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More than half of the global population is unable to consume dairy products due to lactose intolerance (hypolactasia). Current enzyme replacement therapy methods are insufficiently effective as a therapeutic approach to treating lactose intolerance. The encapsulation of β-galactosidase in polyelectrolyte microcapsules by using the layer-by-layer method could be a possible solution to this problem. In this study, adsorption and co-precipitation methods were employed for encapsulating β-galactosidase in polyelectrolyte microcapsules composed of (polyallylamine /polystyrene sulphonate)₃. As a result, the co-precipitation method was chosen for β-galactosidase encapsulation. The adsorption method permits to encapsulate six times less enzyme compared with the co-precipitation method; the β-galactosidase encapsulated via the co-precipitation method released no more than 20% of the initially encapsulated enzyme in pH 2 or 1 M NaCl solutions. In contrast, when using the sorption method, about 100% of the initially encapsulated enzyme was released from the microcapsules under the conditions described above. The co-precipitation method effectively prevents the complete loss of enzyme activity after 2 h of incubation in a solution with pH 2 while also alleviating the adverse effects of ionic strength. Consequently, the encapsulated form of β-galactosidase shows promise as a potential therapeutic agent for enzyme replacement therapy in the treatment of hypolactasia. [ABSTRACT FROM AUTHOR]

Lactose intolerance, which affects about 65–75% of the world's population, is caused by a genetic post-weaning deficiency of lactase, the enzyme required to digest the milk sugar lactose, called lactase non-persistence. Symptoms of lactose intolerance include abdominal pain, bloating and diarrhea. Genetic variations, namely lactase persistence, allow some individuals to metabolize lactose effectively post-weaning, a trait thought to be an evolutionary adaptation to dairy consumption. Although lactase non-persistence cannot be altered by diet, prebiotic strategies, including the consumption of galactooligosaccharides (GOSs) and possibly low levels of lactose itself, may shift the microbiome and mitigate symptoms of lactose consumption. This review discusses the etiology of lactose intolerance and the efficacy of prebiotic approaches like GOSs and low-dose lactose in symptom management. [ABSTRACT FROM AUTHOR]

Primary lactose malabsorption is characterised by a down-regulation of lactase activity after weaning and inability to digest lactose in adulthood. It has been suggested that the historical introduction of dairying led to a positive selection for lactase persistence variants in a regulatory region upstream of the LCT gene. Here, we genotyped 202 Armenian subjects for LCT-13910T, a lactase persistence variant which is widespread in Europeans. The homozygous C/C genotype associated with primary hypolactasia, the heterozygous C/T and the homozygous T/T lactase persistence genotypes were found in 191 (94.6%), 11 (5.4%), and 0 (0.0%) samples, respectively. The frequency for the LCT-13910*T allele was 2.7%. The observed allele frequency of 2.7% for LCT-13910T is even lower than previously reported and supports current phenotypic data about lactose malabsorption in Armenia.

Primary lactose malabsorption is characterised by a down-regulation of lactase activity after weaning and inability to digest lactose in adulthood. It has been suggested that the historical introduction of dairying led to a positive selection for lactase persistence variants in a regulatory region upstream of the LCT gene. Here, we genotyped 202 Armenian subjects for LCT-13910T, a lactase persistence variant which is widespread in Europeans. The homozygous C/C genotype associated with primary hypolactasia, the heterozygous C/T and the homozygous T/T lactase persistence genotypes were found in 191 (94.6%), 11 (5.4%), and 0 (0.0%) samples, respectively. The frequency for the LCT-13910*T allele was 2.7%. The observed allele frequency of 2.7% for LCT-13910T is even lower than previously reported and supports current phenotypic data about lactose malabsorption in Armenia. [ABSTRACT FROM AUTHOR]

Lactose intolerance (LI) may be considered in patients with unspecific gastrointestinal symptoms, but there is no clear consensus on when and how to diagnose the disorder. The LCT-13910 CC genotype is associated with acquired primary lactase deficiency (adult-type hypolactasia; ATH). We aimed to describe the number of tests and test results in the North Denmark Region considering patient age, geographical origin and repeated testing. Retrospective evaluation of the polymerase chain reaction-based LCT-13910 genotype tests registered in the clinical laboratory information system (LABKA II) with data linkage to Danish nationwide registers. Between 18 May 2007 and 31 December 2018, a total of 23,560 individuals were tested. There was a sevenfold increase in the number of tests performed during the study period. About 9.8% of the tests performed in 2018 were repeated testing in the same individuals. Overall, 8.8% of tested individuals were younger than 5 years, 90.7% were of Danish origin and 5.5% originated from outside of Europe. The LCT-13910 CC genotype was identified in 13.3% of all tested individuals, in 16.0% of children younger than 5 years, in 6.8% of Danish individuals and in 90.9% originating from outside of Europe. In the North Denmark Region, a marked increase in the use of genetic testing for hypolactasia was observed and repeated testing was frequent. Furthermore, the use of the test and the test results were dependent on patient age and geographical origin. Results inform the debate on when and how to use genetic testing in the diagnosing of LI. [ABSTRACT FROM AUTHOR]

Although Bifidobacterium bifidum expresses lactase activity, no clinical trials have determined its impact on lactose-intolerant subjects. This study evaluated whether acute and chronic ingestion of ice creams containing B. bifidum 900791 at high (107 CFU/g) or low (105 CFU/g) concentrations improved lactose tolerance in hypolactasic subjects. Fifty subjects were selected based on a positive lactose (20 g) hydrogen breath test (HBT0) and the presence of digestive symptoms. The recruited subjects were required to perform breath tests after the acute ingestion of: (1) ice cream containing 20 g of lactose without a probiotic (HBT1); (2) the same ice cream, accompanied by a lactase tablet (HBT2); (3) the same ice cream containing the low or high dose of probiotic (HBT3-LD and HBT3-HD); and (4) after the chronic consumption of the ice cream without (placebo) or with the low concentration of probiotic for 1 month (HBT4). Significant decreases in H2 excretion during HBT2 and HBT3-HD as well as digestive symptoms during HBT2, HBT3-HD and HBT3-LD were observed compared to HBT0 and HBT1, while the orocecal transit time increased. Chronic consumption of the probiotic ice cream did not enhance lactose tolerance compared to the placebo. These results suggest that the acute ingestion of ice cream containing high or low concentrations of B. bifidum 900791 improves lactose tolerance in hypolactasic subjects.

