Key Takeaway
Nutricost Boron 5 mg is a single-ingredient capsule: 5 milligrams of boron from boron citrate, 240 capsules for $15.95, about 6.7 cents per capsule or roughly $24 for a year of daily use. The research behind boron for lifters is thinner than most supplement pages admit. The headline result, higher free testosterone and lower estradiol after a week, comes from a study of eight healthy men with no separate control group, taking 10 milligrams a day. The bone data is small and old. The reviews that support boron note that benefits appear at intakes of a few milligrams a day, and a review published in 2015 gave an upper intake level of 20 mg a day for adults, so a 5 mg capsule is well inside the safe range but is more than the 3 mg level above which that review saw no added benefit. This is a cheap, low-risk experiment with an unproven payoff.
Boron is the supplement that sounds like it should be on a periodic-table quiz and ends up in testosterone stacks. A few milligrams of a trace mineral, priced at pennies, is supposed to raise free testosterone, lower estrogen, and protect bone. The pitch is cheap and tidy. The research is cheaper and thinner.
This review looks at one specific product, Nutricost Boron 5 mg. We cover what the retailer listing says, what the main human study actually did, what the bone work shows, how the capsule compares with the intake figures that exist, and what it costs. We already cover the proposed mechanism in our boron, testosterone, and bone guide, so this article does not restate it. Here the job is to size up the product and the strength of the evidence. It is a research review, not a claim that we have used the product and measured a result.
What You Are Buying
The details below come from the Amazon listing for Nutricost Boron Capsules 5 mg, 240 vegetarian capsules. The supplement facts panel on the listing is an image, which we read directly, and the text fields provide the directions and the other ingredients.
| Label Detail | What the Listing States |
|---|---|
| Active ingredient | Boron (from boron citrate), 5 mg per capsule |
| Serving size | 1 capsule |
| Servings per container | 240 |
| Other ingredients | Rice flour, hypromellose (cellulose) capsule; the facts panel image also lists magnesium stearate (vegetable source) |
| Directions | 1 capsule daily with 8 to 12 oz of water, or as directed by a healthcare professional |
| Claims | Vegetarian, non-GMO, gluten free; each batch tested by independent ISO-accredited laboratories; made in an NSF-certified, GMP-compliant, FDA-registered facility |
| Listed price | $15.95 for 240 capsules |
Two details deserve a comment. The "from boron citrate" phrasing means the 5 mg figure is elemental boron, not the weight of the citrate compound, which is how you want a mineral labeled. And the ingredient text in the listing's information section lists boron, rice flour, and the capsule, while the label image also shows magnesium stearate, a common flow agent. The difference is small but real, and it is a reminder that the image is the more detailed source.
What Boron Is, Briefly
Boron is a trace element found in fruits, vegetables, nuts, and legumes. Unlike calcium or iron, no official recommended intake exists for it. Pizzorno (2015), in a review in Integrative Medicine, states that no estimated average requirements or dietary reference intakes have been set for boron, only an upper intake level of 20 mg a day for adults aged 18 and older. Nielsen (2014) reviews the case that boron is a bioactive element in nutritional amounts and writes that both animal and human data indicate an intake of less than 1.0 mg a day inhibits the health benefits of boron, and that intakes that low are not rare in dietary surveys. His practical recommendation was not a capsule but a diet rich in fruits, vegetables, nuts, and pulses.
Both reviews are favorable toward boron, which is worth keeping in mind. Pizzorno's abstract also says that in none of the numerous studies conducted to date do boron's beneficial effects appear at intakes above 3 mg a day, and her suggested supplemental amount was 3 mg a day for people with low produce intake or specific bone-health concerns. That is below the 5 mg in this capsule.
The Testosterone and SHBG Evidence
When people claim that boron raises testosterone, they are nearly always citing one paper. Naghii and colleagues (2011) enrolled eight healthy male volunteers and measured hormones across three occasions: day 0, when each took a placebo with breakfast; day 1, when each took a 10 mg boron capsule; and day 7, after a week of 10 mg a day. Blood was drawn every two hours for six hours on the first two days, and once at 8:00 a.m. on day 7.
