Dietary considerations such as reducing daily intake of caffeine and fatty foods may benefit individuals with IBS (Lee 2012). Individuals with IBS are often aware of some foods that exacerbate symptoms; thus, they may be able to improve symptoms by avoiding those foods (Torpy 2011). The following specific diets may help manage IBS symptoms. Each involves the selective exclusion of one or more types of food.
FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols)
A low FODMAP diet is based on the hypothesis that impaired carbohydrate absorption allows excess undigested carbohydrates to reach the lower GI tract (large intestine). There, undigested carbohydrates stimulate the growth of pathogenic microbes, leading to excess gas, diarrhea, and constipation (Ostgaard 2012). Theoretically, the restriction of fermentable foodstuffs deprives the dysbiotic gut flora of their energy source and results in decreased symptoms.
Foods typically avoided on a low FODMAP diet include: fructo-oligosaccharides (eg, wheat, rye, onions, garlic, artichokes), galacto-oligosaccharides (eg, legumes), lactose (eg, milk), fructose (eg, honey, apples, pears, watermelon, mango), sorbitol (eg, apples, pears, stone fruits, sugar-free mints/gums), and mannitol (eg, mushrooms, cauliflower, sugar-free mints/gums). In one study, IBS sufferers assigned to a low FODMAP diet experienced significant improvement in their symptom response (ie, bloating, abdominal pain, and flatulence) relative to a standard diet group (Barrett 2012; Staudacher 2011). These results are supported by a later study showing that IBS patients who were guided to eat a low FODMAP diet experienced a significant decrease in abdominal pain (Ostgaard 2012).
While a gluten-free diet is required for patients with celiac disease, there is a wide spectrum of non-celiac gluten sensitivities that present like IBS (Volta 2012). Gluten is found in grains (eg, wheat, barley, rye), breads, pasta, etc. Similar to the gluten-free diet, the low FODMAP diet also restricts gluten. Both diets are used to manage food sensitivities, suggesting that gluten sensitivity might be a more common contributor to IBS symptoms than previously thought (Carroccio 2012). In one double-blind, randomized, placebo-controlled study of IBS sufferers who specifically did not have celiac disease, addition of gluten worsened abdominal pain, bloating, fatigue, stool consistency, and overall symptoms of IBS (Biesiekierski 2011).