Lactase non-persistent genotype influences on dairy product consumption and gastrointestinal symptoms in Northern Russians

Objective: Milk is an important source of nutrients. However the consumption of milk may cause abdominal complaints in lactose intolerant individuals. It is known that frequency of 13910C/C genotype is high among Northern Russians and exceeds the prevalence in northern Europe. In our study we tested two hypothesis 1) subjects with lactase non-persistent genotype (13910C/C) have more symptoms associated with milk 2) subjects with lactase non-persistence avoid using milk. Methods: In total, 518 students aged 17 to 26 years were randomly selected from different departments of the Northern State Medical University (NSMU) for the genotyping lactase activity defining -13910C/T variant. All subjects filled in a questionnaire about their personal data, self-reported gastrointestinal (GI) symptoms and milk consumption habit. Results: Northern Russians consume very small amount of milk weekly. Among carriers of lactase non-persistent (LNP) genotype there are 10 percent units milk-consumers less than among lactase persistent (LP) persons (p = 0.03). Complaints to GI disorders caused by milk were different between genotypes (p = 0.02). From all analyzed types of food only milk was associated with increased GI symptoms among subjects with LNP genotype (OR =1.95, CI 1.033.69) Conclusions: Our study confirmed that even small amounts of milk result in higher frequency of GI disorders in LNP subjects. Hence both hypotheses were verified. In case of increasing milk consumption symptoms may increase need of medical consultations. Consequently it is important either for people themselves or for health care staff to be aware about lactase persistence/non-persistence.