Why do Healthy Foods Make Us Bloated and Gassy?

You’re exercising, feeling good, and you want to put the healthiest food into your body. You spin through the produce department and then the bulk foods section at the grocery store, loading up on a wonderful mix of broccoli, cauliflower, peppers, and beans, peas, legumes. It is a fairly cheap haul, and a little preparation yields a bounty of raw, steamed, or roasted vegetables with a side of rich red kidney beans.

The nutrient density of this meal protects nearly every cell of your body from cancer, diabetes, and heart disease. Eating all you want of these foods daily, while eliminating processed foods, fats, meat, and dairy, has been proven to dramatically lower your cholesterol, your blood pressure, and your weight. It probably lowers your expenses, too.

But, and here’s the thing, you are uncomfortable after eating these beautiful whole foods. You feel bloated and need to loosen your belt. Soon you have to excuse yourself…because of gas.

Why does this happen? The reality is that most humans pass gas a total of 14-23 times per day, which may include burping. About half of the gas is swallowed air and another 40 percent is carbon dioxide given off by bacteria in the intestines. The remaining ten percent is a mixture of hydrogen, methane, sulfur compounds, and by-products of bacteria, such as indoles, skatoles, ammonia, and hydrogen sulfide. It is this last fraction that is responsible for the offensive odors.

According to the National Digestive Diseases Information Clearinghouse (NDDIC), a service of the National Institutes of Health (NIH), most foods that contain carbohydrates can cause gas. By contrast, fats and proteins cause little gas. The NDDIC explains why—and which—sugars, starches and fiber cause gas:

Sugar. The sugars that cause gas are raffinose, lactose, fructose, and sorbitol.

Raffinose. Beans contain large amounts of this complex sugar. Smaller amounts are found in cabbage, brussels sprouts, broccoli, asparagus, other vegetables, and whole grains.

Lactose. Lactose is the natural sugar in milk. It is also found in milk products, such as cheese and ice cream, and processed foods, such as bread, cereal, and salad dressing. Many people, particularly those of African, Native American, or Asian background, normally have low levels of lactase, the enzyme needed to digest lactose, after childhood. Also, as people age, their enzyme levels decrease. As a result, over time people may experience increasing amounts of gas after eating foods containing lactose.

Fructose. Fructose is naturally present in onions, artichokes, pears, and wheat. It is also used as a sweetener in some soft drinks and fruit drinks.
Sorbitol. Sorbitol is a sugar found naturally in fruits, including apples, pears, peaches, and prunes. It is also used as an artificial sweetener in many dietetic foods and sugar-free candies and gums.

Starch. Most starches, including potatoes, corn, pasta, and wheat, produce gas as they are broken down in the large intestine. Rice is the only starch that does not cause gas.

Fiber. Many foods contain soluble and insoluble fiber. Soluble fiber dissolves easily in water and takes on a soft, gel-like texture in the intestines, which helps the body handle fats, cholesterol, and carbohydrates. Soluble fiber plays a role in helping to lower blood cholesterol levels, one of the main risk factors for the development of cardiovascular disease. Found in oat bran, beans, peas, and most fruits, soluble fiber is not broken down until it reaches the large intestine, where digestion causes gas.

Insoluble fiber, on the other hand, generally thought of as “roughage,” passes quickly and essentially unchanged through the intestines, producing little gas. Wheat bran and some vegetables contain this kind of fiber.

Specific to legumes, the primary compounds causing gas are oligosaccharides, which are made up of three to five sugar molecules linked together in such a way that the body cannot digest or absorb them. Because these oligosaccharides cannot be absorbed, they pass into the intestines where bacteria break them down; the bacteria then produces gas. Properly cooking or sprouting legumes can significantly reduce the amount of oligosaccharides (and gas).

What can you do about gas? The Mayo Clinic suggests over-the-counter products that contain simethicone, charcoal, or an enzyme that assists in breaking down beans and vegetables. Other tips include eating slowly, avoiding carbonated beverages, and chewing gum. Engaging in more physical activities such as walking can help with digestion too.

In terms of nonprescription medicines, the Cleveland Clinic lists a variety of options currently available. Antacids, such as Mylanta and, Maalox, contain simethicone, a foaming agent that joins gas bubbles in the stomach so that gas is more easily belched away. However, these medicines have no effect on intestinal gas. The recommended dose is two to four tablespoons of the simethicone preparation taken 30 minutes to two hours after meals.

Activated charcoal tablets may provide relief from gas in the colon. Studies have shown that intestinal gas is greatly reduced when these are taken before and after a meal. The usual dose is two to four tablets taken just before eating and one hour after meals.

The enzyme lactase, which aids with lactose digestion, is available in liquid and tablet form without a prescription (Lactaid and Lactrase). Adding a few drops of liquid lactase to milk before drinking it or chewing lactase tablets just before eating helps digest foods that contain lactose. Also, lactose-reduced milk (Dairy Ease) and other products are available at many grocery stores.

Beano, a newer over-the-counter digestive aid, contains the sugar-digesting enzyme that the body lacks to digest the sugar in beans and many vegetables. The enzyme comes in liquid form and tablets. Three to 10 drops of the liquid per serving are added to food just before eating to break down the gas-producing sugars. Beano has no effect on gas caused by lactose or fiber. It has been noted that most vegetables also contain fiber, which is gas productive in some people, but usually far less so than the alpha-linked sugars.

“Many of the issues relating to gas are a combination of bowel flora, undigested food, and GI transit. Probiotics may help with altering bowel flora in a positive way,” said Dr. Mona Ridgeway, of Austin Gastroenterology, a graduate of Harvard College and Harvard Medical School who trained at Stanford.

“It is a challenge to get people to eat healthy carbs,” Dr. Ridgeway said. “Exercise may also help GI transit and motility. And with time, many people do adjust to eating a healthy diet.” As for using a product like Beano to add the alpha glactosidase enzyme, Dr. Ridgeway said, “There’s no way to test whether it will help, but it’s not going to hurt you.”