What are the main causes of gut health issues?

Digestive complaints such as constipation, diarrhoea, heartburn and bloating are very common and usually treatable with lifestyle measures and over-the-counter remedies. Around 40% of people have at least one digestive symptom at one time. The most common gut health issues are; abdominal pain, changes in bowel habit (usually constipation or diarrhoea), indigestion and heartburn(1).


Certain medicines prescribed for other medical issues may lead to side effects that can upset your gut including indigestion, diarrhoea or constipation. In addition, antibiotics can determinately affect the balance of the gut bacteira(1). by killing susceptible friendly bacteria(2). This can lead to numerous side effects including abdominal pain, flatulence, diarrhoea and Candida infestation(3). Antibiotic-associated diarrhoea (AAD) develops in 5-39% of people taking antibiotics, either during or up to 2-3 weeks of finishing the course and up to one in five people on antibiotics stop taking their full course of antibiotic therapy due to diarrhoea(3,4).


The brain has a direct effect on the stomach and intestines, known as the gut-brain connection; it can link anxiety to gut problems and vice versa. Your digestive system is sensitive to emotion and feelings such as anger, anxiety, sadness and joy, which can trigger symptoms in your gut. These emotions may also affect the composition of your gut – feelings such as stress can affect the movement and contractions of the GI tract, cause inflammation or make you more susceptible to infections. It has been shown that when patients reduce their stress or treat anxiety or depression through psychologically based approaches, they have a greater improvement in their digestive symptoms compared with patients who received only convectional medical treatment(5).


The digestive system runs from the mouth to the anus (the length of the digestive tube is 9 metres on average!).

The role of the digestive system is to turn food and liquid into building blocks that our body needs in order to function correctly, this is achieved by breaking the food down into smaller molecules(6). Within our body we are made up of around 100 trillion microbes, most of these are found in our digestive system. A diet low in fibre, fruit and vegetables is known to negatively affect the gut bacteria(7). Dietary fibre is the indigestible part of plant material and includes two main parts; soluble fibre and insoluble fibre. Soluble fibre absorbs water to form a thick gel substance whereas insoluble fibre cannot be digested and remains unchanged through the digestive system(8). Both of these fibres have various health benefits as shown in the table below –

Eating the recommended daily intake of fibre (30g) is associated with a lower risk of heart disease, stroke, type 2 diabetes and bowel cancer. A diet rich in fibre can help digestion, encourage the growth of our good bacteria and prevent constipation and therefore, help relieve gut issues(9).

Beans, peas and whole grain are high in fibre alongside various fruits and vegetables. Soluble fibres are common in foods such as beans, peas, oats, barley, apples and citrus fruits. Good sources of insoluble fibre include beans, whole wheat or bran products, green beans, potatoes, cauliflower and nuts(8).


Food intolerances are caused by difficulties digesting certain foods which can result in a number of unpleasant reactions. Common symptoms include bloating, gas and tummy pain which happens usually a few hours after eating them. Food intolerances can also cause skin rashes and itching. Food intolerances can be difficult to diagnose as these symptoms are typical of other conditions and there are no food intolerance tests that are recommended by the British Dietary Associated (BDA)(10). In individuals with a food intolerance, their immune system inappropriately identifies food substances as harmful substances and reacts. It is believed that this shift in our immune system may be caused by too many pathogenic bacteria in our gut and not enough good bacteria.


  1. Common digestive problems – and how to treat them [Internet]. nhs.uk. 2019 [cited 28 August 2019]. Available from: https://www.nhs.uk/live-well/eat-well/common-digestive-problems-and-how-to-treat-them

  2. Govender M, Choonara Y, Kumar P, du Toit L, van Vuuren S, Pillay V. A Review of the Advancements in Probiotic Delivery: Conventional vs. Non-conventional Formulations for Intestinal Flora Supplementation. AAPS PharmSciTech. 2013;15(1):29-43

  3. Kerna NA. Global Health Preventive Medicine Overture: Select Probiotic Use in the Prevention of Antibiotic-Associated Diarrhea and the Treatment of C. Difficile and Distinct Tropical Diseases. SM Prev Med Public Health. 2018; 2(3): 1021.

  4. McFarland (1998) Digestive Diseases 16:292–307

  5. Publishing H. The gut-brain connection - Harvard Health [Internet]. Harvard Health. 2019 [cited 28 August 2019]. Available from: https://www.health.harvard.edu/diseases-and-conditions/the-gut-brain-connection

  6. Healthy Eating and the Digestive System - Guts UK [Internet]. Guts UK. 2019 [cited 28 August 2019]. Available from: https://gutscharity.org.uk/advice-and-information/health-and-lifestyle/diet/

  7. How does diet affect gut health? [Internet]. BBC Good Food. 2019 [cited 28 August 2019]. Available from: https://www.bbcgoodfood.com/howto/guide/how-does-diet-affect-gut-health

  8. Natalie Butler L. Soluble and insoluble fiber: Differences and benefits [Internet]. Medical News Today. 2019 [cited 28 August 2019]. Available from: https://www.medicalnewstoday.com/articles/319176.php

  9. How to get more fibre into your diet [Internet]. nhs.uk. 2019 [cited 28 August 2019]. Available from: https://www.nhs.uk/live-well/eat-well/how-to-get-more-fibre-into-your-diet/

  10. Food intolerance [Internet]. nhs.uk. 2019 [cited 28 August 2019]. Available from: https://www.nhs.uk/conditions/food-intolerance/

  11. Hardy A, Clark A, Mouw M, Clark A. How the gut microbiota plays a role in food sensitivities - Gut Microbiota for Health [Internet]. Gut Microbiota for Health. 2019 [cited 29 August 2019]. Available from: https://www.gutmicrobiotaforhealth.com/en/how-the-gut-microbiota-plays-a-role-in-food-sensitivities/