Junk food, unhappiness

Eat better for better physical... and mental health. This is the conclusion of Tasnime Akbaraly's research, which shows that adopting a healthy diet can reduce the risk of depression. risk of depression.

Cardiovascular disease, cancer, diabetes, obesity... the list of illnesses linked to poor diet is constantly growing. To this list we must now add a new pathology: depression. It affects 350 million people worldwide, or 7% of women and 4% of men. " Depression is the most expensive brain disease in Europe," explains Tasnime Akbaraly, from the Molecular Mechanisms in Neurodegenerative Dementia laboratory.

The nutritional epidemiology researcher has been working for 10 years on the link between food quality and mental health. We don't have a perfect treatment for depression," she laments. Drug and non-drug therapies are effective in only 1 in 3 cases, and the risk of relapse after a major depressive episode is 50%."

Multifactorial disease

It's a multifactorial disease, combining genetic and environmental factors, "which we can't do anything about", explains Tasnime Akbaraly. Researchers therefore set out to find modifiable factors to act on the causes of depression. "Many studies show the importance of nutrients in brain function, so it seemed logical to conduct research into the association between diet and depression."

By examining the diets of volunteers and monitoring their mental health, the researchers found that a healthy diet was associated with a lower risk of depressive symptoms. " Conversely, eating fatty, sugary foods and preferring processed foods increases the risk of depressive symptoms by 60%," explains the researcher.

In a study published in 2018 in the journal Molecular psychiatryTasnime Akbaraly and colleagues examined follow-up data on 36,556 adults. The results speak for themselves: those who adhere most closely to the Mediterranean diet (see box below) have a 30% lower risk of developing a depressive syndrome. How can this link between diet and depression be explained? Researchers have identified two metabolic pathways that may be involved: inflammation and the microbiota.

Pro-inflammatory diet

The study, published in Molecular psychiatry, showed that a pro-inflammatory diet - rich in saturated fatty acids, sugar and refined products - was associated with a higher risk of depression. "The chronic inflammation potentially induced by this type of diet could be directly implicated in the onset of depression. These results support the hypothesis that avoiding pro-inflammatory foods helps prevent depressive symptoms", explains the researcher.

Numerous studies have also shown the importance of diet in the composition of the intestinal microbiota. " The gut-brain axis is very important and remains poorly understood, but we do know that the bacteria that make up our microbiota are involved in the permeability and inflammation of intestinal barriers", explains Tasnime Akbaraly. The relationship between the gut and the brain may therefore play a key role in the onset of depressive disorders.

No negative side effects

In view of these links, Tasnime Akbaraly advocates giving diet its rightful place in the management of depressive disorders. "There is a study that followed two groups of patients suffering from depression who were advised either to adopt the Mediterranean diet or to become more sociable. The result: those who changed their diet saw their risk of depression decrease more than those who emphasized their social life."

When will there be a prescription for healthy eating in cases of depression? Psychiatrists should take up the issue of nutrition, " maintains Tasnime Akbaraly. It's an additional tool in the therapeutic arsenal available to doctors, which allows the patient to take an active role in his or her therapy, and is completely devoid of negative side-effects. What are we waiting for?"

Mediterranean diet, instructions for use

The Mediterranean diet is directly inspired by the traditional eating habits of people living around the Mediterranean. It is based on a high consumption of fruit and vegetables, oilseeds, whole grains, legumes and olive oil. Omega-3-rich oily fish and seafood are regularly recommended. Consumption of meat, deli meats, dairy products, salt and sweet products should be severely restricted. Alcohol can be consumed in moderate quantities.