Depression, among the most common types of mental health issues and a leading cause of disability worldwide, has long been targeted by nutrition scientists aiming to identify which dietary pitfalls may elevate the risk of at least one major depressive episode. Clinical research underway reveals that certain micronutrient deficiencies may be significantly linked to the risk of being diagnosed with depression or experiencing depressive symptoms, while broad eating patterns, such as the DASH (Dietary Approaches to Stop Hypertension) diet, are associated with a reduced risk of depression diagnosis.
 
However, clinical trials which establish a macroscopic view of overall diet quality, and the role it may have in depression rates on an epidemiological level, are lacking for the most part. In one recent clinical trial, though, a group of researchers whose work was published in the journal Nutrients established that higher scores on the Healthy Eating Index (HEI) which are associated with better dieting measurements in the National Health and Nutrition Survey, were associated with a significantly reduced depression risk. HEI is used to assess the amount of several foods survey participants eat, and scores are affected by ratios of intake per total energy on both foods which are recommended, and foods which are not recommended in the Dietary Guidelines for Americans.
 
The authors of the study sourced a sample of adults who participated in the National Health and Nutrition Examination Survey (NHANES) between the years 2005-2016, and cross-referenced each participants’ HEI score with current depressive symptoms, which were measured during the survey using the Patient Health Questionnaire 9, a standard form of self-reporting which evaluates symptoms such as sadness, trouble sleeping, fatigue, and problems concentrating, and has moderate concordance with clinical psychiatric interviews.
 
After adjusting for a number of sociodemographic factors, BMI status, smoking status, alcohol use, diabetes, and more, it was shown among a group of 10,349 NHANES participants that higher HEI scores were associated with less elevated depression symptoms, translating to a lower risk of depression. There was a prevalence of depression in 6.9% of the participants evaluated in this study. With the greatest HEI score possible, participants experienced a reduction in the risk of elevated depressive symptoms by as much as 54.5% compared to an inadequate HEI score.
 
Interestingly, other counterintuitive findings were observed on depression risk. For example, in this study, overweight participants experienced a reduction in depression risk, compared to the normal-weight group. It was also evidenced in this study that, although cancer risk persisted for light and moderate drinking, non-heavy alcohol consumption served as a protective factor against depression.