Milk consumption and gastrointestinal symptoms in preschool girls with different lactase genotypes

AIM: To analyze the frequency of milk consumption and subjective symptoms of intolerance to dairy products in the population of three- to six-year-old girls (born and resident in Samara) based on the genotype of the lactase gene. MATERIALS AND METHODS: We included 103 preschool girls ranging three to six years of age. Parents were questioned about the frequency of milk consumption by the child (per week), as well as the presence of gastrointestinal symptoms in their children (abdominal pain, bloating, flatulence and diarrhea) and the suspected association of symptoms with milk consumption (according to the parents). Buccal samples were taken from all girls to determine the polymorphism of the lactase genes (determination of C/T-13910 variant of the MCM6 gene). RESULTS: A significant relationship between the frequency of milk consumption and the variant of the polymorphic locus of the lactase gene, MCM6 [C > 13910T; which affects the expression of the lactase gene (LCT)] has not been established. There is no correlation in the enlarged gradation of frequent milk consumption (4–7 times a week) and rare milk consumption (2–3 times a week or less): of 53 girls with the CC genotype 27 (51%) often drink milk, 26 (49%) rarely drink milk; of 39 girls with CT genotype 23 (59%) often consume milk, 16 (41%) rarely consume milk; of 11 girls with the TT genotype, 8 (73%) often consume milk, 3 (27%) rarely consume milk (c2 1.94, p = 0.379). There was no significant relationship between the frequency of milk consumption, subjective symptoms of lactose intolerance (abdominal pain, bloating, flatulence and diarrhea) and the genotype; these symptoms were found only in four girls carrying the C allele (CC and CT genotypes) though not detected in girls with TT genotype. CONCLUSION: In girls of 3–6 years old, there is no relationship between the frequency of milk consumption, subjective symptoms of lactose intolerance and genotype of lactase gene.