Lactose avoidance for young children with acute diarrhoea.

BACKGROUND: Young children with acute diarrhoea, typically due to infectious gastroenteritis, may temporarily stop producing lactase, the intestinal enzyme that digests lactose. This means they may not digest lactose, the main sugar in milk, and this may worsen or prolong the diarrhoeal illness. However, there is uncertainty whether avoiding lactose-containing milk or milk products helps young children recover from acute diarrhoea more quickly.

OBJECTIVES: To assess if avoiding or reducing intake of lactose-containing milk or milk products shortens the duration and severity of illness in young children with acute diarrhoea. We also sought other indicators of morbidity and overall mortality.

SEARCH METHODS: We searched the Cochrane Infectious Diseases Group Specialized Register (14 May 2013), Cochrane Central Register of Controlled Trials (CENTRAL) published in The Cochrane Library (Issue 4, 2013), MEDLINE (1996 to 14 May 2013), EMBASE (1974 to 14 May 2013), and LILACS (1982 to 14 May 2013), and the reference lists of potentially relevant trials, key conference proceedings, and wrote to individuals and organizations in the field.

SELECTION CRITERIA: Randomized or quasi-randomized controlled trials that assessed the effects of avoiding or reducing exposure to lactose in young children under five years with acute diarrhoea.

DATA COLLECTION AND ANALYSIS: We extracted data using the standard methods of the Cochrane Infectious Diseases Group, and two review authors independently evaluated trial quality and data extraction. Continuous outcomes were compared using mean difference (MD), and dichotomous outcomes using the risk ratio (RR). We presented all results with 95% confidence intervals (CI) and assessed the quality of evidence using the GRADE approach.

MAIN RESULTS: We included 33 trials enrolling 2973 children with acute diarrhoea. Twenty-nine trials were exclusively conducted on inpatients, all from high- or middle-income countries. Fifteen trials included children aged below 12 months, and 22 excluded children who were being breast-fed.Compared to lactose-containing milk, milk products, or foodstuffs, lactose-free products may reduce the duration of diarrhoea by an average of about 18 hours (MD -17.77, 95% CI -25.32 to -10.21, 16 trials, 1467 participants, low quality evidence). Lactose-free products probably also reduce treatment failure (defined variously as continued or worsening diarrhoea or vomiting, the need for additional rehydration therapy, or continuing weight loss) by around a half (RR 0.52, 95% CI 0.39 to 0.68, 18 trials, 1470 participants, moderate quality evidence).Diluted lactose-containing milk has not been shown to reduce the duration of diarrhoea compared to undiluted milk or milk products (five trials, 417 participants, low quality evidence), but may reduce the risk of treatment failure (RR 0.65, 95% CI 0.45 to 0.94, nine trials, 687 participants, low quality evidence).

AUTHORS' CONCLUSIONS: In young children with acute diarrhoea who are not predominantly breast-fed, change to a lactose-free diet may result in earlier resolution of acute diarrhoea and reduce treatment failure. Diluting lactose-containing formulas may also have some benefits but further trials are required to have confidence in this finding. There are no trials from low-income countries, where mortality for diarrhoea is high, and malnutrition is more common.