Where Does Gas Come From? Gas, also known as flatulence or belching, may be caused by air that you swallow while eating, particularly if you’re rushing. Gas can also result when bacteria break down undigested food in the large intestine. For instance, the stomach and small intestine don’t fully digest fiber as well as the carbohydrates found in many foods. “Not all carbohydrates are easy to digest,” explains dietitian Angela Lemond, RDN, CSP, LD, a spokeswoman for the Academy of Nutrition and Dietetics who has expertise in gastrointestinal nutrition. “Fruits and vegetables are big offenders, especially those in raw form because the body has to work hard to digest these plant-based foods. It’s also very dependent on the individual.” Why Some People Have More Gas Than Others Gas-producing foods affect different people in different ways. How your body reacts to food depends on how well you digest carbohydrates and what type of bacteria is in your intestines. The efficiency of your digestive tract also plays a role in how well you’re able to move and expel gas. An analysis of 68 studies and six review articles on the gastrointestinal effects of low-digestible carbohydrates such as fiber, resistant starch, and sugar alcohols, published in the journal Critical Reviews in Food Science and Nutrition in 2009, found that for many people these carbohydrates can lead to gastrointestinal issues, like excessive gas, abdominal discomfort, and diarrhea, particularly when consumed in large amounts. Among the top gas-producing foods are beans and other legumes as well as cruciferous vegetables, such as:
CabbagesTurnipsKaleBroccoliBrussels sproutsArugulaCauliflower
Other high-fiber foods, like whole grains, may also cause gas or bloating, particularly if you’ve recently increased your fiber intake. The body tends to acclimate to a high-fiber diet over time, Lemond says. “Increased or excessive gas usually gets better,” she says. Lactose, or milk sugar, may also cause gas in some people. If you have trouble digesting milk or dairy products like ice cream and cheese, your body may not be making enough of the enzyme lactase, which is needed to break down the lactose in dairy foods. Common sweeteners, such as fructose, may also be to blame for excessive gas. The small intestine can only absorb a limited amount of fructose daily. When bacteria break down undigested sweeteners in the colon, gas can result. Many fruit beverages, including pear and apple juice, contain fructose. Sodas and some other sugary beverages with high-fructose corn syrup can be culprits of gas as well. Lemond says that anyone concerned about excessive gas should be mindful of the sweeteners added to sugar-free candy, gum, and some packaged foods, such as cereal and granola bars. “On top of the added fiber, some granola bars also contain sugar alcohols known to cause intestinal gas,” she says. Look for sorbitol, mannitol, and xylitol — all sugar alcohols — among the ingredients on nutrition labels. Her advice: Avoid all sugars that end in the letters “ol.” Steps to Reduce Excessive Gas First, determine what’s causing your digestive discomfort. To do that, Lemond suggests keeping a diary of what you eat and drink. Also record how often you burp, pass gas, or experience other uncomfortable symptoms, like bloating. By tracking your symptoms in a food diary, along with what and when you’re eating, you may be able to pinpoint what’s causing you to develop gas. Other ways to find gas relief include: Trial and error. Try experimenting with your diet. Temporarily cutting back on certain foods and then reintroducing them can help isolate gas-producing foods, Lemond says. Once your dietary culprits are found, however, you don’t have to give them up entirely. “Try eating smaller portions of foods that usually cause you gas,” she says. “Also avoid pairing two or more big offenders in one meal.” Even people diagnosed with a food intolerance can modify their diet to ease their symptoms. “Lactose intolerance is a common digestive issue,” Lemond says. “That doesn’t mean you have to cut out all dairy. Yogurt is usually okay. Lactose-free milk and low-lactose cheeses are also available.” Slow down. When trying to reduce gas, it’s also important to consider how you eat. “Eating too fast, not chewing well, and gulping air are going to cause more gas,” she says. “You need to appreciate the enzymes in your mouth that help break down food. If you eat too quickly, you’re not allowing your mouth to start the digestive process.” Eat regularly. Timing is also important when trying to ease gas and bloating. “Many people wait too long to eat, then eat very large portions,” Lemond says. “This can cause gas or even diarrhea because there’s just too much stress on the stomach.” Avoid icy, hot, and fizzy drinks. “Cold or hot liquids and carbonated drinks can also trigger gas or bloating,” she says. If you feel the need to drink a beverage while eating, opt for water at room temperature. Reduce fat intake. Limiting high-fat foods can help reduce gas and bloating. Cut back on fat in your diet to help your stomach empty faster. This will allow gases to move more quickly into your small intestine. “Fat slows the functioning of your intestines, so if you don’t process gas very well, fatty foods could make that worse,” says Lena Palmer, MD, a gastroenterologist, assistant professor in the department of medicine, and medical director of nutritional services at Loyola University Chicago. When to Talk to Your Doctor About Gas When gas is accompanied by other symptoms, such as constipation, diarrhea, or weight loss, it’s time to talk to your doctor, Dr. Palmer says. You should also see your doctor if your symptoms are troublesome or suddenly change. Intolerances to certain foods may cause gastrointestinal distress, but Lemond says it’s not a good idea to restrict your diet without guidance from your doctor first. “It’s concerning when people start pulling certain foods or food groups out of their diet and trying to self-diagnose or self-treat,” she says. “This can have a nutritional impact.” If excessive gas is a real problem for you, consider seeing a doctor who specializes in digestive health (a gastroenterologist) to get to the bottom of it and find ways to reduce gas and discomfort.
