Lactulose
For investigation of distal small intestinal bacterial overgrowth (SIBO). Recommended for oro-caecal transit time and as a positive control for FODMAP malabsorption.
Glucose
For investigation of proximal small intestinal bacterial overgrowth (SIBO).
Fructose
For fructose malabsorption, recommended in all IBS patients, found naturally in all fruits, most vegetables, honey and is commonly added to food and drink as a sweetener (as fructose or high-fructose corn syrup).
Lactose
For lactose malabsorption (lactase deficiency), recommended in all IBS patients, found in milk and dairy products.
Sorbitol
For sorbitol malabsorption, found in some fruits (e.g. stone fruits) and as a sweetener in sugar-free foods. A sorbitol test is also useful in patients with suspected or diagnosed fructose intolerance.
Mannitol
For mannitol malabsorption, recommended particularly in vegetarians. Mannitol is used as a sugar substitute and occurs naturally in some vegetables (e.g. mushrooms, snow peas, cauliflower).
Sucrose
For sucrose malabsorption (sucrase-isomaltase deficiency), found naturally in fruits and vegetables and is often added as a sweetener in processed foods (commonly as table sugar).
