| Lactose-free diet |
No lactose-containing products, except if products are treated with lactase (ie, lactose-free cow’s milk, lactose-free yogurt) |
Only helpful for patients with lactose intolerance; not efficacious for patients with IBS without lactose intolerance81,82
|
| Low-fructose/fructan diet |
Avoid foods high in fructose and fructans. |
Observational studies and RCTs Beneficial effects on symptoms, but results highly rely on compliance16,61,83 Data mostly limited to patients with IBS with breath tests proving fructose malabsorption |
| Paleolithic diet |
Only foods available during the Paleolithic era: seafood, lean meat, fruits, vegetables, nuts, and seeds; no processed food, dairy, added salt, added sugar, grains, legumes, or alcohol83
|
No studies available |
| Specific carbohydrate diet |
Reduce ingestion of disaccharides and polysaccharides. |
Trend toward improvement in symptoms, but not statistically significant; inferior results compared to the low-FODMAP diet84
|
| IgG-based avoidance diet |
Exclude foods to which patients have increased serum IgG antibodies. |
Compared to healthy controls, patients with IBS seem to have higher levels of IgG antibodies to common foods, such as egg, crab, shrimp, soybean, and wheat. Severity of symptoms does not seem to correlate with antibody titers.85 By following an IgG-based avoidance diet, IBS patients had a small reduction in symptoms, varied based on the degree of compliance (10%-26%) when compared to a sham diet.86 |
| Very low–carbohydrate diet or ketogenic diet |
Maximum of 20 g of carbohydrates per day Approximately 5% of daily calories coming from carbohydrates, compared to the national average of 55%13 |
Only one study has been conducted, with a total of 13 patients with diarrhea-predominant IBS. 77% of patients (10/13) noted adequate relief of symptoms; specifically, improvement was seen in stool frequency and consistency, quality of life, and pain scores.87 |
| Fiber supplementation |
Psyllium supplement |
|
| Low-fat diet |
Less than 27 g of fat per day, considering a diet of 2000 kcal/day89
|
Several observational studies and noncontrolled trials to induce or evaluate symptoms, but no RCTs80 High-fat intake is able to induce symptoms in patients with IBS. Decreasing fat intake may have benefits, specifically for patients with meal-related abdominal pain.12,90-95 |
| Low-fiber diet |
Less than 10-15 g of fiber/day |
No evidence available; common practice is to recommend decreasing fiber for patients with diarrhea-predominant IBS to increase transit time |
| Low-histamine diet |
Decrease the amount of histamine-releasing foods. Foods to be avoided include alcoholic beverages, processed or semiprocessed oily fish, shellfish, cured meat, aged cheeses, fermented foods, chocolate, eggs, some specific fruits (eg, kiwi, citrus, pineapple, papaya), and nuts.96 |
No studies for adult IBS patients Several studies for dermatologic conditions, such as chronic spontaneous urticaria97 and atopic dermatitis,98 and one study for pediatric patients with chronic digestive complaints.96 No evidence to support this diet for IBS currently |
