The dietary approach for IBS is to eat foods that are easily digested, so that most of the nutrients can be absorbed higher up in the intestine, away from bacteria.
Foods that are not well absorbed should be minimized or eliminated from the diet, because they end up being a good fuel source for the bacteria residing near the end of the small intestine. High-fiber diets can make symptoms worse for many patients with IBS. Fiber is comprised of carbohydrates that humans can’t digest. Bacteria ferment it, producing bloating. Certain complex sugars also are fermented by the bacteria. We recommend a diet that contains only modest amounts of fiber found naturally in fruits and vegetables, in place of fiber supplements intended as stool-bulking agents.
Eating frequently causes problems because that the cleaning-waves in the small intestine that gets rid of food byproducts, waste, and bacteria and this can only occur when you’re not eating. The more meals that you have per day - and this includes snacks between meals - the less time your body has to produce appropriate cleansing waves, making it easier for the bacteria to remain in the small intestine.
Adequate fluid intake throughout the day is also important. If your diet does not include enough water, it becomes more difficult for your body to have proper bowel motility.
The following guidelines should be followed so that you have the best chance of minimizing the return of bacterial overgrowth.
1. Try to avoid the following sweeteners:
- Corn Syrup (fructose)
- Mannitol
- Sorbitol (often found in gum)
- Sucralose (Splenda)
- Lactose
- Lactulose
You should also limit foods and food products sweetened with fruit juice, which contains fructose. This is hard because so many food products are sweetened with fructose. Try to limit your sugar intake to no more than 40 grams per day, and ideally much less. Reading food labels can help you achieve your goal. The following sugars and sweeteners are acceptable: glucose, sucrose (table sugar), and aspartame (Equal or NutraSweet).
2. Limit or eliminate the following “high-residue” foods.
- Beans (kidney beans, garbanzo beans, pinto beans, etc.)
- Lentils
- Peas (including spilt-pea soup)
3. Drink eight cups of water a day. A good guideline is to drink two cups of water with each of your three meals, then one cup between breakfast and lunch, and one cup between lunch and dinner.
4. Beef, fish, poultry, and eggs are acceptable foods, and are also good sources of protein. You do not need to limit these foods throughout the day. However, be sure to only eat portions that are appropriate for your body size. Most people require only about 4-8 ounces of meat per day.
5. Potatoes, pasta, rice, bread, and cereals are also acceptable. We do find that some people have difficulty with bread and pasta – you may need to experiment. It’s all right to include some of these foods at each meal. They contain carbohydrates that are well absorbed high up in the small intestine, serving as fuel for your body, not for the bacteria. A good rule of thumb is to eat no more than a half cup to one cup of these carbohydrate foods at each meal. Try to keep multigrain breads to a minimum. If whole-grain breads are desired, oat and wheat fibers are better choices. Also avoid wild rice.
6. Fruits should be eaten in moderation – no more than two servings per day. Fruits contain fructose, which is difficult to digest. Choose fresh, not dried fruit. Dried fruits concentrate the fructose into a smaller package and it allows for more fructose ingestion because more is eaten.
7. Fresh, non-starchy vegetables should also be part of your daily food intake. Cooked or lightly steamed vegetables are preferable to raw vegetables, because they are easier to digest and absorb. Avoid large salads full of raw vegetables, as this can lead to too much residue. You can incorporate small amounts of salad, but do not eat raw vegetables exclusively as they are hard to digest. A good rule of thumb is to have three to five cups of cooked vegetables per day.
8. Dairy products are best avoided initially because of the lactose they contain. You may tolerate lactose by the use of Lactaid pills. Try almond or rice milk or Lactaid milk. Soy milk can cause gas in some.
9. Coffee, tea, and soda should be consumed only in moderate amounts. Out of these three types of beverages, tea is probably the most healthful choice. Coffee is also acceptable as long as you limit your intake to one or two cups per day. Sodas, on the other hand, are not a healthy choice. Non-diet sodas may contain corn syrup and other types of sugar. Diet sodas containing NutraSweet may be consumed in moderation. When you are thirsty, however, the best option is to have pure, filtered water. Water flavored with lemon or lime juice is also a good alternative.
10. Finally, make sure you eat a balanced diet and that your meals contain sufficient calories so that you are able to maintain your body weight. In addition, incorporate moderate exercise into your weekly routine at least every other day, as regular physical activity helps to maintain regular bowel movements.
