Happiness Begins in the Gut

Unlikely as it may sound, our digestive system is closely linked with our mood.

Far from simply being a place where food is digested and absorbed, recent research is discovering our gut is a dynamic environment where millions of chemical messengers are produced and released. These travel all over our body, which means our gut communicates with our other organs – including our brain.

This article will look at the link between our mood and our gut.

The Gut / Brain Connection

The link between our digestive system and our brain is called the gut-brain axis. Communication between the brain and the gut works both ways. The gut and the brain are constantly talking to and influencing each other.

We all know anxiety and nerves can affect how well our digestive system functions, but on the other hand our gut influences our thinking. After all, who hasn’t had a gut reaction to a situation?

Millions of nerves line the length of the digestive system, embedded in the gut wall. They’re known as the enteric nervous system and they’re the second largest collection of nerves outside of the brain. These nerves can act on their own initiative, without instructions from the brain and spinal cord.

The gut and the brain are connected by the vagus nerve, which also has links to most of the other organs of the body. It’s the vagus nerve that helps the gut to tell the brain how it’s feeling.

What is Happiness?

Our mood is a by-product of the release of various chemicals in the brain which help brain cells communicate with one another.

Serotonin, nicknamed the happy hormone, is the main hormone which stabilizes mood. It’s plentiful in times of elevated mood and when its levels are depleted we tend to feel low and sad.

Another brain chemical, dopamine, is associated with pleasure and the happiness connected with reward, such as when we win a prize.


Happy Bacteria

Our gut is home to trillions of different bacteria belonging to many different species. These are referred to as our microbiota. What’s fascinating is the quantity and proportions of different species of these bacteria is unique to each one of us. Factors like genetics, food choices, stress and the use of medical drugs influence the makeup of the species residing there.

The bacteria in the microbiome are constantly producing chemicals which act as messengers throughout the body. The types of messenger chemicals vary according to which kinds of bacteria dominate. Some of these messengers are beneficial to our health, and some not so advantageous – for example, certain types can promote inflammation.

An imbalance in the species of bacteria in our microbiome can have far reaching health effects in the entire body including our mental health.

Bacteria and Happy Chemicals

It’s thought the levels of the brain chemicals serotonin and dopamine can be influenced by messages sent out by certain species of gut bacteria.

Gut bacteria can also directly produce neurotransmitters. In fact, the majority of serotonin is manufactured in the gut. This is because it’s not only important for regulation of our mood, but it also plays important roles in the digestive system too. There it regulates bowel function, helps in the production of digestive juices and influences muscular activity. If these neurotransmitters are able to make their way to the brain, they could influence mood.

Bacterial Variety is the Key to Happiness

Variations in the proportions of various bacterial species have been found to correlate with how happy people report they are in general.

People suffering from depression typically have fewer different species of bacteria living in their gut. A good range of different bacterial species in the microbiome is thought to be beneficial to many aspects of health.

Scientists have even found if gut bacteria from depressed people are transplanted into rodents, the animals behave as if they were depressed, losing interest in food they previously enjoyed.

Other studies have found giving people probiotic supplements containing beneficial bacteria with the goal of changing the composition of the gut bacteria can improve their mood.

Mood and Digestive Disorders are Linked

In view of this it’s not surprising depression and anxiety often go hand in hand with digestive issues such as IBS.

Our mental and physical health are closely linked, and the relationship between the gut and our emotions is complex and dynamic. Functional Medicine practitioners look at the body and mind as one entity and consider the effects of lifestyle, food choices and genetics on the microbiome and gut/brain axis.

If you would like to explore further how your gut may be influencing your mood, my good gut health programme will recommend lifestyle and nutritional strategies as well as appropriate functional tests to examine the health of your gut and its microbiome.