Why am I farting so much on a vegan diet!

Updated: Nov 9


After a bit of thinking and planning, you’ve decided to make the switch to go vegan. You’ve been testing lots of different recipes and experimenting with this new group of protein foods called legumes.

You’ve been doing really well, trying chickpea burgers, adding kidney beans to your salad and having lentil dahl for dinner. All of a sudden, you’ve noticed the room is starting smell quite a lot, a significant amount of farts coming out the other end and people around you giving you strange looks.



Is your vegan diet causing you gut discomfort?

Why do we fart?

The majority of our gas (farts) come as a result of the fermentation of undigested foods in the gut.These foods primarily include non-absorbable short-chain carbohydrates which are incompletely absorbed in the small bowel and then enter the colon. Inside the colon, there is a large amount of bacteria which ferment these foods, which as a result, release methane, hydrogen and carbon dioxide in varying amounts. This mixture of gases, becomes the smell of our farts.

You guessed it, vegan diets are especially rich in these non-absorbable (fibre rich) carbohydrates. When we start a vegan diet, we generally increase these fibre rich foods, especially vegetables and beans. So although our eco and animal friendly plant-based diets are well known for their benefits in reducing risk of cardiovascular and other chronic diseases, it is largely recognised that these foods significantly increase our gas production. This especially occurs when we first increase foods such as broccoli, lentils and beans in our diet which are packed full of these non-absorbable fibres which our gut bacteria is just not used to yet.



There is also research to suggest that gas production is related to the metabolic activity of the macrobiotia (or gut bacteria) that resides within our gut. Some studies have shown that imbalances in gut bacteria cause more frequent and odorous flatulence.

In some individuals, in particular those suffering from Irritable Bowel Syndrome (IBS), have difficulty digesting these these short-chain carbohydrates. As a collective, these foods are called FODMAPS. For individuals with IBS, FODMAPS can cause symptoms such as persistent abdominal pain, bloating, constipation and diarrhoea. It is important for individuals with IBS, to undertake a FODMAPS elimination diet (followed by reintroduction) with the help of a dietitian. This is due to the diet being quite tricky, restrictive (especially if you're also vegan!) and should not be taken as a long-term diet.


Chickpeas are a type of FODMAP and can cause abdominal issues in some people

So what should we do?

Adapt to fibre slowly. The main complaints from excessive gas, abdominal pain and bloating generally come when individuals have significantly increased their fibre intake over a short period of time, without letting their bodies adapt. Don’t get me wrong, fibre is very important for our body and linked with producing a high level of healthy gut bacteria, however, fibre can come with some negative side effects when increased to quickly. Be mindful of foods such as lentils, chickpeas, kidney beans, onion, garlic and leek, broccoli and cauliflower, as these are often the biggest causes of smelly farts.


At the end of the day, farting is a good thing and is often a sign of a healthy gut (even if your nose does not agree!).


Kiah Paetz is an Accredited Practising Dietitian and founder of Plant Nutrition and Wellness. She operates her private practice clinic at North Lakes, Hamilton and offers online consultations via Zoom. For bookings, please call 3040 6911 or contact admin@plantnutritionwellness.com


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