UNASSIGNED: Lactose intolerance and coeliac disease are common clinical nutrient malabsorption disorders, with an unclear pathogenesis and limited therapeutic options. It is widely believed that the gut microbiota plays an important role in many digestive disorders, but its role in lactose intolerance and coeliac disease is not yet clear. This study aimed to investigate the correlation between gut microbiota and lactose intolerance and coeliac disease.
UNASSIGNED: This study utilized the genome-wide association study database to investigate the association between gut microbiota and lactose intolerance and coeliac disease using Mendelian randomization (MR). The robustness of our findings was confirmed through subsequent analyses including Cochrane\'s Q statistic, MR-Egger Intercept Regression, MR-PRESSO Global Test and Leave-one-out methods.
UNASSIGNED: By employing the inverse variance weighted method, we identified that family Veillonellaceae, genus Oxalobacter and Senegalimassilia were protective against lactose intolerance, whereas genus Anaerotruncus, Eubacterium rectale group and Ruminococcus2 were found to be risk factors for lactose intolerance. Regarding coeliac disease, class Bacilli and Gammaproteobacteria, family FamilyXIII and Veillonellaceae, genus Eisenbergiella, Lachnoclostridium, RuminococcaceaeUCG014 and Ruminococcus2 were identified as protective factors, while class Betaproteobacteria, genus Eubacterium xylanophilum group and Blautia were risk factors. Furthermore, reverse the MR analysis did not reveal any evidence of a causal relationship between lactose intolerance or coeliac disease and the bacteria identified in our study.
UNASSIGNED: This study provides novel insights into exploring the role of gut microbiota in lactose intolerance and coeliac disease; however, further experiments investigations are required to elucidate the specific underlying mechanisms.

Approximately 30% of milk protein is β-casein. We aimed to determine whether lactose maldigesters who chronically consumed two cups of A1/A2 milk (containing 75% A1 β-casein and 25% A2 β-casein) would adapt to have fewer intolerance symptoms, lower serum inflammatory markers, and/or altered glutathione levels similar to those consuming A2 milk (containing 100% A2 β-casein). A double-blinded, randomized, crossover trial was conducted. Sixteen confirmed lactose maldigesters consumed 250 mL of A1/A2 milk and A2 milk twice daily with meals for two weeks. At the end of the adaptation period on day 15, lactose maldigestion was measured after a challenge with the same milk used for adaptation (0.5 g of lactose per kg of body weight) with a hydrogen breath test. Fecal urgency was higher during the two-week consumption of A1/A2 milk compared to A2 milk (p = 0.04, n = 16). Bloating (p = 0.03, n = 16) and flatulence (p = 0.02, n = 16) were also higher on the 15th day with A1/A2 milk compared to A2 milk challenge. However, day-to-day symptoms, hydrogen, serum inflammatory markers, and antioxidant concentrations were not different after A1/A2 and A2 milk consumption adaptation periods. Adaptation over two weeks did not improve lactose digestion or tolerance of A1/A2 milk to match that of A2 milk.

Infant colic is a common functional gastrointestinal disorder that affects infants during their first months of life. The etiology of this condition remains unclear. However, some studies suggest lactase deficiency may be a contributing factor. Currently, the evidence on dietary treatment and lactase supplementation for management of infant colic is limited. We aim to systematically review evidence on the efficacy and safety of using a lactase supplementation for managing infant colic. The Cochrane Central Register of Controlled Trials (CENTRAL, the Cochrane Library), MEDLINE, and EMBASE will be searched to identify randomized controlled trials comparing oral lactase supplementation with placebo or no intervention in infants aged less than 6-month-old with infant colic using any recognized definition. The risk of bias will be assessed using the second version of the Cochrane Collaboration\'s risk-of-bias tool. The main outcome will be the number of responders in each group after treatment, defined as infants who experienced a decrease in daily crying as reported by the study authors. Additional outcomes will include the duration and frequency of crying episodes, infant sleep duration, parental satisfaction, discomfort of infants, number of hospital admissions, family quality of life, and adverse events during the intervention. The study findings will be published in a peer-reviewed journal and will be submitted to relevant conferences.

