Authors: Vernia P, Di Camillo M, Marinaro V.

Institution: Chair of Gastroenterology 1, La Sapienza University, Rome, Italy. vernia@uniroma1.it

Background: The relationship between lactose malabsorption, irritable bowel syndrome and development of intestinal symptoms is unclear, especially when the ingested dose of milk is small.

Thus, the role of hydrogen breath testing in the diagnostic work-up of patients with nonspecific intestinal symptoms is still debated. AIMS: To establish the relationship between lactose malabsorption, severe self-reported milk intolerance, irritable bowel syndrome and related symptoms.

Results: The prevalence of a positive breath test was comparable in the two groups (337 patients with irritable bowel syndrome (66.9%) vs 240 patients with milk intolerance (71.4%)). The same holds true for the first peak of hydrogen excretion, total hydrogen output and prevalence of symptoms during, and in the four hours after, the test. The predominant presenting symptom was not useful for predicting outcome of the test either in regular milk users or in milk intolerant subjects.

Conclusions: The almost identical results of the lactose breath test of patients with irritable bowel syndrome and subjects with self-reported milk intolerance suggests that the two conditions overlap to such an extent that the clinical approach should be the same. A lactose breath test should always be included in the diagnostic work-up for irritable bowel syndrome, as fermentation of malabsorbed lactose is likely responsible for triggering symptoms. Conversely, lactase deficiency is probably irrelevant in most subjects not affected by irritable bowel syndrome, within a moderate milk consumption.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=11407668&query_hl=50

• The Clinical Relevance of Lactose Malabsorption in Irritable Bowel Syndrome
• Normalization of Lactulose Breath Testing Correlates with Symptom Improvement in Irritable Bowel Syndrome. a Double-Blind, Randomized, Placebo-Controlled Study
• The Effect of a Lactose-Restricted Diet in Patients with a Positive Lactose Tolerance Test, Earlier Diagnosed as Irritable Bowel Syndrome: a 5-year Follow-Up Study
• Lactose Intolerance in Different Types of Irritable Bowel Syndrome in North Indians