Relationship between milk lactose tolerance and body mass in teenage Tswana schoolchildren.

The Tswana and other black races of southern Africa have a high prevalence of the adult type of primary lactose intolerance. It is possible that nutritional status may affect lactose absorption, so that lactose malabsorbers may be less well nourished than lactose absorbers. However, such a poor nutritional status may have caused, or have been caused by, the lactose malabsorption. It is also possible that another factor, such as chronic diarrhoea, may cause both poor nutrition and lactose intolerance. A random sample of 92 Tswana pupils was taken from a school population of 486. Their heights and weights were measured, and the relative weight and body mass index (weight/height2) calculated for each subject. A milk tolerance test was administered to each subject to establish whether they were lactose tolerant or intolerant. There were 79 (85.9%) lactose intolerant subjects, 7 (7.6%) were probably intolerant and only 6 (6.5%) were lactose tolerant. The nutritional status of the lactose intolerant and tolerant subjects were compared. The two groups did not differ in nutritional status, as measured by their relative weights and body mass indices, and were nutritionally similar to a reference population of Tswana schoolchildren.