Boron

What is Boron?

Boron is a naturally occurring trace element that is widely distributed in the environment, primarily in the form of borates. While it is essential for plant growth and is a structural component of plant cell walls, it is not currently classified as an essential nutrient for humans by the Food and Nutrition Board (FNB) of the National Academies of Sciences, Engineering, and Medicine, due to a lack of a clearly identified biological function [1, 2]. However, a substantial and growing body of research suggests that boron is a micronutrient with diverse and vitally important roles in human metabolism, leading some researchers to advocate for its consideration as an essential element [3].

Chemical/Botanical Basics

Boron is found in foods and supplements as inorganic borates (e.g., sodium borate) and organic sugar-borate esters, such as calcium fructoborate [2]. Upon ingestion, most boron is hydrolyzed to boric acid within the gastrointestinal tract, which is the main circulating form in the blood and body fluids [2]. The body absorbs about 85%–90% of ingested boron, and it does not accumulate in most soft tissues, with excretion primarily occurring via the urine [2].

Mechanism of Action

Boron’s beneficial effects are attributed to its ability to interact with and influence the activity of numerous biological molecules and pathways. Key mechanisms include:

• Hormone Regulation: Boron beneficially impacts the body’s use of estrogen, testosterone, and vitamin D [3]. Studies show that boron supplementation can increase serum levels of free testosterone and estrogen (estradiol), particularly in postmenopausal women and healthy males [3, 4].
• Mineral Metabolism: It is involved in the metabolism of key minerals, including calcium and magnesium. Boron supplementation has been shown to reduce the urinary excretion of calcium and magnesium, thereby supporting bone health [3, 5].
• Anti-inflammatory Effects: Boron reduces levels of inflammatory biomarkers, such as high-sensitivity C-reactive protein (hs-CRP) and tumor necrosis factor-alpha (TNF-α), suggesting a significant anti-inflammatory role [3, 4].
• Enzyme & Biomolecule Influence: It influences the formation and activity of key biomolecules like S-adenosyl methionine (SAM-e) and nicotinamide adenine dinucleotide (NAD+), and regulates the expression of genes and proteins related to tissue mineralization and bone growth [3].

2. Chemical Composition/Key Bioactive Roles

The following table summarizes the main bioactive forms and their roles in human health.

Compound/Form	Chemical Type	Key Bioactive Roles
Boron (Elemental)	Trace Element	Essential for plant life; micronutrient in human health.
Boric Acid	Inorganic Borate	Main circulating and biologically active form in the human body.
Calcium Fructoborate	Organic Sugar-Borate Ester	A common, highly bioavailable supplemental form; studied for anti-inflammatory and joint health benefits [2, 6].
Boron Complexed with Steroids	Metal-Ligand Complex	Modulates the metabolism and activity of steroid hormones (Testosterone, Estrogen, Vitamin D) [3].
Boron Complexed with Enzymes	Enzyme Inhibitor/Activator	Facilitates the activity of enzymes involved in wound healing (e.g., collagenase) and bone formation (e.g., alkaline phosphatase) [3].

3. Health Benefits

Bone Growth and Maintenance

Boron is crucial for healthy bones, playing a role in osteogenesis (bone formation) and mineral metabolism.

• Calcium and Magnesium Retention: Boron supplementation has been shown to significantly reduce the urinary excretion of calcium and magnesium, which is vital for maintaining bone mineral density. In a study of postmenopausal women, 3 mg/day of boron reduced daily urinary calcium excretion by 44% [3, 5].
• Hormone and Vitamin D Synergy: It supports bone health by regulating the activity of steroid hormones (estrogen and testosterone) and enhancing the utilization of Vitamin D [3]. Boron stimulates bone growth and alleviates dysfunctions in mineral metabolism characteristic of Vitamin D deficiency [3].

Anti-inflammatory and Joint Health Effects

Boron’s anti-inflammatory properties suggest a benefit for joint health, particularly in conditions like osteoarthritis.

• Inflammatory Marker Reduction: Boron is proven to reduce levels of inflammatory biomarkers such as hs-CRP and TNF-α [3, 4]. A study in healthy males showed that 6 mg/day of boron for one week reduced hs-CRP levels by approximately 50% [4].
• Osteoarthritis Symptom Reduction: Preliminary human studies suggest that boron may be helpful in reducing the symptoms of osteoarthritis. A small, double-blind, placebo-controlled pilot study found that Calcium Fructoborate helped control inflammation associated with diminished bone health [6]. Another study found that 6 mg/day of boron reduced symptoms of osteoarthritis in participants [7].

Hormone Balance and Athletic Performance

Boron is a known modulator of sex hormones, which has implications for muscle development and overall vitality.

• Free Testosterone Increase: In a study of healthy men, supplementation with 10 mg/day of boron for one week resulted in a significant increase in free testosterone levels, which rose from an average of 11.83 pg/mL to 15.18 pg/mL [4].
• Estrogen Modulation: Boron can increase serum estradiol (E2) levels in postmenopausal women, which is beneficial for bone health [3, 5].

