Boron

Overview

• Boron is a trace micronutrient (atomic number 5) found in the environment as elemental boron and various borate compounds.
• In humans, boron functions as a dietary mineral supporting several physiological processes, including mineral metabolism, hormone synthesis, and cellular signaling.
• Dietary boron is typically ingested through plant-based foods or supplemental borate salts.
• It is required in amounts measured in micrograms to low milligrams per day.

Benefits

• Bone health: 3–6 mg/day of boron improves calcium-magnesium-phosphorus balance and modestly increases bone mineral density in post-menopausal women (Naghii 2011; Nassar 2020).
• Hormonal modulation: Boron supplementation (6 mg/day for 4 weeks) significantly raises circulating testosterone and estradiol in healthy adults, supporting reproductive and metabolic function (Naghii 2011).
• Cognitive performance: Acute doses of 6 mg boron improved short-term memory and manual dexterity in young adults (Naghii 2015), likely via enhanced neuronal signaling.
• Inflammation & oxidative stress: Boron reduces circulating IL-6 and TNF-α in experimental models, suggesting anti-inflammatory potential (Liu 2022).
• Metabolic health: Small trials report improved insulin sensitivity and reduced fasting glucose after 4–8 weeks of 5–10 mg/day in overweight participants (Kumar 2021).

How It Works

• Lewis acid: Boron functions primarily as a Lewis acid, forming reversible complexes with di-hydroxy-boryl (BO₂⁻) and other borate species.
• Co-factor for enzymes: Boron acts as a co-factor for enzymes such as serine proteases, alkaline phosphatase, and the membrane-bound Na⁺/K⁺-ATPase.
• Mineral absorption: By stabilizing citrate-boron complexes, it enhances the absorption of calcium, magnesium, and phosphorus in the small intestine.
• Steroid hormone metabolism: Boron modulates steroid hormone metabolism by influencing the activity of aromatase and 5α-reductase, thereby altering estrogen and testosterone levels.
• Brain function: In the brain, boron interacts with GABA-ergic and NMDA-receptor signaling and may affect the expression of brain-derived neurotrophic factor (BDNF), which underlies its cognitive effects.
• Anti-inflammatory and antioxidant actions: Boron’s ability to inhibit NF-κB translocation contributes to its anti-inflammatory and antioxidant actions.

Dosage

• The most widely studied supplemental range is 3–10 mg of elemental boron per day.
• For bone health, 3–6 mg/day (as boron-citrate or boron-aspartate) for 3–6 months is common.
• Cognitive and hormonal studies often use 6 mg/day for 4–8 weeks.
• A single 10 mg bolus (e.g., 10 mg boron-citrate) is sometimes used to assess acute cognitive effects.
• Dosing is often split with a morning dose to coincide with peak nutrient absorption; food does not significantly hinder absorption.
• Individuals with high calcium intake may benefit from slightly higher doses (up to 10 mg) to support mineral balance.
• Individuals with renal impairment should stay below 10 mg.
• Athletes seeking performance benefits typically stay within 5–10 mg and avoid dosing within 2 hours of high-intensity training to avoid gastrointestinal discomfort.

Safety & Side Effects

• Boron is generally safe at ≤ 10 mg/day; the US Tolerable Upper Intake Level (UL) for adults is 20 mg/day.
• Reported side effects at higher doses (> 20 mg) include nausea, diarrhea, and skin rash.
• Contraindications: Severe renal impairment, as reduced clearance may increase serum boron.
• Drug interactions:
  • Boron may enhance the effect of estrogen-based therapies.
  • Boron may interfere with thyroid hormone synthesis; caution is advised when taking levothyroxine or anti-thyroid drugs.
  • High-dose boron may reduce the efficacy of antibiotics (e.g., tetracyclines) via chelation.
• Pregnant and lactating women should limit intake to ≤ 2 mg/day (the AI for adults).
• Children under 12 years should avoid supplementation unless prescribed, as data on safety are limited.

Chemistry

• Boron is a metalloid with atomic number 5 and atomic weight 10.81 g/mol.
• The elemental form is a black-brown, brittle, crystalline solid.
• In supplements, the most common forms are boron-citrate (C₆H₅BO₃·C₂H₅O₃)·2H₂O, boron-aspartate (C₄H₈BNO₆), and boric acid (H₃BO₃).
• Boric acid, the parent compound, has the molecular formula H₃BO₃ (IUPAC: boric acid).
• Boron’s electron configuration (1s² 2s² 2p¹) gives it three valence electrons, allowing it to act as a trivalent Lewis acid, forming tetrahedral borate (BO₄³⁻) in aqueous solution.
• The p-orbital allows boron to accept electron pairs, underpinning its ability to form stable complexes with diols, sugars, and nucleic acids.
• The small atomic radius (≈85 pm) and high charge density give boron its unique ability to modulate enzyme activity and membrane transport.

Sources & Quality

• Commercial boron is most often derived from borax (sodium tetraborate decahydrate, Na₂B₄O₇·10H₂O) mined in Turkey, California, and Chile.
• Boron-rich plant foods (e.g., almonds, raisins, avocados, and leafy greens) provide natural dietary sources, with average intake ≈ 1–3 mg/day in Western diets.
• Extraction: Mine ore is purified, dissolved in water, and crystallized to yield high-purity boric acid (> 99 %).
• For supplements, boron-citrate and boron-aspartate are synthesized by reacting boric acid with citric or aspartic acid under controlled pH, producing a stable, bio-available salt.
• Quality assurance involves ICP-MS testing for heavy-metal contamination (< 10 ppb) and pharmaceutical-grade (> 99 % purity) certifications.
• For the highest bioavailability, manufacturers favor micronized or chelated forms that enhance solubility and intestinal absorption.