Abstract Lactase (LCT) deficiency affects approximately 75% of the world's adult population and may lead to lactose malabsorption and intolerance. Currently, the regulation of LCT gene expression remains poorly known. Peroxisome proliferator activator receptorγ (PPARγ) is a key player in carbohydrate metabolism. While the intestine is essential for carbohydrate digestion and absorption, the role of PPARγ in enterocyte metabolic functions has been poorly investigated. This study aims at characterizing PPARγ target genes involved in intestinal metabolic functions. In microarray analysis, the LCT gene was the most upregulated by PPARγ agonists in Caco‐2 cells. We confirmed that PPARγ agonists were able to increase the expression and activity of LCT both in vitro and in vivo in the proximal small bowel of rodents. The functional response element activated by PPARγ was identified in the promoter of the human LCT gene. PPARγ modulation was able to improve symptoms induced by lactose‐enriched diet in weaned rats. Our results demonstrate that PPARγ regulates LCT expression, and suggest that modulating intestinal PPARγ activity might constitute a new therapeutic strategy for lactose malabsorption.

Retention of lactase activity in adulthood (lactase persistence) is one of the most important adaptive traits for human populations that consume fresh milk from domestic animals. At a molecular-genetic level, lactase persistence is determined by the presence of specific alleles of polymorphic sites in cis-regulatory elements of the LCT gene located on chromosome 2q21. Ascertainment of the molecular-genetic causes of lactase persistence has made this trait one of the most convenient for studying mechanisms of human population adaptation to environmental conditions. But the populations of many regions remain insufficiently investigated in relation to the genetic variability of the LCT loci. This paper presents the results of polymorphism analysis of loci, including the enhancer element for the LCT gene and its flanking regions, in two Turkic-speaking populations from southern Siberia, Altaian Kazakhs and Khakasses. It was found that the “European” allele LCT-13910T is the most characteristic of the Turkic-speaking populations from Altai-Sayan regions among all the polymorphic variants associated with lactase persistence. The expansion of the “European” allele LCT-13910T to the gene pool of the populations in southern Siberia could be related to migration waves of ancient herders form western Eurasia during the Bronze Age (in III – II millennium BC). A decrease of the LCT-13910T allele frequency and the total frequency of its carriers in the Turkic-speaking populations of southern Siberia in comparison with the majority of European populations and the Kazakhs from southern Central Asia can be attributed to: (1) a significant influence on the Altai- Sayan population’s gene pool by Eastern Eurasian populations, for which the LCT-13910T allele is rare; (2) a lesser adaptive significance of lactase persistence for south Siberian populations, compared to the populations of Europe. Rare and unique SNPs in the locus under consideration that were found in the Altaian Kazakhs (LCT-13895G > C and LCT-13927C > G) and Khakasses (LCT-14011C > T) potentially play a role in regulation of LCT gene expression, because they are located within the enhancer, regulating activity of its promoter.

Objective: The main purpose of this work was to identify the prevalence of self-reported stomach symptoms after consuming milk among Sami and non-Sami adults. Study design: A cross-sectional population-based study (the SAMINOR study). Data were collected by self-administrated questionnaires. Method: SAMINOR is a population-based study of health and living conditions conducted in 24 municipalities in Northern Norway during 2003 and 2004. The present study included 15,546 individuals aged between 36 and 79, whose ethnicity was categorized as Sami (33.4%), Kven (7.3%) and Norwegian majority population (57.2%). Results: Sami respondents had a higher prevalence of self-reported stomach symptoms after consuming milk than the Norwegian majority population. The reporting was highest among Sami females (27.1%). Consumption of milk and dairy products (yoghurt and cheese) was high among all the ethnic groups. However, significantly more Sami than non-Sami never (or rarely) consume milk or cheese, and individuals who reported stomach symptoms after consuming milk had an significant lower intake of dairy products than those not reporting stomach symptoms after consuming dairy products. Sami reported general abdominal pain more often than the majority population. The adjusted models show a significant effect of Sami ethnicity in both men and women on self-reported stomach symptoms after consuming milk. In females, the odds ratio (OR)=1.77 (p=0.001) and in males OR=1.64 (p=0.001). Conclusion: Our study shows that the Sami population reported more stomach symptoms after consuming milk, suggesting a higher prevalence of milk intolerance among the Sami population than the Norwegian majority population.

Résumé L’absorption du lactose au niveau de l’intestin grêle est dépendante de son hydrolyse par la lactase. L’activité de cette enzyme, maximale à la naissance, décroit progressivement après le sevrage. Cette perte d’activité (ou hypolactasie) est un phénomène physiologique observé chez 70 à 75 % de la population mondiale. L’hypolactasie est transmise selon un mode autosomique récessif à pénétrance incomplète et est liée à des polymorphismes situés dans la région promotrice du gène codant pour la lactase. Dans les populations indo-européenne, sub-saharienne et nord-africaine, l’hypolactasie est associée à deux polymorphismes rs4988235 (ou-13910C>T) et rs41380347 (-13915T>G). L’objet de cet article est d’évaluer les performances analytiques d’une amplification isotherme médiée par des boucles (LAMP, LC-LacI-LP, Lacar) permettant une recherche rapide de ces deux polymorphismes. Les performances analytiques de la technique ont été évaluées par étude de la répétabilité – reproductibilité et par comparaison des résultats obtenus avec ceux obtenus par séquençage Sanger de la région d’intérêt chez 34 échantillons. La technique présente de très bonnes performances en termes de reproductibilité / répétabilité (CV TM <0,73 % lors de l’étude de reproductibilité). Une parfaite adéquation des résultats par rapport à la technique de référence est observée. La présence d’autres polymorphismes (tel que rs41456145, -13913T>C) est détectée, le risque d’erreur de classification étant faible. Lactose, the principle sugar in milk, is a disaccharide hydrolyzed by intestinal lactase into glucose and galactose, which are absorbed directly by diffusion in the intestine. The decline of lactase expression (or hypolactasia) in intestinal microvilli after weaning is a normal phenomenon in mammals known as lactase deficiency. It is observed in nearly 75 % of the world population and is an inherited autosomal recessive trait with incomplete penetrance. It is caused by SNPs in a regulatory element for lactase gene. Two of them are frequently observed in indo-european, sub-saharian and north-african populations: rs4982235 SNP (or -13910 C>T) and rs41380347 (-13915T>G). The aim of this study is to evaluate the analytical performance of a loop-mediated isothermal amplification (LAMP, LC-LacI-LP, Lacar) assay for detecting these SNPs. Analytical performance of the assay was assessed by evaluating within and between-run precision and by comparing the results (n = 34 samples) obtained with the LAMP assay to those obtained with the gold standard (Sanger sequencing of the region of interest). The LAMP assay has good performance (CV < 0.73 % during the between-run study). A perfect agreement with the gold standard method was observed. The presence of other polymorphisms (such as rs41456145, -13913T>C) within the amplified sequence is detected, the misclassification risk is low. This assay can be used for rapidly diagnosing genetic predisposition to lactose intolerance. [ABSTRACT FROM AUTHOR]

