Depression, a prevalent mental disease, is associated with persistent low mood, disturbed sleep or appetite, fatigue, diminished interest in activities, and feelings of guilt (Swetlitz, 2021; Park and Zarate Jr., 2019). The WHO estimates that over 300 million people globally experience depression (Monroe and Harkness, 2022). Depression poses a major burden on individuals, families, healthcare systems, and societies, resulting in reduced quality of life and heightened risks of disability and suicide (Azeem et al., 2019). Therefore, it is essential to explore the factors contributing to depression and the most effective prevention methods.

Several factors contribute to the development of depression, including neurobiological, psychological, lifestyle, social, and genetic factors (Hammen, 2018; Chau et al., 2021). Dietary is another potential modifiable factor for depression. Based on the previous studies, dietary folate, minerals (zinc, iron, copper, selenium and magnesium), B vitamins, creatine, caffeine, fiber, and niacin intake were inversely associated with depression (Zheng et al., 2020; Li et al., 2018; Wu et al., 2023; Bakian et al., 2020; Iranpour and Sabour, 2019; Mao et al., 2022a, Mao et al., 2022b; Zhao et al., 2023). Vitamin C, as an important antioxidant and co-factor for various enzymes, can potentially help decrease symptoms of depression (Ferreira et al., 2022). In a double-blind, placebo-controlled pilot trial, fluoxetine and vitamin C significantly decreased depressive symptoms compared to the group receiving fluoxetine plus placebo (Amr et al., 2013). Furthermore, a meta-analysis indicated an inverse relationship between dietary vitamin C intake and depression (Ding and Zhang, 2022). However, according to a randomized double-blind placebo-controlled clinical trial, adding vitamin C to citalopram did not improve the efficacy of citalopram in patients with major depressive disorder (Sahraian et al., 2015). More research is needed to confirm the association between dietary vitamin C intake and depression due to conflicting evidence. Accordingly, we conducted a cross-sectional study to explore the association between dietary vitamin C intake and the depression by using the National Health and Nutrition Examination Survey (NHANES) data. In addition, we evaluated the dose-response relationship between vitamin C intake and depression.