise testosterone?
On the current evidence, men over 40 have no trial-backed reason to take boron for testosterone. None of the male studies enrolled men over 40 to test a testosterone outcome with a placebo group, and the trial that had a placebo found no effect in younger men. The doses in the male studies ranged from 2.5 mg to 10 mg a day, all below the 20 mg upper intake level. The positive free testosterone finding came from 10 mg over one week in eight men. The placebo-controlled null came from 2.5 mg over 7 weeks in 19 men. The four-week 10 mg study found estradiol went up, not down. A man whose diet is low in plant foods may be among the people Nielsen described as taking in under 1.0 mg a day. For him, eating more fruit, vegetables, nuts and pulses raises boron along with fibre and other nutrients, and it matches the amounts used in the women's studies. That is a dietary point, not a testosterone treatment. For a man with symptoms of low testosterone, the useful step is a proper morning blood test and a conversation with a clinician, not a mineral capsule. Supplements marketed as testosterone boosters, including boron, zinc and magnesium, tend to have the same evidence pattern: an effect in people who were deficient and little or nothing in people who were not. Boron fits that pattern, with even fewer studies behind it.
Doses and Durations Tested in Men
Daily boron dose (mg) and study length (weeks). Red line: US upper intake level of 20 mg/day. Sources: Ferrando and Green, 1993; Naghii and Samman, 1997; Naghii and colleagues, 2011; Pizzorno, 2015.
- Dose (mg/day)
- Length (weeks)
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