Background: Lactose malabsorption is normally evaluated by measuring exhaled H2 produced by intestinal flora, from unabsorbed lactose. However, differing microbiome composition can lead to the production of CH4 instead of H2; hence, some authors challenge the H2 method sensitivity and favor the evaluation of both intestinal gases. Aim: To compare different approaches to usage of a lactose breath test for lactose malabsorption diagnosis, after medical evaluation of gastrointestinal symptoms. Methods: In a retrospective observational study, we compared the 2 approaches in a population of 282 subjects in Northern Italy. Following oral lactose administration, exhaled samples were harvested every 30 minutes for 4 hours and prepared for H2 and CH4 analysis. Basal gas levels were subtracted from H2 and CH4 ppm and values at 4 hours and peaks were considered for analysis. Results: Applying the standard methodology, which takes separately into consideration H2 and CH4 produced in the intestinal lumen, the results indicated that 11.7% of the patients were diagnosed “positive” for hypolactasia, differently from what was expected. Conversely, taking into consideration the sum of H2 and CH4, the percentage increased to 62.8%, closer to the expected one. No significant differences were found when comparing the 2 groups for age, gender, or symptoms. The sizable difference between the 2 approaches is likely linked to gut microbiome variability, and consequently the different production of the 2 gases, in the population. Conclusion: The threshold normally used for lactose breath test should be reconsidered and changed, merging H2 and CH4 stoichiometric values to increase sensitivity. [ABSTRACT FROM AUTHOR]

The Metabolic Syndrome (MetS) is defined as a pattern of metabolic disturbances, which include central obesity, insulin resistance and hyperglycemia, dyslipidemia, and hypertension. Milk has been promoted as a healthy beverage that can improve the management of MetS. Most human adults, however, down-regulate the production of intestinal lactase after weaning. Lactase encoded by the LCT gene is necessary for lactose digestion. The -13910C > T SNP (rs4988235) is responsible for the lactase persistence phenotype in European populations. We herein investigated whether the lactase persistence genotype is also associated with the MetS in subjects from a Brazilian population of European descent. This study consisted of 334 individuals (average age of 41 years) genotyped by PCR-based methods for the -13910C > T SNP. Clinical data were assessed and the genotypes were tested for their independent contribution to the MetS using chi-square tests and multiple logistic regression analysis. Univariate analyses showed that hypertension and MetS prevalence were higher in individuals with the lactase non-persistence genotype than in lactase persistence subjects. Furthermore, lactase persistence was associated with a lower risk for MetS (OR = 0.467; 95% CI 0.264-0.824; p = 0.009). These results suggest that LCT genotypes can be a valuable tool for the management of MetS treatment.

Lactase (LCT) deficiency affects approximately 75% of the world's adult population and may lead to lactose malabsorption and intolerance. Currently, the regulation of LCT gene expression remains poorly known. Peroxisome proliferator activator receptorγ (PPARγ) is a key player in carbohydrate metabolism. While the intestine is essential for carbohydrate digestion and absorption, the role of PPARγ in enterocyte metabolic functions has been poorly investigated. This study aims at characterizing PPARγ target genes involved in intestinal metabolic functions. In microarray analysis, the LCT gene was the most upregulated by PPARγ agonists in Caco-2 cells. We confirmed that PPARγ agonists were able to increase the expression and activity of LCT both in vitro and in vivo in the proximal small bowel of rodents. The functional response element activated by PPARγ was identified in the promoter of the human LCT gene. PPARγ modulation was able to improve symptoms induced by lactose-enriched diet in weaned rats. Our results demonstrate that PPARγ regulates LCT expression, and suggest that modulating intestinal PPARγ activity might constitute a new therapeutic strategy for lactose malabsorption. [ABSTRACT FROM AUTHOR]

Summary Background & aims There is no consensus on the most accurate method to diagnose primary hypolactasia. We aimed to compare the diagnostic accuracy of the new gaxilose test with 2 traditional tests (lactose tolerance test and clinical criteria) for the diagnosis of primary hypolactasia using the C/T-13910 polymorphism as a reference standard. Methods Patients with a clinical suspicion of lactose intolerance were subjected to gaxilose tests, shortened lactose tolerance tests, and symptom questionnaires before and after overload with 50 g lactose and after a lactose-free diet. The diagnostic accuracy and degree of agreement and correlation were assessed using a genetic test (C/T-13910 polymorphism) as a reference standard and their respective 95% confidence intervals. Results Thirty consecutive patients (70% women) participated in the study. The genetic test confirmed the C/T-13910 polymorphism in 11 patients (36.8%). The presence of diarrhoea and the symptom score after lactose overload, along with the tolerance test, were the variables with the highest degree of agreement ( κ > 0.60). Area under the ROC curve was >0.82 ( p < 0.05), with sensitivity and specificity values of >0.80. However, the gaxilose test obtained lower values: κ , 0.47; area under curve, 0.75 (0.57–0.94); sensitivity, 0.82 (0.55–1); and specificity, 0.68 (0.45–0.92). The multivariate analysis showed an association between the post-overload symptom questionnaire and the results of the genetic test (odds ratio: 1.17; 1.04–1.31; p < 0.01). Conclusions The presence of diarrhoea and the symptom score after overload with 50 g lactose showed a higher degree of agreement and diagnostic accuracy for primary hypolactasia than the gaxilose test when the genetic test is used as a reference standard. [ABSTRACT FROM AUTHOR]

