People with coeliac disease develop a permanent sensitivity to gluten, a protein found in cereals such as wheat, rye, and barley. An estimated 1% of the UK population is affected.
Genes play their part, but it is also thought that some environmental factor in infancy primes the immune system to react to gluten later on.
The researchers systematically reviewed research on breast feeding and the risk of gluten intolerance published between 1996 and 2004.
Of the 15 studies, six matched the criteria set by the researchers. The analysis of more than 900 children with coeliac disease and almost 3500 healthy children showed that the longer a child was breastfed, the lower was his or her risk of the condition.
And infants who were being regularly breastfed when they were first introduced to foods containing gluten cut their risk of developing coeliac disease by 52% compared with those who were not being breastfed.
The analysis did not provide any clues as to whether breastfeeding conferred permanent protection against gluten intolerance or whether it merely delayed symptoms. Nor was it clear exactly how breastfeeding protects a child.
It may be that a child is simply exposed to less gluten during weaning if s/he is being breastfed, suggest the authors. But breastfeeding might also cut the number of gastrointestinal infections, thereby reducing the potential to weaken the lining of the bowel, or it may curb the immune response to gluten, they say.