Bananas don't cause stomach aches in everyone. If you experience a sore stomach after eating a banana, the chances are you have an allergy, a digestive disorder or an infection. It may simply be that you're sensitive to bananas. If eating bananas causes you great discomfort, speak to your doctor. She can diagnose any possible gastrointestinal conditions.
Banana ripeness affects the amount of starch found in the fruit. For example, in a 1986 study published in "The American Journal of Clinical Nutrition" researchers found that unripe bananas contained as much as 12 times more starch than ripe bananas. Highly starchy foods can be more difficult to digest and often produce gas in the gastrointestinal tract. This leads to pain similar to a sore stomach. Eating ripe bananas and avoiding green, unripe bananas helps to avoid this problem.
Irritable Bowel Syndrome
People with irritable bowel syndrome, or IBS, experience symptoms, from diarrhea to sharp cramps. Certain foods trigger IBS in different people. Bananas commonly cause problems in those with IBS, according to Harvard Health Publications, because when a banana breaks down in the gut, it often causes excess gas. In those with normal digestion, this usually doesn't pose a problem but if you have IBS, you may get a sore stomach from the gas and bloating after eating a banana.
Few people are allergic to bananas themselves, but a condition called pollen-food allergy syndrome could trigger allergy symptoms when you eat a banana. If you suffer from hay fever allergies and know that you're allergic to ragweed pollen, then a banana may cause similar reactions. Proteins in the banana have similar properties to ragweed pollen, according to MayoClinic.com. This can cause wheezing problems or a sore stomach if you have such an allergy. People with allergies to birch or latex can also experience banana allergies.
Fructose is a simple sugar found in many types of fruits, including bananas. Though bananas contain relatively low amounts compared to juicier, sweeter fruits, each banana contains around 5 percent fructose, according to the USDA National Nutrient Database. Some people react badly to fructose because they're unable to break it down in the gut. This condition is known as hereditary fructose intolerance. Usually, fructose intolerance is diagnosed at birth.