[Prevalence of the lactase deficiency among the population of the northwestern region of Russia].

The article presents the authors' and literature data on the prevalence of the lactase deficiency among the nations of the Finn-Ugric language group (Finns, Karelians, Vepses, Izhors, Estonians), Eastern Slavs (Russians, Ukrainians, Belorussians) living in the northwestern region of Russia. The lactase deficiency has been established: among Russians--16%, Belorussians--15%, Ukrainians--13%, Finns--22%, Karelians--20%, Vepses--20%, Izhors--20%, Estonians--23%. Confirmations of the cultural and historical hypothesis of the lactase deficiency prevalence have been found. It has been shown that under certain ecological conditions the nature of human nutrition during a continuous period of history can produce significant genetic changes in the population.