Research Of Epidemiological Investigation Of Subjective Lactose Intolerance And Lactase Gene Polymorphisms In Hangzhou Urban Populations

1.The epidemiological investigation of subjective lactose intolerance in Hangzhou urban populations1.1 Investigation of incidence and analysis of relevant factors of lactose intolerance in Hangzhou urban populationBackground:Because of lactase deficiency,a lot of people had the symptoms of abdominal discomfort after intaking milk with a certain amount of lactose,and they subjectively thought that they were lactose intolerance,so they avoided eating dairy products,which might give them a long-term health hazards.However,at present,there is a lack of reports about subjective lactose intolerance and the changes on intaking milk and dairy products induced by subjective lactose intolerance.Aims:To investigate the incidence of subjective lactose intolerance in Hangzhou urban populations,and to explore the related factors.Methods:In accordance with the stratified group random sampling principle,three districts of Hangzhou Urban were taken in,and then a community was extracted from every district as the points to investigate community residents for sample survey.The questionnaire survey was used by face-to-face inquiry questionnaire approach.The contents of questionnaire included the conditions of personal drinking milk and dairy products(involving the category and quantity) and the symptoms of abdominal discomfort after drinking milk and dairy products(including abdominal distension, gastrointestinal flatulence,borborygmus,abdominal pain,diarrhea,nausea,vomiting, etc.),and included the Life Events Scale,Hospital Anxiety and Depression Scale and Intestinal Symptoms Scale.SPSS 13.0 statistical software was used to conduct statistical analysis.Mann-Whitney U test was used to analyze the non-normal distribution data,and Logistic regression analysis was used to evaluate the differences of lactose intake in gender and age group and multiple factors between subjective lactose intolerance and lactose tolerance.Results:Eight hundred people were investigated,then 68 people were removed out of this study because of incomplete information in the questionnaire,and finally there were 732 effective questionnaires analyzed.Among them,261 cases were male and 471 cases were female,whose age was 17-75 years old with the average age of 46.12±14.77.In 732 cases,there were 135 cases with subjective lactose intolerance.There were 40 males and 95 females,and the average of age was 45.59±14.60.Among them,111 cases had mild abdominal discomfort,16 cases with moderate and 8 cases with severe discomfort.There was difference in the category of dairy products consumption,and milk consumption was the major,followed by yogurt and flavoring milk.However, there was little consumption in milk powder and condensed milk or concentrated milk. The major population who consumed much yogurt had relative less milk consumption. Among the different reasons about the category of dairy products consumption,there were 413 cases with the non-drinking habits of dairy products(56.4%,413/732);and 166 cases were the cause of disliking dairy taste(22.7%),and 135 cases had abdominal symptoms after dairy products consumption(18.4%),and only 18 cases(2.5%) consider that they could not bear the economy on the daily consumption of dairy products.The intake of lactose from dairy products in women was more than in men,and there was statistical difference.The intake of lactose was gradually reduced with age,and there was significant difference between the people below 30 years of age and people over the age of 60.The intake of dairy products and lactose in subjective lactose intolerance was much less than in asymptomatic population,and there was statistical difference.There were no significant differences between subjective lactose intolerance and lactose tolerance in gender,age,family per capita monthly income,occupation and level of education.The scores of anxiety,depression,life stress and bowel symptoms all were higher in subjective lactose intolerance than in lactose tolerance.However,there was statistical difference only in anxiety.Conclusions:The intake of dairy products and lactose was gradually reduced with age in Hangzhou urban populations.Among the populations,the ratio of subjective lactose intolerance was high,and the intake of dairy products and lactose in subjective lactose intolerance was much less than in asymptomatic populations.The level of anxiety status was higher in subjective lactose intolerance than in tolerance.1.2 Research of relevance of subjective lactose intolerance and actual lactose intoleranceBackground:There were many researches about lactose intolerance.However,it was still common for misunderstanding in lactose intolerance.In fact,part of people with subjective lactose intolerance could normally digest lactose.Therefore,it was very important on the determination for subjective lactose intolerance.Aims:To explore the situation of subjective lactose intolerance and actual lactose intolerance,and to evaluate the relevance of subjective lactose intolerance and actual lactose intolerance.Methods:Study subjects were the people who lived in Hangzhou,and were selected according to the inclusion and exclusion criteria of this study.The questionnaire survey was used by face-to-face inquiry questionnaire approach for subjects.The contents of questionnaire included the conditions of personal drinking milk and dairy products (involving the category and quantity) and the symptoms