Primary adult lactose intolerance in the Kivu Lake area: Rwanda and the bushi

Abstract

In order to investigate the ethnic differences of lactose intolerance in the Bantu and Hamitic races, lactose loading tests were performed on the populations living around Kivu Lake in central Africa. In addition to the blood sugar rise the identification of the urinary sugars after the loading test was found to be a useful criterion for the diagnosis of lactose intolerance. Two out of 27 Tutsi (7.8%), 21 out of 36 Hutu (58%), 17 out of 22 Twa (77%), and 27 out of 28 Shi (96%) were lactose intolerant. These frequencies are not linked with the actual milk-drinking habits. Of 3 Twa families, 2 were mostly lactose intolerant, whereas the third was predominantly tolerant. For 11 mixed-bred Hutu-Tutsi the frequency of lactose intolerance was 55%. The results are in favor of a genetic origin of lactose intolerance. © 1974 Plenum Publishing Corporation.