How Your Gut Powers Serotonin Production
What if our approach to treating mental health and cognitive decline was missing a key element?
Our gut is home to a complex neural system that is connected to the brain. In fact, we have more neurons going from the gut to the brain than we do from the brain to the gut. The gut has important messages to communicate!
There are 100-500 million neurons embedded in the gut wall which makes up ‘The Enteric Nervous System’, also known as the second brain. It’s the 100 trillion bacteria that live in the gut (mostly in the large intestine) that influence the neural communication from the gut to the brain.
At birth, your gut is sterile. As we are exposed to the vaginal canal, air, pets, people, breastmilk and largely every environmental factor your unique microbiome develops. This development is key to long-term health and it is now believed that the level and diversity of microbes that live in your gut have a part to play in every chronic disease. Gut bacteria influence digestion and metabolism, they produce nutrients and anti-inflammatory molecules and they programme the body’s immune system. They do this through building and maintaining the gut wall which is a key immune barrier preventing pathogens from entering the body. They also produce antimicrobial chemicals to kill unwanted bacteria/viruses.
Gut bacteria also produce neurotransmitters. Here is where the influence on mental health and cognition comes in. Our ability to produce these neurotransmitters depends on the health of our gut, in particular our microbiome.
Serotonin:
Serotonin is often called the ‘happy hormone’ and plays a key role in influencing a happy mood, outlook and contentment. Up to 95% of our serotonin is produced in the intestinal lining of the gut. This is influenced by the food we eat and the level/diversity of bacteria that is in the gut. Specifically spore forming bacteria are responsible for the synthesis of serotonin. The level of serotonin you have will both influence your gut function/motility and also your mood, emotion and sleep.
Dopamine:
Dopamine is a neurotransmitter that is associated with our reward centre in the brain. It’s important for motivation and pleasure. About 50% of the dopamine in the human body is produced in the gut. This neurotransmitter will affect intestinal movement as well as travel to the brain to influence pleasure and reward.
GABA:
GABA is another neurotransmitter that influences mood and wellbeing. It has an inhibitory effect on the nervous system, slowing down excitatory neurons and therefore calming and slowing the nervous system down. A proportion of GABA is also produced in the gut lining and influenced by bacteria activity.
Melatonin:
Melatonin is another neurotransmitter/hormone that is produced in the gut. Its function is well known in regards to sleep but it also has a big role in the gut in regards to intestinal barrier function and microbial populations. Because melatonin is also produced by gut bacteria we see a reduction in melatonin when dysbiosis occurs - imbalanced bacteria in the gut.
In a meta-analysis of 12 studies it was found that probiotic supplementation significantly reduced depression according to the Hamilton Depression Rating Scale.
Considering the large contribution gut bacteria plays to these hormones that influence our mood and cognition highlights the need to see more of an emphasis on gut health when it comes to mental health and conditions such as Parkinson’s Disease and Alzheimer’s.
What can you do right now to harbour a healthy microbiome?
Eat plenty of fibre to feed the beneficial bacteria and help to sweep the large bowel out. Aim for 30g per day which you will get in if you aim for the majority of your diet coming from plants - fruit, vegetables, greens, legumes, nuts, seeds, grains.
Include as much diversity in your diet as possible - the different colours and fibres in different produce feed different bacteria - the more diverse your diet is the more diverse our microbiome will be.
Hydrate well - 2-3L per day.
Eat prebiotic foods which feed the beneficial microbes - apples, mushrooms, leeks, onions, garlic, artichokes, asparagus, oats, barley, cocoa, avocado, bananas, seaweed to name a few.
Eat probiotic foods which contain beneficial bacteria - sauerkraut, kimchi, yoghurt, miso, apple cider vinegar, kombucha, kefir, kvass to name a few.
Move your body daily. This doesn’t need to be excessive amounts of exercise, just aiming for 7000 - 10,000 steps per day is a great goal.
Save alcohol for the weekends and special occasions. Alcohol damages our microbiome and results in less growth and less diversity.
Avoid sugar which feeds unfriendly microbes in the gut.
Manage stress - stress levels will impact the level of beneficial bacteria in your gut.
Consider supplementing with probiotics - particularly of bifidobacterium longum and lactobacillus helveticus
