The association between vitamin C and depressive risk based on the National Health and Nutrition Examination Survey of 2017-2018 and Mendelian randomization study.

OBJECTIVES

There is some debate about the link between vitamin C and depressive risk. This study utilized data from the National Health and Nutrition Examination Survey (NHANES) and Mendelian randomization (MR) methodology to investigate the association between the two.

METHODS

We obtained serum vitamin C levels through laboratory data and determined the intake of vitamin C through a 24-hour dietary recall method on the first day from NHANES 2017 to 2018. Assessment of depressive risk was employed by the 9-item Patient Health Questionnaire (PHQ-9). The association between serum vitamin C levels and depressive risk was examined using logistic regression. Furthermore, the research utilized a two-sample MR methodology to investigate the potential causal connection between vitamin C and depressive risk.

RESULTS

Three thousand four hundred and thirty-four participants aged 20+ with serum vitamin C levels and depressive risk data was included. Among the participants, 18.7% had low serum vitamin C levels and 25.2% had self-reported depressive risk. Serum vitamin C levels were associated with depressive risk [OR 1.64, (95% CI: 1.36-1.97), P < 0.01], which remained significant [OR 1.32, (95% CI: 1.08-1.61), P < 0.01] after adjustments. Distinct genetic SNPs were identified for serum vitamin C levels and depressive risk, allowing detailed analysis. No additional influences were observed between genetic variations. IVW and MR Egger analysis showed a non-causal association between vitamin C levels and depressive risk (All P > 0.05).

CONCLUSIONS

Our findings of the nationally representative survey revealed a strong correlation between serum levels, intake as a supplement or medication of vitamin C and depressive risk, however, without a unidirectional causal association.