The gene xyl B from Caulobacter crescentus has been cloned and expressed in Escherichia coli providing a high yield of xylose dehydrogenase (XylB) production and excellent purity (97%). Purified recombinant XylB showed an absolute dependence on the cofactor NAD + and a strong preference for d -xylose against other assayed mono and disaccharides. Additionally, XylB showed strong stability when stored as freeze-dried powder at least 250 days both at 4 °C and room temperature. In addition, more than 80% of the initial activity of rehydrated freeze-dried enzyme remained after 150 days of incubation at 4 °C. Based on these characteristics, the capability of XylB in d -xylose detection and quantification was studied. The linearity of the method was maintained up to concentrations of d -xylose of 10 mg/dL and the calculated limits of detection (LoD) and quantification (LoQ) of xylose in buffer were 0.568 mg/dL and 1.89 mg/dL respectively. Thus, enzymatic detection was found to be an excellent method for quantification of d -xylose in both buffer and urine samples. This method can easily be incorporated in a new test for the diagnosis of hypolactasia through the measurement of intestinal lactase activity. [ABSTRACT FROM AUTHOR]

Objective. The main purpose of this work was to identify the prevalence of self-reported stomach symptoms after consuming milk among Sami and non-Sami adults. Study design. A cross-sectional population-based study (the SAMINOR study). Data were collected by self-administrated questionnaires. Method. SAMINOR is a population-based study of health and living conditions conducted in 24 municipalities in Northern Norway during 2003 and 2004. The present study included 15,546 individuals aged between 36 and 79, whose ethnicity was categorized as Sami (33.4%), Kven (7.3%) and Norwegian majority population (57.2%). Results. Sami respondents had a higher prevalence of self-reported stomach symptoms after consuming milk than the Norwegian majority population. The reporting was highest among Sami females (27.1%). Consumption of milk and dairy products (yoghurt and cheese) was high among all the ethnic groups. However, significantly more Sami than non-Sami never (or rarely) consume milk or cheese, and individuals who reported stomach symptoms after consuming milk had an significant lower intake of dairy products than those not reporting stomach symptoms after consuming dairy products. Sami reported general abdominal pain more often than the majority population. The adjusted models show a significant effect of Sami ethnicity in both men and women on self-reported stomach symptoms after consuming milk. In females, the odds ratio (OR)=1.77 (p=0.001) and in males OR=1.64 (p=0.001). Conclusion. Our study shows that the Sami population reported more stomach symptoms after consuming milk, suggesting a higher prevalence of milk intolerance among the Sami population than the Norwegian majority population. [ABSTRACT FROM AUTHOR]

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This study aims to describe through a literary review about lactose intolerance causes, prevalence, diagnostic, treatment and care. It is a search of bibliographical and/or literary revision in databases SciELO, LILACS, PUBMED and MEDLINE, having population of 46 scientific articles, separating to sample 27 articles, with a cutout of the years 2000-2014 being only researched Portuguese and Spanish articles. Within this context, lactose intolerance it is a dysfunction in an enzyme called lactase (β-D-Galactosidase), There are three kinds of lactose intolerance, the congenital which is considered rare, being caused by deficiency of β-D-Galactosidase jejunal in babies resulting in diarrhea symptoms, when consume breast milk, and lactose-based foods. Among other kinds of lactase the primary is the most common, and reaches more adults who begin to show dysfunction in the enzyme; already the secondary is presented at any age, being more frequent in childhood, resulting pathologies and intestinal lesions in the small intestine. [ABSTRACT FROM AUTHOR]

Background: The lactose breath test (LBT) is the standard technique for diagnosis of lactose malabsorption. However, it is time-consuming, strenuous for the patient and has been reported to have low sensitivity. The lactose intolerance quick test (LIQT) measures lactase activity in duodenal biopsies and may be performed as part of upper gastrointestinal endoscopy. Aim: The purpose of this study was to assess the role of the LBT and LIQT in the case management of suspected lactose malabsorption. Methods: The study group included 69 consecutive patients evaluated by the LBT followed by the LIQT. The test results were compared, and the sensitivity, specificity, and predictive values of the LBT were calculated. Results: Mean age of the patients was 54.4 years, male/female ratio was 1:3, and mean body mass index was 25.2. None had celiac disease on duodenal biopsy. The LIQT was positive for hypolactasia in 55 patients (80 %): mild in 14 (25 %) and severe in 41 (75 %); 10 (18 %) were symptomatic during the LBT. The LBT was positive for lactose malabsorption in 32 patients (46 %). Of the 37 patients with normal findings on the LBT, 24 (65 %) had positive findings on the LIQT: 11 (30 %) mild hypolactasia, 13 (35 %) severe hypolactasia. In one case, the LBT was positive and the LIQT was negative. The LBT had a sensitivity of 56 %, specificity 93 %, positive predictive value 97 %, and negative predictive value 35 %. Conclusions: The LBT may serve as a diagnostic screening tool for lactose malabsorption. Symptomatic patients with negative LBT results should be referred for second-line testing with the LIQT. [ABSTRACT FROM AUTHOR]

Résumé: Le lactose, principal sucre du lait, est un disaccharide dont l’absorption au niveau de l’intestin grêle est dépendante de son hydrolyse en glucose et galactose par la lactase, enzyme présente au niveau de la bordure en brosse des entérocytes. En cas de déficit de cette enzyme, le lactose non hydrolysé est métabolisé par la flore bactérienne anaérobie du côlon. Les métabolites générés, acides gras à courte chaîne, hydrogène, dioxyde de carbone et méthane, sont retenus responsables des symptômes tels que douleur abdominale, météorisme, flatulence, diarrhée. Le déficit en lactase peut être d’origine congénitale, d’origine primaire acquise ou d’origine acquise secondaire à des pathologies lésant la muqueuse intestinale. La malabsorption du lactose est la conséquence de l’hypolactasie dont l’expression clinique est l’intolérance au lactose : dans la pratique clinique courante, la malabsorption est diagnostiquée grâce au test respiratoire à l’hydrogène après ingestion de lactose, qui doit être couplé au recueil des symptômes d’intolérance éventuellement provoqués par ce test. Le traitement repose sur l’exclusion ou la réduction du lactose de l’alimentation, traitement qui doit être réservé aux sujets symptomatiques (ű intolérants Ƈ). Un suivi diététique est souhaitable afin de ne pas méconnaître d’éventuelles carences nutritionnelles, notamment calcique. [ABSTRACT FROM AUTHOR]

