Antioxidant (protects RBCs and membranes from free radical damage).

Deficiency:- Hemolytic anaemia- Acanthocytosis- Muscle weakness- Posterior column and spinocerebellar tract demyelination→ Neurologic presentation may appear similar to vitamin B₁₂ deficiency, but without megloblastic anemia, hypersegmented neutrophils, or ↑ serum methylmalonic levels.

Excess: - Risk of enterocolitis in infants- High-dose supplementation may alter metabolism of vitamin K → enhanced anticoagulant effects of warfarin.