Why Do Beans Give Us Gas?

Why Do Beans Cause Gas? | Side Effects of Beans | Nutrova

There’s a little poem you may have learnt as a kid and laughed as you did: “beans, beans, the musical fruit, the more you eat, the more you toot!” This is especially relatable for anyone who’s prone to the side effects of beans (flatulence, in case it wasn’t made clear yet) - which brings us to the question we’re answering today: why do beans give us gas?

Read on to understand why consuming beans can cause gas in some people, and what we can do to prevent it.

The first question to be asked, though -

Is it normal to pass gas?

Studies suggest that humans pass gas about 8-14 times a day - even while sleeping. So, yes! Flatulence is completely normal: it’s a part and by-product of the natural digestive process [1]. Even having a bit of extra gas in the body (which may land up increasing the frequency at which one passes gas) isn’t something to worry about unless it’s bothering us or making us feel physically uncomfortable [2].

This is true for gas caused by other foods as well; it’s all mainly dependent on how our body reacts to these foods.

Is it normal to pass gas? | Side Effects of Beans | Nutrova

How do beans affect the human body?

Beans contain a family of sugars called raffinose. Usually, sugars are broken down during digestion and then absorbed in the intestine. Raffinose, on the other hand, doesn’t. It has a unique structure, because of which only a certain enzyme (called alpha-galactosidase) can break raffinose down into smaller molecules - except our body doesn’t produce this enzyme [3].

This means that raffinose reaches the intestine in its original form, where our gut bacteria finally breaks it down, and creates by-products like methane, hydrogen and carbon dioxide (all gases) in the intestine. The production of this excess gas is what causes flatulence in some individuals [4, 5].

Why do some people get more gas than others?

Why Do Beans Cause Gas in some people | Side Effects of Beans | Nutrova

Everybody tolerates foods differently, and that’s true for beans, too. Various factors are responsible for this, but when it comes to the side effects of beans, it all mainly comes down to our gut microbiome (the diversity of bacteria and other microorganisms that live in our gut).

Our gut has trillions of bacteria in it, with over 1000 different species. These bacterial species vary from person to person, and are governed by several factors including age, genetics, diet and environmental exposures [6, 7].

It’s simple - some of these bacteria produce gas while digesting raffinose, while other species don’t. So, anyone whose gut microbiome includes the former tends to experience flatulence. Because of the wide variety of bacteria, and little knowledge about the specific roles that individual species play, the exact species of bacteria that causes this flatulence from raffinose remains unknown.

Should beans be avoided altogether, for those who are sensitive?

Ideally, no. Raffinose imparts many health benefits to the body! These include stimulating the growth of our beneficial gut bacteria, and improving iron’s absorption and our intestinal functionality [8, 9].  Avoiding beans wouldn’t completely help also because they are not the only food item that causes gas - whole grains, broccoli, cabbage, brussels sprouts and cauliflower are some more examples of foods that contain raffinose and could also lead to gas [1, 10].

Foods that cause gas | Side Effects of Beans | Nutrova

Individuals who are especially sensitive to its effects (but don’t want to miss out on its nutrients) can try consuming smaller amounts of beans, gradually increasing the amount to understand their tolerance levels (for example, start with 2-4 tablespoons of beans for a few days and gradually increase it). Once you know how much you can eat without experiencing discomfort, you can spread that quantity across various raffinose-containing foods before including them in their diet [11].

That said, it still takes a high dose of raffinose to lead to flatulence or discomfort for anyone (sensitive or not) - and it’s also possible to simply lower the level of raffinose contained in these foods.

Here’s how:

Ways to avoid gas caused by beans (by lowering their raffinose content):

1. Soak the beans

How to avoid Gas? | Side Effects of Beans | Nutrova

When soaked, raffinose is released into the water, reducing its overall content from the beans. To do this, soak them for 8-12 hours and, ideally, change the water every three hours; discard the water before cooking or eating the beans [11].

Additional benefit - soaking also decreases antinutrients like phytic acid from beans [12].

2. Hot soak the beans

Like the name suggests, it’s the same as soaking but with a precursor! Boiling beans also helps reduce their raffinose content. Simply boil the beans for 2-3 minutes and then soak them for up to four hours. The longer the beans soak, the more raffinose will get released into water [11, 13].

How to prevent Gas caused by beans? | Side Effects of Beans | Nutrova

3. Soak the beans with baking soda

Adding a teaspoon of baking soda to four quarts (1 quart = 4 cups) of water and soaking dried beans in them before cooking is known to significantly decrease raffinose’s content [14].

Additional benefit: Baking soda also speeds up the disintegration of pectin (a kind of fibre), allowing the beans to soften faster.

4. Pressure cooking

Why Do Beans Cause Gas? | Side Effects of Beans | Nutrova

If you own a pressure cooker, you can use it to make beans less gassy too! The pressure helps break down the raffinose molecule into smaller sugars, eliminating the unwanted gas that comes from the gut bacteria needing to break it down [15].

Other home remedies that may help: 

Apart from these methods, adding asafoetida (hing) and carom seeds (ajwain) while cooking beans is believed to have anti-inflammatory properties, which help relieve an upset stomach and flatulence. Although there is little evidence to suggest whether this works, if nothing else, they do impart great flavour!

Speaking of which, we’d like to hear about how you prepare your beans and best enjoy them! Because, at the end of the day, let’s not forget how the poem ends: “the more you toot the better you feel, so let’s have beans with every meal!” These words may not quite be scientifically accurate or the best advice (especially if you’re sensitive to beans), but the point here is not to feel too ashamed of a natural phenomenon that we all experience about 8-10 times a day - with or without beans being responsible for it!

We hope this was a fun, informative article and you enjoyed reading it as much as we enjoyed writing it. Use the comments sections below to tell us if this blog was helpful and if you have any questions. We love hearing from you. :)

Kainat Khan Mirajkar, PGD Dietetics and Applied Nutrition

Kainat is a Nutritionist with a PGD in Dietetics and Applied Nutrition and a Certified Diabetes Educator. With over eight years of experience in the field of nutrition and dietetics, she is Nutrova's in-house research and information expert.

More by Kainat Khan Mirajkar

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