Do boron supplements work?
Not on the evidence so far. The small trial where men’s free testosterone rose used 10 mg a day. That’s also Europe’s adult upper limit for all your boron, food included.
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Do boron supplements work?
Not well enough to rely on. Boron is a trace mineral, one your body uses in tiny amounts. No daily amount you need has been set.
A 2026 review found the human studies on boron are small. Looking at boron and two other trace minerals, it says the human data are insufficient to justify supplements.
| Claim | What trials found | Who was tested |
|---|---|---|
| Raises testosterone | Free testosterone rose after a week of 10 mg. A 7-week trial of 2.5 mg found no change. | 8 healthy men; 19 young bodybuilders |
| Builds muscle or strength | No effect on muscle or strength from 2.5 mg for 7 weeks. | 19 young bodybuilders |
| Protects bones | 3 mg cut calcium lost in urine in one study. A UK study of 3 mg found no effect. | Small groups of women after the menopause |
Sources: Naghii 2011; Ferrando 1993; Nielsen 1987; Beattie 1993
None of these trials shows boron treats low testosterone or weak bones. If a symptom is behind your interest, ask your GP what might be causing it.
Does boron increase testosterone?
In one tiny study, free testosterone went up. That’s the small share of testosterone not stuck to a carrier protein called SHBG.
Eight healthy men took 10 mg a day. After a week, their free testosterone rose and oestradiol fell. Oestradiol is a form of oestrogen.
Other trials found less. In 19 young bodybuilders, 2.5 mg or a dummy pill for 7 weeks made no difference to total or free testosterone.
In a 4-week study of healthy men on 10 mg a day, oestradiol rose and testosterone only trended up.
A week in 8 men is a photo, not a film. It can’t tell you what months of boron would do.
Think yours is low? A blood test tells you more than a capsule can. See low testosterone symptoms, testosterone blood tests and how to raise free testosterone.
Is boron good for bone health?
It hasn’t been shown. In one study, 12 women aged 48 to 82, past the menopause, ate a low-boron diet in a research unit. Adding 3 mg a day cut the calcium and magnesium they lost in urine.
That’s a clue, not proof. Bone strength wasn’t measured.
A study in Aberdeen gave women after the menopause the same 3 mg and found no effect on minerals, hormones or signs of bone breakdown. The authors say the low-boron diet may have hidden an effect.
No trial here tested whether boron prevents broken bones. The NHS gives these steps instead.
NHS steps to keep bones strong if you have osteoporosis or are at higher risk
- Eat plenty of food high in calcium, and take a calcium supplement if your doctor prescribes it.
- Get vitamin D from sunlight in summer and from a supplement in winter.
- Eat plenty of fruit and vegetables, get enough protein and limit salt.
- Exercise regularly, with weight-bearing, strengthening and balance exercises.
- Don’t smoke, and don’t drink too much alcohol.
- Reduce your chance of falls, for example with shoes that grip and a non-slip bath mat.
Source: NHS: osteoporosis
Fruit and veg bring boron too. For meals and supplements that matter more, see diet for bone health and osteoporosis supplements.
How much boron is safe?
That 10 mg is the line. The European Food Safety Authority (EFSA) sets the adult upper limit at 10 mg a day. It counts all your boron, from food and supplements together.
Food usually gives you 0.5 to 3 mg a day. The richest sources are fruit, nuts, leafy greens and beans. So a 10 mg capsule on top can take you over.
- 3 mg a day or belowUsual amount from food.
- Above 3 up to 10 mg a dayMore than food usually gives. Within the EFSA adult limit.
- Above 10 mg a dayAbove the EFSA adult limit.
Sources: EFSA; Nutrients review 2026
Children and teenagers have lower limits. Pregnancy and breastfeeding share the adult 10 mg.
| Age | EFSA upper limit a day |
|---|---|
| 1 to 3 | 3 mg |
| 4 to 6 | 4 mg |
| 7 to 10 | 5 mg |
| 11 to 14 | 7 mg |
| 15 to 17 | 9 mg |
| Adults, including pregnancy and breastfeeding | 10 mg |
Source: EFSA
Why a limit at all? At very high doses, boron harmed reproduction in animals. The same review says routine boron supplements are generally not recommended, as long-term safety data in people are limited.
Before you buy, add up the boron in everything you take and keep the total to 10 mg or less a day.
Do I need a boron supplement?
Probably not. Food already gives you some, and the 2026 review found the human evidence too thin to back supplements.
Boron has been sold to athletes as a testosterone booster since at least the early 1990s. Check the label of any booster you buy. See testosterone booster supplements.
Check these before you take boron
- If low sex drive, tiredness or mood swings are the reason, see your GP first.
- Find the boron amount on the label, in mg.
- Add up boron from every product you take, including multivitamins.
- Keep your total from food and supplements to 10 mg or less a day.
- Ask a pharmacist before adding boron if you take any medicines.
Sources: EFSA; NHS: the male menopause
Never stop or change a prescribed medicine without your prescriber.
When to speak to a GP
Book an appointment if:
- You have low sex drive, erection problems, mood swings, loss of muscle, tiredness, poor sleep or poor concentration. Your GP may check your testosterone with a blood test.
- You have back pain that’s not getting better after a few weeks, or your spine becomes curved or hunched.
- You think you may be at risk of osteoporosis and you’re worried.
- You’ve recently had a fall or injury and the pain is not getting better. Ask for an urgent GP appointment or call 111.
- You have severe pain after a fall or injury. Call 999 or go to A&E.
In many men, these symptoms are nothing to do with hormones. Stress, poor sleep, diet and alcohol can all play a part.