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Intestinal Gas Guide

You are bothered by gas, but you do not have symptoms to suggest a medical cause. Your gas is probably the result of your eating choices.

Gas arises from fermentation of foods that are not completely digested and absorbed in the small intestine. The most important dietary source of gas is undigestible carbohydrates. Different people may be more sensitive to one carbohydrate type than another.

Undigested carbohydrates

Most carbohydrates in your diet can be absorbed in the small intestine. Some food sugars require unique enzymes to break them into absorbable products. Certain food sugars are not easily digested by humans. You can reduce your gas by limiting these foods in your diet.

Sugars from the following groups are likely to cause gas:

  • Vegetable sugars: raffinose, stachyose, verbascose

    Cruciferous vegetables (cabbage, Brussels sprouts, broccoli, cauliflower, kohlrabi, and turnips), legumes (beans, peas and lentils) and certain other vegetables (onions, asparagus, and jerusalem artichokes) contain one or more undigestible sugars. These sugars named raffinose, stachyose and verbascose can not be fully digested by humans, but they can be digested by certain fungi and molds. If you have substantial gas symptoms after eating cruciferous vegetables or beans, you might consider swallowing the dietary supplement alpha-galactosidase (Beano) along with your food. This enzyme is derived from molds and it can chemically digest a portion of these sugar types in your food.

  • Resistant starches

    Corn, wheat, oats, and potatoes may contribute to gas because they are slow to be digested and can pass into the colon where they may be fermented.

  • Fruit sugar: fructose

    Fructose is not easily digested. It can be especially concentrated in fruit juices. Fruits with highly concentrated fructose include figs, dates, prunes, pears, grapes and raisins. Fructose is also found in onions and artichokes.

  • Milk sugar: lactose

    People who are lactose intolerant have significant gas from milk products.

  • Sweeteners: mannitol, sorbitol, and fructose

    Sweeteners that are made of indigestible carbohydrates are sometimes selected for diet foods and drinks, because they do not add calories if they are not absorbed by your body. However, they can create abundant gas. The sweeteners mannitol, sorbitol, and fructose are added to many liquid medicines, health foods, candies and chewing gum, and they are frequently used in powders that are mixed into liquid diet meals.

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Harvard Health Publications Source: from the Harvard Health Publications Family Health Guide, Copyright © 2007 by President and Fellows of Harvard College. All rights reserved.

Used with permission of StayWell.

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