There is evidence that both in the developing and developed world, breastfeeding protects against gastro-enteritis. A recent study (Howie P.W. 1990) concluded that breastfeeding during the first 13 weeks of life confers protection against gastrointestinal illness for up to one year of age.

(Howie, P.W. et al. B M J 1990;300:11-16)