BACKGROUND: Diagnosing lactose malabsorption is usually based on hydrogen excretion in breath after a lactose challenge. However, a proportion of subjects with lactose malabsorption will not present a rise in hydrogen. Measuring excretion of methane or stable isotope labeled 13CO2 after ingestion of 13C-lactose has been proposed to mitigate this problem.
OBJECTIVE: The aim of the study was to assess the performance of measuring methane and 13CO2 in individuals with normal hydrogen excretion compared to a genetic lactase non-persistence test.
METHODS: Individuals referred for lactose breath testing and healthy controls were included. Participants received 13C-enriched lactose, performed breath testing, and underwent genotyping for a marker of lactase non-persistence (13910C*T). Using genotype as gold standard, the performance of measuring methane and 13CO2 excretion was assessed.
RESULTS: 151 subjects participated in the study, 50 of which presented a lactase non-persistent genotype. Of these, 72% were correctly diagnosed through hydrogen excretion of ≥ 20 ppm above baseline. In subjects with normal hydrogen excretion, cumulative 13C excretion had an area under the curve (AUC) of the receiver operating characteristics (ROC) curve of 0.852. Sensitivity was 93% and specificity was 51% for the current cutoff of 14.5%. The optimal cutoff was 12.65% (sensitivity 93%, specificity 70%). The ROC curve of peak methane had an AUC of 0.542 (sensitivity of 14%, specificity of 91% for cutoff ≥ 10 ppm).
CONCLUSIONS: In individuals with genetically demonstrated lactase non-persistence and negative hydrogen breath test, the use of 13C-lactose with measurement of 13CO2 excretion and hydrogen is a well-performing test to detect the lactose malabsorption and performs better than methane in our cohort.

BACKGROUND: Lactose tolerant test (LTT) is the most broadly used diagnostic test for lactose intolerance in Brazil, is an indirect, minimally invasive and a low-cost test that is widely available in primary care and useful in clinical practice. The C/T-13910 polymorphism in lactase persistence has been well characterized in Caucasian populations, but there are no studies evaluating the concordance between C/T-13910 polymorphism genotyping results and LTT results in Brazil, where the population is highly mixed.
OBJECTIVE: We aimed to evaluate agreement between presence of C/T-13910 polymorphism genotyping and malabsorption in LTT results.
METHODS: This is a retrospective analysis of a Brazilian population whose data were collected from a single laboratory database present in several Brazilian states. Results of individuals who underwent both genetic testing for lactose intolerance (C/T-13910 polymorphism genotyping) and an LTT from April 2016 until February 2019 were analysed to evaluate agreement between tests. Groups were classified according to age (<10-year-old (yo), 10-17 yo, ≥18 yo groups) and state of residence (São Paulo or Rio Grande do Sul). Results: Among the 404 patients evaluated, there was agreement between the genotyping and LTT results in 325 (80.4%) patients and discordance in 79 (19.6%) patients (k=0.42 -moderate agreement). Regarding the genotype, 47 patients with genotype C/C (lactase nonpersistence) had normal LTT results, and 32 with genotype C/T or T/T (indicating lactase persistence) had abnormal LTT results. Neither age nor state of residence (Rio Grande do Sul or São Paulo) affected the agreement between test results.
CONCLUSIONS: Considering the moderate agreement between C/T-13910 polymorphism genotyping and LTT results (κ=0.42) in the Brazilian population, we hypothesize that an analysis of other polymorphisms could be a strategy to improve the agreement between genotyping and established tests and suggest that additional studies should focus on exploring this approach.
BACKGROUND: • Lactose intolerance is highly prevalent and may be implicated as a cofactor, or as a differential diagnosis, in many gastrointestinal conditions.
BACKGROUND: • The C/T-13910 polymorphism in lactase persistence is well characterized in Caucasian populations for lactase persistence.
BACKGROUND: • Concordance between genotyping and functional tests does not occur in all patients.
BACKGROUND: • Brazil has a highly mixed population and knowledge regarding presence of other polymorphisms is of importance in clarifying difficult cases.

Lactose intolerance (LI) and vitamin D deficiency (VDD) have been linked to inflammatory bowel disease (IBD). We conducted an observational study in 192 Chilean IBD patients to investigate the prevalence of a specific gene variant (LCT-13910 CC genotype) associated with LI and the prevalence of VDD/Vitamin D Receptor (VDR) gene variants. Blood samples were analyzed using Illumina\'s Infinium Global Screening Array. The LCT-13910 CC genotype was found in 61% of IBD patients, similar to Chilean Hispanic controls and lower than Chilean Amerindian controls. The frequency of the LCT-13910-C allele in Chilean IBD patients (0.79) was comparable to the general population and higher than Europeans (0.49). Regarding VDR and VDD variants, in our study, the rs12785878-GG variant was associated with an increased risk of IBD (OR = 2.64, CI = 1.61-4.32; p-value = 0.001). Sixty-one percent of the Chilean IBD cohort have a genetic predisposition to lactose malabsorption, and a significant proportion exhibit genetic variants associated with VDD/VDR. Screening for LI and VDD is crucial in this Latin American IBD population.

