The Gut Microbiome Series: Gut Brain

The Gut-Brain Connection

Our gut is sometimes referred to as our “second brain”, and this is for good reason: it is responsible for chemical messengers, the creation of our feel-good neurotransmitters and the overall health of our central nervous system. This bidirectional communication is known as the gut-brain-axis; through research we know that an imbalance in bacteria, lingering infection or viruses can be connected to a low mood or increased anxiousness.

Food & your mood

Turns out the butterflies in your stomach are actually neurons which line the wall of our digestive system. Over 90% of our serotonin, the “feel good” brain neurotransmitter, is actually produced in the digestive system. Serotonin also plays an important role in regulating our digestive system and bowel movements.

Certain foods can affect our mental health and mood in different ways; researchers have proven this through clinical trials and introducing a variety of foods via feeding tubes and monitoring changes in mood. Carbohydrates, such as whole grains and starchy vegetables, like squash and sweet potatoes, increase a release in our “feel good” neurotransmitter, serotonin. Foods high in fat, such as olive oil, avocado, and nuts/seeds, increase the release of the neurotransmitter dopamine, the neurotransmitter that plays a role in reward and motivation.

Probiotics such as Lactobacillus strains have been found to increase serotonin levels and help restore a healthy balance of bacteria within the body.

Lactobacillus acidophilus is abundant in dairy products such as cow’s milk, yogurt and eggs, and is generally one of the most popular commercial probiotic strains.

Bacteria counts

Good bacteria is responsible for creating short chain fatty acids (SCFAs) from the fiber we eat. Short chain fatty acids are byproducts of the fermentation of fiber and found in high concentrations in the gut. Fermentation is when sugar and carbohydrate sources are broken down by yeast and bacteria within the colon. SCFAs act as signaling molecules between the gut and the brain. Foods such as cows milk, fiber-rich foods and whole grains produce higher amounts of short-chain fatty acids. A carbohydrate starch called resistant starch is fermented in the large intestine and feeds good bacteria within the gut, some examples of resistance starch include: beans, peas, lentils, plantains and green bananas and rice.

The enteric nervous system is a network of over 100 million neurons, which lines the entire digestive tract. This allows it to send signals through a large visceral nerve, called the vagus nerve. The vagus nerve plays an important role in controlling the parasympathetic nervous system and transferring information from the gut to the brain. It turns out there is truth to butterflies in your stomach or having a "gut feeling".