Irritable Bowel Syndrome, known as IBS, is an increasingly common bowel disorder that affects up to 20% of the population.1 There isn’t a known cause of IBS from a conventional medicine perspective, but there are several underlying factors that can contribute to the development of the condition, highlighting that each case of IBS requires a unique approach. As well as symptoms such as bloating, recurrent abdominal pain, changes in bowel movements and flatulence, people with IBS can often suffer with anxiety and depression which further impacts quality of life.2 A diagnosis may be given if more extensive testing has been done to rule out conditions such as Inflammatory Bowel Disease (IBD), but conclude nothing alarming. IBS can develop at any age, but for most it typically first appears in teenage years with women being more affected. 1 Rome criteria VI, alongside the Bristol Stool Chart help to define and diagnose cases of IBS. There are currently four subtypes of IBS:IBS‐C: Prone to constipation, which relates to having harder stools, or passing a bowel movement less than 3 times per week.IBS‐D: Diarrhoea-associated IBS, with majority of bowel movements being loose or watery.IBS‐M: A mix between constipation and diarrhoea. Some people may find they are constipated for a few days, and their bowel movement proceeding are loose.IBS‐U: Unclassified – doesn’t fit any of the three subtypes above.3
Taking a holistic approach to IBS
It can be useful to categorise underlying factors of IBS to get a better understanding, however it is likely there will be a significant overlap between categories. There are genetic components to IBS, although it has been found that genetics are not as influential to the condition as environmental factors. The areas that are commonly affected in IBS include poor digestion (for example insufficient production of stomach acid or digestive enzymes), an imbalance of gut bacteria (gut microbiome), motility issues, or poor integrity of the gut lining with low-grade inflammation. The central-nervous system also plays a role, with stress being a trigger, the role of the gut-brain axis and hypersensitivity of nerves within the gut. And finally, the role of diet and food sensitivities.4 When taking a holistic approach to IBS, it’s important to take into consideration all these underlying factors, which will allow us to create a more personalised, and effective nutritional plan.
It all starts with digestion Digestion relates to the breakdown of food into smaller components that can be more easily absorbed and assimilated by the body. The process starts in the mouth, whereby chewing of food stimulates the release of enzymes, before the food is passed to the stomach where the stomach acid further breaks it down and promotes absorption of many nutrients, especially zinc and B12. Further down the digestive tract, the pancreas releases a large amount of enzymes, whilst the gallbladder secretes bile which is essential for digestion and absorption of fats. If food is not chewed and digested correctly, larger food particles can pass through the intestines which bacteria can then feed off and ferment. Stress, eating on the go, or using medication such as Proton Pump Inhibitors (PPI’s), can suppress our production of digestive juices, leading to bloating, indigestion, reflux, nutrient deficiencies, and imbalance in gut bacteria.5,6,7 Eating mindfully, at a table, and chewing food until mushy significantly improves your digestion and sends signals to your brain to produce digestive secretions. It can also be useful to try some digestive enzyme to easy symptoms and take the pressure off the digestive tract.8 A broad-spectrum digestive enzyme which contains enzymes such as protease, lipase, amylase, and lactase to improve the digestion of proteins, fats, carbohydrates, and lactose in dairy products. Enzymes such as cellulase or xylanase can help with fibre-rich foods, which may help if there’s issues with digestion of certain vegetables, legumes, or grains. 9
The role of the gut microbiome The gut microbiome is heavily influenced by our diet, stress, lifestyle, medications, and environment, making it incredibly diverse between individuals. For some, they can pinpoint the sudden onset of the condition after an infection or food poisoning, with studies concluding around 10% of people who have a gastrointestinal infection go on to develop IBS, known as post-infectious IBS.10,11 Though antibiotics are essential to reduce the growth of pathogenic bacteria, they also reduce the growth of beneficial commensals which can be problematic for gut health, increasing the likelihood of developing bowel complaints months after treatment.12 Antibiotic use has been found to reduce microbiota diversity and richness, which in turn can cause alterations in the intestinal barrier, production of short chain fatty acids (SCFA’s), and the immune system.13 In contrast, some people with IBS have an overgrowth of certain microorganisms which can contribute to the condition.14,15 Certain bacteria in the gut can produce gases such as hydrogen and methane as they ferment on foods from the diet. This process of fermentation can cause bloating, abdominal pain and flatulence. In addition to the more notable gut symptoms, an overgrowth of bacteria or fungi can increase the number of endotoxins produced in the gut, which can damage the intestinal lining, increase intestinal permeability, and contribute to low-grade inflammation of the gut mucosa, all of which have been found in people with IBS. 16,17 If there is an overgrowth of bacteria, or pathogens have been found in the gut through testing, it can be good to start with some antimicrobial herbs. Botanicals such as oregano, garlic, wormwood and thyme have been found to reduce the growth of bacteria, fungi & parasites. Supplementation of probiotics can help to inhibit the growth of Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Candida albicans and Klebsiella pneumoniae.18
