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Objectives Lactose malabsorption is generally assessed by hydrogen breath testing (HBT). However, this test is not recommended in patients with high baseline hydrogen concentrations (H2B). In addition, breath testing is not recommended in the current situation created by the COVID-19 pandemic, due to the potential infectiveness of the samples. The objective is to assess concordance between HBT and lactose tolerance test (LTT) depending on H2B concentrations. Methods A total of 430 patients (40 years, Q1–Q3 = 28–54 years; 66.7% women) suspected of lactose malabsorption were included in the study. Breath and heparinized blood samples were collected at baseline and sequentially after the intake of 50 g of lactose, to measure hydrogen in breath and glycemia in blood, respectively. Results H2B was 20 ppm in 15.8% of subjects. In patients with H2B 2B levels obtained in HBT. Conclusions LTT emerges as an alternative to HBT to assess lactose malabsorption in the presence of high H2B levels or when breath testing is not recommended by the circumstances. The best concordance was obtained when the cut-off for LTT was set at 15 mg/dL.

Lactose malabsorption (LM), celiac disease (CD), non-celiac gluten sensitivity (NCGS), and irritable bowel syndrome (IBS) are conditions associated with food triggers, improvement after withdrawal, treatment with dietary restriction, and subsequent nutritional detriments. LM occurs when there is incomplete hydrolysis of lactose due to lactase deficiency and frequently produces abdominal symptoms; therefore, it can cause lactose intolerance (LI). A lactose-restricted diet is frequently recommended, although it can potentially lead to nutrient deficiencies. Furthermore, lactose is an essential component of fermentable oligo-, di-, and monosaccharides and polyols (FODMAPs) and is subsequently associated with intolerance to these compounds, especially in IBS. LM commonly presents in CD. Nutritional deficits are common in CD and can continue even on a gluten-free diet (GFD). Conditions triggered by gluten are known as gluten-related disorders (GRDs), including CD, wheat allergy, and NCGS. IBS can also be associated with a gluten sensitivity. A GFD is the treatment for CD, GRDs, and gluten sensitive IBS, although compliance with this restricted diet can be difficult. Strict dietary therapies can have a negative effect on quality of life. This review aims to provide an overview of the difficult nutritional elements of these disorders, which are critical for medical providers to recognize when managing these patients.

Lactose is the most important source in mammalian milk. In normal children, Lactose is hydrolyzed by lactase, and directly absorbed into bloodstream by an active transport mechanism. The term of lactose malabsorption is reserved to patients in whom impaired intestinal lactose hydrolysis and uptake has been proven by an appropriate test. The severity of lactose malabsorption and the extent of symptoms vary widely and are the results of several factors such as the amount of ingested lactose, gastric emptying time, intestinal transit time, and colonic flora. The diagnosis of lactose malabsorption is based on clinical findings and the results of appropriate tests. The breath hydrogen test has obvious advantages for pediatric population because it is painless, non-invasive, sensitive and specific. In the absence of bacterial colonization in the small intestine, the elevation of the concentration of hydrogen in the expired air implies the arrival of lactose in the colon. The increasing respiratory excretion of hydrogen is indicative of a deficit of lactase in enterocyte brush border. This test can also be used to show the existence of bacterial growth. Dietary fiber, some drugs, preparation for colonoscopy, colonic pH, and diarrhea can influence the result of breath hydrogen test.

