Why Do Lentils Cause Gas? And How to Get Rid of It!

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If you’re bloating after eating lentils, you might decide to stop eating them – but, don’t. They’re seriously good for you. Instead, it’s a better plan to look at why lentils might be causing you gas – and see if you can reduce the effects.

This article was reviewed by Jennifer May, Clinical Nutritionist. See more about her and our editorial accuracy process here

If you grew up in England like I did, you probably know a little ditty about beans and gas. Why no one also wrote a song about lentils, I don’t know because they’re just as likely to create wind as their bigger brethren.

You see while beans and lentils aren’t quite the same thing, they do belong to the same family – legumes – and the reasons why they cause gas are very similar. So, let’s investigate…

Bright coloured different types of lentils in a pile. They're orange, yellow, green and brown. Three scoops dip into the pile

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Why Do Lentils Cause Gas?

There are actually a few different reasons why you might get gassy from lentils.

The Fibre Story

The most common reason and the reason why it’s likely to happen in most people is that lentils are very high in fibre.

That’s a good thing as fibre is good for us and most of us don’t eat enough of it. But we’re not the only things that consume fibre in our body.

Fibre feeds the bacteria in the gut, and as they consume it, they produce gas.

If you’re not used to consuming fibre, or eat a lot in one go, then the bacteria produce more gas than is comfortable – which leads to bloating and farting!

The Raffinose Story

As well as fibres, lentils contain a sugar called raffinose. Human stomachs don’t contain the enzyme that we need to break this down, and, so, this enters the gut undigested – and, also provides food for the bacteria that live there – cue more gas!

This can happen to anyone, but raffinose, and three other ingredients in lentils stachyose, ciceritol and verbascose, fall into a group of sugars called oligosaccharides – and these are part of the FODMAP family.

We talk about FODMAPs a lot in these posts as they are one of the major causes of gas and bloating from food.

The acronym stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyls – and if you didn’t spot it, the word fermentable reveals that they tend to produce gas in the system.

In people who are sensitive to it, the pressure of that gas can actually get quite uncomfortable leading to feelings of bloating and stomach cramps.

The Resistant Starch Story

One delicious way to eat lentils is in salads – they’re a great way to add some extra protein, particularly if you don’t eat meat – but, lentils contain high levels of a substance called resistant starch (higher than many other carbs) and when you cook, and then cool, lentils you increase the amount of resistance starch that they contain further.

And resistant starch is another favourite food of your gut bugs.

So, those are the three main reasons why you might experience gas after eating lentils, but, before we talk about how to reduce this, we need to cover one more thing.

Don’t Blame the Wrong Thing

I don’t know about you, but when I tend to eat the most lentils when I’m eating Indian cuisine – and, if this is also the case for you, just be careful that you’re not damning the wrong ingredient.

Capsaicin in spicy dishes can irritate the lining of the gut which can lead to gas and diarrhea.

So, if the only time you eat lentils is encased in a delicious spicy sauce, then just check it’s not the spices that are causing your issues rather than the lentils!

Are Lentils Gluten Free?

Talking of blaming the wrong thing, gluten can cause gas and bloating in some people and so, if you’re experiencing gas after eating lentils you might be wondering if gluten is a factor.

It’s not. Lentils are gluten-free.

Bowl of lentil soup in a black bowl with a green garnish. The bowl sits on a black counter top, a small bowl of red lentils sits next to it.

Why You Should Eat Lentils

If bloating after lentils is making you uncomfortable you might think about quitting them, but that’s not a good idea.

I can sum up why in one line – according to the team behind the Blue Zones project, the longest-living populations on earth are also those who eat the most beans and lentils!

But if you want some specific reasons…

Eating just one serving of lentils or beans a day can help reduce cholesterol found a study published in the Journal of the Canadian Medical Association.

Replacing even just half of a serving of a high GI carb like white rice in a meal with lentils or beans helped decrease the amount of sugar produced from a meal – lowering levels of blood glucose by 20 per cent in this study. That could have a knock-on effect on your risk of developing type 2 diabetes.

Adding a serving of lentils or beans to the diet increases feelings of fullness by 31 per cent – and this can actually lead to weight loss. According to Canadian researchers, people adding a serving of lentils to their daily diet naturally started to cut calories – which lead to a weight loss of 0.75lb in six weeks.

There’s loads more but we’re here to talk about gas – so, let’s get on with that! So, if giving up lentils isn’t the best idea to stop your bloating, what can you do instead?

How to Make Lentils Less Gassy

There are a few things you can do to reduce gas from lentils.

Eat Canned Lentils

Soaking beans and lentils helps reduce the levels of raffinose and other oligosaccharides that they contain – and, as canned lentils are soaking in the can, they can contain some of the lowest levels. Just make sure you rinse them before cooking to remove any traces of the liquid.

Do note canned lentils are quite high in sodium, so if you’re avoiding sodium, or, find this makes fluid-type bloating worse, then choose fresh lentils.

Soak Fresh Lentils

If you’re using fresh lentils, soak them for at least 3 hours – or ideally overnight – before cooking.

Again, make sure you use different water from cooking than soaking.

