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Causes, Risk Factors and Prevention of Gas and Bloating

By Russell Havranek, M.D. ; Updated August 14, 2017

As humans, we don’t produce gas on our own. So when we have gas and bloating it is due to two main causes — either swallowed air or gas produced by bacteria.

Swallowing Air

We all swallow certain amounts of air throughout the day. This commonly happens during eating and drinking, especially if we eat very fast. It’s also more common in people who chew gum, smoke and drink carbonated beverages. Typically we don’t swallow enough air to be problematic, but some people do, and what they develop is gas and bloating.

Gas Production by Bacteria

This is a much more complex topic than swallowing air. We have literally trillions of bacteria that live in our gastrointestinal tract. They don’t cause us harm and, in fact, without them we couldn’t survive. They help us break down foods we eat, and some of them even produce nutrients that our bowels need to stay healthy. However, certain foods we eat get fermented by these bacteria, and in the process they make gas. This is the basis for the majority of the gas in our bowels. There is a long list of reasons they produce more gas in some people than others, and I will cover the most common ones.

Diet Choices

One of the biggest factors in how much gas is produced in our bowels is what we put into them. Bacteria love to ferment carbohydrates like pasta, breads, rice, pastries, sodas, fruits and vegetables. People who have diets high in carbohydrates tend to make more gas. One common category of foods I have my patients focus on is what we call FODMAP foods. The main FODMAP foods are:

  • Fructose (fruits, high-fructose corn syrup)
  • Lactose (dairy)
  • Fructans (wheat, onions) 
  • Galactans (beans)
  • Polyols (sweeteners, sorbitol, stone fruits like avocado, cherries, peaches and plums)


Another topic I focus on when investigating the cause of gas and bloating is medication. Not just prescription medications, but also over-the-counter ones, including supplements. Some medications cause gas because they contain fermentable products, such as lactose or gluten. Some medications affect gas production because they alter our normal bowel bacteria. When we take things like acid blockers (for heartburn) or antibiotics (for infections), they temporarily affect the bacteria in our bowels and can alter the way they ferment foods.

Medical Conditions

There are certain health problems that can predispose us to more gas and bloating as well. The main way they cause an increase in gas is by affecting either the motility or movement of food and fluids through our bowels or by affecting our immune systems. Either of these problems will lead to a condition we call small intestinal bacterial over growth (SIBO).

Diabetes is a common one. It affects both the motility of our bowels and affects our immune system.

Prior surgery on our bowels will affect motility.

Celiac disease is a condition in which you have intolerance to gluten (a protein found in foods like wheat and some grains). If you have celiac disease and ingest gluten you may develop more gas.

Dietary intolerances, such as lactose intolerance or fructose malabsorption, may cause gas and bloating.

Irritable bowel syndrome (IBS) may cause gas and bloating.

Inflammatory bowel disease, like ulcerative colitis or Crohn’s, may cause gas and bloating.

Intestinal blockage, heart disease, gallstones and appendicitis can also cause symptoms similar to gas and bloating. For this reason, it’s important to have new onset gas and bloating checked out by your physician.


It’s easier to prevent gas and bloating than it is to treat it, so this is always my focus with patients. If we think swallowed air is part of the problem, we work on eating slower and trying not to talk while eating. We also minimize carbonated drinks, chewing gum and cigarettes.

Next, we focus on dietary changes. I start them on a low-carbohydrate diet (which is good for overall health and weight as well), and we focus on reducing the FODMAP foods. We minimize unnecessary medications and over-the-counter supplements and optimize treatment of underlying medical conditions.

These types of changes are hard, especially when we are changing lifelong habits, but they work. When prevention doesn’t work, we focus on diagnosing an underlying cause and treating it.

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