Constantly feeling low mood and blue, losing of pleasure in life and appetite or having difficulties to have good sleep.
These are just some of the symptoms of one of the most prevalent mental conditions worldwide: depression. It affects hundreds of millions people globally, particularly women. Although depression seems to have a genetic component, lifestyle factors like diet have been suggested to play possible roles in the development of this condition and the degree of their symptoms. In fact, many different studies have suggested that different healthy diets may have important benefits for depression.
In a recently published meta-analysis at the prestigious scientific journal Molecular Psychiatry, Lassale and coworkers aimed to summarize current epidemiological evidence in relation to healthy dietary patterns and depression. They included a total of 41 high quality observational studies conducted in healthy people from different countries, focusing on several types of well-known healthy dietary indices: Mediterranean diet, the Dietary Approaches to Stop Hypertension (DASH) diet, the Healthy Eating Index (HEI) and Alternative HEI (AHEI), and the Dietary Inflammatory Index. These healthy dietary indices score favorably for the consumption of different “healthy” foods, such as fruits and vegetables, nuts, cereals, legumes and healthy fats; and they penalize the consumption of “unhealthy” foods, such as processed foods.
The main findings of the Lassale meta-analysis revealed that those persons following more closely the Mediterranean diet, and those following less the pro-inflammatory diet, showed lower risk of depression and depressive symptoms. Similar beneficial results were observed with a high adherence to the HEI and AHEI diets, yet the evidence was not as strong as with the Mediterranean diet. Indeed, the dietary patterns evaluated in this study contain foods and nutrients which may modulate important biological processes related with depression. For example, healthy diets may reduce oxidative stress and inflammation processes, improve insulin sensitivity and blood circulation in the brain.
These important findings give a strong basis to the role of healthy dietary patterns like the Mediterranean diet in preventing depression and depressive symptoms, and they contribute to build future dietary recommendations to prevent this mental condition.
However, as the authors comment, it is important to keep in mind that all the studies included are observational, meaning, it is not possible to establish causal effects between diet and depression.
To establish causality that can be used to directly translate the knowledge into clinical practice, science needs specific intervention studies. In these studies, a healthy diet is followed for a long time and depression incidence is evaluated.
An example of this is the study conducted in the frame of the PREDIMED study with a population of Mediterranean adults at high cardiovascular risk. In this study, participants consuming the Mediterranean diet supplemented with nuts showed 41% protection against depression, although these benefits were only observed in people with diabetes. In view of the PREDIMED-Plus trial, a multicenter study is being conducted in Spain for the primary prevention of cardiovascular disease using an intensive lifestyle intervention. It will be possible to confirm these results and have new knowledge in the field of depression. With PREDIMED-plus, the investigators will be able to evaluate whether an energy-restricted Mediterranean diet, with promotion of physical activity, may be effective for reducing the risk of depression in elders at high cardiovascular risk. In case of the Eat2BeNice study we plan to analyse in the future the effect of PREDIMED-PLUS interventions not only on depression but also on mood and especially on impulsivity and compulsivity, two important domains related to brain function.
Overall, following a healthy diet, like Mediterranean diet, not only has important benefits for different aspects of human health but also it is likely that the diet prevents depression, depressive-related symptoms and possible other mental related conditions. For this reason, a healthy diet nourishes a healthy mind.
Lassale C, Batty GD, Baghdadli A, Jacka F, Sánchez-Villegas A, Kivimäki M, Akbaraly T. Healthy dietary indices and risk of depressive outcomes: a systematic review and meta-analysis of observational studies. Mol Psychiatry. 2018 Sep 26. doi: 10.1038/s41380-018-0237-8.
Sánchez-Villegas A, Martínez-González MA, Estruch R, Salas-Salvadó J, Corella D, Covas MI, Arós F, Romaguera D, Gómez-Gracia E, Lapetra J, Pintó X, Martínez JA, Lamuela-Raventós RM, Ros E, Gea A, Wärnberg J, Serra-Majem L. Mediterranean dietary pattern and depression: the PREDIMED randomized trial. BMC Med. 2013 Sep 20;11:208. doi: 10.1186/1741-7015-11-208.