Gut-Brain Axis – Know How Gut Talks To Your Brain

By – Dr Rujuta Patil

BDS, MDS, PDCR

You might have noticed that eating tasty food elevates your mood. Have you ever wondered why this happens? It happens due to connection between gut and brain which is termed as the Gut-Brain Axis. The Gut Brain Axis has become topic of interest in past few years. Such a link is unique and plays important role in keeping us healthy. Hence, “What we eat not only influences our general health but mental health as well”.

So how actually is Gut connected to our Brain? Interestingly our gut has its own nervous system called the ‘Enteric Nervous System’ (ENS) which consists of over 100 million neurons and is sometimes called as the second brain. This ENS is connected to Vagus nerve that goes high up till brain forming connection between gut and brain. There are specialized cells found in gut epithelium that act as gut sensors which sense any chemical, mechanical and thermal stimuli such as nutrients and bacterial byproducts in gut lumen and sends signals to brain via Vagus nerve. Our brain in turn controls several activities like gut motility, permeability, digestion, feeling of fullness after eating etc. Now we know the reason for using this common phrase “Gut Feeling”.

There is something called as Microbiome – Gut – Brain Axis which is being immensely studied by researchers. You might be wondering what microbiota has got to do with GBA? There are trillions of microorganisms in gut which are considered as regulators of gut brain axis. Approximately 10^13- 10^14 microorganisms are known to colonize gut and they form a community which is unique to each individual much like your Finger print. Not all the bacteria are harmful, good bacteria helps us absorb nutrients and it also takes up space not allowing harmful bacteria to colonize. This microbial community is made up of bacteria, virus, fungi and parasite which directly stimulate blood immune cells to fight against invaders by secreting many chemical mediators like neurotropins and cytokines (e.g. -Serotonin, IL-1, Short chain fatty acids) in blood. These chemical mediators in turn affect brain functions. The change in this gut flora composition has shown increased intestinal permeability – known as Leaky gut which allows neuroactive compounds to enter blood stream.

Such a change in microbiota is shown to cause depression and influences ones reaction to social situations. The brain in turn modulates gut microbial community by releasing hormones that effect microbial gene expression. The earliest studies on gut microbiome showed lowered memory and exaggerated stress response in germ free mice. It is amazing that not only organ transplant but faecal matter transplant can also be done. A women with gut clostridial infection was transplanted with fecal matter of her daughter and surprisingly she was cured of her illness but developed a body type similar to that of her daughter. This shows how significantly gut microbiome influences our body.

After knowing all this we can surely come to a conclusion that this cross talk between our gut, brain and gut microbiome plays crucial role in maintaining both our body and mind in state of health.