Background: Lower levels of B vitamins (particularly folate, vitamin B 12 and vitamin B 6 ) may be associated with psychological distress. Little is known about the impact of childhood nutrition on psychological distress in adult life. Objective: We investigated whether prospectively measured childhood and adult dietary intakes of thiamin, riboflavin, niacin, folate, vitamin B 6 and vitamin B 12 were related to the psychological distress of women in mid-age, taking into account socio-economic, behavioural and lifestyle factors. Design: Prospective data were collected from a cohort of 636 British women followed up since their birth in 1946. Participants completed a 28-item, scaled version of the General Health Questionnaire (GHQ-28) to measure psychological distress at age 53 years. Dietary intakes in childhood (at age four) were determined by 24 h recall and in adulthood (at age 36, 43 and 53 years) by a 5 d food record. Results: Low dietary vitamin B 12 intake at age 53 was associated with higher psychological distress at that age. Women in the lowest third of vitamin B 12 intake in adulthood had a higher GHQ-28 score compared with those in the highest third (percentage change, adjusted regression coefficient, 21 (95 % CI 3, 39)). There were no other significant associations between dietary B vitamin intake in childhood or adulthood and psychological distress in the cohort. Conclusions: Overall, there is evidence that intake of vitamin B 12 at age 53 is related to adult psychological distress but there is no evidence for the effects of other adult B vitamin intakes or childhood intakes on psychological distress.