Probiotics are ‘good’ microorganisms found in food products or supplements. They can benefit our health by improving the balance of the gut bacteria. They are found in many different forms such as yoghurts, tablets, capsules and sachets. For some time we have known that they could do more than improve the health of your digestive system. They also may indirectly enhance your brain, too.
Research shows that the digestive system and brain are linked, we call it the gut-brain axis. The two are linked through biochemical signalling between the nervous system in the digestive tract. They pass information between them using the vagus nerve, the longest nerve in the body.
The digestive system has been likened to a "second brain" because it produces many of the same neurotransmitters as the brain does, like serotonin, all of which play a key role in regulating mood. In fact, it is estimated most of our serotonin is made in the digestive tract.
As a result, what affects the digestive system often affects the brain and vice versa. When your brain senses that something is seriously wrong i.e the ‘fight-or-flight response’, it sends warning signals to the gut, which is why stressful events can cause digestive problems like a nervous butterflies or diarrhoea. On the flip side, flares of gastrointestinal issues linked to changes in microbiota (bacteria etc) like irritable bowel syndrome (IBS), Crohn's disease, or chronic constipation may trigger anxiety or depression.
How might probiotics fit in the gut-brain axis? Some research has found that probiotics (Bifidobacterium bifidum and Bifidobacterium longum) given for 12 weeks may help promote mental flexibility and alleviate stress in healthy older adults, along with causing changes in gut microbiota.
Recent studies indicate that patients with anxiety or eating disorders (anorexia nervosa, bulimia nervosa, and binge-eating disorders) show a specific profile of gut microbiota, and this imbalance can be partially restored after a single or multi-strain probiotic supplementation.
There’s so many other studies out there, but it's too early to say the exact role probiotics play in the gut-brain axis. Probiotics may not only support a healthier gut, but a healthier brain as well!
https://www.bda.uk.com/resource/probiotics.html
Chudzik A, Orzyłowska A, Rola R, Stanisz GJ. Probiotics, Prebiotics and Postbiotics on Mitigation of Depression Symptoms: Modulation of the Brain-Gut-Microbiome Axis. Biomolecules. 2021 Jul 7;11(7):1000.
Kim CS, Cha L, Sim M, Jung S, Chun WY, Baik HW, Shin DM. Probiotic Supplementation Improves Cognitive Function and Mood with Changes in Gut Microbiota in Community-Dwelling Older Adults: A Randomized, Double-Blind, Placebo-Controlled, Multicenter Trial. J Gerontol A Biol Sci Med Sci. 2021 Jan 1;76(1):32-40.
Navarro-Tapia E, Almeida-Toledano L, Sebastiani G, Serra-Delgado M, García-Algar Ó, Andreu-Fernández V. Effects of Microbiota Imbalance in Anxiety and Eating Disorders: Probiotics as Novel Therapeutic Approaches. Int J Mol Sci. 2021 Feb 26;22(5):2351.