Acute diarrhoea, typically due to bacterial or viral infection, is a common childhood illness and, in low-income countries, remains an important cause of death. Over two million children under five years of age die each year in poorer countries because of acute diarrhoea. In richer countries, it does not usually cause death but it is a common reason for young children needing medical advice or hospital admission.
Young children with acute diarrhoea may temporarily be unable to digest lactose, the most common type of sugar in milk. Inability to digest and absorb lactose can make the diarrhoea worse and last longer. We looked for evidence that reducing children's lactose intake, either by feeding lactose-free milk or by diluting lactose-containing milk, shortens the duration of diarrhoea and prevents complications such as dehydration.
We looked for research up to 13 May 2013 and included 33 trials in our analyses. Twenty-two trials compared outcomes for children given a lactose-free feed with those for children given a lactose-containing feed and 11 trials compared outcomes for children fed a diluted milk feed with those for children given an undiluted milk feed.
We found evidence that feeds that do not contain lactose may reduce the duration of diarrhoea by an average of about 18 hours (low quality evidence). Lactose-free feeds probably lower the risk of children having prolonged or worsening diarrhoea (moderate quality evidence).
We did not find any evidence that diluted milk feeds reduce the duration of diarrhoea (low quality evidence) but these feeds may lower the risk of children having prolonged or worsening diarrhoea (low quality evidence).
The majority of trials excluded breast fed infants, and none were conducted in low-income countries where diarrhoea can cause death, so the review is relevant to infants and young children who are receiving formula or are weaned in high- and middle-income countries.
MacGillivray, S.; Fahey, T.; McGuire, W. Lactose avoidance for young children with acute diarrhoea. Cochrane Database of Systematic Reviews (2013) (Issue 10) Art. No.: CD005433. [DOI: 10.1002/14651858.CD005433.pub2]