[LUM#10] Junk food, malaise

[LUM Magazine] - Published on September 19, 2019 in Health, Social Issues & Disability, Science & Society

Eating better for better physical... and mental health. This is revealed in the work of Tasnime Akbaraly, which shows that adopting a healthy diet can reduce the risk of depression.

Cardiovascular disease, cancer, diabetes, obesity... The list of diseases linked to poor nutrition continues to grow. Now there's a new disease to add to that list: depression. It affects 350 million people worldwide, or 7% of women and 4% of men. "Depression is the most costly brain disease in Europe, " says Tasnime Akbaraly of theMolecular Mechanisms in Neurodegenerative Dementias Laboratory.

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

Multifactorial disease

A multifactorial disease that combines genetic and environmental factors, "which we cannot influence, " explains Tasnime Akbaraly. Researchers therefore set out to identify modifiable factors that could influence the causes of depression. "Many studies show the importance of nutrients in brain function, so it seemed logical to conduct research to study the association between diet and depression."

By analyzing the diets of volunteers while monitoring their mental health, researchers noted that a healthy diet is associated with a lower risk of depressive symptoms. "Conversely, eating fatty, sugary foods and favoring processed foods increases the risk of depressive symptoms by 60%, " says the researcher.

In a study published in 2018 in the journal Molecular Psychiatry, Tasnime Akbaraly and her colleagues examined data from 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 depression. How can this link between diet and depression be explained? Researchers have identified two metabolic pathways that could be involved: inflammation and the microbiota.

Pro-inflammatory diet

The study published in Molecular Psychiatry showed that a pro-inflammatory diet—rich in saturated fats, 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 involved in the onset of depression. These findings 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 gut microbiota. "The gut-brain axis is very important and remains poorly understood, but we know that the bacteria that make up our microbiota are involved in the permeability and inflammation of intestinal barriers," says Tasnime Akbaraly. The relationship between the gut and the brain therefore appears to play a key role in the onset of depressive disorders.

No negative side effects

In light of these links, Tasnime Akbaraly advocates giving nutrition the place it deserves in the treatment 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 socialize more. The result: those who changed their diet saw their risk of depression decrease more than those who focused on their social life."

When will we see prescriptions for healthy eating in cases of depression? "Psychiatrists should address the issue of nutrition," argues Tasnime Akbaraly. "It's an additional tool in the therapeutic arsenal available to doctors, which allows patients to take an active role in their treatment and has no negative side effects whatsoever. 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 Sea. It is based on a high consumption of fruits and vegetables, oilseeds, whole grains, legumes, and olive oil. Fatty fish rich in omega-3 and seafood are recommended on a regular basis. The consumption of meat, cold cuts, dairy products, salt, and sugary foods should be severely limited. Alcohol can be consumed in moderation.

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