Half-baked? B vitamins and depression1,2

and Richard Tranter The study by Skarupski et al (1) in this issue of the Journal has made an important contribution to a long-running fascination with the associations between B vitamins and depression. Epi-demiologic, observational, and case-control studies dating back to the 1960s have indicated a strong association between func-tional or absolute folate deficiency and depressive symptoms, symptom severity, and treatment outcomes in adults and the older adult population (2–6). Patients with depression are reported to have lower concentrations of folate than patients with other psychiatric disorders and nonpsychiatric comparison groups. Low folate concentrations are also associated with poor antide-pressant response. These findings together with robust evidence of the role of folate in other disease areas, particularly in the prevention of neural tube defects, have prompted large-scal