Objective(s) Primary or adult type hypolactasia, the most common enzyme deficiency in the world, is due to reduced lactase activity in the intestinal cell after weaning. Lactase non-persistence is inherited as an autosomal recessive trait. A DNA variant, single nucleotide polymorphism C/T-13910 which is located on 13910 base pairs (bp) upstream of the lactase gene (LCT) at chromosome 2 has been show to associate with the lactase persistence/non-persistence. The prevalence of the C/T-13910 variant is different for hypolactasia in European, Asian, African-American and Northern African populations. In this study, we investigated, for the first time the allele frequent of the single nucleotide polymorphism C/T-13910 in the Iranian population in khorasan province with hypolactasia. Materials and Methods Peripheral blood was collected from 100 subjecs with primary hypolactasia and 100 healthy individuals as a control group. Genomic DNA was extracted. The genotype was analyzed with the PCR-RFLP method. A statistical analysis was performed by chi-square test using SPSS software. A P-value of <0.05 was considered statistically significant. Results In case group allelic frequency for SNP T-13910C (C, T) was respectively 95%, 5% vs. control group 86% and 14%. Genotype frequency (CC, CT, TT) in patient group was 90%, 10%, 0% vs. control group 74%, 24% and 2%. So according to our findings, there were significant differences between allelic frequencies (P=0.03), and in genotype frequency between case and control groups (P=0.006). Conclusion Based on our results, analysis of C\T-13910 polymorphism can be used as a simple genetic test for diagnosis of primary type hypolactasia in the Iranian population. [ABSTRACT FROM AUTHOR]

Introduction: Primary hypolactasia is a physiological process in human intestines observed after the 5th year of age. It manifests itself as the age-dependent loss in the activity of lactase responsible for digesting lactose present in milk and dairy products. Aim of the study: The impact of hypolactasia on consumption of milk and dairy products. Material and method: The study covered 200 randomly selected respondents aged 10-23 who were divided into two groups: 48 people with hypolactasia (H) and 152 without (BH); in each group the age sub-groups were distinguished: children (10-14, n=36), youth (15-19, n=77) and students (20-23, n=87). The consumption of milk and dairy products was assessed by means of a questionnaire, while the hypolactasia was examined by means of the hydrogen breath test performed with Bedfond Gastrolyzer. Results: Hypolactasia was diagnosed in 48 people (11% of children, 22% of youth, 31% of students). The consumption of milk and dairy products was reduced by 23 participants (11%), more frequently by children -- 28% than by youth and students (both 8%). In the BH group the reduced consumption was declared by 10% (28% of children, 7% of youth and 3% of students), while in the H group -- by 17% (25% of children, 12% of youth and 18% of students) (p<0.05). 71% of the H group (children: 75%, youth: 82%, students: 63%) and 72% of the BH group (children: 81%, youth: 73%, students: 67%) drank milk (ns). Hard cheese was consumed daily by 85% of H (100% of children, 88% of youth, 81% of students) and by 76% of BH (59% of children, 75% of youth, 87% of students) (ns), yogurt was consumed by 79% of H (100% of children, 71% of youth, 81% of students) and by 82% of BH (children: 81%, youth: 75%, students: 90%) (ns). Conclusions: It is eating habits rather than the incidence of hypolactasia that are the main factor determining the volume of milk and dairy product consumption among children, youth and students. Among the 10-23-year-olds, independently of hypolactasia, the most frequently consumed milk products were yogurt, hard cheese and small amounts of milk. [ABSTRACT FROM AUTHOR]

The majority of mammals are unable to digest lactose due to post-weaning deactivation of the LCT gene, which is responsible for encoding the enzyme lactase ( i.e., adult-type hypolactasia). A substitution of C with T at position −13910 bp upstream of the LCT gene has been linked to the lactase persistence phenotype in European populations. We investigated the frequency of LCT-13910C>T polymorphism in 223 blood donors from central Poland. All samples were genotyped by polymerase chain reaction and direct sequencing. The LCT-13910 T allele (lactase persistence) was present in 51% of individuals sampled from the Polish population. We did not find any non-European variants associated with lactase persistence (LCT-13907C>G, LCT-13913T>C, LCT-13915T>G), or any new polymorphisms within the sequenced region. Allele frequencies obtained are in agreement with results from other countries and confirm the unique pattern of distribution of the LCT-13910C>T genotype in Europe. [ABSTRACT FROM AUTHOR]

Background. Adult-type hypolactasia (lactase non-persistence) is a common cause of gastrointestinal symptoms. Several DNA sequence variants have been identified for the lactase-persistence/non-persistence (LP/LNP), the most common being the C to T residing -13910 bp upstream of the lactase gene (LCT). We have analysed sequence variants of LP/LNP in subjects originating from Northern Russia. Methods. A total of 148 subjects with gastrointestinal complaints were genotyped covering about 400 bp around the -13910C/T variant using direct PCR-sequencing. All patients were interviewed about milk-related symptoms using the questionnaire. Disaccharidase activities were measured from intestinal biopsy specimens of the index person. Results. The prevalence of the -13910C/C genotype among 148 patients was 28.4%. A G to A variant residing 13914 bp upstream from the LCT gene (-13914G>A) was identified in one participant carrying the -13910C/C genotype. In two biopsy specimens her lactase activity was above the generally accepted cut off level for adult-type hypolactasia, 10U/g protein. Three other family members also carried the -13914G>A genotype. Among eight family members five had the LNP genotype -13910C/C. Conclusion. A rare variant G to A residing 13914 bp upstream of the LCT gene was identified in a subject carrying the more frequent variant -13910C/C. The -13914G>A variant in heterozygous state was associated with increased lactase activity, suggesting that the increased lactase activity is most likely to be associated with the -13914G>A variant. Further studies need to be done to confirm the functional role of this variant. [ABSTRACT FROM AUTHOR]

