Beans, whether they are cannellini, pinto, black, kidney, or lima, are celebrated for their versatility, nutritional punch, and delicious taste. However, they also carry a notorious side effect: the tendency to cause flatulence. You might have wondered, “why do beans make you fart?” This article dives deep into the science behind this common phenomenon, offering insights and practical tips to enjoy beans without the unwanted wind.
What’s in Beans That Causes Gas?
Beans are nutritional powerhouses, packed with essential nutrients like protein, potassium, polyphenols, magnesium, folate, iron, and zinc. Crucially for our topic, they are also exceptionally high in fiber.
The Fiber Factor: Fuel for Gut Bacteria
Fiber is indispensable for maintaining a healthy gut microbiome and contributes significantly to overall well-being. Beans are particularly rich in soluble fiber, a type that dissolves in water and forms a gel-like substance in your digestive system.
While humans cannot digest soluble fiber directly, our gut bacteria thrive on it. As these beneficial bacteria ferment soluble fiber, a byproduct of this process is gas. This gas accumulates and eventually needs to be expelled from the body. While beans are a prominent source of soluble fiber, it’s important to note that many other plant-based foods, including fruits, vegetables, and legumes, also contain significant amounts of this type of fiber.
Raffinose: The Oligosaccharide Culprit
Beyond fiber, beans contain another compound that contributes to their gas-inducing reputation: raffinose. Raffinose is a type of carbohydrate known as an oligosaccharide.
Similar to soluble fiber, humans lack the enzymes to break down raffinose. Instead, it becomes food for our gut bacteria. As gut bacteria process raffinose, they release substantial amounts of gas, specifically hydrogen, methane, and carbon dioxide.
However, raffinose isn’t detrimental to our health. In fact, it functions as a prebiotic, fostering the growth of beneficial bacteria in our gut and hindering the proliferation of harmful bacteria. Besides beans, raffinose is also present in smaller quantities in other gas-producing foods like chickpeas, soybeans, lentils, cabbage, broccoli, and Brussels sprouts.
It’s the combination of high fiber content and the presence of raffinose in beans that primarily leads to increased gas production in the digestive system.
Strategies to Reduce Bean-Related Flatulence
While passing gas is a normal bodily function, excessive flatulence can be uncomfortable. If you are a bean enthusiast but wish to minimize the associated gas, there are several effective strategies you can employ. We consulted experts like ZOE’s U.S. medical director, Dr. Will Bulsiewicz, a board-certified gastroenterologist, and ZOE’s senior nutrition scientist, Dr. Emily Leeming, for their insights.
Dr. Leeming points out that gas production is a natural part of the gut microbiome’s food metabolism, and it can even indicate a healthy gut. However, for those sensitive to increased gas, the following tips can be helpful:
Simple Steps for Less Gas
1. Gradual Introduction of Fiber
If your diet is typically low in fiber, introducing beans suddenly can overwhelm your digestive system. Gradually increasing your fiber intake allows your gut microbiome to adapt to the increased workload, reducing gas production over time. Start with small portions of beans and slowly increase the amount as your body adjusts.
2. Hydration is Key
Drinking ample water, especially with meals, can aid digestion and reduce flatulence. Soluble fiber absorbs water, which helps maintain smooth digestion and prevents constipation, a condition that can exacerbate gas. Staying hydrated ensures that fiber can move through your digestive system efficiently.
3. Soaking and Rinsing Beans
Dr. Bulsiewicz recommends soaking dry beans overnight as an effective method to reduce raffinose content. Raffinose and similar gas-producing compounds are water-soluble. Soaking beans allows these compounds to leach out into the water. It is crucial to discard the soaking water and cook the beans in fresh water to eliminate the dissolved raffinose. Additionally, rinsing beans multiple times before cooking can further reduce raffinose levels. Sprouting beans before cooking or cooking them in alkaline water are also suggested methods to decrease oligosaccharides.
4. Gentle Exercise
Engaging in light physical activity, such as a walk, after consuming a bean-rich meal can promote digestion and help expel gas naturally, thus reducing discomfort and bloating.
5. Over-the-Counter Aids
Over-the-counter products containing alpha-galactosidase, an enzyme that breaks down raffinose and similar oligosaccharides, can be beneficial. Studies have demonstrated that these products effectively reduce flatulence in adults, children, and individuals with irritable bowel syndrome. Taking these supplements before eating beans can help pre-digest raffinose, lessening gas production.
