B-complex vitamins and cognitive function

Kennedy, D.O.

Published in Human Psychopharmacology

Abstract

Systematic review of B vitamin complex effects on cognitive function and mood

Methodology

Narrative review of the biochemistry, dietary status data and human supplementation trials for the eight B vitamins in relation to brain function, mood and cognition.

Key Findings

Review of B-complex vitamins and brain function argues that the eight B vitamins act as an interdependent group in energy metabolism, methylation and neurotransmitter synthesis, that suboptimal (not merely deficient) status is common even in developed countries, and that trials of single B vitamins such as folate alone are poorly designed compared with whole B-complex supplementation, which shows more consistent effects on mood, stress and cognitive performance.

Conclusions

B vitamins function collectively rather than individually, and the review argues that supplementation research should test the full B complex at doses above minimal requirements rather than isolated vitamins.

Limitations

Narrative review by a single author with industry research links; no systematic search or quantitative synthesis; selective emphasis on supportive trials; does not resolve whether benefits extend to well-nourished people.