3 · Anxiety disorders are not the exception
They affect more than one person out of five (aged 18 to 65 years) at least once in their lifetime14. Family history increases vulnerability to ADHD, but people who are not predisposed are not immune. Chronic anxiety is at least partially associated to inflammatory processes that are potentially promoted by gut bacteria. Constant and excessive worry difficult to control, unpredictable and regular panic attacks, obsessive-compulsive disorders, post-traumatic stress disorder... Anxiety disorders refer to various diseases whose common thread is fear. These patients are prisoners of their fears and implement disproportionate avoidance strategies.
Among other factors is, once again, gut dysbiosis! It leads to an increase of intestinal permeability and a disruption of stress response, as well as an increase in inflammatory activity.
All roads lead to the microbiota15
Scientists agree that gut bacteria play a role in this process. But according to scientific studies, the microbiota could either have an anxiety-inducing effect or an anxiolytic effect16. The use of antibiotics– that disrupt and impoverish the gastrointestinal flora–could be associated to the onset of anxiety disorders, or conversely, to a decrease in anxiety in animals.
The flora is being explored “blindly”
In animal models, antibiotics seem to decrease anxiety during the treatment period. The drawback is that an early disruption of the gut microbiota by antibiotics could lead to behavioral changes that persist into adulthood17,18. Some probiotic strains could also have an anxiolytic effect. Finally, fecal microbiota transplant could reduce anxiety levels19. All these results still have to be confirmed in humans.
What to eat to stay zen?
Fermented foods such as cheese, yogurts, kefir, kombucha or soy sauce are excellent sources of probiotics and prebiotics. They act as anti-inflammatory agents by strengthening the integrity of the intestinal barrier, improving the composition and function of gut bacteria, and stimulating immune cells in the digestive tract. Probiotics decrease frequency and severity of anxiety symptoms in rat models. In humans, they decrease cortisol levels in urine21. In healthy people with no psychiatric disorders, consumption of fermented milk leads to changes in brain activity in regions that are responsible for emotions and pain.
15 Aslam H et al. Fermented foods, the gut and mental health: a mechanistic overview with implications for depression and anxiety. Nutr Neurosci
17 Leclercq S, Mian FM, Stanisz AM et al. Low-dose penicillin in early life induces longterm changes in murine gut microbiota, brain cytokines and behavior. Nat Commun 2017; 8 : 15062 doi : 10.1038/ncomms15062
18 Tochitani S, Ikeno T, Ito T et al. Administration of non- absorbable antibiotics to pregnant mice to perturb the maternal gut microbiota is associated with alterations in offspring behaviour. PLoS One. 2016 Jan 20;11(1):e0138293. doi: 10.1371/journal.pone.0138293
19 Bercik P et al. The intestinal microbiota affects central levels of brain-derived neurotropic factor and behavior in mice. Gastroenterology 2011 ; 141 : 599-609
20 Misra S, Mohanty D. Psychobiotics: A new approach for treating mental illness? Critical Reviews in Food Science and Nutrition, DOI: 10.1080/10408398.2017.1399860. 2017
21 Aslam H et al. Fermented foods, the gut and mental health: a mechanistic overview with implications for depression and anxiety. Nutr Neurosci