What to watch with B12 and fertility?

Vitamin B12 is relevant for fertility because it participates in DNA synthesis, cell division, and homocysteine metabolism. Deficiency may contribute to ovulatory dysfunction in women and reduced sperm quality in men. Studies link low B12 levels with elevated homocysteine, which can impair implantation and embryonic development. However, the evidence is not fully conclusive: observational data support an association, but few randomized controlled trials prove a causal benefit of B12 supplementation on fertility outcomes. Other nutrients like folate, zinc, and overall nutritional status also matter. In fertility workups, B12 should be measured as part of a comprehensive panel, not in isolation. The Fitness | LifestyleCheck provides a single B12 reading, which can flag potential issues but cannot replace clinical lab testing. Genetic variants (e.g., MTHFR) can affect B12 metabolism but are not included in most direct-to-consumer tests. Safety note: B12 supplements are safe at standard doses, but megadoses are unnecessary. Evidence level is human-strong, though causality remains debated.