Cow’s milk related gastrointestinal symptoms in adults

Gastrointestinal symptoms are frequent in the adult working-age population. Sufferers often relate them to ingested food substances, especially cow’s milk. The purpose of this study was to evaluate subjective food-related gastrointestinal symptoms and their relation to cow’s milk. This was done by determining the genotype of adult-type hypolactasia, measuring antibodies against milk protein, and screening the most common cause for secondary hypolactasia, namely coeliac disease, in adults in primary care. The aim was also to evaluate the clinical role of the laboratory tests used in the study. The whole study group comprised 1900 adults who gave a blood sample for the study when they attended a health care centre laboratory for various reasons. Of these 1885 completed a questionnaire on food-related gastrointestinal symptoms. The response rate was 99%, which is exceptionally high. Study No. I evaluated the prevalence of adult-type hypolactasia and its correlation to self-reported milk induced gastrointestinal symptoms. The questionnaires requested data on dairy consumption and abdominal symptoms. The testing for hypolactasia was done by determination of the C/T-13910 genotypes of the study subjects. The results show that patients with the C/C-13910 genotype associated with adult type hypolactasia consume less milk than those with C/T-13910 and T/T-13910 genotypes (high lactase activity). Study No. II evaluated the prevalence and clinical characteristics of undiagnosed coeliac disease in the whole study population with transglutaminase and endomysium antibodies and their correlation with gastrointestinal symptoms. The prevalence of undiagnosed coeliac disease was 2%, which is surprisingly high. Serum transglutaminase and endomysium antibodies are valuable tools for recognising an undiagnosed coeliac disease and should be used in outpatient clinics for diagnosing gastrointestinal symptoms. In the study No. III the evaluation of milk protein IgE related hypersensitivity was carried out by stratifying all 756 study subjects with milk related problems and randomly choosing 100 age and sex matched controls with no such symptoms from the rest of the original study group. In the study No. IV 400 serum samples were randomly selected for analyzing milk protein related IgA and IgG antibodies and their correlation to milk related GI-symptoms. The measurement of milk protein IgA, IgE or IgG (studies No. III and IV) did not correlate clearly to milk induced symptoms and gave no clinically significant information; hence their measurement is not encouraged in outpatient clinics. In conclusion, this large study of milk-related gastrointestinal symptoms in adults shows that GI-symptoms are subjectively very common. Adult type hypolactasia is often considered the reason for them, and determination of the C/T-13910 genotypes is a practical way of diagnosing the possibility of adult type hypolactasia in an outpatient setting. Undiagnosed coeliac disease, the possible cause of secondary hypolactasia, should be actively screened and diagnosed in order to apply a gluten free diet and avoid the GIsymptoms and nutritional deficiencies. Cow’s milk hypersensitivity in the adult population is difficult to diagnose since the mechanism in which it is mediated is still unclear. Measuring of cow’s milk protein specific antibodies IgE, IgA or IgG do not correlate with subjective milk-related GI-symptoms.