Body mass index modifies the relationship between dietary iron intake and depressive symptoms among adults: A national population-based cohort

Abstract

Background: Research on the effects of dietary iron intake on depression is limited and controversial. The aim of this study was to explore the association between iron intake and the prevalence of depressive symptoms.

Methods: The present study used cross-sectional data from people who participated in the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2016. Logistic regression models and restricted cubic spline models were applied to investigate the relationship between iron intake and depressive symptoms.

Results: A total of 16,098 adults aged 20 years or older were included in this study. Compared with individuals with lowest iron intake Q1 (≤8.31 mg/day), the adjusted OR values for dietary iron intake and depression in Q2 (8.32-11.47 mg/day), Q3 (11.48-15.02 mg/day), Q4 (15.03-20.28 mg/day), and Q5 (≥20.29 mg/day) were 0.69 (95 % CI: 0.52-0.91), 0.68 (95 % CI: 0.50-0.94,), 0.59 (95 % CI: 0.42-0.82,), and 0.63 (95 % CI: 0.40-0.98), respectively. The relationship between iron intake and depressive symptoms exhibited a non-linear. Our findings suggested an interaction between body mass index (BMI) and iron intake (P = 0.03). Additionally, the relationship between dietary iron intake and depressive symptoms in adults with a BMI <25 kg/m² was U-shaped. And the OR of developing depressive symptoms was 0.93 (95 % CI: 0.87-0.99) in individuals with iron intake ≤19.72 mg/day.

Limitations: Cross-sectional study and relevant data was based on self-reports.

Conclusion: A higher iron intake is significantly associated with a decreased prevalence of depressive symptoms, and different levels of BMI can modify the association between them.

Keywords: Body mass index; Depressive symptoms; Dietary iron intake; NHANES.