Introduction: The relationship between genetic and food factors (presence of dairy animal industries) of lactase deficiency and gastrointestinal symptoms in native children of Siberia has not been clearly defined.
Aim: To determine the prevalence of lactase deficiency among Evenkia native and alien children (northern region of Siberia, without dairy animal industries, the Evenks (Mongoloids) is the main nationality) and Tuva (southern region of Siberia, with dairy animal industries, the Tuvinians (Mongoloids) is the main nationality) and to describe their clinical characteristics.
Methods: Qualitative estimation of galactose in urine after the introduction of lactose with the help of standard strip-tests (Kabi Diagnostika, Sweden) in children aged from 7 to 14 years. We examined 529 children of Evenkia (natives - 386, aliens - 144) and 582 children of Tuva (natives - 474, aliens - 108). Alien children were mainly non-Mongoloids. To reveal differences between the groups we implemented Chi-square test, data are given as the proportion (95% confidence interval – CI).
Results: Lactase insufficiency was revealed in 60.1% (CI 55.9–64.2) children of Evenkia (69.0% natives (CI 64.2–73.4), 36.8% aliens (CI 29.4–45.0), p<0,001) and in 63.7% (CI 59.8–67.6) children of Tuva (65.19% natives (CI 60.8–69.4), 57.41% aliens (CI 48.0–66.3), p=0,12). Lactose insufficiency was more prevalent in the Evenk and the Tuvin children, which is explained, probably by their Mongoloid origin. We have not found connection between lactase deficiency and such clinical signs as recurrent abdominal pain, chronic diarrhea, nausea, vomiting in siberian children.
Conclusion: Thus, presence of lactase deficiency is strongly determined by genetic factors. Presence of dairy animal industries (southern region of Siberia - Tuva) is the second important factor after genetics. On the other hand, lower prevalence of lactose insufficiency in alien children of Evenkia as compared to Tuva can be caused by different number of mixed marriages in these regions and the selection of healthier people for the work under severe conditions of the North.