of abdominal discomfort after drinking milk and dairy products(including abdominal distension,gastrointestinal flatulence,borborygmus,abdominal pain,diarrhea,nausea,vomiting,etc.),and the situation of abdominal pain and stool within nearly three months,and included the Life Events Scale,Hospital Anxiety and Depression Scale and Intestinal Symptoms Scale.If the individual suffered from abdominal discomfort after intaking milk and dairy products,or refused to intake due to the above symptoms of abdominal symptoms,he or she was determined as subjective lactose intolerance.All subjects underwent lactose hydrogen breath test.If the concentration of hydrogen increased over 20ppm of basic values accompanied by gastrointestinal symptoms,or gastrointestinal symptoms were appeared regardless of whether the concentration of hydrogen increased over 20ppm of basic values,it was judged to be lactose intolerance.Lactose maldigestion was judged when the concentration of hydrogen increased over 20ppm of basic values but not accompanied by gastrointestinal symptoms.Lactose normal digestion was defined when the change of hydrogen concentration did not exceed 20ppm of basic values and without gastrointestinal symptoms.The abdominal symptom score,which was the sum of multiplication product of each symptom score coefficient and the degree of severity within 12h after intake of lactose,was recorded during hydrogen breath test and 12 hours later of the test.SPSS 13.0 statistical software was used to conduct statistical analysis.Chi-square test was used for the comparison between subjective lactose intolerance and actual lactose intolerance tested by hydrogen breath test.Logistic regression analysis was used to evaluate the differences of multiple factors among lactose intolerance,lactose maldigestion and digester of subjective lactose intolerance. One-way ANOVA was used to evaluate the difference of lactose intake in gender. Mann-Whitney U test was used to analyze the non-normal distribution data.Results:A total of 209 people who all had gone through 20g lactose hydrogen breath test were included in this study.Among them,33 cases were lactose normal digestion (15.8%),and there were 14 males and 19 females.37 cases were lactose maldigestion (17.7%,17 males and 20 females),and 139 cases were lactose intolerance(66.5%,74 males and 65 females).There was no statistical difference in three types at gender.In this study,54 cases were subjective lactose intolerance,and the ratio in all subjects was 25.8%(54/209).Among them,there were 42 cases diagnosed as lactose intolerance by lactose hydrogen breath test,and the ratio in subjective lactose intolerance was 77.8% (42/54).There were 5 cases of lactose maldigestion(9.2%) and 7 cases of lactose normal digestion(13.0%).For determining actual lactose intolerance by subjective lactose intolerance from questionnaire,the sensitivity was 30.2%(42/139),the specificity was 82.9%(58/70),the positive predictive value was 77.8%(42/54),and the negative predictive value was 37.4%(58/155).According to the ROMEⅢcriteria, there were 35 cases of irritable bowel syndrome in 54 cases of subjective lactose intolerance.Among the irritable bowel syndrome,29 cases were actual lactose intolerance,three cases were lactose maldigestion and three cases were lactose normal digestion.There was no statistical difference among actual lactose intolerance,lactose maldigestion,lactose normal digestion in subjective lactose intolerance and irritable bowel syndrome(p= 0.394).There were no significant differences among lactose intolerance,lactose maldigestion and digester of subjective lactose intolerance in gender, age,family per capita monthly income,occupation,level of education,anxiety, depression,life stress and bowel symptoms.Conclusions:Subjective lactose intolerance should not accurately reflect the situation of actual lactose intolerance in Chinese populations.Because the sensitivity was low and the specificity was not enough high,subjective lactose intolerance could not well determine the actual lactose intolerance.However,because of the positive predictive value in a certain degree,it could conduce to improve the detective rate of actual lactose intolerance.Subjective lactose intolerance should be performed lactose hydrogen breath test to clear his or her specific types and exclude the people mistaken for lactose intolerance.In addition,lactose hydrogen breath test was able to detect some potential lactose intolerance.2 Research of the mechanisms of difference between lactose intolerance and lactose maldigestionBackground:In lactase deficiency,some were lactose maldigestion and others were lactose intolerance,and the symptoms of intolerance were different.There was not yet very clear on the mechanism of difference between lactose intolerance and lactose maldigestion.Aim:To explore the differences in the gastrointestinal dynamic and intestinal flora between lactose intolerance and lactose maldigestion and the mutual influence between them.Methods:Lactose hydrogen breath test was done for the adults without organic disease, by which lactose intolerance,lactose maldigestion or lactose normal digestion was identified,and the abdominal symptoms were recorded including borborygmus, abdominal distension,abdominal pain and diarrhea,etc.The abdominal symptom score of lactose intolerance was assessed,and the oral cecum transit time was evaluated by hydrogen breath test.Five kinds of specific probes were selected to detect the intestinal flora of lactose intolerance,lactose maldigestion