2. Intestinal Gas

Lebanese International University School of Pharmacy Non-Prescription Drugs Fall 2026– 2027 Chapter 2 Intestinal GasIntroduction 2 — Intestinal gas symptoms are: — Common — May cause discomfort and lifestyle impairment — Frequent symptoms are: — Eructation (belching of swallowed air) — Bloating (excessive gas particularly after eating) — Flatulence (excessive passage of air from the stomach or intestines through the anus) — Differentiation of temporary symptoms from a chronic gastrointestinal (GI) disorder or condition such as irritable bowel syndrome (IBS), lactose intolerance, or celiac disease is important in recommending appropriate nonprescription treatmentPathophysiology 3 — Source and composition of intestinal gas vary throughout the GI tract — Gas in the upper GI tract arises from the swallowing of atmospheric air (aerophagia): — Consists of N2 and O2 — Most swallowed air in the stomach is subsequently eliminated through belchingPathophysiology 4 — In the first portion of the small intestine: — CO2 is produced from secretion of bicarbonate to neutralize gastric acid and from metabolism of dietary substrates (e.g., fat and protein) — Most of the CO2 that is formed diffuses rapidly from the small intestine into the blood — è Does not contribute significantly to the volume of gas passed through the rectumPathophysiology 5 — The colon and rectum contain: — Less O2 — More CH4 (methane) — Similar amount of N2 — Variable amounts of H2 and CO2 Gas production results from the fermentation of food (by colonic bacteria) that escape digestion earlier in the GI tract and enter the colonCauses 6 1. Diet — e.g., onion, cabbage, dairy products, fatty food, dietary sugars, food rich in complex starch such as wheat, and fibers 2. Underlying medical conditions — e.g., IBS, Celiac disease 3. Alterations in intestinal floraCauses 7 4. Drugs: A variety of drugs may cause intestinal gas symptoms. These drugs can be categorized broadly by MOA leading to symptoms caused by physiologic changes: ü Agents that affect intestinal flora: • Lactulose, • Antibiotics ü Drugs that affect metabolism of glucose and other dietary substances: • α-glucosidase inhibitors (acarbose and miglitol) • Biguanides (metformin) • GI lipase inhibitors (orlistat) ü Drugs that affect GI motility: • Narcotics, anticholinergics, CCBs • Agents that are high in fiber (psyllium) • Nonabsorbable polymers (cholestyramine) ü Products that contain or release gas: • Effervescent solutionsCauses 8 5. Air that enters the upper GI tract upon swallowing e.g., smoking, chewing gum, sucking on hard candies, drinking carbonated beverages, wearing poor-fitting dentures, hyperventilating, or being overly anxious. Also, poor eating habits (e.g., “wolfing down” food, gulping beverages) may cause larger amounts of air to enter the stomach. 6. Carbohydrate malabsorption ( e.g. Lactase deficiency) & pancreatic insufficiency — The odor attributable to flatulence may be worsened by the ingestion of sulfate-containing foods, such as: — Cruciferous vegetables (e.g., broccoli, cabbage); — Breads and beers containing sulfate additives; — Proteins with a high content of the sulfur-containing amino acids methionine and cysteine (e.g., eggs, macadamia nuts, peanuts, pistachio nuts, red meats).9 Gas-Producing Foods Foods Associated With Minimal Gas Production • Meats: fowl, fish • Vegetables: lettuce, peppers, avocado, tomato, asparagus, zucchini, okra, olives • Fruit: cantaloupe, grapes, berries, fruit juice • Carbohydrates: refined white sugar and refined white flour • Other: all nuts, eggs, gelatin Foods Associated With Moderate Gas Production • Fruits: citrus, apples • Carbohydrates: refined white sugar and refined white flour Foods Associated With Major Gas Production • Vegetables: onions, celery, carrots, brussels sprouts, cucumbers, cabbage, cauliflower, radishes, leeks, parsnips, peas, leafy greens such as kale, beans, potatoes, eggplant • Fruit: raisins, bananas, apricots, prunes, dried fruit • Carbohydrates: whole grains, wheat germ, bran, brown rice • Dairy products: milk, ice cream, cheese (in patients who have trouble digesting lactose; check food labels of processed foods for added lactose or milk-derived ingredients) • Other: carbonated beverages10 Vegetables Grains, Cereals, Seeds, and Nuts Beans (all varieties) Bagels Beets Barley Broccoli Bran products (oat, rice, or wheat) Brussel sprouts Granola Cabbage Pistachios Carrots Rye Cauliflower Sesame flour Corn Grain Cucumbers Sunflower flour Leeks Whole-grain breads Lettuce Other Foods Onions Chili Parsley Pasta Peppers, sweet Peanut butter Peas (all varieties) Soy products (including lentils, soy milk, and tofu) Oligosaccharide-Containing Foods Associated With Intestinal Gas Production With Potential Treatment Benefit From α-Galactosidase