Beans are the single food most likely to make you fart, thanks to high concentrations of a complex sugar called raffinose that your body can’t break down on its own. But they’re far from the only culprit. Cruciferous vegetables, dairy products, certain fruits, and sugar-free candies all generate significant intestinal gas through slightly different mechanisms. For context, passing gas 14 to 23 times a day is medically normal, so the goal isn’t to eliminate flatulence but to understand which foods push you well past that range.
Why Beans Top the List
Beans contain large amounts of raffinose, a complex sugar your small intestine lacks the enzyme to digest. Because it passes through unabsorbed, raffinose arrives intact in your large intestine, where bacteria ferment it rapidly and produce gas as a byproduct. This is essentially what happens with every gas-producing food: something your upper digestive tract can’t handle becomes fuel for bacteria in your colon, and those bacteria release gas while breaking it down.
The raffinose content in beans is high enough that more than 20% of the population reports abdominal pain specifically from the gas they produce, according to Harvard Health Publishing. Lentils, chickpeas, black beans, and kidney beans are all major offenders. Soaking dried beans before cooking and discarding the soaking water can reduce some of the raffinose, but it won’t eliminate the effect entirely.
Cruciferous Vegetables and Sulfur
Broccoli, Brussels sprouts, cabbage, cauliflower, and kale belong to the cruciferous family, and they cause gas through two overlapping pathways. First, they contain smaller amounts of the same raffinose found in beans. Second, they’re rich in sulfur-containing compounds called glucosinolates, which are responsible for their slightly bitter, pungent flavor.
When you chew these vegetables or when bacteria in your colon break them down, glucosinolates get converted into various sulfur-rich byproducts. This is why gas from cruciferous vegetables tends to smell worse than gas from other sources. The volume of gas may be lower than what beans produce, but the odor is often more noticeable. Cooking these vegetables softens the cell walls and changes some of the chemical breakdown, but your gut bacteria still ferment the residual compounds and generate gas.
Onions, Garlic, and Wheat
These everyday staples are high in fructans, a type of short-chain carbohydrate that falls under the FODMAP category (fermentable sugars that aren’t fully absorbed in the gut). When fructans reach your large intestine, bacteria ferment them quickly, producing gas and drawing extra water into the bowel. Onions and garlic are particularly concentrated sources, which is why even small amounts can trigger bloating in sensitive people.
Wheat and rye also contain fructans, though in lower concentrations per serving. The cumulative effect matters here. If you eat toast for breakfast, a sandwich for lunch, and pasta for dinner, you may be consuming enough fructans throughout the day to produce noticeable gas, even if no single meal feels like the obvious cause.
Dairy Products
Milk, soft cheeses, ice cream, and yogurt contain lactose, a sugar that requires a specific enzyme to digest. If your body doesn’t produce enough of that enzyme, lactose passes undigested into your colon, where bacteria ferment it and produce gas. This is lactose intolerance, and it’s extremely common globally. The severity varies widely. Some people can handle a splash of milk in coffee but not a bowl of cereal. Others react to even trace amounts in processed foods.
Hard aged cheeses like cheddar and parmesan contain very little lactose and rarely cause problems. Yogurt is partially pre-digested by its bacterial cultures, so some lactose-intolerant people tolerate it better than milk.
Fruit and Fructose
Apples, pears, mangoes, and watermelon are high in fructose or sorbitol, both of which can ferment in the colon when they aren’t fully absorbed in the small intestine. Dried fruits concentrate these sugars further, so a handful of dried apricots packs a much bigger gas-producing punch than fresh ones. Prunes are a well-known example: they contain both sorbitol and fiber, making them effective as a natural laxative but also a reliable source of flatulence.
Sugar-Free Products
Sugar alcohols like sorbitol, xylitol, and mannitol are common in sugar-free gum, candy, protein bars, and “diet” snacks. Your body can’t fully digest them, so they follow the same path as raffinose and lactose: straight to the colon, where bacteria ferment them into gas. The FDA requires products containing sorbitol or mannitol to carry a warning that excessive consumption can cause a laxative effect.
Research suggests that 10 to 15 grams a day of sugar alcohols is a safe threshold for most people, but many processed sugar-free foods exceed that in a single serving. If you chew several pieces of sugar-free gum a day or regularly eat sugar-free candy, the cumulative dose can easily cause significant gas and cramping.
Soluble Fiber Is the Common Thread
Nearly every food on this list shares one characteristic: it delivers fermentable material to your large intestine. Soluble fibers that dissolve in water, like inulin, oligosaccharides, and resistant starches, are readily fermented by gut bacteria and produce gas as a direct result. This is why high-fiber foods in general tend to increase flatulence, especially when you increase your intake suddenly.
Insoluble fiber, like the cellulose in wheat bran, behaves differently. It doesn’t dissolve in water and is poorly fermented, so it adds bulk to stool without generating as much gas. That said, the American College of Gastroenterology notes that insoluble fiber like wheat bran can still cause bloating and discomfort in some people, particularly those with irritable bowel syndrome. If you’re ramping up fiber intake for health reasons, doing it gradually over a few weeks gives your gut bacteria time to adjust and typically reduces the gas response.
What About Carbonated Drinks?
Sparkling water, soda, and beer seem like obvious gas producers, but the reality is more nuanced. The carbon dioxide in carbonated beverages diffuses rapidly across the gastrointestinal wall and is almost entirely absorbed before it reaches the lower digestive tract. Intestinal gas typically contains only about 9.6% carbon dioxide. So while carbonation can cause burping and upper stomach discomfort, it contributes surprisingly little to actual flatulence. The bigger issue with soda is often the high-fructose corn syrup or artificial sweeteners, which do reach the colon and ferment.
Reducing Gas From High-Offender Foods
An enzyme supplement containing alpha-galactosidase (sold as Beano) can break down raffinose before it reaches the colon. You take it with your first bite of a meal containing beans or cruciferous vegetables. It won’t eliminate gas completely, but it prevents a significant portion of the fermentation that would otherwise happen. For dairy, lactase enzyme supplements work on the same principle, breaking down lactose before it reaches the large intestine.
Cooking methods matter too. Soaking beans for several hours and discarding the water removes some raffinose. Cooking cruciferous vegetables rather than eating them raw breaks down some glucosinolates in advance, though your gut bacteria will still ferment what’s left. Peeling fruits like apples removes some of the fiber and sorbitol concentrated in the skin.
Your gut microbiome also adapts over time. People who eat beans regularly tend to produce less gas from them than people who eat them rarely, because their bacterial populations shift to process raffinose more efficiently. If beans are new to your diet, starting with small portions and building up over several weeks can make a noticeable difference.