Cognitive Function

Boron has been linked to improved brain function and cognitive performance.

• Improved Brain Activity: Boron improves the brain’s electrical activity, cognitive performance, and short-term memory, particularly in older individuals [3]. Studies have shown that a low-boron diet might reduce mental alertness and impair executive brain function [2].

Potential Anti-Cancer Effects

Preliminary evidence suggests an inverse association between boron intake and the risk of certain cancers.

• Reduced Cancer Risk: Observational studies have found that boron intakes are inversely associated with the risk of prostate, cervical, and lung cancers [2, 3]. Boron-containing compounds are also being researched for their therapeutic potential in cancer treatment [3].

4. Dosage and Usage

Recommended Dosages

There is no Recommended Dietary Allowance (RDA) or Adequate Intake (AI) for boron [2]. However, based on the body of evidence, the following dosages are commonly studied and considered safe:

• General Supplementation: Beneficial effects are generally observed at intakes ≥ 3 mg/day [3].
• For Bone and Hormone Support: Dosages of 3 mg/day to 6 mg/day have been used in studies showing beneficial effects on mineral and hormone metabolism [3, 4].
• For Acute Anti-inflammatory Effects: Dosages of 6 mg/day to 10 mg/day have been used in short-term studies to observe significant reductions in inflammatory markers [4].

Food Sources

Boron is naturally present in many foods, with the highest concentrations found in plant foods.

Food Source	Boron Content (mg per serving)
Prune juice (1 cup)	1.43
Avocado (½ cup cubed)	1.07
Raisins (1.5 ounces)	0.95
Peaches (1 medium)	0.80
Apples (1 medium)	0.66
Peanuts (1 ounce)	0.48
Coffee (1 cup)	0.07
Milk (1 cup)	0.04

The total median boron intake from food and supplements in the US adult population is typically around 1.0 to 1.5 mg/day [2].

5. Safety and Precautions

Tolerable Upper Intake Level (UL)

The FNB has established a Tolerable Upper Intake Level (UL) for boron based on reproductive and developmental effects observed in animals [2].

Age Group	Tolerable Upper Intake Level (UL)
Adults (19+ years)	20 mg/day
Adolescents (14–18 years)	17 mg/day
Children (9–13 years)	11 mg/day
Children (4–8 years)	6 mg/day
Children (1–3 years)	3 mg/day

Side Effects

Boron is generally well-tolerated at or below the UL of 20 mg/day.

• High Doses: Doses over the UL may cause adverse effects. Symptoms associated with excessive intake (often accidental consumption of boric acid/borax) include nausea, gastrointestinal discomfort, vomiting, diarrhea, skin flushing, rash, excitation, and convulsions [2].
• Extremely High Doses: Extremely high doses of boron can be fatal; for example, 15,000 to 20,000 mg can cause death in adults [2].

Contraindications and Warnings

• Pregnancy and Lactation: The UL for pregnant and lactating women aged 19+ is 20 mg/day. However, caution is advised, and intake should be monitored.
• Infants and Young Children: The ULs for children are significantly lower (3–11 mg/day). WARNING: Accidental consumption of high-boron-containing household products (e.g., borax) has led to severe toxicity and death, particularly in children under 6 years old [2].
• Renal Impairment: Given that boron is primarily excreted by the kidneys, individuals with severe renal impairment should exercise caution and consult a healthcare professional before supplementing.

Drug Interactions

Boron is not known to have any clinically relevant interactions with medications [2].

6. References

1. Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press; 2001.
2. Office of Dietary Supplements. Boron – Health Professional Fact Sheet. National Institutes of Health. Updated June 9, 2022. Available at: https://ods.od.nih.gov/factsheets/Boron-HealthProfessional/
3. Pizzorno L. Nothing Boring About Boron. Integrative Medicine: A Clinician’s Journal. 2015 Aug;14(4):35–48. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC4712861/
4. 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. Journal of Trace Elements in Medicine and Biology. 2011;25(1):54-8. Available at: https://pubmed.ncbi.nlm.nih.gov/21129941/
5. Nielsen FH, Hunt CD, Mullen LM, Hunt JR. Effect of dietary boron on mineral, estrogen, and testosterone metabolism in postmenopausal women. FASEB Journal. 1987;1(5):394-7. Available at: https://pubmed.ncbi.nlm.nih.gov/3678698/
6. Scorei R, Mitrut P, Petrisor I, Scorei I. A double-blind, placebo-controlled pilot study to evaluate the effect of calcium fructoborate on systemic inflammation and dyslipidemia markers for middle-aged people with primary osteoarthritis. Biological Trace Element Research. 2011;144(1-3):253-63. Available at: https://pubmed.ncbi.nlm.nih.gov/21976211/
7. Newnham RE. Essentiality of boron for healthy bones and joints. Environmental Health Perspectives. 1994;102 Suppl 7:83-5. Available at: https://pubmed.ncbi.nlm.nih.gov/7882909/