© 1990 by Oxford University Press
research-article |
Age Dependency of the Lactase Persistence and Lactase Restriction Phenotypes Among Children in Sri Lanka and Britain
*Department of Clinical Biochemistry, Institute of Child Health/Hospitals for Sick Children London, UK
**Academic Department of Paediatric Gastroenterology, Queen Elizabeth Hospital for Children London
***Princess Alexandra Hospital Brisbane, Australia
Correspondence: Dr S. Thomas, Institute of Child Health, 30 Guilford Street, London WC1, UK.
All neonates are born with intestinal lactase activity. In most of them the intestinal lactase activity is lost during childhood (lactase restriction phenotype). In a minority of children normal intestinal lactase activity is retained (lactase persistence phenotype). In this study the progression of the lactase restriction phenotypes has been studied in 94 Sri Lankan children by oral lactose loads and 162 British children by intestinal lactase estimation (adult Sri Lankans and British predominantly belong to the lactase restriction and lactase persistence phenotypes, respectively). Lactase was present in infancy at birth in all Sri Lankan children and declined around the age of eight years, the majority (59 per cent) of the 10–15-year-olds belonging to the lactase restriction phenotype. In contrast the majority of the British children (95 per cent of all the British children studied) demonstrated the lactase persistence phenotype. The low prevalence rate of the restriction phenotype found among British children was largely contributed by children of African and Asian origin.