Estimated prebiotic intake and depression in US adults: repeated cross-sectional analyses of NHANES 2015–2018 and 2021–2023

Abstract

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.