The Relationship between Dietary Fat Intake and Depression: A Cross-sectional Study from NHANES 2007–2018

Abstract Background Depression is a serious public mental health problem, and the mechanism of depression is not unequivocal. Previous studies show a detrimental relationship between trans fatty acid intake and depression risk. Furthermore, it is still unclear how diet-related fat intake and depression are related. Consequently, this study aimed to create a formula and scale to forecast the association between diet-related fat intake and depression. Methods A total of 5,746 samples from the National Health and Nutrition Examination Survey (NHANES) were included in the study. Fat intake was assessed by 24h dietary recalls and summed for two days to prevent data bias. Depression was assessed using the Patient Health Questionnaire-9 (PHQ9). Multivariate logistic regression and the generalized additive model (GAM) were used to analyze the relationship between dietary fat intake and depression. Results It was negatively correlated with a segmented regression model, and the threshold was 155.45 [β= -0.0077 (-0.0115, -0.0039), p < 0.0001]. After re-selecting the data (fat intake < 155.45 g/2 days) according to the inflection point (n = 3,391), the formula was y = y0 + Ae^(2x/t) (R-Square was 0.72967). The y is the PHQ9, and x is the dietary fat intake (g/day). The difference between the scale value and the actual PHQ9 score was not statistically significant in this investigation, which used a scale based on the Polychoric correlation (p=0.22499). Conclusions This study illustrates a negative association between fat intake and depression. Moreover, this negative association was explored in terms of quantitative relationships. The fitted formulas and scales were reasonable consistency, and both can be used for the dietary evaluation of depressed patients. By adjusting the diet, we can provide nutritional advice to depressed patients and reduce the risk of medication and the psychological stress of patients. Although Proper fat intake can reduce the severity of depression, we need to be alert to other problems caused by excessive fat intake, such as hypertension, diabetes, or atherosclerosis.