What causes abdominal bloating?

Contrary to what many people believe, bloating is not necessarily due to too much gas in the stomach. Researchers have performed studies on patients who feel bloated using CT scans, and shown that they often do not have any more gas in the belly than people who have no symptoms. Excessive gas production probably plays a part, but does not explain the whole picture.

So if too much gas isn’t the main cause of bloating, then what is?

There are several different factors which may play a role:

• Too much water or liquid travelling into the small intestine. Certain food contents drag liquid into the intestines, which has been shown to cause the sensation of bloating
• Constipation and backed up stool in the colon (faecal impaction) can cause the sensation of bloating
• “Sluggish bowel,” or poor motility of the bowel – where the bowel pushes gas through very slowly
• Altered function of the diaphragm – the diaphragm is the big muscle between the chest and abdomen that moves up and down when you breathe. When you eat and drink, this muscle should relax and move upwards to make more space in your abdomen. Studies have shown that in people who bloat, the diaphragm incorrectly moves downwards, causing the belly to protrude.

Change your diet to reduce bloating

• Avoid fizzy drinks
• Some fibre supplements may help, but need to be chosen carefully. Fibres that undergo a lot of fermentation by gut bacteria can make bloating worse (e.g. whole wheat bran). The best are non-fermentable fibres such as sterculia (Normafibe)
• Trial cutting out dairy and/or gluten for one month, as conditions such as lactose intolerance and gluten sensitivity are very common causes of bloating in Australia. If you don’t feel better after one month, then reintroduce them into the diet.
• Trial a low-FODMAPs diet under guidance of a dietitian – this is a diet developed in Australia and now used all over the world for treatment of bloating. Foods high in FODMAPs increase the amount of fluid in the bowels, which in some people can lead to bloating and swelling of the abdomen. Through a process of elimination and reintroduction, the dietitian can assist you in finding out which ‘high-FODMAPs’ foods are the most problematic for you

Natural remedies that help with bloating

• Iberogast is a herbal supplement that has been shown in clinical studies to be helpful for bloating and other gut symptoms in irritable bowel syndrome. You can find it at most pharmacies.
• Kiwifruit has recently been shown to be beneficial for helping gut motility (ability of the bowel to contract and propel digestive contents). If you don’t like the fruit, you can take kiwifruit extracts instead!

Other strategies to help you with bloating

If you also have constipation, try taking regular sterculia fibre or laxatives that you find over the counter from the chemist. Usually, getting rid of the constipation helps the bloating too.

When to seek further advice or support

See your GP or gastroenterologist if your bloating is not improving with the above measures. You should also see your doctor if you have other symptoms along with your bloating such as unintentional weight loss, vomiting, being woken up at night to open the bowels or due to pain, or a change in bowel habits. These may be indicative of an underlying disorder rather than just ‘simple’ bloating.

Your doctor can perform a physical examination and may order further investigations such as blood tests, x-rays, stool specimens, or gastroscopy and colonoscopy. Your doctor may recommend other medical treatments for bloating such as prokinetics (medicines that stimulate the contraction of the gut and propulsion of gas and other contents) and medicines that change the composition of the gut microbiome in favour of more “good bacteria”.