Estimated prebiotic intake and depression in US adults: repeated cross-sectional analyses of NHANES 2015-2018 and...

Prebiotics are selectively utilised dietary substrates that may influence depression through gut microbiota-related pathways, but population-level estimates of intake and associations with depression are limited. This repeated cross-sectional study estimated intake of International Scientific Association for Probiotics and Prebiotics (ISAPP)-recognised prebiotics and examined associations with depression among US adults using National Health and Nutrition Examination Survey (NHANES) 2015-2018 and NHANES August 2021-August 2023, analysed as independent survey periods. Estimated intakes of galactooligosaccharides and inulin-type fructans were assigned to foods using published source-food values, Food and Nutrient Database for Dietary Studies food codes, and ingredient-level information for mixed dishes. Depression was defined as Patient Health Questionnaire-9 score of 10 or greater. Survey-weighted analyses estimated intake distributions, and logistic regression models estimated ORs and 95% CIs for depression per 5 g/day higher estimated prebiotic intake in restricted adult samples. Mean estimated prebiotic intake was 6.44 g/day in NHANES 2015-2018 and 6.09 g/day in NHANES 2021-2023. In NHANES 2015-2018, higher estimated intake was associated with lower odds of depression overall (OR: 0.69; 95% CI: 0.49-0.98) and among females (OR: 0.65; 95% CI: 0.45-0.94), but not among males. In NHANES 2021-2023, estimated intake was not associated with depression overall (OR: 1.03; 95% CI: 0.74-1.43) or in sex-stratified models. These repeated cross-sectional findings provide nationally representative estimates of intake of ISAPP-recognised prebiotics and indicate that the inverse association observed in 2015-2018 was not replicated in 2021-2023. Prospective studies are needed to clarify whether prebiotic intake is associated with depression risk.