Association between all aspects of dietary diversity and risk of depressive symptoms in US adults.

The impact of dietary diversity on depressive symptoms remains one-sided. We aim to explore the associations between all aspects of dietary diversity and the risk of depressive symptoms in US adults and their dose-response relationships. We selected 16 820 adults from the National Health and Nutrition Examination Survey (NHANES) from 2013 to 2018. Depressive symptoms were assessed using patient health questionnaire-9 (PHQ-9). Dietary diversity contains four indexes: count (dietary diversity score, DDS), evenness (Healthy Food Diversity Index, HFDI), dissimilarity (Jaccard distance, JD), and quality (Healthy Eating Index, HEI). Binary logistic regression was conducted to assess relationships between the four aspects of dietary diversity and depressive symptoms in whole and subgrouped populations. A restricted cubic spline was performed to explore the dose-response relationships. We revealed that DDS [0.20 (0.05, 0.73)], HFDI [0.51 (0.28, 0.94)], and HEI [0.46 (0.26, 0.80)] were inversely associated with the risk of depressive symptoms for the highest VS lowest quintile, especially in females and elders. Analysis of dose-response relationships determined linear relationships of DDS, HEI and depressive symptoms, while an "L" shaped relationship of HFDI and depressive symptoms. Adequate dietary diversity showed a significant effect on decreasing the risk of depressive symptoms at a score of 4 in DDS, 0.3 in HFDI, and a score of 51 in HEI. In conclusion, this study found that higher levels of dietary diversity, including count, evenness, and quality, might be protective factors against depressive symptoms, especially in females and elders. The DDS, HFDI, and HEI scores are recommended as 4, 0.3, and 51, respectively. Further investigation is needed to validate our results.