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

Objective To determine lactose metabolism and lactase activity in Chinese children of diff erent ages, prevalence of lactase deficiency (LD), and lactose intoleran ce (LI). Methods All 1168 healthy subjects between 3 and 13 years were recruited from schools in four large cities in China. They were screened by a 25 g lactose tolerance tes t. Some subjects were challenged with 50 g milk powder on different days. Bot h indicators, the expiratory H(2) concentration and intolerance symptoms, were a nalyzed.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 LD may be at 7-8 years among Chinese children. The prevalence of LI among Chinese children w as 12.2% at age 3-5 years, 33.1% at age 7-8 years, and 30.5% at age 11-13 yea rs, respectively.Conclusion The results demonstrate that LD is very common in Chinese children from these fo ur cities. LD and LI have a dose dependent response: lactose absorption and sym ptoms are based on lactase activity. The relationship between breast feeding hi story (or the history of cow milk intake) and lactase activity among Chinese chi ldren has not been established.