Biotin — The Carboxylase Cofactor
Biotin is a water-soluble B-vitamin essential for cellular energy metabolism, fatty acid synthesis, and epigenetic regulation via histone modification. While crucial for preventing deficiency-related metabolic dysfunction, there is currently no robust evidence that supratherapeutic biotin supplementation extends lifespan or healthspan in humans.
Mechanism of Action
Biotin (Vitamin B7) functions as an essential covalently bound coenzyme for five mammalian carboxylases: acetyl-CoA carboxylases (ACC1 and ACC2), pyruvate carboxylase (PC), methylcrotonyl-CoA carboxylase (MCC), and propionyl-CoA carboxylase (PCC). These enzymes are critical for fatty acid synthesis, gluconeogenesis, and amino acid catabolism. Beyond its metabolic role, biotin participates in epigenetic regulation through the biotinylation of histones, which may influence gene expression and DNA repair. While biotin deficiency in Drosophila has been shown to decrease lifespan, its direct modulation of canonical longevity pathways (like mTOR or AMPK) in humans remains poorly characterised.
Human Trial Evidence
No published human longevity trials. Clinical research has primarily focused on high-dose biotin for progressive multiple sclerosis, where large phase 3 trials ultimately failed to show efficacy over placebo. Evidence for hair, skin, and nail health is largely anecdotal or based on limited case reports, with no robust RCTs demonstrating systemic anti-aging benefits.
Dosing Protocol
10,000 mcg (10 mg) per day is a common supplemental dose, though standard daily requirements are much lower (30 mcg). High-dose protocols (up to 300 mg/day) have been tested in multiple sclerosis but are not established for longevity. Note: High-dose biotin can interfere with clinical laboratory tests (e.g., thyroid function, troponin), so supplementation should be paused before blood work.
Safety & Contraindications
Generally well tolerated with a high safety profile, as excess water-soluble biotin is excreted in urine. The most significant safety concern is assay interference; high circulating biotin levels can cause falsely high or falsely low results in immunoassays that use streptavidin-biotin technology, potentially leading to misdiagnosis of conditions like hyperthyroidism or masking myocardial infarction (troponin assays).