A staggering 4000 million people cannot digest lactose, the sugar in milk, properly. All mammals, apart from white Northern Europeans and few tribes in Africa and Asia, lose most of their lactase, the enzyme that cleaves lactose into galactose and glucose, after weaning. Lactose intolerance causes gut and a range of systemic symptoms, though the threshold to lactose varies considerably between ethnic groups and individuals within a group. The molecular basis of inherited hypolactasia has yet to be identified, though two polymorphisms in the introns of a helicase upstream from the lactase gene correlate closely with hypolactasia, and thus lactose intolerance. The symptoms of lactose intolerance are caused by gases and toxins produced by anaerobic bacteria in the large intestine. Bacterial toxins may play a key role in several other diseases, such as diabetes, rheumatoid arthritis, multiple sclerosis and some cancers. The problem of lactose intolerance has been exacerbated because of the addition of products containing lactose to various foods and drinks without being on the label. Lactose intolerance fits exactly the illness that Charles Darwin suffered from for over 40 years, and yet was never diagnosed. Darwin missed something else - the key to our own evolution - the Rubicon some 300 million years ago that produced lactose and lactase in sufficient amounts to be susceptible to natural selection. [ABSTRACT FROM AUTHOR]

Low calcium intake hampers bone mineral acquisition in adolescent girls. This study explores dietary calcium sources and nutrients possibly associated with vertebral mass. Milk intake is not influenced by genetic variants of the lactase gene and is positively associated with serum IGF-1 and with lumbar vertebrae mineral content and density. Low calcium intake hampers bone mineral acquisition during adolescence. We identified calcium sources and nutrients possibly associated with lumbar bone mineralization and calcium metabolism in adolescent girls and evaluated the possible influence of a genetic polymorphic trait associated with adult-type hypolactasia. Lumbar bone mineral content (BMC), bone mineral density (BMD), and area, circulating IGF-1, markers of bone metabolism, and −13910 LCT (lactase gene) polymorphism; and intakes of milk, dairy products, calcium, phosphorus, magnesium, proteins, and energy were evaluated in 192 healthy adolescent girls. After menarche, BMC, BMD, serum IGF-1, and serum PTH were tightly associated with milk consumption, but not with other calcium sources. All four parameters were also associated with phosphorus, magnesium, protein, and energy from milk, but not from other sources. Girls with milk intakes below 55 mL/day have significantly lower BMD, BMC, and IGF-1 and higher PTH compared to girls consuming over 260 mL/day. Neither BMC, BMD, calcium intakes, nor milk consumption were associated with −13910 LCT polymorphism. Milk consumption, preferably to other calcium sources, is associated with lumbar BMC and BMD in postmenarcheal girls. Aside from being a major source of calcium, milk provides phosphates, magnesium, proteins, and as yet unidentified nutrients likely to favor bone health. [ABSTRACT FROM AUTHOR]

Objective. The age at manifestation of primary hypolactasia varies between ethnic groups. Many people report experiencing the first symptoms of lactose intolerance at adult age. The purpose of this study was to investigate whether primary hypolactasia can appear after the age of 20 among the Finnish population and to investigate the outcome of different diagnostic methods of lactose maldigestion. Material and methods. Lactose digestion status was assessed by the lactose tolerance test with ethanol (LTTE) in 42 subjects (38-71 years) who reported having gastrointestinal symptoms after the ingestion of 20 g or less of lactose and who were diagnosed as lactose digesters in earlier studies. Thirteen of the study subjects underwent upper gastrointestinal endoscopy, and 35 gave a blood sample for DNA analysis. Results. Only one of the 42 subjects studied had the genotype C/C-13910 indicating hypolactasia. Lactase activity was higher in those with the genotype T/T (69.2 U/g protein) than in those with the heterozygous genotype C/T (36.3 U/g protein) (p=0.017). Conclusions. Although primary hypolactasia normally appears before the age of 20 years, the decline in lactase activity may on rare occasions continue after that age. Genotyping of the C/T-13910 variant was found to be a reliable diagnostic approach in defining the lactase persistence/non-persistence status of the study subjects. [ABSTRACT FROM AUTHOR]

Abstract: Background: Adult-type hypolactasia is a genetically determined inability to digest lactose after weaning. Two single-nucleotide polymorphisms (C-13910T, G-22018A) located upstream of the lactase gene (LCT) within the gene MCM6 are associated with the lactase persistence/non-persistence trait in patients of European descent. Therefore, the genotyping of these SNPs has been established as a diagnostic tool for adult-type hypolactasia. We have recently shown that several novel allelic variants located in close proximity to the C-13910T SNP interfere with the diagnostic accuracy of real-time PCR-based genotyping methods. Methods: We describe here the validation of a comprehensive reverse-hybridization teststrip-based assay for the detection of common and novel LCT SNPs (C-13907G, C-13910T, T-13913C, G-13914A, T-13915G, and G-22018A). This assay is based on multiplex DNA amplification and ready-to-use membrane teststrips containing variant-specific oligonucleotide probes immobilized as an array of parallel lines. Results: We evaluated the novel reverse-hybridization StripAssay on 125 DNA samples in comparison to LightCycler analysis and sequencing. The outcome of StripAssay genotyping was found to be completely concordant with that obtained by sequencing. Conclusions: The StripAssay represents an accurate and robust screening tool to identify multiple LCT/MCM6 variants in a rapid manner. It overcomes diagnostic pitfalls that were reported and allows the simultaneous genotyping of closely spaced LCT variant sites in a single-step diagnostic approach. [Copyright &y& Elsevier]

Adult-type hypolactasia, as mediated by a widespread genetic predisposition, not only reduces calcium intake but also calcium absorption in the presence of high amounts of lactose and may, therefore, promote osteoporosis. A lactose-reduced diet and lactose-free calcium supplements may reverse this imbalance. Adult-type hypolactasia (HL) defined by the LCT(−13910) polymorphism may reduce calcium intake by reducing dairy consumption and, therefore, promote osteoporosis. This study aimed to evaluate whether lactose also decreases intestinal calcium absorption in subjects with HL and whether lactose-reduced diet and lactose-free calcium supplementation as recommended could maintain bone mineral density (BMD). Based on LCT genotyping, 73 postmenopausal women with and without HL underwent a conventional H2 breath test with a concomitant oral strontium absorption test lasting 150 minutes, which closely reflects intestinal calcium absorption. In addition, we compared bone-specific laboratory parameters, lumbar and femoral BMD, and spinal radiographs to a similar bone assessment 5 years earlier. LCT genotyping and functional lactose malabsorption tests were highly correlated. Dairy product consumption was reduced by 80% in HL individuals. During concomitant lactose application, mean strontium absorption was blunted by 54% in HL subjects after 150 minutes (1272 ± 629 μg/L vs. 2020 ± 1130 μg/L in lactose tolerant subjects, p = 0.001). Nevertheless, BMD in HL subjects remained stable with lactose-free calcium supplements during the observation period. Both decreased calcium intake as well as lactose-associated impaired calcium absorption may predispose subjects with HL to osteoporosis. Lactose-free calcium supplementation may help to maintain BMD in HL subjects. [ABSTRACT FROM AUTHOR]

