Beans, beans, the musical fruit. There’s no doubt that beans have a reputation for being gassy. But does that mean you should avoid them if you have a sensitive gut?
Facts about farting
First, let’s talk about farting. Farting - or releasing gas from your anus - is a completely normal part of digestion. Most of it is carbon dioxide and hydrogen, produced by your gut bacteria when they break down fibre and other indigestible carbohydrates.
Research shows that healthy adults release an average of 700ml of gas a day through farting. We tend to fart more after meals and less during sleep when gut activity slows down.
One study found healthy males farted an average of 14 times a day (and other studies suggest there’s little difference between men and women). But this varies a lot between individuals - some people produce more gas, some less. This is partly down to differences in diet, but might also reflect differences in the gut microbiome.
For most people, gas passes without bloating or pain. However, if you have irritable bowel syndrome (IBS), gas can trigger bloating and discomfort due to increased gut sensitivity —a phenomenon known as visceral hypersensitivity, thought to affect up to 90% of people with IBS.
Why do beans cause gas?
Some foods are more ‘gas-forming’ than others because they contain a greater amount of fibre or fermentable carbohydrates that the human gut can’t break down. Beans fall into this category. They contain a group of carbohydrates called oligosaccharides. When your gut bacteria break these down, they produce gas - mostly carbon dioxide and hydrogen.
So, if you suddenly add lots of beans to your diet, your gut bacteria will have more food, and will likely produce more gas. In my experience, this often leads people with sensitive tummies to swear off beans altogether. But I want to persuade you otherwise.
Beans means nutrients!
There’s a good reason to keep beans in your diet; they’re a really nutrient dense food. They’re a brilliant source of plant-based protein and important minerals like iron and folate (which support healthy red blood cells). They are also rich in phytonutrients, plant compounds which have anti-oxidant and anti-inflammatory effects.
Plus they’re rich in fibre and those indigestible carbs act as prebiotics, specifically feeding your beneficial gut bacteria. So instead of avoiding beans, let’s talk about how to include them in your diet, without the discomfort.
How to include beans with less bloat
Start small
When it comes to tolerating beans, portion size matters. Smaller servings are usually well tolerated, since they contain fewer fermentable carbohydrates. I usually suggest starting with 2 tablespoons per meal but if you haven’t eaten beans in a long time, begin with 1 tablespoon and gradually increase after a week or two.
If you have IBS and follow a low FODMAP diet, refer to the guide below - or check the Monash app - as some beans are higher in fermentable carbs than others.
Low FODMAP Serving Sizes (Canned, Drained)
- Butter beans – ¼ cup (35g)
- Black beans – 2 tbsp (40g)
- Cannellini beans – ⅓ cup (76g)
- Chickpeas – 5 tbsp (80g)
Go canned
Choosing canned beans or lentils - and rinsing them well before eating - can make a difference to their gassiness. This is because oligosaccharides leach into the canning liquid, and draining/ rinsing, helps remove some of this. Similarly, soaking and rinsing dried beans before cooking may reduce their fermentable content.
Consider using an enzyme
Enzymes are specialised proteins that help us break down food into absorbable nutrients. The enzyme that’s needed to break down the carbs in beans is ‘Alpha Galactosidase’. Humans don’t make this enzyme, but it can be purchased as a dietary supplement. If you find it difficult to tolerate beans but want to have a larger portion, this could be a good option from time to time.
Make beans a habit
There’s some evidence that eating beans regularly may help improve tolerance over time. In one study participants added half a cup of beans to their daily diet. Initially, half the group reported an increase in gas, but by the second or third week of eating the beans, symptoms fell back to normal levels. Aiming to include beans (even a small serving) two to three times per week is a good goal.
Read more from our fact v fiction series
Could cold carbs feed your microbes better than hot carbs?
You don't need grains for fibre?
The truth behind 7 common bloating claims
Ultra-processed foods: Are they really harmful
Glucose spikes and gut health - what you need to know
Sources
Gas and bloating. Gastroenterology and Hepatology. (2006). Link.
Perceptions of flatulence from bean consumption among adults in 3 feeding studies. Nutrition Journal. (2011). Link.
Insights into human colonic physiology obtained from the study of flatus composition. American Journal of Physiology - Gastrointestinal and Liver Physiology. (1997). Link.
Identification of gases responsible for the odour of human flatus and evaluation of a device purported to reduce this odour. Gut. (1998). Link.
Soaking and cooking modify the alpha-galacto-oligosaccharide and dietary fibre content in five Mediterranean legumes. International Journal of Food Sciences and Nutrition. (2019). Link.
