What do probiotics have to do with the mind?
Although the gut and the mind seem far away from each other, they are actually very closely linked, and the connection is known as the gut-brain axis. They are linked through biochemical messaging between the nervous system in the gut, known as the enteric nervous system, and the central nervous system, including the brain. The two are connected by the longest nerve in the body called the vagus nerve.
Probiotics and brain chemicals
The mind works in wonderful ways, and the chemicals required to create healthy moods, emotions and a healthy sleep / wake cycle actually originate from the gut. These chemicals are known as neurotransmitters and include serotonin, dopamine, GABA and melatonin. It is estimated that 90% of the serotonin in the brain originates from the gut. Serotonin is the happy hormone and the motivator, so poor gut healthy = poor moods and motivation.
Neurotransmitters start off as amino acids. Amino acids originate from protein in the diet. Probiotics are required to convert these amino acids into neurotransmitters in the gut, which then travel into the brain with insulin, a hormone that takes sugar around the body for use.
The gut-brain axis
Whatever affects your gut, affects your brain, and whatever affects your brain affects your gut. In stressful situations, many people feel it in their gut, or some may get a sensation of butterflies before an important event. And it works the other way too. People with gut issues often also experience anxiety or depression as the same time as worsening symptoms.
Another example of the close link between probiotics and the brain is that probiotics also control the desire for food, where they help to regulate appetite. Around 20 minutes after eating, probiotics release chemicals that tell your brain to stop eating and may trigger sensations of fullness.
Probiotics for a healthy mood
The serotonin produced by probiotics may help towards positive moods and motivation. Once in the brain, serotonin converts into the sleep hormone melatonin when the lights start to dim, making you feel tired and helping you to get to sleep and keeping you asleep throughout the night. Good quality sleep often leads to improved moods and motivation.
In the absence of adequate probiotics, low levels of serotonin may occur, and trigger a variety of mood symptoms and sleep issues.
What causes a low number of probiotics in the gut?
The probiotics in the gut can be disrupted for a variety of reasons, including stress, poor diet, antibiotic use, chlorine in drinking water and gut infections. Ironically, stress is one disruptor of the probiotics in the gut, and a disrupted level of probiotics may contribute to an increased sensitivity to stress. This can cause a downward spiral, and taking a probiotic supplement is often recommended. It is also important to increase your intake of fibre, which is a food source for probiotics. Fruit and vegetables provide a great source of fibre. Ideally 7-9 portions of vegetables and fruit per day should be consumed.
What does the research say?
Researchers looking into probiotics and the mood gave 38 volunteers a probiotic supplement for 6 weeks which included Lactobacillus rhamnoses and Lactobacillus plantarum among others. A significant improvement in mood was observed in the experimental group, with a reduction in depressive mood state, anger, and fatigue, and an improvement in sleep quality. The researchers concluded that administration or probiotics may improve psychological well-being by ameliorating aspects of mood and sleep quality. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6445894/
In a systemic review, researchers analysed the relationship between depression and anxiety and probiotics. Almost all research reviewed demonstrated significant improvements in one or more area or mind health. The researchers found an even greater benefit in patients with IBS alongside their anxiety and depression. The researchers suggest using probiotics as a useful adjunctive treatment for patients with anxiety and depression. https://nutrition.bmj.com/content/3/2/351