What causes bloating?

What causes bloating?

Team ErbologyErbology

Feeling bloated after a large meal is normal. However if you struggle with chronic feelings of bloating, this is not normal and should be addressed.

July 19, 2022 5:17 pm

What is bloating? 

Bloating is an uncomfortable feeling that is unfortunately all too common. It’s normal to feel bloated after a particularly large meal (hello Christmas dinner) however it is definitely not normal to feel bloated all the time. 

The main cause of bloating is excess gas in your intestines. Sometimes the gas may come from drinking carbonated beverages or from swallowing air if you eat very fast. Has anyone ever told you that you should chew each bite of your food slowly and repetitively? Some experts even suggest chewing your food up to 40 times per mouthful. There is some logic behind this. In fact, chewing intentionally would lead to more mindful eating, and may prevent swallowing air which tends to occur when you inhale your food too quickly.(1)

woman looking at trees


However, most of the time, specific foods cause gas. The first food that comes to mind when most people think of bloating is any type of bean! However there are many other foods that you may not suspect which cause bloating in some people, but not in everyone. The way in which your body and gut react to foods is highly individual and influenced by your digestive enzymes and gut bacteria. In fact, any foods that we cannot digest leads our gut bacteria to produce gas, specifically methane and hydrogen. If you don’t digest a particular food, your small intestine will not absorb it, therefore it will travel into the large intestine where your gut bacteria produces gas from it.(2)

Food triggers 

You may notice that your gut reacts differently to certain foods, this means your intestines are not absorbing them well. For some people, this could be dairy products. Do you notice that you feel bloated after drinking dairy milk or eating fresh cheeses? You may have lactose intolerance. It’s best to consult your doctor or dietitian rather than self-diagnosing lactose intolerance. Otherwise you may risk overlooking a bigger health issue or eliminating dairy unnecessarily. 

There is also evidence that some people have adverse reactions to fructose, the sugar naturally found in fruit. If you notice that you are bloated after eating fructose rich foods such as pears, peaches, watermelon and cherries, you may have fructose malabsorption.(3)

Related reading

“Foods that we cannot digest leads our gut bacteria to produce gas, specifically methane and hydrogen. If you don’t digest a particular food, your small intestine will not absorb it, therefore it will travel into the large intestine where your gut bacteria produces gas from it.”

FODMAP foods: what are they?

FODMAP foods refer to foods that contain specific types of sugar which can cause bloating in some individuals (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols). These sugars include sucrose, fructose and lactose. It also includes fibres such as inulin which our bodies cannot digest but can be fuel for bacteria. Sugar alcohols such as xylitol, sorbitol and mannitol are also classified as FODMAPS.(4)

  • Monash University has a comprehensive and useful list of high FODMAP foods and low FODMAP alternatives. Common high FODMAP foods include garlic, onion, mushrooms, green peas, cauliflower, apples, pears, cow’s milk, most legumes, wheat, rye, honey and cashews. So what are the different types of FODMAPS?
  • Fructans- these sugars include fructooligosaccharides and inulin (fibre) and are typically found in rye, wheat, onions, garlic, artichokes, asparagus, broccoli, cauliflower and brussels sprouts. 
  • Fructose- naturally found in many fruits including apples, pears, watermelon, mango, peaches, cherries and watermelon. It’s also found in apple juice, honey, agave nectar and high-fructose corn syrup. 
  • Lactose- a sugar naturally found in dairy including cow’s milk, yoghurt, all soft cheeses, ice cream and milk-based desserts. 
  • Galactooligosaccharides- sugars found in legumes including chickpeas, lentils, soybeans and baked beans. 
  • Polyols- sugar alcohols- Many sugar-free gums, candy and even some cough medicine contain these sugar alcohols. Don’t be fooled by the name though, sugar alcohols don’t actually contain any alcohol. They are simply derivatives of sugar that provide little to no energy. This is why they are so popular in sugar-free and low-calorie products. Given that our body doesn’t use these sugar alcohols for energy, they are used by our gut bacteria.(5)

Should you go low FODMAP?

It may seem counterintuitive because the same vegetables that are high FODMAP and can cause bloating in some people are also those which provide gut-friendly fibre. But our gut bacteria is complex and highly individual, and if it’s out of balance, our bodies can react negatively. Even healthy foods could worsen your symptoms. You may find that following a low FODMAP diet could significantly help with your bloating. This is called an elimination diet, where you remove high FODMAP foods from your diet and gradually reintroduce them to your diet to see which ones provoke an adverse reaction.

It’s highly recommended to work with a dietitian when following a FODMAP diet because it can be challenging to do alone. Furthermore, it is not recommended to follow an elimination diet for extended periods of time, this could make you even more sensitive to certain foods.Fortunately, a low FODMAP diet can significantly help many people with bloating and other symptoms of IBS (Irritable Bowel Syndrome). 