and lactose normal digestion by fluorescence in situ hybridization.Results:163 participants were recruited including 80 men and 83 women.Among them, there were 11.7 cases of lactose intolerance(62 males and 55 females),24 cases of lactose maldigestion(9 males,15 females),22 cases of lactose normal digestion,(9 males,13 females).There was no statistical difference between lactose intolerance and lactose maldigestion in age and gender.The oral cecum transit time of lactose intolerance was 54.23±30.12 minutes,while it was 77.50±31.49 minutes for lactose malndigestion,and there was statistical difference between them.The value of OR of the OCTT was 0.977,and there was statistical difference(p=0.003).The total intestinal bacteria and four kinds of intestinal bacteria corresponding to the specific probes were found in the lactose intolerance,lactose maldigestion and lactose normal digestion by fluorescence in situ hybridization,and there were statistical differences among the three types.Bacteroides and Prevolla spp.was specifically hybridized with Bac303 probe and Eubacterium rectale- Clostridium coccoides was specifically hybridized with Erec482 probe.They were significantly higher in lactose intolerance than in lactose maldigestion and lactose normal digestion.Bifidobacterium was specifically hybridized with Bif164 probe and lactobacillus was specifically hybridized with Lab722 probe.They were significantly lower in lactose intolerance than in lactose maldigestion and lactose normal digestion.There were statistical differences(p< 0.05).Conclusions:It was strong relevance between the oral cecum transit time,the changes of the composition of intestinal flora and lactose intolerance.The oral cecum transit time of lactose intolerance was significantly shorter than of lactose maldigestion.There were significant differences in the composition of the intestinal flora between lactose intolerance,lactose maldigestion and lactose normal digestion.It was significantly higher for Bacteroides and Prevolla spp.and Eubacterium rectale- Clostridium coccoides in lactose intolerance than in lactose maldigestion and lactose normal digestion,while Bifidobacterium and Lactobacillus were significantly lower in lactose intolerance than in lactose maldigestion and lactose normal digestion.3 Research of correlation between lactase gene polymorphisms and lactase persistence in Hangzhou urban populationsBackground:The frequency of lactase persistence varies widely in different human populations.A single nucleotide polymorphism in the gene encoding lactase(T-13910) is associated with the ability to digest milk as adults(lactase persistence) in Europeans, but it is not associated in Africans and north China.Aim:To explore the situation of T-13910 lactase gene polymorphism,and to evaluate the correlation between the lactase genetic polymorphisms and lactase persistence in Hangzhou urban populations.Methods:Lactose hydrogen breath test was done for the adults in Hangzhou urban populations without organic disease,by which lactase persistence or lactase non-persistence was identified.DNA was extracted from peripheral blood,and then the Polymerase Chain Reaction and sequencing was done.The outcome of the DNA sequencing was blasted in GenBank to find whether there were new polymorphisms of lactase gene.Lactase genotype and lactase phenotype were compared and analyzed.Results:One hundred and sixty-three participants from the Hangzhou urban populations were recruited.Among them,there were eighty men and eighty-three women.Their age was from 21 to 70 years,and the average age was 42.20±11.45 years.In these 163 participants,lactase persistence was found in 22 cases(22/163, 13.5%,9 males,13 females),and lactase non-persistence was 141 cases(141/163, 86.5%,71 males,70 females) by lactose hydrogen breath test.Among lactase non-persistence,lactose intolerance was 117 cases(117/141,83.0%) and lactose maldigestion was 24 cases(24/141,17.0%).There was no statistical difference in gender between lactase persistence and lactase non-persistence.The frequency of lactase persistence was very low in Hangzhou urban populations.T-13910 allele was not detected in all cases,in turn,the homozygote C/C-13910 was found in this location. Several other new polymorphisms sites different from C/T-13910 were found,such as C/T-13908,A/C-13926,G/A-14010,T/G-13951 and C/T-13952.Among these polymorphisms sites,A/C-13926 was found in three different cases,C/T-13908 in two, G/A-14010 in one,T/G-13951and C/T-13952 in the same case.The T-13908 allele all existed in lactase persistence,and the C-13926 allele all existed in lactase non-persistence.The T-13908 allele was associated with lactase persistence,and there was statistical difference(p= 0.017).However,there was no statistical difference between C-13926 allele and the correlation of lactase non-persistence.In addition,there was no statistical difference between A-14010,G-13951,T-13952 allele and lactase phenotype.Conclusions:It was first report that there were many new single nucleotide polymorphisms of lactase gene in this study including T-13908,C-13926,A-14010,G-13951,T-13952 allele,and T-13908 allele might be associated with lactase persistence in Hangzhou urban populations.The frequency of lactase persistence was very rare in Hangzhou urban populations.The T-13910 allele frequency was very low and it did not match the lactase persistence phenotype in these populations.Therefore the T-13910 allele could not be served as a predictor for lactase persistence in Hangzhou urban populations.