The prevalence of lactase deficiency and lactose intolerance in Chinese children of different ages

Objective To determine lactose metabolism and lactase activity in Chinese c hildren of different ages, prevalence of lactase deficiency (LD), and lacto se intolerance (LI). Methods All 1168 healthy subjects between 3 and 13 years were recruited fro m schools in four large cities in China. They were screened by a 25 g lacto se tolerance test. Some subjects were challenged with 50 g milk powder on d ifferent days. Both indicators, the expiratory H-2 concentration and intole rance symptoms, were analyzed. Results LD occurred in 38.5% of children in the 3-5 year age group, and 87% of the 7 - 8 year and 11 - 13 year old groups. The age of occurrence for L D may be at 7 - 8 years among Chinese children. The prevalence of LI among Chinese children was 12.2% at age 3 - 5 years, 33.1% at age 7 - 8 years, an d 30.5% at age 11-13 years, respectively. Conclusion The results demonstrate that RD is very common in Chinese childr en from these four cities. LD and LI have a dose dependent response: lactos e absorption and symptoms are based on lactase activity. The relationship b etween breast feeding history (or the history of cow milk intake) and lacta se activity among Chinese children has not been established.