Objective. Adult-type hypolactasia (AtH) can be diagnosed by genotyping in addition to functional tests or intestinal biopsy. The aims of this study were to estimate the prevalence of AtH by genotyping and to investigate whether AtH prevalence has changed in Sweden during the 20th century. Material and methods. Schoolchildren (n=690) born in 1983 and 1989, and elderly individuals (n=392) born between 1920 and 1932 were genotyped for AtH using Pyrosequencing technology. Results. The overall prevalence of AtH among children was 14.1%. The majority of children (92%, n=635) were Caucasians with genotype prevalences: CC, 61 (10%); CT, 259 (41%); TT, 307 (49%). The frequency of the mutated allele q was 0.300 in this cohort. The prevalence of AtH estimated from the Hardy-Weinberg equilibrium (HWE) (q 2), was 9.0% (95% CI: 6.7–11.2%). Eight percent (n=55) of the children were non-Caucasian; genotype prevalences were CC, 36 (66%); CT, 15 (27%); TT, 4 (7%). The prevalence of AtH in these children estimated from HWE was 62.5% (95% CI: 49.7–75.3%). The elderly subjects were all Caucasians. Their genotype prevalences were: CC, 20 (5%); CT, 166 (42%); TT, 206 (53%); the frequency of the mutated allele q was 0.262 and their AtH prevalence estimated from HWE was 6.8% (95% CI: 4.3–9.2%). Conclusions. The overall prevalence of AtH in children (14%) was higher than previously thought. Among Caucasians, higher figures were seen in children than in the elderly (9% versus 6.8%). The prevalence thus seems to be increasing and this may be due to the immigration of both non-Caucasian and Caucasian groups with a higher prevalence of AtH. [ABSTRACT FROM AUTHOR]

OBJECTIVE.Thc effect of adult-type hypolactasia, caused by the lactase-phlorizin hydrolase C/C-13910 genotype, on growth is unknown. We studied whether this polymorphism was associated with body height growth, the use of milk products, or dietary calcium intake. METHODS. A prospective cohort study was performed among 3596 randomly selected Finnish children and adolescents (3 18 years of age) in 1980, with reexaminatiml in 1983, 1986, and 2001 (after a 21-year follow-up period). Lactase-phlorizin hydrolase C/T-13910 polymorphism was determined for 2265 participants in 2002. Nutrient intakes were measured for 1137, 858, and 1031 snbjects in 1980, 1986, and 2001, respectively. RESULTS. The lactase-phlorizin hydrolase C/T-13910 polymorphism was nut related to mean height growth speed for either boys or girls or to final mean body height in adulthood. The constmlption of milk products, protein, and calcium was lowest for female subjects with the lactase-phlorlzin hydrolase C/C-13910 gem)type over the study years, but there were no genotype-related differences in the intake of vitamin D. For boys, significant differences were found in the consumption of milk products but m)t in the mean dietary intake of calcium, protein, or vitamin D. CONCLUSIONS. The lactase-phlorizin hydrolase C/C-13910 genotype was not associated with mean growth speed or final mean body height for either boys or girls. However, it contributed significantly to milk product consumption and dietary calcium intake from childhood into young adulthood. [ABSTRACT FROM AUTHOR]

A staggering 4000 million people cannot digest lactose, the sugar in milk, properly. All mammals, apart from white Northern Europeans and few tribes in Africa and Asia, lose most of their lactase, the enzyme that cleaves lactose into galactose and glucose, after weaning. Lactose intolerance causes gut and a range of systemic symptoms, though the threshold to lactose varies considerably between ethnic groups and individuals within a group. The molecular basis of inherited hypolactasia has yet to be identified, though two polymorphisms in the introns of a helicase upstream from the lactase gene correlate closely with hypolactasia, and thus lactose intolerance. The symptoms of lactose intolerance are caused by gases and toxins produced by anaerobic bacteria in the large intestine. Bacterial toxins may play a key role in several other diseases, such as diabetes, rheumatoid arthritis, multiple sclerosis and some cancers. The problem of lactose intolerance has been exacerbated because of the addition of products containing lactose to various foods and drinks without being on the label. Lactose intolerance fits exactly the illness that Charles Darwin suffered from for over 40 years, and yet was never diagnosed. Darwin missed something else - the key to our own evolution - the Rubicon some 300 million years ago that produced lactose and lactase in sufficient amounts to be susceptible to natural selection. [ABSTRACT FROM AUTHOR]

The sugar absorption test is a non-invasive test for investigating intestinal permeability by simultaneous measurement of four probe sugars. In this study, we evaluated the utility of raffinose, lactose, sucrose and mannitol as probe sugars and calculated their urinary recovery as a percentage of ingested dose (mol/mol) and the recovery ratios of raffinose/mannitol, lactose/raffinose and sucrose/raffinose. The reference ranges for these ratios, established from 39 healthy volunteers, are 0.005-0.015, 0.13-0.63 and 0.09-0.47, respectively. This sugar absorption test was performed in three patient groups. i) In 109 patients with aspecific gastrointestinal symptoms of whom intestinal histology was studied by duodenal biopsies: the urinary raffinose/mannitol recovery ratio highly correlated with gradation of duodenal damage; the sensitivity and specificity of the raffinose/mannitol ratio for detection of intestinal damage were 93% and 91%, respectively, using a cut-off level of 0.020. ii) In 70 patients in whom intestinal lactase activity was investigated by the lactose tolerance test: the urinary lactose/raffinose recovery ratio provided high diagnostic accuracy for hypolactasia (sensitivity 81% and specificity 89% at a cut-off level of 0.70). In analogy with the lactose/raffinose ratio, we suppose that the sucrose/raffinose ratio can be used as a marker of hyposucrasia. iii) In 40 patients with localized small intestinal damage, Crohn's disease of the ileum (n = 21) and celiac disease with histologically proven duodenal damage (n = 19): the raffinose/mannitol recovery ratio was increased in 100% of patients with celiac disease and in 81% of patients with Crohn's disease; increased lactose/raffinose recovery ratio (hypolactasia) and increased sucrose/raffinose (hyposucrasia) were present in 89% and 95% of celiac patients and 19% and 0% of Crohn's disease patients, respectively. The combination of the raffinose/manifold ratio and and sucrose/raffinose ratio... [ABSTRACT FROM AUTHOR]

