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9 Root Causes of Abdominal Bloating

Updated: Jun 9

Most of us will experience a certain amount of occasional gastrointestinal bloating, but when it is occurring regularly it can become uncomfortable, distressing, and frustrating, and it's worth looking into what might be the root cause of your bloating.

What is abdominal bloating?

Abdominal bloating is a common gastrointestinal complaint that can be painful and extremely uncomfortable. It usually refers to swelling or distention of the stomach which can feel very full or tight.

Bloating is a common complaint but it’s not always easy to find the root cause. As there are so many potential causes of bloating, it can be difficult to pinpoint what is causing your abdominal discomfort, and very often it can be a combination of factors.

As there are many possibilities, which will be different for everyone, it’s usually a matter of trial and error, in order to determine your triggers.

Bloating occurs when bacteria in the intestines ferment carbohydrates and fibre, which produces gases such as hydrogen, methane, or hydrogen sulfide, leading to bloating and a feeling of fullness or insufficient digestion.

Some common causes of bloating include:

1. Irritable Bowel Syndrome (IBS)

Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder, and it is actually a diagnosis of exclusion. This means that other problems such as Inflammatory Bowel Disease (IBD) and Coeliac disease have been ruled out. Up to 15% of people are affected by IBS worldwide (1), with more women being affected than men.

Symptoms such as stomach cramps and pain, bloating, diarrhoea, and constipation are most commonly experienced (2). The symptoms can range from mild to severe and can have a huge negative impact on the quality of life of those affected.

2. Inflammatory Bowel Disease (IBD)

Inflammatory Bowel Disease includes ulcerative colitis (UC) and Crohn’s disease, which are distinct chronic and lifelong bowel-relapsing inflammatory disorders, with similar symptoms to IBS. Causes of IBD are thought to be due to genetics, environmental factors, intestinal microbial flora, and immune responses (3). If your IBD goes into remission, it’s likely that your bloating will go away.

3. Small Intestinal Bacterial Overgrowth (SIBO)

Small Intestinal Bacterial Overgrowth is a condition where there is an accumulation of bacteria in the small intestine. This overgrowth of bacteria, which should normally reside in the large intestine, can interfere with our normal digestion and the absorption of our food and nutrients.

These bacteria consume our food and then produce gas within our small intestine. This gas can cause abdominal bloating, pain, constipation, diarrhoea, belching and/or flatulence. The main symptoms of SIBO are the same as Irritable Bowel Syndrome (IBS), and it is thought that SIBO is the underlying cause of IBS, as SIBO exists in up to 84% of IBS patients.

A common complaint is suddenly looking or feeling 6 months pregnant after a meal. This can be due to a deficient migrating motor complex (MMC). The MMC’s job is to clear out and remove bacteria, cellular debris and chyme from the small intestine into the large intestine. If you have experienced an episode of food poisoning, it may be that the nerve cells in the small intestine have been damaged, preventing the MMC from working as it should.

Structural alterations in the small intestine, for example, adhesions, tumours, small intestine diverticula, as well as any twists or kinks, can compromise the small intestine from clearing adequately, and may be a cause of relapse of symptoms if not addressed.

Breath testing can help to determine if SIBO is responsible for your bloating.

4. Coeliac Disease

A lifelong gluten-free diet is the therapy for Coeliac disease, and although improvements can be noticed fairly quickly, the mucosal healing can take several years. A gluten-free diet removes all foods that contain wheat, barley, rye, spelt, triticale and oats (sometimes GF oats are tolerated). Ingredient lists should always be carefully scrutinised as gluten is often hidden in many processed food and drink products, as well as medications and natural supplements.

Many coeliacs can also be allergic to other grains, so therefore they need to be extremely careful with their diet. Digestive symptoms can vary in severity, from serious malabsorption to diarrhoea, flatulence, weight loss, undigested fats and bloating.

5. Bacterial Infection

Intestinal parasites, pathogenic bacteria and fungal overgrowth are common causes for gastrointestinal distress and can be a driving factor in bloating. Comprehensive microbiome stool testing can help to pinpoint any imbalances.

6. Low Digestive Enzymes, Stomach Acid or Bile Production

We need adequate levels of stomach acid and digestive enzymes for further break down and absorption of our nutrients. The pancreas secretes amylase, lipase, trypsin, and chymotrypsin, which are the some of the enzymes necessary for metabolism of our carbohydrates, fats, and protein.

We can support this process by eating bitter foods such as dandelion greens, mizuna, kale, rocket, and watercress. Bitter greens stimulate digestive enzymes and bile flow, which promotes digestion.

If the gallbladder has been removed, this poses a risk factor for ineffective bile production and delivery, as bile is essential for breaking down our fats.

7. Food Intolerances

Foods high in FODMAPs can be a trigger for bloating. FODMAP stands for Fermentable, Oligosaccharides, Disaccharides, Monosaccharides and Polyols, which are specific short-chain carbohydrates (sugars) found in soluble and insoluble fibres that rapidly ferment in the gut and can be poorly absorbed.

Gluten intolerance and non-Coeliac gluten sensitivity are becoming increasingly widespread, and although the symptoms are similar to Coeliac disease, there is no damage caused to the intestinal villi.

People are becoming more intolerant to wheat and gluten because, for one, we are eating more of it now than days gone by, but also because of the farming and processing methods used to produce it. Heavy use of herbicides, fungicides and pesticides are leaving the final product toxic and difficult to digest. If you suffer from digestive symptoms, reducing or eliminating gluten from your diet may help. It is imperative to get checked by your GP if you think you might have Coeliac disease.

