actose malabsorption and lactose intolerance were determined in 30 Tibetan teen-agers and 30 Han teen-agers byhybrogen breath test(HBT)

There were 21 cases of lactose malabsorption in 30 Tibetan tenn- agers(70%)and 2 cases oflactose intolerance in those 21 lactose malabsorbers(9.57%)However

lactose malabsorption was found in 29 out of 30cases(96.67%)and lactose intolerance 16 out of 29 cases(55 17%)of lactose malabsorption in Han teen-agers. The fre-quencies of lactose malabstorption and lactose intolerance in Tibetan teen-agers were obviously lower than those ofHan’sre-spoctively(P<0.01 & P < 0. 05) It is proposed that the difference of frequencies in lactose malabsorption and lactose in-tolerance betWeen Tibetan and Han may be due to their distinctive enviromental factors and dietarv habits.