Plasma boron rose significantly. Six hours after the first dose, sex hormone binding globulin (SHBG), high-sensitivity C-reactive protein, and TNF-alpha were lower. After a week, in the morning samples only, mean plasma free testosterone had increased and estradiol had decreased significantly, with dihydrotestosterone, cortisol, and vitamin D elevated, and all three inflammatory markers lower. The authors themselves called it the first human study reporting increased free testosterone after boron consumption.
That is a real result, and it is also a small and weak design. Eight men is not a trial in the sense needed to make claims for the population. There was no concurrent control group, since each man served as his own baseline, so anything that changed between day 0 and day 7 for any reason, including time of testing and normal hormone variation, is mixed into the result. The dose was 10 mg a day, twice the capsule in this product. The study ran for one week. And free testosterone is a calculated or assayed number that moves with SHBG, so a drop in SHBG can raise free testosterone without any change in testosterone production. We searched PubMed for a larger randomized replication in men and did not find one, so we cite none. Until someone runs it, boron's testosterone effect should be read as a hypothesis from one pilot.
What the Evidence Is Really Saying
The boron-and-testosterone story rests on one eight-man, one-week study without a control group, at twice this capsule's dose. It is a reason to run a better trial, not a reason to expect a result from a 5 mg capsule.
Bone and the Rest
The bone case is older and no sturdier. Meacham, Taper, and Volpe (1994) followed 17 female college athletes and 11 sedentary controls for a year of boron supplementation or placebo. The athletes showed a slight increase in bone mineral density while the sedentary group showed a slight decrease, which the abstract reports as a group difference, not a boron effect. The clearer findings were about blood chemistry: serum phosphorus was lower in boron-supplemented subjects, serum magnesium responses differed by group and activity, and boron excretion rose with supplementation. That is a mineral-metabolism study with 28 participants, not a fracture trial.
The broader reviews are enthusiastic in tone and cautious in substance. Khaliq, Juming, and Ke-Mei (2018) wrote that boron has pleiotropic effects and that findings on higher boron status are generally mixed, which they attribute to the supplemental amount needing to be appropriate, and they called for more research on mechanisms and requirements. Heffernan and colleagues (2019), in a systematic review of 130 experiments on minerals and trace elements in athletes, found only four boron experiments and concluded that there is little evidence to support mineral and trace element supplementation for improving athletic performance, with iron and magnesium the possible exceptions. So there is no performance, hypertrophy, or fracture trial for boron that we would call convincing.
Where 5 mg Sits
| Reference Point | Boron Per Day | One 5 mg Capsule Is |
|---|---|---|
| Intake below which benefits are said to be inhibited (Nielsen 2014) | Under 1.0 mg | 5 times that threshold |
| Amount above which no added benefit appeared (Pizzorno 2015) | 3 mg | about 1.7 times that level |
| Dose in the one testosterone study (Naghii 2011) | 10 mg | half of that dose |
| Upper intake level for adults, as reported by Pizzorno 2015 | 20 mg | 25 percent of the upper limit |
The table shows a capsule that lands in an unusual place. It is far above the low intakes that supposedly hold boron's benefits back, above the 3 mg level the supportive review says is enough, and below the dose used in the only testosterone study. If boron works the way advocates describe, 5 mg may be more than you need. If it does not, it is an inexpensive amount to take.
The 20 mg upper limit comes from the Institute of Medicine's 2001 dietary reference intake report, which we were unable to open directly for this review, so we cite it as relayed by Pizzorno. Confirm the number against the primary document if you rely on it. Because the capsule supplies only a quarter of that limit, and because diet also contributes boron from fruits, vegetables, and nuts, a lifter eating a normal diet and taking one capsule is unlikely to approach it.
What a Fair Test Would Look Like
Since the literature cannot answer the question, some lifters will decide to try it, and it is worth saying how to do that without fooling yourself. A fair self-test needs at least a baseline blood panel with total testosterone, SHBG, and ideally free testosterone and estradiol, drawn at the same time of morning and the same fasting state as the follow-up, ideally on multiple days, because those hormones vary from day to day. Naghii's own design is a cautionary example: a single morning draw a week apart cannot distinguish a boron effect from ordinary variation. Hold sleep, training load, body weight, alcohol, and other supplements as constant as possible, and change one thing at a time. Even then one person's before-and-after is an anecdote, not a trial, and a lab value moving within its normal range is not proof of anything.
That is the standard we will hold our own checkpoint updates to. The checkpoints reflect the editor's notes and any data the editor chooses to share, and they will not be presented as controlled evidence.
