Vitamin B6 in Elite Athletes: Potential Implications of High Intakes.

Vitamin B6 plays a role in over 100 enzymatic reactions, and it is purported that athletes have higher requirements compared with the general population. Deficiency, while rare, may lead to adverse symptoms if severe or prolonged. Conversely, excessive intake may increase the risk of toxicity. This article discusses the potential implications of high vitamin B6 exposure in athletes and includes illustrative observational data on plasma pyridoxal 5'-phosphate (PLP) from routine biomarker monitoring in elite athletes. Observation-level deficiencies (< 30 nmol/L; 5.2%) and raised (> 125 nmol/L; 38.7%) PLP measurements (n = 654) in elite athletes (N = 396) participating in routine biomarker screening, alongside implications of possible intakes above athletes' requirements are discussed. Athletes' use of nutritional supplements, sports beverages, or even intravenous nutrition, which contain highly bioavailable doses of vitamin B6, are a plausible contributor to the observed high PLP concentrations. Chronic total vitamin B6 intake above 21 mg/day, particularly with low protein intake, may increase toxicity risk.