Why Do Beans Make You Fart? Raffinose and Gas (2024)

It’s not a myth that beans make you fart. The rhyme “Beans, beans, the magical fruit. The more you eat, the more you toot!” has a basis in science. But, you may not know why beans make you fart or whether there is anything you can do about it. Here’s the science of what you need to know.

Beans makes you fart because they contain an oligosaccharide called raffinose that humans can’t digest, but gut bacteria ferment. One product of fermentation is gas.

Why Beans Make You Fart

Beans increase gas production, leading to bloating and farting (flatulence) because they are high in fiber. From a nutritional standpoint, this is great. Fiber slows down digestion so you feel full longer and extract the maximum amount of nutrients from food. It helps control blood sugar and cholesterol levels. Fiber promotes cardiac and bowel health. But, some of the fiber in beans comes in a form the human body can’t digest. Specifically, beans cause gas because they contain a type of fiber called raffinose. Raffinose passes through the stomach and small intestine intact, but gut bacteria ferment it and the products of fermentation include hydrogen gas, carbon dioxide, and sometimes methane.

All Beans Are Not Created Equal

All beans contain raffinose, but they don’t increase the amount of gas, bloating, and flatulence by the same amount. For example, a 2011 study published in Nutrition Journal reports pinto beans and baked beans cause more farting than black-eyed peas, which in turn produce more gas than carrots. But, less than half of the study participants eating pinto beans or baked beans experienced an increase in gas production. This implies eating beans usually does increase farting, but probably not by as much as you might think.

Other Foods That Cause Gas and Make You Fart

Beans get a bad rap, but they are by no means the only foods that make you fart. Basically, any food that contains fiber causes gas production. Also, any food or beverage that causes you to swallow air increases farting.

Foods that make you fart include:

• asparagus
• beans
• beer
• broccoli
• Brussels sprouts
• cabbage
• carbonated drinks
• cauliflower
• dairy products
• fatty foods
• hard candy
• garlic
• onions
• sugar alcohols (e.g., xylitol, maltitol)
• wheat

Asparagus, the cruciferous vegetables (broccoli, Brussels spouts, cabbage, cauliflower), onions, and garlic pack a double-whammy because they not only increase gas, but also contain sulfur compounds that contribute to fart odor.

How to Reduce Farting From Beans

There are two easy ways to reduce farting from beans. First, soaking beans in water before cooking them reduces gas production. The second way to fart less is to keep eating beans and other foods high in fiber. Over time (three to four weeks), the body adapts to an increase in fiber. People who experience a lot of gas and bloating from fiber-rich foods typically don’t eat enough of them.

Some over-the-counter products reduce gas production by providing the enzyme that digests raffinose. This enzyme is called alpha-galactosidase. It is the active ingredient in Beano. Research indicates Beano is effective, but it’s not a good solution for everyone. Because it breaks down oligosaccharides into simpler sugars, it increases blood sugar. Specifically, it raises levels of the sugar named galactose. Taking alpha-galactosidase may cause problems for diabetics and people with galactosemia.

Scientifically Proven Ways to Reduce the Odor of Farts

Fermentation of raffinose releases odorless gases. So, beans make you fart, but they don’t necessarily make your farts stink. Odor often comes from eating foods that contain sulfur compounds. One way of reducing fart odor is limiting your intake of these foods. However, many foods that increase gas odor are quite nutritious, such as cruciferous vegetables.

One over-the-counter remedy for flatus odor is bismuth subgallate. It is the active ingredient in the FDA-approved internal deodorant called Devrom. Related remedies contain bismuth subsalicylate. Bismuth subsalicylate is the active ingredient in Pepto-Bismol and Bisbacter. Bismuth compounds reduce gas odor by binding hydrogen sulfide molecules. While effective, bismuth compounds carry health risks. They can cause black tongue and stools, accumulate in the body to potentially toxic levels, and are excreted in breast milk.

Safer deodorants include charcoal, yucca plant extracts (Yucca shidigera), or zinc acetate. According to the World Health Organization (WHO), activated charcoal or activated carbon is among the world’s safest medicines. Pet foods often contain yucca as an ingredient because it decreases fart odor, lowers bad cholesterol levels, and increases vitamin and mineral absorption. Zinc acetate is a common zinc supplement and cold remedy. Reducing gas odor is a pleasant side-effect.

References

• Azpiroz, F. (2005). “Intestinal gas dynamics: mechanisms and clinical relevance.” Gut. 54 (7): 893–95. doi:10.1136/gut.2004.048868
• Ganiats, T.G.; Norcross, W.A.; et al. (1994). “Does Beano prevent gas? A double-blind crossover study of oral alpha-galactosidase to treat dietary oligosaccharide intolerance.” The Journal of Family Practice. 39 (5): 441–45.
• Giffard, C.J.; Collins, S.B.; et al. (2001). “Administration of charcoal, Yucca schidigera, and zinc acetate to reduce malodorous flatulence in dogs.” Journal of the American Veterinary Medical Association. 218 (6): 892–96. doi:10.2460/javma.2001.218.892
• Suarez, F.L.; Furne, J.K.; Springfield, J.R.; Levitt, M.D. (1998). “Bismuth subsalicylate markedly decreases hydrogen sulfide release in the human colon”. Gastroenterology. 114 (5): 923–29. doi:10.1016/S0016-5085(98)81700-9
• Wagner, J. R.; Carson, J. F.; et al. (1977). “Comparative Flatulence Activity of Beans and Bean Fractions for Man and the Rat.” The Journal of Nutrition. 107(4): 680–689. doi:10.1093/jn/107.4.680
• Winham, D.M.; Hutchins, A.M. (2011). “Perceptions of flatulence from bean consumption among adults in 3 feeding studies.” Nutrition Journal. 10: 128. doi:10.1186/1475-2891-10-128

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