Reading the Hormone Numbers Without Fooling Yourself
Because boron's testosterone claim is about free testosterone and SHBG rather than total testosterone, it helps to understand what those terms mean on a lab report. Most circulating testosterone is bound to proteins, mainly SHBG and albumin, and the free fraction is the small remainder that is available to tissues. A lab can measure free testosterone directly or estimate it from total testosterone, SHBG, and albumin, and different methods give different numbers, which is one reason results from different labs are hard to compare. When a study reports lower SHBG and higher free testosterone, as Naghii's did (SHBG lower at six hours, free testosterone higher at one week), the two findings are mechanically compatible: less binding protein can leave more hormone unbound without any change in how much the testes produce. The study did not establish that this is what happened.
None of this makes the result false. It does mean that "boosts testosterone" overstates what a change in free testosterone would show, and that total testosterone, the number most men mean when they say testosterone, was not the headline. Before attributing a lab change to a capsule, ask three questions: which marker moved, was there a comparison group, and could the change be measurement or timing noise? For the single boron study, the answers were free testosterone and SHBG, no comparison group, and a single morning draw a week apart.
What It Costs Per Day
Price is the product's clear strength. At $15.95 for 240 capsules, each capsule costs about 6.6 cents.
| Use Pattern | Capsules Per Day | Cost Per Day | Days Per Bottle |
|---|---|---|---|
| Label directions | 1 | about $0.07 | 240 |
| One year of daily use | 365 total | about $24 per year | about 1.5 bottles |
That is cheap, and it means the financial downside is small. The real cost is attention: any change you attribute to boron, especially without a control, is likely to be something else. We have not fetched competing boron products and make no price comparison. If you compare, look for the milligrams of elemental boron per capsule and the form, since a label that gives only the weight of the compound can overstate the boron.
Safety and Interactions
The safety information on the listing is brief: for healthy individuals 18 and older, consult a healthcare professional before use if you are pregnant or nursing, taking medication, or have a medical condition, and do not use it if the safety seal is broken or missing. The reviews we read describe boron as having a wide margin at nutritional amounts. Khaliq and colleagues note that low or high boron status is a concern and that high boron status has been linked to cell injury and toxicity in animals and humans, which is the reason an upper limit exists. At 5 mg a day, a quarter of the reported 20 mg upper limit, we found no evidence in the sources we read of a problem for healthy adults, but we did not review long-term human safety data in detail and do not claim it has been established for every group.
Boron effects on hormones are the part to take seriously, in a different way. If boron does change SHBG, free testosterone, and estradiol, as the single study reported, then it is a hormonally active supplement, and people with hormone-sensitive conditions or who are on hormone therapy should talk to a clinician before using it. That is logic from the claimed mechanism, not a documented harm.
When to Talk to Your Doctor First
Ask your clinician before taking boron if you are pregnant or nursing, take medication, have a hormone-sensitive condition, or are using testosterone or other hormone therapy. The listing itself advises consulting a healthcare professional in several of these cases. This article is research summary, not medical advice.
Quality and Third-Party Testing
The listing makes two quality statements worth separating. One is that each batch of every product is tested by independent, ISO-accredited laboratories to ensure safety and quality, which is a claim about the manufacturer's testing practice, not a published certificate for this lot. The other is that the capsules are made in an NSF-certified, GMP-compliant, FDA-registered facility, which describes the factory. The retrieved page does not state that this product itself carries a product-level third-party certification, and we will not imply one. If lot-level verification matters, ask Nutricost for a certificate of analysis for your lot number, and confirm it covers boron content as well as contaminants such as heavy metals.
Who Should Buy It and Who Should Skip It
It may make sense if you want a very cheap trace-mineral experiment, your diet is low in fruits, vegetables, and nuts, and you understand that the human evidence is a handful of small studies. Some people may prefer to start by eating more produce, which raises boron intake along with fiber and other nutrients.
Skip it, or at least temper expectations, if you want a testosterone boost, you expect measurable bone or strength gains, you are pregnant or nursing, or you are on hormone therapy. We would also skip it if you prefer to take only supplements with randomized trial support, since boron does not clear that bar. For a deeper look at the testosterone side, our zinc guide covers a mineral with a documented link to testosterone when it is low, and our tongkat ali guide reviews another testosterone claim that has some human data behind it.
