Why beans cause gas (and how to avoid it) (2024)

On Nutrition

Beans pack a lot of nutrition into tiny packages, providing protein, fiber, phytochemicals and a range of vitamins and minerals, most notably the B vitamins. They’re also associated with a range of health benefits, including better blood sugar management, lower LDL (“bad”) cholesterol levels and a healthier heart. Plus, they’re budget-friendly. Unfortunately, they may also make you gassy.

Production of excess gas, sometimes with the added discomfort of bloating, is a reason many people avoid eating beans. That presents a real challenge if you’re interested in eating a more plant-based diet. The good news is that, in most cases, there are ways to break the impasse.

Beans contain raffinose and other oligosaccharides (a type of carbohydrate) that our digestive system can’t break down because we lack the enzyme alpha-galactosidase. This can increase gassiness. This isn’t just true for beans — lentils, peas and cruciferous vegetables such as broccoli, Brussels sprouts, cabbage and cauliflower are high in similar oligosaccharides.

Because we don’t directly digest these oligosaccharides, they pass through to the large intestine, where bacteria in our gut microbiota digest — or ferment — them. This bacterial fermentation is good for our health, but the downside is that it’s also what produces the gas — specifically hydrogen, carbon dioxide and methane.

Of course, gas is a normal part of the digestive process, and studies suggest that the average person passes gas eight to 14 times per day — and passing gas up to 25 times per day is normal. If your digestive system is functioning normally, gas formed in the intestine will keep moving through for release. If you stop yourself from releasing gas — perhaps because you’re embarrassed — or if you have a health condition that impairs normal gas release, gas will build up and can cause bloating and abdominal distention.

Some people with irritable bowel syndrome (IBS) find that they can’t tolerate beans — specifically, the oligosaccharides — at all, as they trigger abdominal pain, diarrhea and/or constipation, often with bloating and excess gas. But most people can enjoy more beans with less gas with the help of these tips:

• Soak beans overnight in water, then drain, rinse and cook in fresh water. This decreases the oligosaccharide content. Cooking the beans in a pressure cooker may reduce the oligosaccharides even further.
• Try canned beans, which have lower levels of oligosaccharides because of the high-pressure processing. Canned chickpeas are significantly lower in oligosaccharides than other beans.
• Cook beans with kombu, a type of dried seaweed used extensively in Japanese cuisine, especially in soup stock. Kombu contains alpha-galactosidase, the enzyme that breaks down oligosaccharides.
• Take supplemental alpha-galactosidase, which is readily available in pill form, including under the brand name Beano. Note that these supplements are not recommended for people with diabetes or mold allergies, or those who have the genetic disease galactosemia.
• Try different beans to find out which types you tolerate best. A 2011 study of participants who ate a half-cup of beans daily for eight or 12 weeks found that almost 50% reported increased flatulence from eating pinto or baked beans during the first week of the study, but only 19% experienced more gas when eating black-eyed peas. Lentils, especially brown, red and green varieties (not the French green Le Puy lentils) are also low-to-moderate in oligosaccharides when serving size is a half-cup or less.
• When increasing intake of bean or any fiber-rich food, do so gradually and drink plenty of water to help your body adjust.

Posting comments is now limited to subscribers only. View subscription offers here. For more information, visit our FAQ's.