The Benefits of the Mediterranean Diet on Mental Health and Depression

What and when we eat can have a profound effect on our mental well-being. Improving our diet could be a way of preventing depression.

What and when we eat can have a profound effect on our mental well-being. That is why we have launched a project investigating the effects of diet and sleep habits on the onset of depression. Findings from an initial study reinforce the idea that better eating could be an effective, accessible, and cost-efficient means of preventing depression. While more research is needed, public health policies and clinical services should promote healthy eating. Let's look at this a little more closely.

What role can diet play in mental health?

The connection between diet and depression is both complex and multifaceted. Some biological explanations for why a poor diet might contribute to depression include increased inflammation, oxidative stress, and disruption of the gut-brain axis. Recent studies suggest that people who follow healthier dietary patterns, like the Mediterranean diet—rich in fruit, vegetables, plant-based foods, and fish—may have a lower risk of developing depression. Many studies, however, have struggled to establish a direct cause-effect relationship. My doctoral thesis addresses these limitations by exploring the link between diet and the risk of depression over time in large adult population-based cohorts.

Following a Mediterranean diet may reduce the risk of depression

In the first study of diet and depression by our group, published in the European Journal of Nutrition, we examined the link between diet quality and the onset of depression in the REGICOR cohort, which includes about 4000 adults from the province of Girona, Spain. We used food frequency questionnaires covering more than 150 items to calculate different diet quality scores, including Mediterranean diet adherence scores, the DASH (Dietary Approaches to Stop Hypertension) score, and the 2015 World Health Organization (WHO) Healthy Diet Index (WHO-HDI-2015). We found that participants with better adherence to the Mediterranean diet had a 16% lower risk of developing depressive symptoms after 6 years and that those following WHO dietary guidelines had a 19% lower risk of clinical depression after 12 years. The results remained unchanged after accounting for sociodemographic factors, such as age, sex, and education, and clinical factors, such as body mass index and pre-existing cardiovascular disease, leading us to conclude that the relationshop between diet quality and depressive symptoms exists independently of these variables.

We found that participants with better adherence to the Mediterranean diet had a 16% lower risk of developing depressive symptoms after 6 years

What’s next? Exploring how sleep habits and diet type influence depression

The next stage of our project will focus on analyzing how specific food groups (fruit, vegetables, legumes, meat, dairy, sugary drinks, and ultra-processed products) and nutrients (omega-3 fatty acids, fibre, calcium, and sodium) contribute to the burden of disease. The study will be conducted within the framework of the GLAD initiative, led by researchers from Deakin University in collaboration with the Global Burden of Disease team. We will use data from the French NutriNet-Santé cohort study, which has detailed, high-quality dietary information from more than 40,000 participants. We will also investigate how certain eating patterns that disrupt natural circadian rhythms, such as late-night eating and skipping meals, affect mental health. While there is some evidence that night-shift workers, who often experience circadian disruptions, have a higher risk of depression, less is known about how everyday eating patterns affect mental well-being. We will also take into account related factors such as sleep quality and individual chronotypes (whether one is a "morning" or "night" person).

Mental health requires reflection and collective action

While diet and sleep are personal habits, they are not usually linked directly to mental health. It is also crucial to remember that depression has structural and systemic causes, and attributing it to individual behaviours is both incorrect and stigmatizing. Factors such as instability, work, and caregiving responsibilities all shape our daily routines, often beyond our control and often forcing us to modify our habits. Addressing depression and its causes requires collective decisions and action aimed at promoting and enabling healthier eating habits. This involves implementing public health policies and clinical services to support these changes.

Stay tuned for more updates on this important work!