Psychonutrition: The impact of food on mental health

What is psychonutrition?

The brain is the most demanding organ in our body. It has enormous energy requirements and depends on amino acids, vitamins, minerals, fats and many other elements for its proper functioning.

Psychonutrition studies the relationship between essential nutrients and optimal neuronal development.

The number of people affected with mental conditions has been increasing worldwide. According to some studies, it is expected to almost double every twenty years. Scientists are working on a way to prevent and mitigate these mental illnesses. A new field of studies, psychonutrition, explores the right alliance between food and mind.

Psychonutrition investigates the way in which our diet influences our brain and our mental health. It covers all psychiatric conditions but not only that: proper nutrition helps people feel better even if they are not suffering from any mental health issue.

What does the research say about psychonutrition?

Several studies have shown that stressed individuals often have a depleted microbiota (billions of bacteria that populate our intestines). Experiments on rats have demonstrated that the ingestion of a lactic acid bacterium (Lactobacillus farciminis) reduces their state of tension in a non-negligible way, by decreasing the permeability of the intestinal barrier. Indeed, the entry of lipopolysaccharides (responsible for triggering neuroinflammation that accentuates the effects of the stress) into the intestines, could be limited if we protect the intestinal barrier.

Another study has shown that the administration of intestinal flora (microbiota) from depressed and anxious individuals to healthy rats was sufficient to contaminate them. The "anxiety" component thus seems to be transferable through the microbiota.

Scientists are now looking into the question of probiotics which, according to studies already carried out, tend to reduce anxiety in individuals with an impoverished microbiota. The question of the necessary quantity of bacteria to be administered remains open for the moment.

In addition, a study has shown that the Mediterranean diet has a positive effect on mental well-being. More than 12,000 Spaniards were monitored for over 6 years. According to the results, those who eat a Mediterranean diet (oily fish, olive oil, lots of fruit and vegetables, legumes, etc.) are up to 30% less likely to suffer from depression than others. This diet helps both to prevent and to cure depression. This dual power has so far only been attributed to physical activity and the practice of mindfulness.

Thus, there is a growing body of evidence supporting the effectiveness of psychonutritional approach. Diets such as the Mediterranean diet, the DASH diet and anti-inflammatory diets have been found to be effective in treating and preventing depression. This has been confirmed by numerous meta-analyses including several dozen observational studies. Omega-3 fatty acids and probiotics have also been found to be effective in treating major depression, either as monotherapy or in combination with antidepressants.

What should we eat to improve our mental health?

According to cdc.gov, 1 in 5 Americans will suffer from a mental disorder in a given year. And yet, as stated above, mental health can be improved by changing our eating habits.

Scientists blame it all on ultra-processed foods. Processing the food makes it lose its nutritional value and increase its calorie count. These foods are often high in added sugar, saturated fat and salt and low in protein, fiber, vitamins, minerals and phytochemicals.

A 2020 meta-analysis showed that regular consumption of vegetables reduced the risk of depression by 9% and fruit by 15%.

In addition, polyunsaturated fatty acids (fatty fish, rapeseed or walnut oil, etc.) and monounsaturated fatty acids (nuts, olive oil) are good for our mental health. They are known to reduce brain ageing.

In addition, a series of meta-analyses has shown that patients that are subject to depression have a lower than average level of Omega-3 fatty acids, which can be found in abundance in olive oil or fatty fish such as salmon. Their regular consumption is therefore good for our mental health. Omega-3 fatty acids also have an impact on various body mechanisms. For example:

• They participate in the functioning of neuronal membranes (key elements of communication between neurons) essential to the proper functioning of the brain,
  
• They have anti-inflammatory properties. According to some studies, 2 out of 3 depressed patients have a low intensity chronic inflammation of the brain. This inflammation is suspected to be one of the causes of depression.
  
  

While adopting a certain diet can play in important role in improving our mental health, it is important to remember that many aspects of our life can contribute to its deterioration.

Further research is needed but current studies suggest that our food choices can influence our mental health.

Despite these findings, the use of psycho-nutritional approach is still not widespread in psychiatric practice. However, there is a strong demand from patients, especially those who do not respond well to antidepressants or those who develop numerous side effects, particularly metabolic ones. Psychonutrition could be particularly useful in preventing metabolic syndrome, which is a major risk factor for cardiovascular disease and cancer.

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