A Gut Feeling: How Gut Health Impacts your Physical and Mental Health

By Sarah O’ConnorGut health, or the health of your intestines, affects both physical and mental health. Here in  UCC, research into the interaction of the brain and gut is leaping forward thanks to the work of  UCC Professors like John Cryan and Ted Dinan, co-authors of The Psychobiotic Revolution, a book that has been described as ground-breaking in the field. Despite major advances in research  exploring gut health, and psycho-biotics, many of us remain unaware of the many factors that  influence gut health. The gut itself has its very own brain – the Enteric Nervous System - that controls its own  activity. It is the only system in the body that is not controlled only by the brain via the Central  Nervous System. What’s more than just the actual nervous system of the gut, it is also home to  a huge number of bacteria that are commonly known as ‘The Microbiome’. For every human  gene in your body, you have roughly 360 microbial genes, so this should show you the sheer  number of bacteria present in our gut, particularly the large intestine. The bacteria of the gut are absolutely vital for us to survive and different species of different  bacteria carry out various different functions. For example, some produce Vitamin K for us  which is essential for blood clots to form when we get a cut. Other bacteria produce serotonin  which I’m sure you’ll recognise as one of the hormones responsible for happiness. It is  estimated that 90% of serotonin is produced in the gut, so there is no doubt that gut health  absolutely affects how we feel. Various other neurotransmitters are also made here which  strongly indicates that our gut affects our brain chemistry. No two people have the same microbiome, as genetics, environment and diet all play a role in that variation. Studies have found that some mental health conditions including schizophrenia  and depression are associated with less diversity in the gut bacteria. It is not quite sure why exactly this is, but it really emphasises the importance of a good, varied diet to feed not only yourself, but also these bacteria that do some much for our overall health. Our microbiomes start developing the moment we are born. Studies show that babies born  naturally have greater diversity in their microbiome compared to babies born via Caesarean  section, as they make contact with their mother’s vaginal microbiota during birth. Babies born  by Caesarean unfortunately do not have this and they tend to pick up bacteria from the skin and surrounding environment instead. There is strong evidence to suggest these babies have a higher risk of developing allergies, and a less robust ecosystem. Babies born by Caesarean section are much more likely to develop asthma also. However, with proper nutrition, babies  born via Caesarean are well able to acquire a diverse and healthy microbiome, but it is  interesting to see just how early on our microbiomes start to take shape. Another major influence on gut health is antibiotics. Antibiotics are no doubt a miraculous class  of drugs, having made many diseases that once proved fatal, easily and cheaply treatable.  However, antibiotics kill bacteria indiscriminately, meaning they cannot tell the difference  between friendly bacteria in our gut and the harmful ones causing disease. The danger is that  taking antibiotics will knock out the friendly bacteria and the pathogenic, disease causing ones  will gain a foothold in your gut and cause problems. An example of this is clostridium difficile, or C Diff, that hospital patients sometimes acquire. After a course of antibiotics for something  unrelated, for instance a respiratory infection, the friendly microbiota is also killed. C Diff  rapidly colonises in the gut and causes horrible diarrhoea for the patient. In already sick patients, this can prove fatal. An interesting (if not slightly disgusting treatment) for this is what’s known as a faecal transplant. This is exactly what it sounds like; a healthy sample of stool with a diverse, healthy microbial population is transplanted into the patient. It is actually very effective in repopulating the patient’s own microbiome with friendly bacteria and often the patient makes a rapid recovery. Although the thought of this procedure sounds quite repulsive, the recovery of the patient shows exactly how important the commensal bacteria are in keeping you healthy.  The gut also contains 80% of the body’s immune cells. This makes sense, considering most of  the foreign bodies that enter your body are the ones you feed yourself. So, it is clear that your  gut is underappreciated in protecting you from infections and illnesses. The presence of the microbiomes mean that other pathogenic bacteria cannot colonise in your body as they are  outcompeted for resources and space by friendly bacteria.So, what can you do to improve your gut health, and reap the associated rewards of enhanced  mental and physical health? UCC’s Cryan and Dinan emphasise the benefits of a mixed diet,  consisting of plenty of vegetables and variety. Yoghurt is an excellent source of probiotics that  improve gut health, and many fermented food and drinks such as sauerkraut, kimchi,  kombucha, and even sourdough are also beneficial for gut health. You don’t need to totally  transform your diet by incorporating all of these foods at once. Any sudden, radical change to  your diet might cause sudden changes in bowel movements, but even everyday items like  almonds, peas and bananas are loaded with the type of fibre that good bacteria in the gut loves, so a probiotic rich natural yoghurt with some almonds and a sliced banana for breakfast would be an easy way to care for your friendly gut bacteria. Aside from dietary adjustments, avoiding antibiotics unless totally necessary is another way to safeguard your gut health, and prevent the unpleasantness of having your gut’s good bacteria killed off.