Small intestinal permeability to mannitol and lactulose in the three ethnic groups resident in west Birmingham

Asymptomatic residents of tropical countries have differences in small intestinal morphology and permeability compared with residents of temperate zones. The aim of this study was to investigate small intestinal permeability and morphology in three ethnic groups resident in Birmingham, UK.

28 white patients, 101 Indian (Indian subcontinent), and 49 Afro-Caribbean adult patients with dyspepsia had endoscopic distal duodenal biopsies and a hyperosmolar lactulose/mannitol permeability test. Twenty normal white subjects had the permeability test.

Lactulose/mannitol excretion ratios (LMER) were: white subjects 0.022 (median), white patients 0.022, Indians 0.031, Afro-Caribbeans 0.033. Differences between the immigrant groups and the two white groups were significant (p < 0.001); 33% of Indians and 45% of Afro-Caribbeans had LMER outside the range of the white groups. Afro-Caribbeans born in the UK had significantly lower LMER than those born abroad (p < 0.05); a similar trend was seen in Indians. Villous height/mucosal thickness ratios, calculated from small intestinal biopsy specimens, were lower in the immigrant groups and correlated inversely with LMER (r = 0.28; p < 0.05). Time resident in the tropics also correlated inversely with LMER.

There were significant differences in small intestinal permeability and morphology between immigrants resident in a Western country and the native white population. The data suggested that these differences were related to environmental factors.