Can Beans Cause Diarrhea and Digestive Upset?

While beans have likely been the source of jokes about flatulence for most of history, eating a single portion of beans shouldn't cause most people to experience gas, much less diarrhea, according to the United Nations. If you're not used to consuming much fiber, or you eat more than your digestive system can handle, beans' high fiber content can cause diarrhea, notes Amenta Nutrition, a virtual practice based in the New York City area. Diarrhea can also be a symptom of another medical condition, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). If you develop diarrhea every time you eat beans or other legumes, you may have an allergic reaction or an intolerance to legumes. Legumes include beans, peanuts, and soy.

Bean Allergy or Intolerance

Peanuts and soy are two of the nine most common allergens in the United States, according to Food Allergy Research & Education. It's believed that about 6.2 million Americans have a peanut allergy, and 1.9 million have a soy allergy. Although beans aren't considered a common food allergen, according to research, their close relationship to peanuts and soy can cause an overreaction of the immune system. You can also have an allergy to beans specifically.

A food allergy causes the immune system to react as if it was under attack. It mistakes the proteins in the beans as a harmful substance and creates antibodies that trigger common food allergy symptoms, such as diarrhea, Mayo Clinic notes. Allergic reactions can be life-threatening, even if previous reactions were typically mild, according to the American College of Asthma, Allergy, & Immunology. Allergic reactions also occur in people with mast cell activation syndrome (MCAS), a condition that causes immune dysfunction, research notes. These reactions can also be severe or life-threatening.

It's also possible to have an intolerance to beans if your body can't digest something in them, according to Cleveland Clinic. While an intolerance can cause disruptive symptoms including diarrhea, it's not life-threatening like an allergic reaction can be. A common culprit in bean intolerance is their FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) content, as these carbohydrates can't be digested well by some people, Children's Wisconsin hospital notes. In people with irritable bowel syndrome (IBS) in particular, FODMAPs can cause uncomfortable and painful symptoms including diarrhea, according to the Canadian Digestive Health Foundation.

Gastric Effect

If the diarrhea is the result of an allergy to beans, your symptoms will develop within minutes to hours of eating the beans, according to MedlinePlus. If you have MCAS, a reaction can occur within minutes, hours, or even be delayed up to 24 to 48 hours after a trigger, the Accurate Clinic in Kenner, Louisiana, notes. The immune system begins to release chemicals, including serotonin, that cause inflammation, according to research. This leads to an allergic reaction, such as diarrhea.

Diarrhea

Diarrhea is loose, watery stools that cause frequent bowel movements, according to the NIDDK. Diarrhea from an allergic reaction is common, according to Cleveland Clinic. It's also common in MCAS reactions, Cleveland Clinic notes. And you guessed it — it also happens with food intolerances, according to Mayo Clinic.

If the diarrhea continues for more than 48 hours, talk with your doctor, notes MedlinePlus. Diarrhea can lead to dehydration — when your body loses both fluids and electrolytes, such as sodium, potassium, and magnesium. You should drink more water and increase your electrolyte intake at the first sign of diarrhea to prevent dehydration.

Treatment

Diarrhea from a bean allergy is most effectively treated by removing beans from your diet, according to Cleveland Clinic. Antihistamines can help stop or slow an allergic reaction. This applies whether it's an allergy or an MCAS reaction, according to Mast Cell Action. Aside from hydration, antidiarrheal medications can also help, notes the NIDDK. If you have a bean intolerance, you might have to eliminate them from your diet, but it's more likely that you may just need to eat less of them. It's often possible to tolerate small amounts of your trigger, Cleveland Clinic notes.