The FODMAP Approach: what is it?
The FODMAP Approach is the restriction of foods which fall into FODMAP categories. These foods contain undigestible carbohydrates that are not digested and absorbed — rather they are fermented by bacteria in the colon. Gas is a natural result of fermentation and may cause symptoms, which some individuals describe as excessive gas and or bloating. When the normal tasks of the gastrointestinal tract are not functioning well, these symptoms are demonstrative of what gastroenterologists have termed functional gastrointestinal disorders (FGID). Various and numerous treatments have been tried, seldom with significant positive results. However, more recently, with the recognition of symptoms associated with specific food intake, the use of the FODMAP diet is demonstrating better treatment outcomes. The primary investigation of the therapy was conducted in Victoria, Australia by Professor Peter R. Gibson and Susan J. Shepherd. 1
FODMAP is an abbreviation for: Fermentable Oligo-, Di-and Monosaccharides and Polyols. More commonly known as fructose, lactose, fructo-and galacto-oligosaccharides (fructans and galactans) and polyols. Fructose is found in high fructose corn syrup, but also in fruits, and lactose is the carbohydrate found in milk. Oligosaccharides are in many foods of plant origin and polyols in some fruits, vegetables, and sweeteners, such as sorbitol, mannitol, zylitol and maltitol.
The researchers advise a medical workup which includes gathering information on the symptoms, their frequency and description, and whether or not this investigation leads to a diagnosis of FGID. Breath hydrogen tests are advised for fructose and lactose. The tests measure hydrogen in the breath coming from the gastrointestinal tract after a measured dose of the suspect carbohydrate. The tests then give the physician an indication of the degree of food restriction that is necessary.
Dietitians are given the responsibility for identifying the typical diet of the patient with particular emphasis on daily intake of FODMAP foods. The dietitian also explains what “poorly absorbed” and “malabsorption” mean and the consequences of fermentation. Based on the medical testing and the dietitian’s findings, specific instructions are given for the FODMAP diet tailored for the specific patient.
The actual listing of high FODMAP food sources along with low FODMAP sources is contained in Gibson’s paper. In Gibson’s listing, an example is the elimination of fruits in the high listing with excessive fructose: apples, pears, clingstone peaches, mango, sugar snap peas, watermelon, canned fruit in natural juices. In the low FODMAP category are listed foods which are suitable alternatives: banana, blueberry, grapefruit, grape, honeydew melon, kiwifruit, lemon, lime, raspberries, and strawberries.
The diet, as studied by Gibson and Shepherd, was a dietitian-directed, one-on-one instructed diet, with a strict trial of 6-8 weeks. After that time, the dietitian assessed symptoms and, with a consideration of the total FODMAP load, began to test tolerance to small servings of foods that had been eliminated. The researchers found that if the patients complied with the diet, it was effective in providing relief of symptoms in about 75% of their patients.
As a dietitian I am particularly concerned about the elimination of yogurt, as it is listed in the high FODMAP category. Yogurt is a source of live active cultures (probiotics). Garlic, onions, and shallots listed in the high oligosaccharide category and they are sources of prebiotics. Both are good for GI health. Gibson and Shepherd in their research paper, provide a cautionary statement: “altering diet carries a risk of nutritional compromise and it is a good principle not to restrict foods if not necessary.” In addition, there is a warning that: “Restriction of FODMAP intake might have a downside. It does mean restriction of dietary components with prebiotic effects. This might be detrimental to large bowel health (such as the promotion of colorectal carcinogenesis), although no studies have addressed this issue to date.
My advice, if you want to try FODMAPs, is to work with a team comprised of a physician and dietitian who are knowledgeable in this arena, who can first determine if you are a candidate for the FODMAP Approach, and evaluate if the diet provides relief of your symptoms. Most important foods need to be added back according to tolerance for gut health, nutrient intake, and general nutrition.
This diet is not intended to be used as a weight loss diet, as is being promoted by some, as that is not its purpose. Using this diet for other than its original purpose, which is to treat FGID after a diagnostic workup, I fear will only dilute its significance as a treatment modality.
Jo Ann Hattner RDN is a consulting nutritionist practicing in San Francisco California and author of Gut Insight: probiotics and prebiotics for digestive health and well being.
1. Gibson PR, Shepherd SJ. Evidence-based dietary management of functional gastrointestinal symptoms: The FODMAP approach. J Gastroenterol Hepatol. 2010 25(2):252-8. PubMed PMID:201369
Jo Ann Hattner