Dietary food folate and synthetic folic acid co-exposure patterns with elevated depressive symptoms: Findings from NHANES 2005-2018.

BACKGROUND: This study investigates the associations of dietary food folate and synthetic folic acid co-exposure patterns with elevated depressive symptoms, a relationship previously underexplored. METHODS: A total of 25,354 participants who participated in the National Health and Nutrition Examination Survey 2005-2018 were included. Dietary folate intake was evaluated by 24-h dietary recall. The Patient Health Questionnaire 9 was used to assess depressive symptoms. The unsupervised K-means clustering method, logistic regression model, and restricted cubic spline regression were used to assess the associations of dietary folate co-exposure patterns with elevated depressive symptoms. RESULTS: After adjustment for potential confounders, U-shaped nonlinear associations of intake of total folate equivalent and dietary folate equivalent with elevated depressive symptoms were observed (all the P non-linearity <0.05). Besides, a linear association of food folate with elevated depressive symptoms was observed (P non-linearity <0.05). Four co-exposure patterns were generated based on the intake of folate, as follows: "folate deficiency group" to cluster 1, "dietary folate sufficiency group" to cluster 2, "folic acid supplement group" to cluster 3, and "mixed sources folic acid group" to cluster 4. Compared with cluster 1, participants in cluster 2 had lower risks of elevated depressive symptoms (OR = 0.78[0.68, 0.89]), and participants in cluster 3 and cluster 4 did not. LIMITATIONS: Cross-sectional data and potential biases stemming from recall and reporting inaccuracies. CONCLUSIONS: Our findings indicated that a higher intake of dietary folate, especially natural folate, was associated with a lower risk of elevated depressive symptoms.