Objective: Legumes have been recommended as staple foods in the anticipation of disease prevention. However, the scientific evidence of their benefits, particularly on mental well-being, remains preliminary. We longitudinally assessed the association between legume consumption and the risk of severe depressed mood (SDM) among a national cohort.

Design: The study included adults aged 25–74 years who were examined in 1971–1975 as a part of the National Health and Nutrition Examination Survey. Legume consumption at baseline was obtained from a 3-month FFQ and categorized as infrequent (/week), moderate (1–2 times/week) and frequent (≥3 times/week). SDM was defined as Center for Epidemiologic Studies Depression Scale score ≥22 or taking anti-depression medication after an average of 10•6 years of follow-up (from 8•0 to 12•5 years).

Results: Among women, the proportion of individuals with SDM was 17•75 %. For premenopausal women (n 1778), a significant linear trend of deleterious effect from legume consumption was observed (P for trend = 0•0148). The relative risks (RR) for infrequent, moderate and frequent consumptions were 1 (reference), 1•24 (95 % CI = 0•91, 1•70) and 1•75 (1•12, 2•75), respectively. However, moderate consumption showed a significant protective effect (RR = 0•52 (0•27, 1•00)) among women undergoing the menopausal transition (n 454). No association was obtained from either postmenopausal women (n 601) or men (n 2036).

Conclusions: These findings suggest that gender and menopausal status were effect modifiers of the association between legume consumption and SDM. Detrimental effects of frequent consumption of legumes may exist among premenopausal women; moderate consumption, however, may protect perimenopausal women against SDM.