FODMAP intolerance
FODMAPs (Fermentable Oligo-, Di- and Mono-saccharides And Polyols) are a group of short-chain sugars that can be poorly absorbed and rapidly fermented in the small intestine. Poor absorption leads to increased gas and fluid in the bowel, which have been identified to contribute to the symptoms of bloating, abdominal pain, wind and altered bowel habits in IBS.
The efficacy of a low-FODMAP diet for IBS symptom management is well known. However simply eliminating suspected FODMAPs from your diet without objective proof is inadvisable as FODMAPs are natural prebiotics that help maintain good intestinal microbiota and general gut health. Likewise, it is inadvisable to eliminate food groups such as milk/dairy (containing lactose) or fruits and vegetables (containing fructose) without clinical justification because of their nutritional importance.
If you are suffering from these common gastrointestinal conditions you or your doctor can consider hydrogen and methane breath testing to assess your absorptive capacity for FODMAPs. Breath test results will assist in providing a more complete clinical picture leading to more effective health outcomes. Professional dietetic advice can also help to maximise food options whilst minimising symptoms. Seek answers, reduce anxiety, and get solutions to your IBS problems today.
Common FODMAPs
High FODMAP Foods
Major Food Sources
Milk, ice cream, yoghurt, custard, ricotta/cream/cottage cheese
Apple, pear, watermelon, mango, cherry, asparagus, artichoke, honey; foods with high-fructose corn syrup (e.g. soft drinks, pastries, commercial cereals)
Peach, plum, prune, apricot, dried fruit, avocado, apple, pear, mushroom, cauliflower, snow pea; sugar-free mints/gum
Mango, peach, date, sugar beet, sweet pea, most dried fruit; confectionery, soft drinks, biscuits/cookies, commercial cereals, ice cream/sorbets, desserts
Lactose
Lactose, often described as ‘milk sugar’, is a disaccharide found in mammalian milk and dairy products. The enzyme lactase is required in the stomach to digest lactose for intestinal absorption. Lactase enzyme can be either absent (congenital alactasia) or deficient (hypolactasia). Lactase deficiency increases with age, usually starting from early childhood. Ethnic origin affects the risk of lactase deficiency, with the highest prevalence occurring in those from Asian and African backgrounds. Patients with problems digesting milk may confuse lactose intolerance with allergy to the milk proteins casein and/or beta-lactoglobulin, a much rarer condition.
Fructose
Fructose, often described as ‘fruit sugar’, is a monosaccharide 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). Fructose is thought to be absorbed in the small intestine by facilitated diffusion (through a luminal transporter) and paracellular transport (with glucose). In paediatric patients, there is growing evidence that a significant percentage of children with recurrent abdominal pain of childhood (RAPC) have fructose intolerance.
Fructose shouldn’t be confused with fructans, which are chains of fructose molecules naturally occurring in a variety of vegetables and grains. Humans cannot digest fructans, so they are instead fermented by bacteria in the gut. While this can provide health benefits to some, it may cause gastrointestinal distress in others.
Polyols: Sorbitol & Mannitol
Polyols (also called sugar alcohols) are found naturally in a range of fruits and vegetables. They are also added as a sweetener in commercial foods such as chewing gum, mints, sugar-free and diabetic products. Polyols are slowly absorbed in the small intestine and symptoms will probably depend on the amount of polyols consumed, what else you have eaten with it (including other FODMAPs), and how sensitive your gut is at the time. A breath test will determine your ability to absorb a small load of polyols which will then determine whether dietary restriction is required to improve symptoms.
Sucrose
Sucrose, also known as saccharose or more commonly as table sugar, is a disaccharide found naturally in fruits and vegetables and is often added as a sweetener in processed foods. The enzyme sucrase-isomaltase is required in the stomach to digest sucrose and maltose (the sugar found in grains) for intestinal absorption. Congenital sucrase-isomaltase deficiency is a rare condition and is usually apparent in early childhood after introduction of fruits, juices and grains. Sucrose malabsorption can also develop secondary to gastrointestinal illness such as SIBO. Because many foods contain sucrose, it can be difficult to completely remove it from the diet and oral enzyme supplements (sacrosidase) can assist sucrose absorption.
NOTE: Hereditary fructose intolerance (HFI).
HFI is a rare genetic condition caused by deficiency of the enzyme aldolase B. Where HFI is suspected individuals should strictly avoid fructose, sucrose and sorbitol, and should NOT undergo hydrogen/methane breath testing for these three sugars.
Food intolerance vs food allergy
If you have a reaction after eating certain foods, it may be either a food intolerance or food allergy. However, the two are different medical conditions. Food reactions in general are common, but food intolerances are far more common than food allergies. It can be easy to confuse food intolerance with food allergy but here are some key differences.
Food allergy
Mostly children
Rare condition
Few foods
Immediate symptoms (e.g. rashes, hives, watery eyes)
Immunological
Reproducible and usually dangerous reactions
Reproducible and usually dangerous reactions
Small Intestinal Bacterial Overgrowth (SIBO)
In health, there are relatively few bacteria living in the stomach and small intestine due to several natural defence mechanisms preventing bacterial overgrowth. Some of these are: gastric acid secretion, peristalsis (muscle contractions that move food through the digestive tract), intact ileo-caecal valve (that separates the small intestine and the large intestine), and various intestinal secretions containing antibacterial/bacteriostatic properties.
The cause of SIBO is complex however it is associated with disorders of these defence mechanisms. For example, overgrowth of bacteria may occur in achlorhydria (an absence or deficiency of stomach acid) arising from hypothyroidism, medications (overuse of antacids and proton pump inhibitors), surgery (e.g. for weight loss), Helicobacter pylori infection, or certain autoimmune disorders.
In addition to IBS-like symptoms, patients with SIBO can also experience weight loss, steatorrhoea (fatty stool), and nutritional deficiencies such as vitamin B12 and vitamin D. The mainstay of treatment of SIBO is antibiotics, although some patients will be able to have surgery to correct the underlying cause.
It has recently been suggested that IBS symptoms are due partly to SIBO because IBS patients have altered gut microbiota. There is evidence supporting treating a subset of IBS patients (diarrhoea-predominant-IBS) with antibiotics to treat the underlying SIBO. There is also evidence of a role of SIBO in rosacea, with eradication of SIBO resulting in complete resolution.