Studies have determined that people with genetically defined lactase non-persistence have lower dairy intake that may lead to an increase risk of various non-communicable diseases. Furthermore, lactase non-persistence itself has been associated with insulin resistance. However, data on lactase non-persistence status and dairy intake in developing countries are sparse. We therefore aimed to define 1) the prevalence of lactase non-persistence among individuals with diabetes and non-diabetes in Thai population and 2) the links between lactase non-persistence, milk consumption, and risk of diabetes mellitus.
We conducted a case-control study from participants of the National Health Examination Survey. DNA was isolated from the blood for LCT -13910C>T (rs4988235) polymorphism and processed using the Bio-rad c1000 touch thermal cycler and MALDI-TOF Mass Spectrometry MassARRAY Typer v4.0 (Agena Bioscience, San Diego, CA, USA) at the Center for Medical Genomics, Faculty of Medicine Ramathibodi Hospital. Cases were participants with previously diagnosed diabetes mellitus or fasting plasma glucose ≥126 mg/dL (n = 1,756) vs. the controls (n = 2,380).
We included 4,136 participants, 62% female, and 98.8% were > 30 years old. Homozygous CC genotype (i.e., lactase non-persistence) was noted in 98.6% and only 1.4% carried heterozygous CT. Most (76%) consumed milk <1 portion/month. Participants with either CC or CT genotype had comparable milk consumption and the risk of diabetes mellitus. Males, older adults, and lower education had a lower chance of consuming milk at least one portion per month. Besides various baseline variables, we found that higher milk consumption was associated with a lower DM risk (P = .01).
The prevalence of lactase non-persistence in Thai population is very high. A significant difference in milk consumption frequency in relation to the lactase non-persistence status was not found. However, higher milk consumption is associated with a lower risk of diabetes mellitus.

BACKGROUND: Primary lactose intolerance (PLI) is characterized by the inability to digest lactose. Homozygotes for the lactase gene polymorphisms (CC or GG) are considered to be genetically predisposed to PLI. Still, symptoms may only be present later in life. The evidence supporting a link between PLI, dairy intake, and quality of life (QoL) is limited in children.
OBJECTIVE: This study investigates the link between LCT polymorphisms and suggestive symptoms and the influence of the genetic predisposition to PLI on dairy intake and QoL in Romanian children.
METHODS: We recruited consecutive children evaluated in our ambulatory clinic. We asked all participants to complete a visual-analog symptoms scale, a dairy intake, and a QoL questionnaire. We used strip genotyping to identify genetic predisposition to PLI.
RESULTS: 51.7% of children had a CC genotype, and 34.5% also had a GG genotype. Most children reported no or mild symptoms. Dairy intake and QoL were similar across study groups.
CONCLUSIONS: Our study shows that genetic predisposition does not necessarily assume the presence of specific symptoms. Genetic predisposition to PLI did not lead to dairy avoidance, nor did it negatively influence our children\'s QoL.

Lactase persistence-the ability to digest lactose through adulthood-is closely related to evolutionary adaptations and has affected many populations since the beginning of cattle breeding. Nevertheless, the contrast initial phenotype, lactase non-persistence or adult lactase deficiency, is still observed in large numbers of people worldwide.
We performed a multiethnic genetic study of lactase deficiency on 24,439 people, the largest in Russia to date. The percent of each population group was estimated according to the local ancestry inference results. Additionally, we calculated frequencies of rs4988235 GG genotype in Russian regions using the information of current location and birthplace data from the client\'s questionnaire.
The attained results show that among all studied population groups, the frequency of GG genotype in rs4988235 is higher than the average in the European populations. In particular, the prevalence of lactase deficiency genotype in the East Slavs group was 42.8% (95% CI: 42.1-43.4%). We also investigated the regional prevalence of lactase deficiency based on the current place of residence.
Our study emphasizes the significance of genetic testing for diagnostics, i.e., specifically for lactose intolerance parameter, as well as the scale of the problem of lactase deficiency in Russia which needs to be addressed by the healthcare and food sectors.

Lactose maldigesters report an increase in abdominal pain due to the consumption of milk containing a mixture of A1 and A2 β-casein as compared to milk containing only A2 β-casein. Gastric transit affects gastrointestinal symptoms and rapid transit has been associated with an increase in abdominal pain. We conducted a double-blinded, randomized, crossover trial in 10 lactose maldigesters. Subjects consumed each of the two types of milk: conventional milk containing 75% A1 β-casein and 25% A2 β-casein and A2 milk containing 100% A2 β-casein. Magnetic resonance images were acquired, and abdominal pain was rated and recorded at 0, 10, 30, 60 and 120 min after milk consumption. The volume of milk in the stomach was calculated using FSL software. The volume of milk in the stomach after consuming milk with 75% A1 β-casein and 25% A2 β-casein was significantly lower at 30 (p = 0.01), 60 (p = 0.002) and 120 (p < 0.001) minutes as compared to milk with 100% A2 β-casein in the 10 lactose maldigesters. The transit of New-World milk containing A1 and A2 β-casein was more rapid as compared to Old-World milk containing only A2 β-casein. This difference in transit may mediate symptoms of lactose intolerance.