Mediterranean diet could prevent depression, new study finds” [CNN]; “Mediterranean diet ‘may help prevent depression‘” [BBC]. The publication of Lassale and her colleagues in the prestigious scientific journal Molecular Psychiatry on the association between Mediterranean Diet and depression, received a lot of attention in the media last week.

So, can diet really influence your mental health? The publication of Lassale shows that there are indications that what you eat is related to how you feel. But because this study is an observational study, we can’t conclude anything yet about causation. In other words, we don’t know yet whether eating healthy causes you to feel less depressed, or whether feeling depressed causes you to eat unhealthy.

Causal links between diet and mental health

Diet and mental healthThe researchers of the European consortium Eat2beNICE are investigating exactly this causal link. The way we do this is through clinical trials. In this way, we first let chance decide whether a person receives a particular diet or is part of the control group. Through this randomization we can be sure that the differences that we find between the two groups are really due to the dietary intervention that people received, because all other factors are the same between the two groups.

Specifically for the effects of the Mediterranean diet on behaviour, in the Eat2beNICE project we are using the information and measurements available from the PREDIMED-PLUS trial. In this study, we are looking specifically for the effect of a calorie-restricted Mediterranean diet, combined with physical activity, on several behavioral outcomes related with several psychiatric diseases of adults at high cardiovascular risk.

At the same time, we are conducting three other clinical trials:

  1. In Nijmegen (The Netherlands), we investigate the effects of a very strict, hypo-allergenic diet on behavioural problems in children with ADHD.
  2. We are investigating the effects of vitamin supplements in a clinical trial that will be conducted in Mannheim(Germany) and Groningen(The Netherlands).
  3. Researchers in Barcelona (Spain) and Frankfurt (Germany) are investigating the effects of probiotics (i.e. bacteria that are good for you) on mental health in adults that are highly impulsive and/or aggressive.

Through these studies we hope to be able to identify if these types of food improve mental health and in which circumstances. This can have big implications for psychiatry, where putting someone on a specific, personalised diet may be a way to improve treatment. Also, people who are at a risk for developing mental health problems may benefit from specific diets to reduce this risk. But before this can be put into action, we first need good scientific data on what really works.

How can food drive human behaviour?

A second aim of our large research consortium is to identify the mechanisms between nutrition and the way the brain works. We think that the bacteria that live in your gut play a large role in this, as they interact with other systems in your body, including your brain. So we are collecting poop samples of the people that are participating in our clinical trials to identify which bacteria are more or less common in our participants compared to the control population. We are also measuring our participants’ behaviour and we will scan their brains. We hope that this will help us understanding better why certain types of food can be beneficial for mental health, and why some others increase the risk for mental health problems. This too will help to elucidate, and understand, the causal links between food and behaviour.

In short, we are very thankful for the study of Lassale and her colleagues, for backing up the evidence that what you eat is related to how you feel and behave. Now there’s work for us to do to prove the causal and mechanistic links. We’ll keep you posted here!

 

Authors Jeanette Mostert and Alejandro Arias-Vasquez work at the department of Genetics at the Radboud University Medical Center in Nijmegen, The Netherlands. Alejandro Arias-Vasquez is the project coordinator of the Eat2beNICE project. Jeanette Mostert is the dissemination manager.

 

Further reading

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.

 

Blog by Jordi Salas explaining the Lassale paper and the PREDIMED trial:
http://newbrainnutrition.com/category/nutrition/mediterranean-diet/

Blog by Jolanda van der Meer on hypo-allergenic diet (TRACE study): http://newbrainnutrition.com/adhd-and-food-elimination-diet/

Blog by Julia Rucklidge on trials with vitamin supplements: http://newbrainnutrition.com/micronutrients-and-mental-health/

Blog by Judit Cabana on the Gut-Brain axis: http://newbrainnutrition.com/the-gut-brain-axis-how-the-gut-relates-to-psychiatric-disorders/

 

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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.

did i eat thatIn 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.

 

References

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.

 

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