Your gut contains over 100 trillion bacteria, collectively known as the microbiota. So far in this blog series, we have explored what the microbiota actually is and how the important bacteria which make up the microbiota play a key role in the body’s immune system.
What you may not know, however, is how important the role of the gut is in providing your body with energy, whether that is physically or mentally. The bacteria in your gut are responsible for breaking down plant-based fibre from your diet, through fermentation. This fermentation not only provides the gut bacteria inside us with a source of energy, but it also provides us otherwise un-obtainable energy and allows us to assimilate important nutrients such as vitamin K and B from our food (1).
Vitamin K is extremely important for ensuring your blood clots appropriately. B vitamins on the other hand, are a diverse group of water-soluble vitamins that play a role in metabolism (2), helping us break down and release energy from food as well as keep the skin and nervous system healthy.
The gut bacteria have an important role in the health of your brain, and in particular, regulating your mood. Serotonin is a neurotransmitter, which means it helps the brain carry signals from one part of the brain, along nerves, to other parts of the brain. Traditionally serotonin has been understood to play a crucial role in brain function. It is sometimes called “the happy chemical” because it contributes to feelings of happiness and positive mood. However, it has been estimated that the vast majority of the happy chemical serotonin is actually found in the gastrointestinal tract (3). This is one of the main reasons why having a healthy gut may be really important in mood. Additionally, it has recently been discovered that the brain and gut are connected by what is known as the “gut-brain axis”. Researchers are discovering day by day how important the gut-brain-axis in controlling mood and also keeping the brain healthy.
What is the gut-brain axis?
The gut-brain axis is a two-way connection between the gut and the brain as the name suggests. Whilst the brain can send signals down to the gut to regulate motility, digestion and absorption, the gut and associated microorganisms influence neurotransmitters in the brain – this has been shown to have effects on stress, anxiety, mood, and behaviour (4).
This research is very recent, so for that reason, we don’t understand exactly which bacteria in the gut have the most mood-boosting effects. But what we do know is that there are certain things which keep the gut healthy, for example, a diverse diet. A good rule of thumb is a healthy microbiota is a diverse microbiota. That means many different species living all over and inside our bodies. We also know that other things are detrimental. For example, the routine overuse of antibiotics.
How can you increase the diversity of the species of microbe in your gut?
Firstly, eat a wide range of plant-based foods. A healthy gut has a diverse community of microbial organisms, all of which prefer different plant-based sources of fuel. The more variety in your diet, the better. Part of the reason why plant-based foods such as fruits, vegetables, legumes and nuts are good for the gut is that they contain plenty of fiber which helps keep your digestive system regular, and also keeps your gut microbes happy. Additionally, avoid highly processed foods. They often contain ingredients that either suppress 'good' bacteria or increase 'bad' bacteria. When cooking at home choose extra-virgin olive oil as it’s packed full of gut-friendly polyphenols (5) Finally, probiotic foods, such as kefir, live yogurt and fermented foods such as kimchi and kombucha may all encourage more microbes to grow. Not to mention a high quality probiotic supplement.
Antibiotics kill ‘good’ bacteria as well as ‘bad’, they are not selective. If you need antibiotics, make sure you eat lots of foods that boost your microbes afterward.
References: LeBlanc, J.G., Milani, C., de Giori, G.S., Sesma, F., van Sinderen, D. and Ventura, M., 2013. Bacteria as vitamin suppliers to their host: a gut microbiota perspective. Current opinion in biotechnology, 24(2), pp.160-168. Huskisson, E., Maggini, S. and Ruf, M., 2007. The role of vitamins and minerals in energy metabolism and well-being. Journal of international medical research, 35(3), pp.277-289. Kim, D.Y. and Camilleri, M., 2000. Serotonin: a mediator of the brain–gut connection. The American journal of gastroenterology, 95(10), p.2698. Foster, J.A. and Neufeld, K.A.M., 2013. Gut–brain axis: how the microbiome influences anxiety and depression. Trends in neurosciences, 36(5), pp.305-312. Cicerale, S., Lucas, L.J. and Keast, R.S.J., 2012. Antimicrobial, antioxidant and anti-inflammatory phenolic activities in extra virgin olive oil. Current opinion in biotechnology, 23(2), pp.129-135.