Could rebalancing your gut microbiota help alleviate depression ?

Depression

Le microbiote intestinal pourrait-il influencer notre santé mentale en agissant sur notre énergie ? Une étude chez l’humain et la souris explore ce lien entre bactéries intestinales, métabolisme et symptômes dépressifs.

Rééquilibrer son microbiote pour sortir de la dépression ?

About this article

Created 28 September 2026

Updated 01 October 2026

What if restoring a healthy gut microbiota could help you alleviate depression by giving your body an energy boost?

Depression doesn’t just affect mood and cognitive function. It frequently goes hand in hand with changes in energy metabolism and gut microbiota, as confirmed by a study^¹ involving 100 patients with major depressive disorder and 68 healthy controls.

1,5 Depression is about 1.5 times more common among women than among men.²

10% Worldwide, more than 10% of pregnant women and women who have just given birth experience depression (perinatal depression).²

A link between microbiota, metabolism, and depression

The results are clear: in people with depression, several pathways involved in energy production are disrupted, with some metabolites present in excess—such as lactate, glutamate, and arginine—and others in lower-than-normal levels, including glucose and ornithine. These metabolic disturbances are associated with more severe symptoms, including increased anxiety, more pronounced depressive symptoms, and greater cognitive difficulties.

But that’s not all. The authors also found differences in the gut microbiota of people with depression: a dysbiosis is present, involving around 100 bacterial species that are either more or less abundant than in stool samples from healthy controls.

What if everything were connected? Among these microorganisms that are over- or underrepresented in the gut, several may influence our energy metabolism and, in turn, negatively affect our mood. Or, conversely, they could improve our mental health—provided we give good bacteria in our gut a little boost. But before considering such an approach, researchers first needed to establish a causal relationship. That has now been demonstrated.

4% An estimated 4% of the population experience depression, including 5.7% of adults (4.6% among men and 6.9% among women), and 5.9% of adults aged 70 years and older.²

332 million Approximately 332 million people in the world have depression.³

3rd Suicide is the third leading cause of death in 15–29-year-olds.²

A mouse experiment to test causality

Researchers subjected mice to chronic stress that induced depressive-like behaviors. As observed in patients with depression, the mice developed alterations in both their gut microbiota and energy metabolism.

The study focuses on the microbiota—the gut bacterial community—and its links to metabolism and mental health.
Previous studies had already identified changes in the gut bacteria of patients with major depressive disorder, but the links between these changes and metabolism had remained largely correlational.

The researchers then transplanted the mice’s own fecal microbiota, collected before they were exposed to chronic stress, back into the animals after they had developed depression-like behaviors. Following this procedure, known as an autologous fecal microbiota transplant (each mouse received its own gut microbiota), several metabolic abnormalities were corrected, and the mice showed improvements in their mental health. Mitochondrial function—which provides energy—was also restored in brain regions involved in mood and memory.

"The transplant reintroduced bacteria that had been present in the gut before exposure to the stressor.”

“From a mental-health perspective, these findings add to the growing evidence supporting the importance of the gut–brain axis. However, they do not demonstrate that interventions targeting this axis can treat depression in humans.”

What about humans?

So far, this causal relationship has only been demonstrated in animals. Further studies are needed to determine whether the same mechanism exists in people with major depressive disorder and, above all, whether modulating the gut microbiota could one day have therapeutic potential. In the meantime, to give your mood a boost, you can start by taking care of your gut microbiota. How? Through diet, for example, by choosing citrus fruits and cutting out soda.

Three examples to help you understand

Reducing excess (toxic) lactate

In people with depression, chronic stress can impair mitochondrial function—the mitochondria being the powerhouses of our cells—and cause brain cells to switch to an alternative energy-producing pathway known as anaerobic glycolysis. This can lead to an abnormal and harmful buildup of lactate in the blood and brain. This excess of lactate may contribute to depressive behaviors and memory deficits. However, the gut bacterium Anaerostipes hadrus may alleviate anxiety and depression by reducing brain lactate levels, thus allowing the mitochondria to resume their normal function and reversing this anaerobic glycolytic shift.

Reducing excess (toxic) glutamate

In people with depression, glutamate is thought to accumulate at abnormally high levels in the blood and brain. These elevated glutamate levels are thought to interfere with brain energy metabolism and may exacerbate depressive symptoms. The gut bacterium Anaerostipes hadrus may play a potentially beneficial role in improving depression and anxiety: it seems to have a protective effect by reducing certain key metabolites, including glutamate, as well as lactate and isocitric acid.

Increasing ornithine (a protective agent) when levels are low

In people with depression, ornithine levels are believed to be very low in the blood and brain. This deficiency could contribute to the accumulation of toxic metabolites by impairing ammonia detoxification and increasing glutamate production. It may also deprive the brain of neuroprotective compounds, since ornithine serves as a precursor for their synthesis. Together, these changes could increase vulnerability to depression, fatigue, and cognitive decline. However, several intestinal bacteria, such as Dorea formicigenerans and Eubacterium ramulus , appear to be major sources of ornithine for the host.