Background Adult lactase non-persistence (LNP) is due to low lactase expression, resulting in lactose malabsorption (LM). LNP is a genetic trait, but is typically determined by LM markers including breath H2, blood glucose, and urinary galactose after a lactose tolerance test. Known validity of these markers using milk is limited, despite being common practice. Compositional variation, such as β-casein variants, in milk may impact diagnostic efficacy. This study aimed to evaluate the diagnostic accuracy to detect LNP using these commonly measured LM markers after both lactose and milk challenges. Methods Fourty healthy young women were challenged with 50 g lactose then randomized for separate cross-over visits to ingest 750 mL milk (37.5 g lactose) as conventional (both A1 and A2 β-casein) and A1 β-casein-free (a2 Milk™) milk. Blood, breath and urine were collected prior to and up to 3 h following each challenge. The presence of C/T13910 and G/A22018 polymorphisms, determined by restriction fragment length polymorphism, was used as the diagnostic reference for LNP. Results Genetic testing identified 14 out of 40 subjects as having LNP (C/C13910 and G/G22018). All three LM markers (breath H2, plasma glucose and urinary galactose/creatinine) discriminated between lactase persistence (LP) and LNP following lactose challenge with an area under the receiver operating characteristic (ROC) curve (AUC) of 1.00, 0.75 and 0.73, respectively. Plasma glucose and urinary galactose/creatinine were unreliable (AUC 2 remained high (100%) when milk was used, but sensitivity was reduced with conventional (92.9%) and a2 Milk™ (78.6%) compared to lactose (sensitivities adjusted for lactose content). The breath H2 optimal cut-off value was lower with a2 Milk™ (13 ppm) than conventional milk (21 ppm). Using existing literature cut-off values the sensitivity and specificity of breath H2 was greater than plasma glucose to detect LNP following lactose challenge whereas values obtained for urinary galactose/creatinine were lower than the existing literature cut-offs. Conclusion This study showed accurate diagnosis of LNP by breath H2 irrespective of the substrate used, although the diagnostic threshold may vary depending on the lactose substrate or the composition of the milk. Trial registration ACTRN12616001694404. Registered prospectively on December 9, 2016.

Background. Lactose malabsorption (LM) is a frequent clinical problem associated with several digestive and extra-digestive diseases. The aim of this manuscript was to clarify the real clinical impact of LM on these disorders. Methods. A literature search for digestive and extra-digestive disorders related to LM was carried out using PubMed, Medline and Cochrane. Results. A transient lactase deficiency is present in celiac disease (CD) on a normal diet. The persistence of symptoms in CD on a gluten-free diet may be instead, in part, attributed to a primary LM. Similar circumstances are present in inflammatory bowel diseases (IBD), in which LM can be responsible for a part of persistent symptoms in IBD on clinical remission. LM and irritable bowel syndrome (IBS) are instead independent conditions. On the other hand, a lactose-restricted diet may be useful for some IBS patients. A reduced lactose intake can lead to low bone mass and limited risk of fragility fractures. Finally, the absorption of levothyroxine could be conditioned by LM. Conclusions. LM can be responsible for persistent symptoms in CD and IBD. The association with IBS seems to be casual. Bone mass and levothyroxine absorption can be affected by LM.

Background: Dairy products are frequently considered responsible for post-prandial symptoms and are withdrawn from the diet, even against medical advice. We analysed the symptoms patients consider as lactose related; we also evaluated if psychological profile may affect the interpretation of the relationship between lactose and symptoms. Methods: In 268 patients undergoing lactose breath test, symptoms considered evoked by lactose intake were recorded and their severity measured. In the second part, symptom onset of 40 randomly selected patients was detected after both lactose and glucose breath test were blindly performed. Questionnaires evaluating anxiety, suggestibility and personality trait were administered. Key Results: Symptoms depending on functional gastrointestinal disorders or reflux disease were frequent in self-reported lactose-intolerant patients. In comparison with lactose malabsorption, these symptoms proved to be more frequent in patients with negative lactose breath test. The blinded administration of lactose and glucose demonstrated that a correct link between lactose intake and symptom onset was possible, only in 47.5% of the subjects, making this test inaccurate. None of the investigated psychological characteristics were different between patients with a nocebo response and patients not experiencing nocebo. Conclusions: Patients with self-reported lactose intolerance are frequently unaware about clinical presentation of this condition, and correct information is needed. The detection of symptom onset after lactose is an inaccurate test for lactose intolerance. Furthermore, the analysis of psychological characteristics of patients undergoing hydrogen breath test is not useful to select the subgroup at risk for a nocebo response. New strategies to diagnose lactose intolerance are mandatory.

