Milk protein IgG and IgA: the association with milk-induced gastrointestinal symptoms in adults.

AIM: To study the association between serum levels of milk protein IgG and IgA antibodies and milk-related gastrointestinal symptoms in adults. METHODS: Milk protein IgG and IgA antibodies were determined in serum samples of 400 subjects from five outpatient clinics in Southern Finland. Subjects were randomly selected from a total of 1900 adults undergoing laboratory investigations in primary care. All 400 participants had completed a questionnaire on abdominal symptoms and dairy consumption while waiting for the laboratory visit. The questionnaire covered the nature and frequency of gastrointestinal problems, the provoking food items, family history and allergies. Twelve serum samples were disqualified due to insufficient amount of sera. The levels of specific milk protein IgG and IgA were measured by using the ELISA technique. The association of the milk protein-specific antibody level was studied in relation to the milk-related gastrointestinal symptoms and dairy consumption. RESULTS: Subjects drinking milk (n = 265) had higher levels of milk protein IgG in their sera than non-milk drinkers (n = 123, P < 0.001). Subjects with gastrointestinal problems related to milk drinking (n = 119) consumed less milk but had higher milk protein IgG levels than those with no milk-related gastrointestinal symptoms (n = 198, P = 0.02). Among the symptomatic subjects, those reporting dyspeptic symptoms had lower milk protein IgG levels than non-dyspeptics (P < 0.05). However, dyspepsia was not associated with milk drinking (P = 0.5). The association of high milk protein IgG levels with constipation was close to the level of statistical significance. Diarrhea had no association with milk protein IgG level (P = 0.5). With regard to minor symptoms, flatulence and bloating (P = 0.8), were not associated with milk protein IgG level. Milk protein IgA levels did not show any association with milk drinking or abdominal symptoms. The levels of milk protein IgA and IgG declined as the age of the subjects increased (P < 0.004). CONCLUSION: Milk protein IgG but not milk IgA seems to be associated with self-reported milk-induced gastrointestinal symptoms.

Should milk-specific IgE antibodies be measured in adults in primary care?

OBJECTIVE: To study the association of milk-IgE antibodies in serum to milk-related gastrointestinal symptoms in adults in primary care. DESIGN: Open clinical study. SETTING: Five outpatient clinics in primary care in Southern Finland. SUBJECTS: A total of 756 subjects who reported milk-related gastrointestinal symptoms in primary care and as controls 101 subjects with no such symptoms. METHODS: IgE values for specific food antigens were measured (Pharmacia CAP System) in a total of 857 subjects. All food screen-positive samples (>0.35 IU/l) were analysed further for IgE for untreated skimmed milk (milk-IgE) and for boiled milk. Those found positive for milk-IgE were invited for an open milk challenge test. RESULTS: Some 5.4% (46/857) of all subjects had a positive IgE antibody screen for food antigens. Of those with a positive food screen, 28% (13/46) had milk-IgE antibodies comprising 1.5% of the total group screened. The prevalence of milk-IgE was not statistically different between those with milk-related symptoms and those with no such symptoms. IgE antibodies for boiled milk were rare. All specific IgE antibody levels were low. Bloating was the only observed symptom in milk challenge tests. CONCLUSION: IgE antibodies to cow's milk were relatively rare in the adult population and were not indicative of milk protein allergy. The observed IgE levels were low and did not correlate with subjective milk-related symptoms. The measurement of milk-specific IgE in adults should be discouraged in outpatient clinics.

Molecularly defined adult-type hypolactasia among working age people with reference to milk consumption and gastrointestinal symptoms.

AIM: To study milk consumption and subjective milk-related symptoms in adults genotyped for adult-type hypolactasia. METHODS: A total of 1900 Finnish adults were genotyped for the C/T(-13910) variant of adult-type hypolactasia and filled in a structured questionnaire concerning milk consumption and gastrointestinal problems. RESULTS: The C/C(-13910) genotype of adult-type hypolactasia was present in 18% of the study population. The prevalence of the C/C(-13910) genotype was higher among subjects who were undergoing investigations because of abdominal symptoms (24%, P < 0.05). Those with the C/C(-13910) genotype drank less milk than subjects with either the C/T(-13910) or the T/T(-13910) genotype of lactase persistence (18% vs 38%; 18% vs 36%, P < 0.01). Subjects with the C/C(-13910) genotype had experienced more gastrointestinal symptoms (84%) during the preceding three-month period than those with the C/T(-13910) (79%, P < 0.05) or the T/T(-13910) genotype (78 %, P < 0.05). Only 9% (29/338) of the subjects with the C/C(-13910) genotype consumed milk and reported no symptoms from it. CONCLUSION: Gastrointestinal symptoms are more common among adults with the C/C(-13910) genotype of adult-type hypolactasia than in those with genotypes of lactase persistence.