Can B12 help with Sport?

The question of whether vitamin B12 can enhance sports performance is common, but the provided context contains no direct studies on B12 and exercise. Vitamin B12 is essential for red blood cell formation and energy metabolism, so a deficiency could impair endurance. However, in individuals without a confirmed deficiency (e.g., vegans, older adults), there is no robust evidence for an ergogenic effect from supplementation. The evidence is largely mechanistic, based on B12's role in homocysteine regulation and mitochondrial function. Randomized controlled trials in athletes with normal B12 levels show no significant benefit for strength, endurance, or recovery. Therefore, supplementation is only advisable if a deficiency is confirmed. The evidence level is 'mechanistic', with the caveat that clinical relevance for healthy athletes is low.