Why gut motility matters Gut motility refers to the passing of food and liquids through the digestive tract. To be effective, it needs to be happening at the correct pace to allow clearance of toxins and waste from the body, but slow enough for absorption of nutrients from our food. Both slow and fast motility can be present in IBS as people can suffer from diarrhoea and constipation. Thyroid function can influence motility of the gut, with it being decreased in hypothyroidism, and increased in hyperthyroidism.19An imbalance in gut bacteria can influence motility too, with higher amounts of methane-producing bacteria such as Methanobrevibacter smithii being found to slow transit time and contribute to constipation, whereas higher levels of hydrogen-producing bacteria are more correlated with diarrhoea.20 Prebiotics such as FOS, inulin and psyllium are great forms of dietary fibre to help bulk up and soften the stool to improve both constipation and diarrhoea. Prebiotics also feed beneficial bacteria, supporting overall digestion.21 Magnesium can be used as a natural laxative in cases of constipation as it helps to soften the stool and stimulate gut motility. 22
Leaky Gut Lining A healthy gut lining is essential for the appropriate production of digestive enzymes, colonisation of beneficial gut bacteria, regulation of motility, and for creating a protective barrier, guarding us from toxins and harmful microorganisms. When the gut lining becomes damaged and the junctions between cells are open for a prolonged period of time, we call it ‘intestinal permeability’, or ‘leaky gut’. This leads to a loss of the protective barrier, increased immune activation causing gut inflammation and sensitivity to foods, as well as toxins, bacteria, or undigested foods escaping into the bloodstream. Factors that can cause leaky gut include certain medications like NSAIDs (e.g. ibuprofen) or aspirin, alcohol, lack of sleep, low fibre and nutrient intake, and bacterial imbalance. But one of the biggest factors, that is common to many IBS sufferers is stress. Individuals with IBS will often be able to link increased feelings of stress and anxiety to the worsening of their condition.23,24 Bacteria within the gut continuously interact with the brain through their production of neuroactive compounds such as GABA and serotonin, as well as modulating inflammation and interacting with the vagus nerve.25,26 Chronic stress can have a dramatic impact on gut function, by modifying the gut microbiome, suppressing digestive function, increasing intestinal permeability and altering motility.27,28 To aid repair of the gut lining and help to reduce inflammation, nutrients such as vitamins A, C, D, L-glutamine, and nucleotides support the immune response and protect the integrity of the mucosal epithelium.29,30 Vitamin D deficiency can be common in people with gut conditions and allergies, so it may be useful to test your levels and supplement accordingly.31,3233 Furthermore, supplementation of Lactobacillus and Bifidobacterium strains has been found to improve mood in people with anxiety and depression,33 while also improving gastrointestinal symptoms in people with IBS,34 indicating a two-way benefit to probiotic supplementation. 25
Is removing foods the answer? It is estimated that up to 89% people with IBS feel their symptoms are triggered by foods such as grains, vegetables, dairy products, spicy foods, alcohol and coffee. 35 Food intolerances can occur due to increased intestinal permeability combined with digestion issues, as it allows larger molecules from our food to pass through, initiating an immune response to particular food antigens.36 Removing some common culprits such as gluten and dairy can be extremely useful, but overly restrictive diets (e.g. low FODMAP diet) can be detrimental not only to the gut microbiome, but overall wellbeing in the long term. So it may be best to work alongside a health professional to implement diet changes while working on repairing the gut lining and supporting the immune system.
Where to start? Each person’s IBS is different, but by taking a holistic approach and addressing underlying imbalances, symptoms can be significantly improved. As there are so many underlying factors to IBS, it can be increasing hard to work out what exactly might be an issue. In these cases, a stool test can take out a lot of the guess work and allow for a more personalised approach to the condition through highlighting specific imbalances within the gut. Our Clinical Nutrition team are available to help further to personalise your diet and supplements based on your symptoms, and if you would like to see if gut testing could be useful for you.