A salad full of lettuce and vegetables is packed with healthful nutrients. But salads can sometimes cause bloating -- particularly if you aren't used to eating a lot of vegetables. Increased intestinal gas is typically the culprit. If salads are a new addition to your diet, bloating might decrease once your body gets accustomed to the vegetables. But you may need to avoid certain salad ingredients if they continue to bother you. One-time bloating may be due to food contamination, which can happen with uncooked foods. Bloating that is persistent or accompanied by other symptoms, such as cramps or diarrhea, could signal an intestinal disorder.
Plant-based foods contain fiber. Vegetables commonly used in salads typically contain high amounts of fiber, which helps keep your bowel movements regular and provides other health benefits. High-fiber foods can sometimes be problematic because bacteria naturally present in the large intestine ferment certain types of fiber, which leads to production of intestinal gas. This can potentially cause bloating, particularly if you are not used to eating much fiber. Some people build up a tolerance to gas-producing foods over time, meaning bloating becomes less problematic. Reducing the portion size of your salads might also be helpful.
Many vegetables used in green salads contain plant sugars, such as raffinose and stachyose, that are not digested in the small intestine. Bacteria in the colon ferment these plant sugars with accompanying gas production that can cause bloating in some people. These indigestible plant sugars are abundant in common salad ingredients, such as lettuce, onions, arugula, artichokes, radishes, broccoli, cucumbers, celery, chickpeas and sweet peppers. However, the effects of these gas-forming foods differs from one person to another. Vegetables that cause bloating in one person may not bother someone else. If you have cheese in your salad, it can cause bloating if you have a hard time digesting the milk sugar lactose.
Unexpected, one-time bloating that occurs after eating a salad could be due to germ contamination and food poisoning. The Centers for Disease Control and Prevention estimates that each year, 1 in 6 Americans gets sick due to eating germ-contaminated foods. Fresh vegetables, such as those used in salads, are particularly risky since they are not cooked before eating. Cooking kills many food contaminants. Other symptoms, such as abdominal cramps, stomach noise, diarrhea and possibly fever, might suggest food poisoning.
Irritable bowel syndrome (IBS) is a common digestive condition associated with a number of symptoms, including bloating, cramping, constipation and diarrhea. With this condition, the digestive system is physically normal but it doesn't always not function normally. Although there is no proven association between specific foods and IBS symptoms, some people with the condition report that lettuce and salads aggravate their symptoms. It's also possible, but unlikely, that bloating related to eating salad represents an allergic reaction to an ingredient in the salad. However, a true allergy to typical salad vegetables, such as lettuce, is rare. Other causes are far more likely.
An isolated case of bloating after eating a salad is typically not cause for concern. You might try eating smaller portions and gradually increasing the amount or number of salads you eat. If bloating still occurs, you can try taking out specific ingredients in a trial-and-error process to see if a certain salad ingredient is causing your bloating. However, if your bloating continues, is severe or accompanied by other symptoms, it's best to see your doctor. She can evaluate you for possible medical causes of the bloating, including an underlying intestinal disorder. Seek medical attention right away if you are concerned you might have food poisoning.
Reviewed by: Tina M. St. John, M.D.
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- University of Michigan Health System: Helpful Hints for Controlling Gas (Flatus)
- American Journal of Gastroenterology: American College of Gastroenterology Monograph on the Management of Irritable Bowel Syndrome and Chronic Idiopathic Constipation
- Associates in Gastroenterology and Liver Disease: Gas and Bloating
- Food and Agriculture Organization of the United Nations: Physiological Effects of Dietary Fibre
- Oregon State University Linus Pauling Institute: Fiber
- Centers for Disease Control and Prevention: Foodborne Germs and Illnesses