Background/aims Self-reported lactose intolerance (LI) is frequent in patients with functional bowel disorders (FBD) that could be interpreted as irritable bowel syndrome (IBS). The present study aims to characterize the responses of patients with FBD, without small intestinal bacterial overgrowth (SIBO), and LI, in terms of lactose malabsorption (LM) and lactose sensitivity (LS) according to psychological and clinical features. Methods One hundred and fifty-eight consecutive FBD outpatients with LI, and no SIBO, were classified according to the Rome III questionnaire and filled Beck Depression Inventory, and State and Trait Anxiety questionnaires. They underwent a lactose tolerance test in which glycemia during 60 minutes and digestive symptoms for 3 hours were recorded. Results Abnormal lactose tolerance tests were found in 110 patients (70%), 44 (28%) with LM, 96 (61%) with LS, and 30 (19%) having both LM and LS. LM patients had a higher frequency of functional diarrhea (P = 0.040) and a lower frequency of dysphagia (P = 0.031). LS patients had a higher depression score (P = 0.007), higher frequency of globus (P = 0.042), irritable bowel syndrome (IBS) (P = 0.027) and mixed IBS (P = 0.049), and lower frequency of abdominal pain (P = 0.040). LS was significantly associated with a higher depression score (P = 0.002), and a higher frequency of globus (P = 0.046). Conclusions Thirty percent of LI patients have normal lactose absorption and normal LS. In the other 70% of patients, LI could be associated with LM and/or LS.

Amaç Laktoz malabsorbsiyonu, doğuştan, primer veyasekonder olarak ortaya çıkabilir. Çölyak hastalığı, sekonder laktozmalabsorbsiyona neden olan bir hastalıktır. Bu çalışmada, çölyak hastası çocuklar ile sağlıklıçocuklarda laktoz hidrojen nefes testi ile laktoz malabsorbsiyon sıklığınınbelirlenmesi amaçlanmıştır.Gereçve Yöntem Çalışmaya, 64 çölyakhastası ve 52 sağlıklı çocuk dahil edildi. Çölyak hastaları yeni tanı alanlarve takipli çölyak hastaları olarak iki gruba ayrıldı. Takipli çölyak hastaları tedaviye(glutensiz diyete) tam uyumlu olanlar ve tedaviye uyumsuz olanlar olarak ikigrupta incelendi. Laktoz hidrojen nefes testi 0-500 ppm hidrojen seviyesinialgılayabilen ve 1 ppm düzeyinde duyarlı gaz analiz cihazı kullanılarakyapıldı. BulgularÇocukların ortalama yaşı 10,4 ±4,5 yıldı. Çölyak hastalarının 16’sıyeni tanılı, 48’i takipli idi. Takipli çölyakların 24’ü (%50) glutensiz diyetetam uyumluydu. Yeni tanı çölyak hastalarının %62,5’inde, glutensiz diyeteuyumsuz olanların %54,2’sinde, glutensiz diyete tam uyumluların %33,3’ünde,sağlıklı çocukların ise %19,2’sinde laktoz hidrojen nefes testi pozitifti. Yenitanılı ve glutensiz diyete uymayan çölyak hastalarının laktoz hidrojen nefestesti pozitiflik oranı (sırasıyla, %62,5; %54,2), sağlıklı çocuklardan (%19,2)anlamlı olarak yüksekti (sırasıyla, p=0,002ve p=0,003). Hem çölyak hastalarındahem de sağlıklı çocuklarda, laktoz hidrojen nefes testi pozitif olanların bedenkitle indeksi z skoru, negatif olan çocuklardan anlamlı olarak düşüktü (p, Purpose.Lactose malabsorption(LM) can be congenital, primary, or secondary. Celiacdisease (CD) is a secondary cause of lactose malabsorption. This study aimed todetermine lactose malabsorption frequency using a lactose hydrogen breath test(LHBT) in children with celiac disease and healthy children. Materials and methods.The study included 64 children with CD and 52 healthy controls. Celiac patients were dividedinto groups as newly diagnosed and followed celiac patients. The latter weredivided into groups as compliance or noncompliance with gluten-free diet (GFD).LHBT was performed using a gas analyser with a1-ppm sensor sensitivity of hydrogen levels of 0–500 ppm.Results.Mean age of thechildren was 10.4 ± 4.5 years. Sixteen of the patients had newly diagnosedceliac disease, and 24 (50%) were compliant with GFD. LHBT results were positive in 62.5% of the newly diagnosed CDpatients, 33.3% of those compliant with GFD,54.2% of those non-compliant with GFD,and 19.2% of controls. Asignificantly higher proportion of newly diagnosed CD (62.5%) and non-compliantwith GFD (54.2%) had positive LHBTresults than controls (19.2%) (p=0.002and p=0.003, respectively). The body mass index z scores of the childrenwith LHBT positivity were significantly lower than others in both healthychildren and children with CD (p

