Post by Emily White
Recently there has been huge interest in the possibility that there is a powerful link between the human brain and gut bacteria. Whilst majority of the current research has been conducted on animals, there are a few studies that show a compelling link between behaviour and gut bacteria in humans.
What many people do not know is that a crucial part of the nervous system is located in the gut- the enteric nervous system. This part of the nervous system contains 100 million neurons and is embedded in the lining of your GI tract. The enteric and the central nervous system are connected by the vagus nerve, which conveys information about body organs back to the central nervous system (1). This has been implicated in mouse studies as being involved in gut microbiota- brain interaction. It is common knowledge that your brain communicates with your enteric nervous system (you just need to think of the ‘butterflies’ sensation in your stomach when you are nervous, or potential gastrointestinal upset if you are stressed or anxious), however research is heading in the direction to suggest that there is also significant communication from your gut to your brain in the way that problems in the gut could have a potential affect on mental health and associated problems such as anxiety (2).
New research published in the journal of psychopharmacology is suggesting just that. Results from this study are showing a link between supplements (prebiotics) designed to increase numbers of healthy bacteria in the GI tract and lessened anxiety due to them potentially altering the way that people process emotional information. The subjects who had been supplementing with a prebiotic for 3 weeks paid less attention to negative information and more attention to positive information compared to the placebo group. This effect is similar to that of which has been seen among individuals who have been taking antidepressants or anti-anxiety medication (3).
Another study done with humans saw a group of healthy females given a fermented milk product with 5 probiotic strains whilst the other group received a placebo. At the end of the month they underwent an emotive stress test and compared with the same test done prior to supplementation, found significant differences in the brain response between the groups. The knowledge that signals are sent from the GI tract to the brain and could potentially be altered by dietary change is an exciting new area of research that could potentially revolutionise the way we view and treat mental health (4).
There is growing evidence for a link between enteric microbiota and brain function. In particular research is heading in the direction to show a link between the ingestion of probiotics and a healthy gut to the way we process information that is strongly linked to anxiety and depression. This is suggesting now more then ever the importance of looking after your gut. For more information on maintaining excellent gut health you can check out this post. So is a healthy gut and supplementation the key to our mental health worries? A lot is still unknown so I wouldn’t be shouting from the rooftops how taking a probiotic and avoiding gut unfriendly foods can replace the need for medications prescribed by a doctor, however there is definitely no harm in placing a focus on improving the health of your gut.
1. Collins, S. M., Surette, M., & Bercik, P. (2012). The interplay between the intestinal microbiota and the brain. Nat Rev Micro, 10(11), 735-742.
2. Hsiao, E. Y., McBride, S. W., Hsien, S., Sharon, G., Hyde, E. R., McCue, T., . . . Mazmanian, S. K. (2013). Microbiota modulate behavioral and physiological abnormalities associated with neurodevelopmental disorders. Cell, 155(7), 1451-1463. doi: 10.1016/j.cell.2013.11.024
3. Schmidt, K., Cowen, P. J., Harmer, C. J., Tzortzis, G., Errington, S., & Burnet, P. W. (2015). Prebiotic intake reduces the waking cortisol response and alters emotional bias in healthy volunteers. Psychopharmacology (Berl), 232(10), 1793-1801. doi: 10.1007/s00213-014-3810-0
4. Tillisch, K., Labus, J., Kilpatrick, L., Jiang, Z., Stains, J., Ebrat, B., . . . Mayer, E. A. (2013). Consumption of Fermented Milk Product With Probiotic Modulates Brain Activity. Gastroenterology, 144(7), 10.1053/j.gastro.2013.1002.1043. doi: 10.1053/j.gastro.2013.02.043