Chickpeas and Gas: The Science Behind the Bloat
Chickpeas are a nutritional powerhouse, but they are also notorious for producing gas. Here is the science behind why these humble legumes leave so many people feeling bloated.
Why Chickpeas Make You Gassy
Chickpeas, like other legumes, contain a group of hard-to-digest carbohydrates called galacto-oligosaccharides, primarily raffinose, stachyose, and verbascose. Human beings lack the enzyme alpha-galactosidase needed to break the specific bonds in these sugars, so they pass through the small intestine completely undigested. When they reach the large intestine, the trillions of bacteria that live there ferment them eagerly, releasing gas as a byproduct. Chickpeas are especially rich in these oligosaccharides compared to many other foods, which is why a single serving can produce a noticeable amount of flatulence. In addition to oligosaccharides, chickpeas contain resistant starch and soluble fiber, both of which also reach the colon largely intact and feed gas-producing microbes. The combination of these fermentable compounds makes chickpeas one of the most reliably gas-inducing foods in the human diet.
The Chemistry of Chickpea Fermentation
When gut bacteria ferment the oligosaccharides and fiber in chickpeas, they produce a mixture of gases through anaerobic metabolism. The main products are hydrogen, carbon dioxide, and, in people who host methane-producing archaea, methane. These three gases are odorless, and together they account for the vast majority of the volume of any fart. Only trace amounts of sulfur-containing compounds, such as hydrogen sulfide, give flatulence its characteristic smell, and chickpeas produce relatively little of these compared to sulfur-rich foods like eggs or cabbage. The specific mix of gases depends heavily on the individual's microbiome. Some people harbor bacteria that consume hydrogen almost as fast as it is produced, resulting in less bloating, while others accumulate large volumes. Fermentation also generates short-chain fatty acids like butyrate, which nourish the cells lining the colon and are considered beneficial to gut health.
How to Reduce Chickpea Gas
There are several proven techniques for making chickpeas gentler on the digestive system. Soaking dried chickpeas for eight to twelve hours and discarding the soaking water removes a portion of the water-soluble oligosaccharides before cooking. Cooking them thoroughly, and even boiling with a change of water partway through, reduces the content further. For canned chickpeas, draining and rinsing them well washes away oligosaccharides that have leached into the liquid. Sprouting chickpeas activates their own enzymes, which begin breaking down the problematic sugars naturally. Over-the-counter enzyme supplements containing alpha-galactosidase, sold under names like Beano, supply the very enzyme humans lack and can dramatically cut gas production. Finally, introducing chickpeas gradually allows the gut microbiome to adapt over a few weeks, as the bacterial populations shift toward more efficient fermentation. Eating smaller portions more frequently also helps prevent overwhelming the colon.
Health Benefits Worth the Gas
For most people, the gas produced by chickpeas is a small price to pay for their impressive nutritional profile. Chickpeas are an excellent source of plant-based protein, providing roughly fifteen grams per cooked cup, making them a staple for vegetarians and vegans. They are packed with dietary fiber that supports healthy digestion, stabilizes blood sugar, and promotes feelings of fullness that can aid weight management. The very oligosaccharides that cause flatulence act as prebiotics, selectively feeding beneficial bacteria such as Bifidobacteria and encouraging a diverse, resilient microbiome. Chickpeas also deliver iron, folate, magnesium, and manganese, along with antioxidant compounds. Regular legume consumption is associated in large studies with lower rates of heart disease, type 2 diabetes, and certain cancers. In other words, a bit of extra flatulence is often a sign that you are feeding your gut bacteria exactly what they thrive on.
Did You Know?
- Chickpeas contain more of the gas-causing sugar raffinose than many other common legumes.
- The enzyme humans lack to digest chickpeas, alpha-galactosidase, is the active ingredient in anti-gas products like Beano.
- Aquafaba, the liquid from canned chickpeas, is rich in leached oligosaccharides, which is partly why rinsing reduces gas.
- Sprouting chickpeas can cut their oligosaccharide content by up to half before you even start cooking.
Fun Fact
Aquafaba, the viscous chickpea cooking liquid prized by vegan bakers as an egg-white substitute, owes much of its foaming ability to the very same soluble compounds that later fuel your gut bacteria.
Sources
- Winham, D.M. & Hutchins, A.M., Perceptions of flatulence from bean consumption among adults in 3 feeding studies, Nutrition Journal, 2011
- Fabek, H. et al., The effect of the food matrix on galacto-oligosaccharide fermentation and gut microbiota, British Journal of Nutrition, 2020
- Jenkins, D.J.A. et al., Effect of legumes as part of a low glycemic index diet on glycemic control, Archives of Internal Medicine, 2012