Lactose malabsorption (LM) is caused by the incomplete hydrolysis of lactose due to lactase deficiency [...]

Background The prevalence of lactose malabsorption varies widely throughout the world. Only people of Caucasian genetic background continue to produce high amount of lactase throughout adulthood. Previous studies in Indonesia revealed that the prevalence of lactose malabsorption was 21-58% in children aged 3-11 years. Objective To determine the prevalence of lactose malabsorption in the older age group and whether a change in milk drinking habit can affect it. Methods A cross sectional descriptive study was conducted on 98 children aged between 12 and 14 years (junior high school) in Jakarta. Lactose malabsorption was evaluated with Lactometer Breath Hydrogen Test (Hoek Loes, Amsterdam). Milk drinking habit was recorded, and drinking at least 1 glass of milk everyday since 6 months or more before the study was considered as regular milk drinking. Results This study showed 73% of the children had lactose malabsorption. Regular milk drinking habit was found in 32 (33%) children and lactose malabsorption occurred in 26. From 66 children who were irregular milk drinkers, lactose malabsorption was found in 46 (70%). Lactose intolerance was about the same in both groups. Conclusion There was an increasing prevalence of lactose malabsorption in older children. Milk drinking habit is a major concern to review the practical implications of lactose malabsorption.

OBJECTIVES: To study the association between milk consumption and lactose malabsorption in Indonesian children aged 3-12 years. METHODS: This cross sectional study was conducted in randomly selected presumed healthy children with good nutritional status aged 3-12 years in Central Jakarta, Indonesia (n=174), including 72 children aged 3-5 years and 102 children aged 6-12 years. RESULTS: The prevalence of lactose malabsorption in children aged 3-5 years and children aged 6-12 years was 20.8% (15/72) and 35.3% (36/102), respectively. There was no association between milk or milk product consumption and lactose malabsorption (P>0.05). In the 51 children with lactose malabsorption, the predominant clinical symptoms were diarrhea (62%), abdominal pain (52%), and nausea (5%) during the hydrogen breath test. CONCLUSIONS: There is no association between milk consumption and lactose malabsorption in Indonesian children aged 3-12 years, suggesting that genetic predisposition may be more important than adaptive mechanisms to lactose consumption.

OBJECTIVE: To study the association between milk consumption and lactose malabsorption in Indonesian children aged 3-12 years. METHODS: This cross sectional study was conducted in randomly selected presumed healthy children with good nutritional status aged 3-12 years in Central Jakarta, Indonesia (n=174), including 72 children aged 3-5 years and 102 children aged 6-12 years. RESULTS: The prevalence of lactose malabsorption in children aged 3-5 years and children aged 6-12 years was 20.8% (15/72) and 35.3% (36/102), respectively. There was no association between milk or milk product consumption and lactose malabsorption (P>0.05). In the 51 children with lactose malabsorption, the predominant clinical symptoms were diarrhea (62%), abdominal pain (52%), and nausea (5%) during the hydrogen breath test. CONCLUSIONS: There is no association between milk consumption and lactose malabsorption in Indonesian children aged 3-12 years, suggesting that genetic predisposition may be more important than adaptive mechanisms to lactose consumption.

