Bean gas happens because your body lacks the enzyme needed to break down certain sugars found in legumes. Those sugars pass through your stomach and small intestine intact, then arrive in your large intestine where bacteria ferment them and produce hydrogen, methane, and carbon dioxide. The good news: you can significantly reduce this effect with the right preparation, cooking habits, and a few simple tricks.
Why Beans Cause Gas in the First Place
Beans contain a family of complex sugars called raffinose family oligosaccharides, or RFOs. Humans don’t produce the specific enzyme (alpha-galactosidase) needed to digest them. So instead of being broken down and absorbed in your small intestine like other sugars, RFOs travel all the way to your colon completely intact. There, your gut bacteria feast on them through fermentation, releasing gases as a byproduct. That fermentation is what causes bloating, cramping, and flatulence.
This isn’t a sign that something is wrong with your digestion. It’s simply a mismatch between what your body can process and what beans contain. Every human lacks the enzyme, though people who eat beans regularly tend to have gut bacteria that handle the fermentation more efficiently, producing less gas over time.
Soak and Discard the Water
The gas-causing sugars in beans are water-soluble, which means soaking pulls a portion of them out of the beans and into the surrounding liquid. The key step most people skip: pour that soaking water down the drain and cook with fresh water. This simple habit removes a meaningful amount of the problem sugars before cooking even begins.
For a standard overnight soak, cover dried beans with several inches of water and let them sit for 8 to 12 hours. A quick-soak method works too: bring beans to a boil for two minutes, then cover and let them sit for an hour. Either way, drain and rinse thoroughly before cooking. You’ll lose a small amount of water-soluble vitamins and minerals, but the tradeoff in digestive comfort is worth it for most people.
Some cooks take this a step further by changing the water partway through cooking as well. Bringing beans to a boil, draining, and then starting again with fresh water gives you one more chance to wash away dissolved oligosaccharides.
Rinse Canned Beans Too
If you use canned beans, rinsing them under running water before eating or cooking with them helps. That liquid in the can contains dissolved sugars that leached out during the canning process. A registered dietitian at Case Western Reserve University’s School of Medicine has noted that rinsing canned beans reduces sodium by up to 40% and may also lower gas-causing carbohydrates. It doesn’t strip away the fiber, protein, or other nutrients you’re eating beans for in the first place, and it improves both flavor and digestibility.
Choose Lower-Gas Varieties
Not all beans are created equal when it comes to gas. A study published in the Journal of Agricultural and Food Chemistry measured the gas-causing sugar content across 23 varieties of dry beans and found real differences.
Chickpeas (garbanzo beans) came out on top as the least gas-producing option, with about 28.7 mg/g of total gas-causing sugars and the most favorable ratio of digestible to indigestible sugars. Black beans, kidney beans (both light and dark red), and white kidney beans all landed in a middle tier, ranging from about 42 to 46 mg/g. Lentils, despite their reputation as an easy-to-digest legume, actually had the highest flatulence potential in the study, largely because of their high verbascose content.
If you’re particularly sensitive, starting with chickpeas and working your way toward other varieties gives your gut bacteria time to adapt.
Cook Beans Thoroughly
Undercooked beans cause more gas. Longer cooking times break down more of the complex sugars and make beans easier to digest overall. Pressure cooking is especially effective because the high temperature and pressure break down oligosaccharides more completely than stovetop simmering. If you have an electric pressure cooker, it’s one of the best tools for making beans more digestible.
Whatever method you use, cook beans until they’re completely soft. If you can’t easily mash one between your fingers, they need more time.
Add Carminative Herbs and Spices
Certain herbs and spices have been used for centuries specifically because they help reduce gas. These “carminative” ingredients work by relaxing the smooth muscle of the digestive tract and increasing blood flow to the gut lining, which helps gas pass more easily rather than building up painfully.
Epazote is the most traditional choice. This herb is widely used in Mexican cooking specifically because it acts as an anti-gas agent when cooked directly with beans. Cumin, ginger, fennel seeds, and asafoetida (common in Indian lentil dishes) all have carminative properties as well. Adding a strip of dried kombu seaweed to the cooking pot is a Japanese technique that some cooks swear by. These additions won’t eliminate gas entirely, but they reduce discomfort and they make your beans taste better, so there’s no downside.
Over-the-Counter Enzyme Supplements
Products like Beano contain alpha-galactosidase, the exact enzyme your body doesn’t produce. The idea is straightforward: take the enzyme with your first bite, and it breaks down the problem sugars before they reach your colon. In practice, results vary quite a bit from person to person.
One reason for the inconsistency is that your stomach works against the supplement. The enzyme functions best at a pH around 5.0, but stomach acid drops the pH well below 2.0, which can destroy the enzyme before it does its job. Digestive enzymes in your stomach and small intestine also attack it, since it’s a protein itself. Research has found that eating the supplement alongside protein-containing food offers some protection. In one study, the enzyme retained 100% of its activity throughout a three-hour simulated digestion when paired with enough soy protein, while the enzyme in water alone was completely inactivated within an hour. So if you’re going to use these supplements, taking them with your meal (not on an empty stomach) likely improves their effectiveness.
Build Up Your Tolerance Gradually
Your gut bacteria adapt to what you feed them. If you rarely eat beans and then have a large serving, your colon bacteria are unprepared for the sudden influx of fermentable sugars, and you’ll produce more gas. If you eat beans regularly in smaller amounts, your gut microbiome shifts toward bacteria that handle these sugars more efficiently, producing less gas in the process.
Start with a quarter cup of beans a few times per week. Over two to three weeks, gradually increase your portions. Many people who follow this approach find that the gas problem largely resolves on its own, without any special preparation techniques at all. Combining gradual introduction with proper soaking and thorough cooking gives you the best chance of eating beans comfortably from the start.