Dairy consumption is also correlated with bloating and other intestinal symptoms for some people.

8. Endometriosis

Endometriosis can take a long time to be diagnosed as some of the symptoms of endometriosis are very similar to gastrointestinal symptoms found in IBS. Bloating is a common complaint with endometriosis. Diet and lifestyle changes and specific herbs and supplements may help to reduce the symptoms of endometriosis.

9. Indigestion and Constant Grazing

Digestion begins in the mouth where salivary enzymes, combined with thorough chewing (mastication), starts the breaking down of our food. Eating slowly in a relaxed environment is beneficial, and thorough chewing is essential as the longer that food is exposed to salivary enzymes, the easier it is for the body to absorb all of the necessary nutrients.

It is also important that we fast between meals to allow the digestive process to have a rest. The Migrating Motor Complex (MMC) is a complex mechanism that occurs in the stomach and the small intestine during the fasting state. It sweeps out food debris, keeping the bacterial ecosystem balanced, and it is interrupted by feeding. Therefore, if we are constantly grazing, the MMC cannot be activated, which can impair enzymatic processes, resulting in fermentation and bloating. Fasting for around 4 hours between meals is usually adequate to allow the MMC to do its' job (4).

What can be done to relieve your bloating?

  • Drinking 1 tablespoon lemon juice or 1 tablespoon raw apple cider vinegar in warm water 20 minutes before meals stimulates the digestive process. However, it is not advisable to drink lemon juice or cider vinegar in this way long term, as acidic liquids can erode tooth enamel. Consider drinking it through a straw to avoid direct contact with the teeth.

  • As mentioned, eating bitter greens such as dandelion greens, mizuna, kale, rocket, and watercress stimulates digestive enzymes and bile flow, which promotes digestion.

  • Pre-soaking and thoroughly rinsing nuts, grains and legumes reduces and eliminates the phytates or phytic acid (anti-nutrients), lectins and enzyme inhibitors. Soaking and rinsing helps us to metabolise these difficult to digest proteins.

  • Practice mindful eating – eat in a slow and relaxed way and chew your food thoroughly before swallowing. Sitting down at a table, taking a few deep breaths before you begin to eat, and giving thanks for the food on your plate can all be helpful strategies to ensure optimal digestion. Remove all electronic devices from the table while eating to reduce distractions and enhance the digestive process.

  • Kefir, kombucha or other fermented foods may help to settle a bloated stomach. *Always start with a small amount to make sure you tolerate them well.

  • Alternatively, strain-specific probiotic supplements that include Bifidobacterium longis, Bifidobacterium infantis, Lactobacillus acidophilus, and Lactobacillus paracasei have good research to show effectiveness against abdominal bloating (5).

  • Studies show that drinking peppermint tea reduces digestive symptoms such as bloating, flatulence and indigestion (6). Drinking fennel or ginger tea may also help to reduce bloating.

  • Consider a digestive enzyme supplement to support the digestive process.

  • Reduce your portion sizes and consider longer fasting periods between meals.

  • Going outside for a walk after a heavy meal may help to move any gas through your digestive system.

  • Consider trialling a dairy-free and/or gluten-free diet, or a short-term low FODMAP diet with the help of a suitably trained health professional.

Helen Ross is a Registered Nutritionist ® specialising in gut health and IBS support. If you'd like to know more about eating for a healthy gut, and/or how to keep your gut healthy, book in for a FREE call here to discover how she can help you.

Helen offers a virtual (online) clinic and local IBS support and nutritional therapy services to the Bridport, Dorchester, Weymouth, Poole, Bournemouth, and East Devon areas.

My Simple Gut ReSet is designed to help us get to the root cause or causes of your health issues. The aim is to nourish and support the gut lining to assist it back to a healthy state. A robust intestinal lining is an essential first step for finding freedom from painful, frustrating and embarrassing symptoms of IBS and other gut-related symptoms and health problems.

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1. Ford, A. C. (2020) ‘Commentary: estimating the prevalence of IBS globally—past, present and future’, Alimentary Pharmacology and Therapeutics. doi: 10.1111/apt.15508.

2. Sibelli, A. et al. (2016) 'A systematic review with meta-analysis of the role of anxiety and depression in irritable bowel syndrome onset', Psychological Medicine. doi: 10.1017/S0033291716001987.

3. Zhang, Y. Z. and Li, Y. Y. (2014) ‘Inflammatory bowel disease: Pathogenesis’, World Journal of Gastroenterology. doi: 10.3748/wjg.v20.i1.91.

4. Deloose, E. et al. (2012) ‘The migrating motor complex: Control mechanisms and its role in health and disease’, Nature Reviews Gastroenterology and Hepatology. doi: 10.1038/nrgastro.2012.57.

5. Hungin, A. P. S. et al. (2013) ‘Systematic review: Probiotics in the management of lower gastrointestinal symptoms in clinical practice - An evidence-based international guide’, Alimentary Pharmacology and Therapeutics. doi: 10.1111/apt.12460.

6. Hu, G. et al., 2015. 'Research on choleretic effect of menthol, menthone, pluegone, isomenthone, and limonene in DanShu capsule'. International Immunopharmacology.

7. Seo, A. Y., Kim, N. and Oh, D. H. (2013) ‘Abdominal bloating: Pathophysiology and treatment’, Journal of Neurogastroenterology and Motility. doi: 10.5056/jnm.2013.19.4.433.

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