It may take a few weeks before seeing improvements but the results are worth the perseverance. If you are following a low FODMAP diet and are lacking inspiration, you can treat yourself to a matcha latte, in fact matcha green tea is suitable for low FODMAP diets.  

Bloating and IBS 

IBS (Irritable Bowel Syndrome) refers to any number of gut symptoms which do not classify as other diseases including Crohn’s disease and inflammatory bowel disease. If you have regular stomach pains, bloating and constipation and/or diarrhoea for over six months and your doctor has ruled out all other diseases, you likely have IBS.  The unique characteristic of IBS, in contrast to other diseases, is that there is no clear biomarker for it. In fact, in an otherwise healthy individual with IBS, all blood and gut tests may very well appear completely normal. As a comparison, blood tests can reveal celiac disease which makes it a lot easier to diagnose.(6)

The science is yet to fully understand the causes of chronic IBS symptoms. Frustratingly, there is no approved cure for IBS. Management of IBS is highly individual and involves diet and lifestyle interventions and in some cases medication. Psychological intervention can also be very beneficial for people with IBS. It can be very disheartening for both people with this condition and their doctors when there isn’t a clear cause of their symptoms.  

Previously, IBS was highly misunderstood and underdiagnosed due to a lack of tests available to confirm the condition. However, nowadays self-reported symptoms are widely accepted amongst health professionals as criteria to diagnose IBS in patients. 

How do you know if you have IBS?

Most people with IBS have abdominal pain or cramps that occur with bowel movements. If you have IBS, you may also experience unusually high or low frequency of bowel movements. Less than three per week or over three per day may qualify as IBS. IBS is a spectrum and you may be on either end. In fact, IBS can manifest as either constipation or diarrhoea, in some people it manifests as both. 

Hormones can greatly affect IBS. In fact, some women with IBS notice a flare-up around their cycle. Many women report an increase in bowel movements and diarrhoea prior to the start of their cycle, and conversely, constipation during menstruation. This can be explained by hormonal changes. If you have IBS, you are not alone.(7) In fact it is quite common, it is estimated that up to 15% of the population is affected by IBS and these statistics may potentially be higher given the prevalence of underdiagnosis. IBS is also more common in women than in men.(8) 

Should I be concerned about fibre intake if I have IBS?

Fibre is generally very helpful for most people to ensure regular bowel movements and maintain a healthy gut. However, certain types of fibre can exacerbate symptoms in those who suffer from IBS. There is evidence to suggest that psyllium husk fibre can help with IBS symptom management.(9) Conversely, bran fibre may cause IBS flare-ups. There is high individual variation when it comes to the effects of fibre on the gut so the only way to find out is to monitor your symptoms, perhaps keep a food diary and work with a dietitian to understand what your trigger foods are. 

Fibre is not digested by the human GI tract. Our gut bacteria uses some types of fibre to ferment it. For example, inulin is a commonly found fibre in garlic and onions which our gut bacteria thrives on. Other types of fibre can’t be used by our gut bacteria and are therefore used to create bulk for our stool. Examples of such fibre include psyllium husk (metamucil is used as a gentle laxative), cellulose in vegetables (lettuce) and wheat bran. 

For most of us, fibre such as inulin that our gut bacteria can feed on is beneficial to our gut health. However, there is such a thing as too much of a good thing, especially if you have IBS. If you notice that your gut plays up after eating inulin rich foods, it may be a sign that you struggle to digest this type of fibre. 

Foods that may trigger IBS and bloating 

  • Many veggies, especially those that are high FODMAP, may trigger your IBS and cause gas. You can find a list of these foods here
  • Processed foods that contain sorbitol, fructooligosaccharides and polydextrose. Make sure you check food labels if you are sensitive to these ingredients.
  • Resistant starch is a type of starch that is found in carbohydrate foods which may cause bloating and abdominal discomfort. Check food labels for names such as hydrolysed starch, modified food starch and cornstarch. Resistant starch is also naturally occurring in certain foods such as green or unripe bananas, cooked and cooled potatoes, legumes and corn flakes. Be aware that resistant starch can form when carbohydrate foods such as potatoes and rice are cooked and then cooled, so eating such foods as soon as they are prepared can affect how you digest them. 

Should I avoid fructose and lactose? 

If you have diagnosed lactose intolerance or fructose intolerance, your symptoms may resemble those of IBS. Malabsorption and maldigestion of lactose can lead to diarrhoea in many cases. Similarly, this can also happen with fructose intolerance. Some people may find that they can adequately digest fructose in whole fruits but not in fruit juice. In