title: Lactase non-persistent genotype influences milk consumption and gastrointestinal symptoms in Northern Russians.
abstract: BACKGROUND
  Milk is an important source of nutrients. The consumption of milk, however, may cause abdominal complaints in lactose intolerant individuals. The frequency of -13910C/C genotype is known to be high among Northern Russians, exceeding the prevalence in northern Europe. In our study we tested two hypotheses: 1) subjects with lactase non-persistent genotype (-13910C/C) have more gastrointestinal (GI) 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 in the Northern State Medical University (NSMU) for genotyping the lactase activity-defining -13910C/T variant. All subjects filled in a questionnaire covering their personal data, self-reported GI symptoms and milk consumption habits.
  
  
  RESULTS
  Northern Russians consume very small amounts of milk daily. Among carriers of the lactase non-persistent (LNP) genotype there were 10 percentage units of milk-consumers fewer than among lactase-persistent (LP) subjects (p = 0.03). Complaints of GI disorders caused by milk were different between the genotypes (p = 0.02). Among all types of food analyzed only milk was associated with increased GI symptoms among subjects with the LNP genotype (OR = 1.95, CI 1.03-3.69)
  
  
  CONCLUSIONS
  Subjects with -13910C/C have more GI symptoms from milk. Subjects with lactase non-persistent genotype avoid using milk. In the case of increasing milk consumption symptoms may increase the need for medical consultation. It is thus important either for people themselves or for health care staff to be aware of lactase persistence/non-persistence.
authors.affiliation: Department of Family Medicine, Northern State Medical University, Arkhangelsk 163000, Russia and Medical School, Tampere University 33014, Finland. yuliakaterina@rambler.ru
authors.forename: Yulia
authors.initials: Y
authors.lastname: Khabarova
authors.forename: Suvi
authors.initials: S
authors.lastname: Tornianen
authors.forename: Sari
authors.initials: S
authors.lastname: Tuomisto
authors.forename: Irma
authors.initials: I
authors.lastname: Järvelä
authors.forename: Pekka
authors.initials: P
authors.lastname: Karhunen
authors.forename: Mauri
authors.initials: M
authors.lastname: Isokoski
authors.forename: Kari
authors.initials: K
authors.lastname: Mattila
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D016001:Confidence Intervals; D005247:Feeding Behavior; D005767:Gastrointestinal Diseases / Q000209:etiology; D005838:Genotype; D006801:Humans; D043322:Lactase / Q000172:deficiency / Q000235:genetics*; D007787:Lactose Intolerance / Q000235:genetics*; D016015:Logistic Models; D008892:Milk / Q000009:adverse effects* / Q000201:enzymology; D016017:Odds Ratio; D012426:Russia; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D043322:Lactase
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