Transient lactose intolerance has been identified as a possible causative factor in infant colic. A double-blind randomised placebo-controlled crossover study to investigate this has been undertaken in 53 babies with symptoms of colic. Pre-incubation of the feed with lactase resulted in breath hydrogen levels and total crying time which were both at least 45% lower than figures with placebo treatment, in 26% of the full trial group (95% confidence interval 12.9% to 44.4%), and in 38% of compliers (95% confidence interval 18.8% to 59.4%). The remainder did not respond to the same extent. These findings suggest that infant colic may have a multiple aetiology, and that in a significant number of cases the immediate cause is transient lactose intolerance, in which cases pretreatment of feeds with lactase can result in considerable symptomatic benefits. [ABSTRACT FROM AUTHOR]

BackgroundThe prevalence of genetically determined lactase nonpersistence is based on the results of the lactose H2 breath test. This test, however, is an indirect test, which might lead to misinterpretation. DesignWe determined lactase activity in healthy Chinese and Dutch students using a novel 13C-lactose digestion test. The cut-off value of this test was established in a Chinese population with a homogenous genetic background of lactase nonpersistence and was compared with the results obtained in a Caucasian population. Twenty-five grams of a 13C-lactose solution was consumed by 12 known H2-positive and 5 H2-negative Chinese students and 48 Dutch students and, subsequently, 13C-glucose concentration in plasma and H2 excretion in breath were measured. ResultsA similar 13C-glucose response curve was found in all Chinese students. The mean response curve in the Dutch students was more pronounced (P < 0.01). The 1 h (peak) plasma 13C-glucose concentration was the best discriminator between lactose digesting and maldigesting subjects. The cut-off level of 2 mmol L-1 13C-glucose in plasma was defined in the H2-positive Chinese students group. Based on the 13C-glucose response the prevalence of lactose maldigestion in the Dutch subjects was 25%; based on the lactose H2 breath test 17%. ConclusionsUsing the 13C-lactose digestion test the results demonstrate a higher prevalence of lactose maldigestion in a Caucasian population than indicated by the results of the H2 breath test. A moderate increase in the plasma 13C-glucose concentration after consumption of 13C-lactose in the young adult Chinese subjects indicates a residual lactase activity in that age group, even when a positive H2 breath test result is obtained. These results indicate that the... [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to investigate the frequency of the LCT*-13910C>T polymorphism associated with a high expression of lactase in the small intestine during adulthood, and to infer the lactase persistence and adult-type hypolactasia phenotypes among Euro-Brazilians and Mennonites from South Brazil.Materials and Methods: A sequence-specific PCR method to genotype the LCT*-13910C>T polymorphism in 292 Euro-Brazilians and 151 Mennonites (a group with European ancestry and a long history of endogamy) was developed. Using an exact test of population differentiation, the genotype and allele frequency between these and other Brazilian populations were compared.Results: The frequency of -13910*T was significantly higher among the Mennonites when compared to the Euro-Brazilian cohort (0.63 vs. 0.33, p < 0.000001). Accordingly, Mennonites had a higher prevalence of the lactase persistence genotype (88.1 vs. 55.5%, p < 0.000001). The distribution of -13910*T differed between Mennonites and all other Brazilian groups (p < 0.0001). The Euro-Brazilians from Curitiba displayed differences when compared to all other Brazilian groups (p < 0.0001), even to Euro-Brazilians from a different geographic region (p = 0.0003), but were similar to those from Porto Alegre (p = 0.2).Conclusion: Differences in the -13910*T-associated lactase persistence distribution among Euro-Brazilian groups reflect the ancestry and admixture of each particular group and should be considered for adult-type hypolactasia screening. [ABSTRACT FROM AUTHOR]

Although Bifidobacterium bifidum expresses lactase activity, no clinical trials have determined its impact on lactose-intolerant subjects. This study evaluated whether acute and chronic ingestion of ice creams containing B. bifidum 900791 at high (107 CFU/g) or low (105 CFU/g) concentrations improved lactose tolerance in hypolactasic subjects. Fifty subjects were selected based on a positive lactose (20 g) hydrogen breath test (HBT0) and the presence of digestive symptoms. The recruited subjects were required to perform breath tests after the acute ingestion of: (1) ice cream containing 20 g of lactose without a probiotic (HBT1); (2) the same ice cream, accompanied by a lactase tablet (HBT2); (3) the same ice cream containing the low or high dose of probiotic (HBT3-LD and HBT3-HD); and (4) after the chronic consumption of the ice cream without (placebo) or with the low concentration of probiotic for 1 month (HBT4). Significant decreases in H2 excretion during HBT2 and HBT3-HD as well as digestive symptoms during HBT2, HBT3-HD and HBT3-LD were observed compared to HBT0 and HBT1, while the orocecal transit time increased. Chronic consumption of the probiotic ice cream did not enhance lactose tolerance compared to the placebo. These results suggest that the acute ingestion of ice cream containing high or low concentrations of B. bifidum 900791 improves lactose tolerance in hypolactasic subjects. [ABSTRACT FROM AUTHOR]

A study of regional differences in prevalence of primary adult lactose malabsorption in Italy was conducted on 205 subjects. Their origin was determined by their grandparents' birthplaces 89 from northern, 65 from central, and 51 from southern areas of Italy. Lactose malabsorption was diagnosed with standard oral lactose tolerance test and blood glucose determinations. Lactose malabsorbers showed symptoms more frequently than absorbers after the test load of lactose(p < 0.01); they also reported milk intolerance more frequently (p <0.01). Prevalence of lactose malabsorption is significantly lower in the central sample (19%) than in the northern (52%) and southern (4 1%) samples (p <0.01). This finding contrasts with the hypothesis of a continuous increase in frequency of lactose malabsorption from northern to southern Europe and is probably due to the complex genetic history of the Italian population. [ABSTRACT FROM AUTHOR]