UC Merced

Depression is a leading cause of disability in the United States. Previous research has shown that added sugar consumption and stress are both risk factors for depression. Despite evidence that added sugar consumption and stress both affect the HPA axis and may thus interact to amplify the risk of depression, no research has explored this interaction. In this dissertation, I investigated the possible effects of total added sugar and sugar-sweetened beverage consumption on depression, and their potential interactions with chronic stress. In a two-study series, measures of sugar consumption, chronic stress, and depression were taken in an adult community sample at two time points (Study 1) and a sample of pregnant women followed into the postpartum period (Study 2). I hypothesized that high sugar consumption would predict more depression, and stress amplify this effect. In summary, across two studies, sugar consumption predicted depressive symptoms. However, these results were no longer statistically significant when various covariates or baseline depression levels were added into the models. No interactions between sugar and stress were found in the predicted direction. These results suggest that, while added sugar consumption and depressive symptoms are positively correlated, their relationship is complex and further research is warranted.