Try Serving Different Ways

As we said, cooked, then cooled lentils contain higher levels of resistant starch than freshly cooked ones which might increase your chance of bloating after eating lentils – BUT, there again, some other research has shown that when you cook and cool lentils you reduce the amount of raffinose in them.

If you’re reacting to just one of these ingredients then changing the state in which you serve them – freshly cooked, or cooked and then cooled, could make a difference.

So, give it a try. Try lentils freshly cooked and then cooked and then cooled and see if this makes a difference to any reaction you have.

A bowl of cooked lentils tossed with dill and red peppers in a glass bowl. Cooking then cooling lentils is one way to potentially stop lentils causing gas.

Know Your Portion Sizes

If you are sensitive to the FODMAPs in lentils, it doesn’t mean you need to avoid them entirely, you just need to moderate your portion sizes.

According to the team at Monash University, a 46g portion of canned lentils is classed as low for all different types of FODMAP and so should be okay for anyone to consume that size portion.

As portions get larger, people who are sensitive to the GOS family of FODMAPs might experience more issues – 65g is classed as medium FODMAP, while 77g and above is not only high in GOS FODMAPs, it might also cause a reaction in people who are sensitive to fructans.

When it comes to fresh lentils, sticking to under 30g a serving is best – but, as you’ll see below, exactly how low you need to go might depend on their colour.

Lentil Soup and Gas

Larger portion sizes are also why lentil-based products like lentil burgers, or lentil soup might cause gas more often than a small serving of fresh lentils.

If you’re consuming 400g of lentil soup (the size of a large can) the portion size might be more than enough to tip you over the edge of your sensitivity threshold.

Even 100g of lentil soup is classed as a high FODMAP food by the Monash team.

Pick Your Colour

Different types of lentils can contain very slightly different amounts of FODMAPs depending on factors like genetics and even the climate in which they are grown (see study here) and as such, if you only have a mild sensitivity to the sugars in lentils you might tolerate some types better than others.

While colour might not exactly determine FODMAP levels, Monash does class different serving sizes of the three main lentil colours as low FODMAP.

According to Monash, a 30g serving of Le Puy lentils is low FODMAP, 29g of green lentils is low, while just 23g of red lentils counts as low FODMAP.

Try mixing up your colours, or trying lentils from different climates, and see if it makes a difference.

More bright coloured lentils in a pile with scoops - different types of lentils may have different effects in the gut.

Build Up Slowly

As we said, the most common reason why lentils cause gas is a sudden increase of fibre in the diet. If you’re on a health kick, then dropping back your intake for a few days, letting your body get used to things and then adding in a little more is less of a shock to the system than suddenly improving things.

Try Beano

The reason why we get gas from the raffinose in lentils is that we can’t break it down before it reaches the gut – but, gas-reducing supplements like Beano aim to do the hard work for you.

They include an enzyme called alpha-galactosidase which can break down raffinose (and some of the other oligosaccharides in lentils and other beans) meaning there’s less for your gut bacteria to work on.

You shouldn’t rely on the supplement as it’s good to feed your gut bugs, but, if there’s a reason why you’re likely to be eating lentils at a time when producing gas might be embarrassing for some reason, you can take a dose before eating to reduce the results.

Do Undercooked Lentils Cause Gas

Yes – and worse.

Not cooking lentils well can also cause stomach upsets, cramping and nausea.

The reason is that lentils contain substances called lectins that irritate the gut lining.

Cooking lentils properly, particularly if you’ve soaked them properly first, destroys these, but if the lentils are undercooked enough can be left that they upset the stomach (and you should NEVER eat lentils raw).

Bowls of different coloured lentils, pulses and peas on a rustic blue background. Handfuls of the ingredients are tossed around the background.

How Long Does Gas From Lentils Last?

Gas caused by any food fermenting the gut will normally pass naturally within a few hours.

If your reaction lasts longer it might be a sign of a more sensitive gut, or, that something else that you’re consuming more regularly is to blame (take a look at our post on how to keep a food intolerance diary to find out why it can be so hard to tell what’s causing your bloating).

If you want to help the gas pass faster, then head over to our longer post on ways to get rid of gas which gives all the advice on things like using peppermint tea, yoga poses and more to help eliminate gas as fast as possible.

This is also where we have to mention that if you’re suffering regular bloating that doesn’t go away, or if your bloating or other digestive issues are interfering with your daily life, it’s very important to see a doctor to get things checked out just in case it’s another condition that might need more specific treatment.

So, there you have it. The reasons why lentils cause gas and a few strategies that might help you avoid it happening to you.

What to Read Next

If you find you get gas regularly when you eat (and everything has been checked out) have a look at our general guide on why certain foods and activities can cause bloating after eating – that’ll also link you to lots of other individual posts on things like why mushrooms cause gas, why chia seeds cause gas , why coffee causes gas – and more.


Who is The Wellness Nerd?

My name is Helen Foster, and I’m a health journalist and wellness author. Publications I’ve written for include Women’s Health, Reader’s Digest, Body and Soul, Good Health at the Daily Mail, and more. I have also written 16 books on health and nutrition.

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