6. The Onion Myth (and other cooking methods)
While one study suggested that cooking beans with onions might reduce flatulence, this is not widely supported, and onions themselves contain fructans, another type of oligosaccharide that can cause gas in some individuals. Dr. Bulsiewicz suggests that cooking beans in a pressure cooker or with a strip of kombu seaweed can be more effective in reducing bean-related flatulence. Pressure cooking can break down complex carbohydrates more efficiently, and kombu seaweed contains enzymes that can help digest oligosaccharides in beans.
Beans: Are They Really the Gassy Villains?
Despite the common perception, beans might not be the primary culprit of excessive flatulence compared to other vegetables. While dietitians often hear complaints of increased gas from clients after recommending beans, studies suggest that the reality might be less dramatic.
Debunking the Bean-Fart Myth
Researchers have investigated the actual impact of beans on flatulence. One study compared self-reported flatulence after participants consumed black-eyed peas, pinto beans, baked beans, or carrots (as a control). Interestingly, fewer than half of the participants reported increased flatulence after eating pinto or baked beans, and only 19% noticed an increase after eating black-eyed peas. Even a small percentage of those eating carrots reported increased gas.
Moreover, even for those who initially experienced increased flatulence from beans, gas levels typically returned to their baseline within a few weeks of consistent bean consumption. This suggests that the body adapts to digesting beans over time.
It’s important to note that these studies were based on perceived flatulence rather than precise measurements of gas volume. However, they indicate that beans might not significantly increase flatulence for everyone, and any initial increase is often temporary.
The Bigger Picture: Bean Benefits Outweigh the Gas
The nutritional benefits of beans are undeniable. They are a cost-effective source of protein, fiber, vitamins, and minerals, making them a valuable addition to a balanced diet. The potential for increased gas should not overshadow their numerous health advantages.
Conclusion
In conclusion, while beans can contribute to flatulence due to their fiber and raffinose content, they are not necessarily the gassy villains they are often made out to be. Simple preparation and consumption strategies can significantly reduce gas production. More importantly, the nutritional benefits of beans far outweigh the temporary discomfort of increased gas for many individuals.
Listen to your body and experiment with different types of beans and preparation methods to find what works best for you. If you experience persistent bloating or digestive discomfort unrelated to bean consumption, it’s always wise to consult with a healthcare provider to rule out any underlying issues. Embrace beans as a nutritious and delicious part of your diet, and don’t let the fear of farts hold you back from enjoying these wonderful legumes.
Sources
Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. The Lancet. (2019). https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(18)31809-9/fulltext
Dietary fibre in foods: A review. Journal of Food Science and Technology. (2012). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3614039/
Efficacy and tolerability of α-galactosidase in treating gas-related symptoms in children: a randomized, double-blind, placebo controlled trial. BMC Gastroenterology. (2013). https://pubmed.ncbi.nlm.nih.gov/24063420/
Foods likely to cause gas. (n.d.). https://iffgd.org/gi-disorders/symptoms-causes/intestinal-gas/foods-that-may-cause-gas/
Increasing symptoms in irritable bowel symptoms with ingestion of galacto-oligosaccharides are mitigated by alpha-galactosidase treatment. The American Journal of Gatroenterology. (2017). https://pubmed.ncbi.nlm.nih.gov/28809383/
Legume promotion in counselling: an e-mail survey of dietitians. Canadian Journal of Dietetic Practice and Research. (2001). https://pubmed.ncbi.nlm.nih.gov/11742561/
Nutritional and health benefits of dried beans. The American Journal of Clinical Nutrition. (2014). https://academic.oup.com/ajcn/article/100/suppl_1/437S/4576589
Perceptions of flatulence from bean consumption among adults in 3 feeding studies. Nutrition Journal. (2011). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3228670/
Raffinose family oligosaccharides: Friend or foe for human and plant health? Frontiers in Plant Science. (2022). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8891438/
Role of onion in reducing flatulence and other problems of indigestion among people eating beans in Imo State South East Nigeria. Journal of Biological and Genetic Research. (2000). https://www.iiardjournals.org/get/JBGR/VOL%201/ROLE_OF_ONION_IN_REDUCING_FLATULENCE.pdf
Soaking and cooking modify the alpha-galacto-oligosaccharide and dietary fibre content in five Mediterranean legumes. International Journal of Food Sciences and Nutrition. (2019). https://www.tandfonline.com/doi/full/10.1080/09637486.2018.1544229
The effect of oral alpha-galactosidase on intestinal gas production and gas-related symptoms. Digestive Diseases and Science. (2007). https://pubmed.ncbi.nlm.nih.gov/17151807/
