Boron and Testosterone: What the Studies Used
Written by the Horsewood Formula editorial desk
Last updated · Who reviewed this page · How we write and review
The study behind boron and testosterone claims gave 8 healthy men 10 mg of boron a day for one week; free testosterone rose and estradiol fell. For adults, the upper limit is 20 mg of elemental boron a day. Horsewood lists 20 mg of boron amino acid chelate, so its elemental boron is lower and not stated.
What boron dose did the testosterone study use?
It used 10 mg of boron a day for one week in 8 healthy men. Free testosterone rose and estradiol fell over that week (Naghii et al., 2011).
That single study is the source of most boron and testosterone claims. It is worth knowing exactly how small it was before reading any ad that cites it.
| Study detail | What it was |
|---|---|
| Daily boron | 10 mg a day |
| Length | 1 week |
| People | 8 healthy men |
| Testosterone result | Free testosterone went up |
| Estrogen result | Estradiol went down |
| Main limit | Tiny group and a very short test |
Free testosterone is the share not bound to proteins in the blood. A rise over one week in eight men is a signal to study further, not proof of a lasting change.
What is elemental boron, and why does the label form matter?
Elemental boron is the weight of the boron atoms alone. Supplements bind boron to another molecule, and that carrier adds weight that is not boron.
The NIH Office of Dietary Supplements says labels should list elemental boron for this reason (NIH ODS, 2022). The Horsewood label lists 20 mg of boron amino acid chelate. That is the weight of the whole compound.
What that leaves out
The elemental boron in the 20 mg is not stated. It is some part of the 20 mg, but the label does not say how much, and the maker has not published it.
What is the upper limit for boron, and how much do people already get?
For adults, the upper limit is 20 mg of elemental boron a day. Most adults already take in about 1 to 1.5 mg a day from food.
Supplements on the market usually hold 0.15 to 6 mg of elemental boron, according to the same NIH fact sheet. The 10 mg study dose sits above that common range and below the upper limit.
| Amount | Elemental boron a day | Source |
|---|---|---|
| Usual diet | About 1-1.5 mg | NIH ODS |
| Common supplements | 0.15-6 mg | NIH ODS |
| Testosterone study | 10 mg for 1 week | Naghii et al., 2011 |
| Adult upper limit | 20 mg from all sources | NIH ODS |
| Horsewood label | Not stated (20 mg is the chelate weight) | Horsewood Supplement Facts |
One fact follows from the label math. A 20 mg compound cannot hold more than 20 mg of boron, so the elemental share is below the upper limit on its own. Whether it comes anywhere near the 10 mg study dose is unknown.
How can you work out the boron in Horsewood or any other product?
Start with the form printed on the label, then look for an elemental figure. If there is none, the honest answer is that the boron dose is unknown.
The steps below work for any mineral line, not only boron.
- 1
Read the form
Note the compound named. On Horsewood it is boron amino acid chelate, 20 mg.
- 2
Look for the word elemental
A good label prints the elemental amount next to the compound or in a footnote.
- 3
Ask when it is missing
Contact the seller and ask for the elemental boron per serving in writing.
- 4
Compare with the research
Set the elemental figure against the 10 mg study dose and the 20 mg upper limit.
- 5
Add up every source
Count your multivitamin and any other boron product toward the same daily limit.
The Horsewood Supplement Facts page walks through every line on the panel, including this one.
Can boron lower estrogen in men?
One tiny study saw estradiol fall after a week of 10 mg a day. That is the whole of the evidence in the sources used here.
Estradiol is the main form of estrogen, and men need some of it. A one-week change in eight men does not show that boron lowers estrogen in a useful or safe way over time.
How does one week of boron compare with other men's supplement studies?
It is very short. Studies of tongkat ali, another common ingredient in men's formulas, ran for weeks or months.
Laying the study lengths side by side shows how little time boron has been tested for this purpose.
- 1 week
Boron, 10 mg a day
Eight healthy men. Free testosterone rose and estradiol fell (Naghii et al., 2011).
- 4 weeks
Tongkat ali, 200 mg a day
Stressed adults had lower saliva cortisol and higher saliva testosterone than placebo (Talbott et al., 2013).
- 5 weeks
Tongkat ali, 400 mg a day
A small pilot in active seniors with no placebo group (Henkel et al., 2014).
- 12 weeks
Tongkat ali, 100-200 mg a day
Older men with low testosterone saw a rise versus placebo (Chinnappan et al., 2021).
Longer studies are not automatically better, but they can show whether a change lasts. Boron has no such data for testosterone in the sources reviewed here.
Is boron glycinate better than boron chelate?
Nobody can say. The NIH Office of Dietary Supplements reports no data showing which boron form the body absorbs best.
Ads often present one form as superior. Without absorption data, the more useful question is how much elemental boron a serving holds, and that is the number most worth asking for.
- Glycinate, citrate and chelate are all carrier forms
- Each carrier changes the compound weight, not the boron itself
- Only an elemental figure lets you compare two products fairly
Is taking 10 mg of boron a day safe?
It is below the adult upper limit of 20 mg of elemental boron a day. That limit covers every source combined, so a multivitamin counts too.
The 10 mg study ran for only one week. It does not tell you what happens at that level over months. Ask your doctor before long-term use, and say what else you take.
What does the boron research mean for Horsewood?
It means the boron line cannot be matched to the study. The label gives a compound weight, and the elemental boron that the 10 mg study measured is not published.
No study of the finished Horsewood formula exists either. The FTC expects health claims to rest on human trials whose dose and formula match the product (FTC, 2022).
The form is named and weighed: 20 mg of boron amino acid chelate per 2 capsules.
The elemental boron per serving, the figure that research and the upper limit use.
Horsewood is not a treatment for low testosterone, and no testosterone change is promised.
Horny goat weed has a similar gap, which our post on horny goat weed and icariin explains. If you decide to try Horsewood as a daily habit, the pricing page lists each pack and the side effects page covers the other ingredients.
Boron and testosterone: common questions
Common search questions, answered from the label and the sources cited on this page.
How much boron raises testosterone?
The study people quote used 10 mg of boron a day for one week in 8 healthy men. Free testosterone went up, but a group that small and a test that short cannot set a reliable dose.
What is the upper limit for boron?
For adults, the NIH Office of Dietary Supplements sets the upper limit at 20 mg of elemental boron a day from all sources. That counts food, multivitamins and any other supplement together.
What foods are high in boron?
Boron comes mainly from everyday food, and most adults already get about 1 to 1.5 mg a day from their usual diet. The NIH boron fact sheet lists the main food sources.
Is boron glycinate better than boron chelate?
No one knows. The NIH Office of Dietary Supplements says there are no data showing which form of boron the body absorbs best.
What is elemental boron?
It is the weight of the boron itself, without the compound it is bound to. A label line such as 20 mg of boron amino acid chelate, as on Horsewood, weighs the whole compound, so the boron share is smaller.
How long did the boron testosterone study last?
One week. The men took 10 mg of boron a day for seven days, so the study says nothing about longer use.
Can boron lower estrogen in men?
In that one small study, estradiol, a form of estrogen, went down after a week. Eight men over seven days is far too little to call boron an estrogen treatment.
Is taking 10 mg of boron safe?
It sits below the adult upper limit of 20 mg of elemental boron a day. The study that used 10 mg lasted only a week, so ask your doctor before taking that much for months.
