Treatment Efficacy of Low FODMAP Versus Low Lactose Diet in IBS Patients

Treatment Efficacy of a Low FODMAP Diet Compared to a Low Lactose Diet in IBS Patients: a Randomized, Cross-over Designed Study

A low FODMAP diet (LFD) has become a standard treatment in irritable bowel syndrome (IBS) patients. Compliant adherence to a LFD is challenging. The investigator looked at the effect of a LFD compared to a less restrictive low lactose diet (LLD) in a randomized cross-over trial with IBS patients.

Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder. It affects 10 - 20% of the adult population. Pharmaceutical therapy as bulking agents, anticholinergics, antispasmodics, and antidiarrheals are mostly unsatisfactory and many gastroenterologists recommend therefore dietary management. Most patients note that various foods elicit abdominal symptoms and therefore restrict their diet .

The low fermentable oligosaccharide, disaccharide, monosaccharide and polyol (FODMAP) diet has currently the greatest evidence for efficacy in IBS. The rationale behind the LFD is the exclusion of poorly absorbed short-chain carbohydrates which would create an osmotic load, drag fluid into the small intestine and would be fermented by the colonic microbiome, both leading to abdominal distention and increased luminal influx. FODMAPs do not cause symptoms in healthy adults as they neither show these abnormalities in gut physiology nor suffer from visceral hypersensitivity .

It is not known however whether change in symptoms is induced by a reduction in all FODMAPs or simply a single component as for example lactose. If there is a lactase deficiency, as it is the case in 2-20% of Central- / Northern Europeans, lactose cannot be hydrolysed and causes the above mentioned symptoms. Many IBS patients avoid lactose, even though only few have a lactase deficiency. Lactose intolerance but not lactase deficiency is more frequent in patients with IBS. The investigator wanted to examine if the demanding LFD is more effective than elimination of lactose alone.

Our study, comparing in detail the effects of low FODMAP versus low lactose diet in IBS patients is a novelty, analysing a clinically highly relevant topic.

Inclusion Criteria:

• functional bowel symptoms as defined by the Rome IV criteria
• subjective lactose intolerance

Exclusion Criteria:

• pharmacologic agents to alter symptoms (laxatives, antidiarrheal agents)
• smoking
• antibiotic therapy within the last 4 weeks
• gastrointestinal diseases (Celiac disease was excluded by negative serologic testing while on a gluten containing diet
• any type of food allergy