What Buyers Report
Buyer reviews on supplement retailer pages are mostly positive and focus on size, value and packaging.
- Swallowing and taste: Many describe tiny capsules that are easy to swallow and tasteless.
- Value: The large capsule count at a low price is the most frequent praise, along with trust in the brand.
- Tolerability: Several say it was easy on the stomach, even taken without food.
- Complaints: Complaints are scarce and scattered. Individual buyers mention an off smell in one bottle or a personal reaction, and others say they noticed nothing.
Takeaway: buyers describe a small, inexpensive capsule with few complaints. Buyer reports are anecdotal and are not the same as the research above; they are not evidence about what a supplement does and not advice.
How HonestLifter Is Reviewing This Product
HonestLifter's editorial model is longitudinal. A one-time first-impressions post tells you very little about a supplement, so the plan for each product we review is a written research review at the start, followed by dated checkpoint updates at 30 days, 60 days, 90 days, 6 months, and 12 months of use. The checkpoint updates are meant to report real use, real notes, and, where available, real data exports, not recycled research. The program is described in our longitudinal review program post.
The checkpoint schedule is below.
| Checkpoint | Due | Status |
|---|---|---|
| 30 day | 30 days of use | Combined note published |
| 60 day | 60 days of use | Combined note published |
| 90 day | 90 days of use | Combined note published |
| 6 month | 6 months of use | Combined note published |
| 12 month | 12 months of use | Not yet published |
This is a research review built on the product's listing and published studies. Our own notes will be added as dated updates later.
Checkpoint Update: 30-Day, 60-Day, 90-Day and 6-Month Notes (October 2026)
HonestLifter's owner reports the following from regular use. These are personal notes, not measurements.
- Use: Daily, in the morning, swallowed as a capsule with other morning supplements.
- Verdict: Would buy again.
Several supplements are taken together, so none of these notes isolates the effect of this product. No effects, good or bad, are being claimed here. The 12-month update will be added when it is written.
The Bottom Line
Nutricost Boron 5 mg is a clean, single-ingredient capsule at a very low price, about $24 a year. As a product it does what it says. As an investment in testosterone or bone it rests on a single eight-man, one-week study without a control group and a few small, older mineral-metabolism trials, and the reviews that favor boron say the benefit appears at about 3 mg a day or less. Five milligrams sits comfortably below the 20 mg upper limit as reported in the literature, and above the amount at which the favorable evidence stops adding anything.
Buy it if the price and the low risk make a curiosity purchase easy, and treat any change you notice with skepticism. Skip it if you need something with proof. Watch this page for dated checkpoint updates from the editor's own notes.
References
- Naghii, M.R., Mofid, M., Asgari, A.R., Hedayati, M., & Daneshpour, M.S. (2011). Comparative effects of daily and weekly boron supplementation on plasma steroid hormones and proinflammatory cytokines. Journal of Trace Elements in Medicine and Biology, 25(1), 54-58. doi:10.1016/j.jtemb.2010.10.001. PMID 21129941.
- Meacham, S.L., Taper, L.J., & Volpe, S.L. (1994). Effects of boron supplementation on bone mineral density and dietary, blood, and urinary calcium, phosphorus, magnesium, and boron in female athletes. Environmental Health Perspectives, 102(Suppl 7), 79-82. doi:10.1289/ehp.94102s779. PMID 7889886.
- Nielsen, F.H. (2014). Update on human health effects of boron. Journal of Trace Elements in Medicine and Biology, 28(4), 383-387. doi:10.1016/j.jtemb.2014.06.023. PMID 25063690.
- Pizzorno, L. (2015). Nothing boring about boron. Integrative Medicine (Encinitas), 14(4), 35-48. PMID 26770156.
- Khaliq, H., Juming, Z., & Ke-Mei, P. (2018). The physiological role of boron on health. Biological Trace Element Research, 186(1), 31-51. doi:10.1007/s12011-018-1284-3. PMID 29546541.
- Heffernan, S.M., Horner, K., De Vito, G., & Conway, G.E. (2019). The role of mineral and trace element supplementation in exercise and athletic performance: a systematic review. Nutrients, 11(3), 696. doi:10.3390/nu11030696. PMID 30909645.
Product details were taken from the manufacturer's Amazon listing and may change. HonestLifter carries no affiliate links. This article is educational and is not medical advice.