BACKGROUND Lactose malabsorption is a common condition that affects a broad segment of the population. Clinical diagnosis based on symptom recall can be unreliable and conventional testing can be inconvenient, requiring expensive laboratory-based equipment and conduction of the testing in a clinical setting. OBJECTIVE The aim of this study is to assess the performance of a digital handheld hydrogen breath monitor (GIMate) in diagnosing lactose malabsorption compared to a US Food and Drug Administration (FDA)–cleared device (H2 Check) for the same indication. METHODS An interventional crossover study was performed in adult participants with a prior confirmed diagnosis of lactose malabsorption or a suspected history of lactose intolerance. RESULTS A total of 31 participants (mean age 33.9 years) were enrolled in the study. There was 100% positive percent agreement and 100% negative percent agreement between the GIMate monitor and the H2 Check. Correlation between gastrointestinal symptoms and hydrogen values was positive at 0.82 (P CONCLUSIONS The digital handheld GIMate breath monitor achieved equivalent diagnostic performance to that of an FDA-cleared device in the diagnosis of lactose malabsorption. CLINICALTRIAL ClinicalTrials.gov NCT04754724; https://clinicaltrials.gov/ct2/show/NCT04754724

The lactose hydrogen breath test is a commonly used, non-invasive method for the detection of lactose malabsorption and is based on an abnormal increase in breath hydrogen (H₂) excretion after an oral dose of lactose. We use a combined (13)C/H₂ lactose breath test that measures breath (13)CO₂ as a measure of lactose digestion in addition to H₂ and that has a better sensitivity and specificity than the standard test. The present retrospective study evaluated the results of 1051 (13)C/H₂ lactose breath tests to assess the impact on the diagnostic accuracy of measuring breath CH₄ in addition to H₂ and (13)CO₂. Based on the (13)C/H₂ breath test, 314 patients were diagnosed with lactase deficiency, 138 with lactose malabsorption or small bowel bacterial overgrowth (SIBO), and 599 with normal lactose digestion. Additional measurement of CH₄ further improved the accuracy of the test as 16% subjects with normal lactose digestion and no H₂-excretion were found to excrete CH₄. These subjects should have been classified as subjects with lactose malabsorption or SIBO. In conclusion, measuring CH₄-concentrations has an added value to the (13)C/H₂ breath test to identify methanogenic subjects with lactose malabsorption or SIBO.

The aim of this study was to compare the impact of whole milk supplementation on gut microbiota and cardiometabolic biomarkers between lactose malabsorbers (LM) and absorbers (LA). We performed a pair-wise intervention study of 31 LM and 31 LA, 1:1 matched by age, sex, body mass index, and daily dairy intake. Subjects were required to add 250 mL/day whole milk for four weeks in their routine diet. At the beginning and the end of the intervention period, we collected data on gut microbiota and cardiometabolic biomarkers. Whole milk supplementation significantly increased Actinobacteria (P &lt, 0.01), Bifidobacterium (P &lt, 0.01), Anaerostipe (P &lt, 0.01), and Blautia (P = 0.04), and decreased Megamonas (P = 0.04) in LM, but not LA. Microbial richness and diversity were not affected. The fecal levels of short-chain fatty acids (SCFAs) remained stable throughout the study. Body fat mass (P &lt, 0.01) and body fat percentage (P &lt, 0.01) reduced in both groups, but the changes did not differ between groups. No significant differences in other cardiometabolic markers were found between LM and LA. When compared with LA, whole milk supplementation could alter the intestinal microbiota composition in LM, without significant changes in fecal SCFAs and cardiometabolic biomarkers.

Introduction Coeliac disease (CD) is a frequent cause of secondary lactose malabsorption. Many methods are available for the diagnosis of lactose malabsorption. The aim of this study was to assess the prevalence of lactose malabsorption in individuals with CD, as well as symptom correlation with test results. Methods Patients were prospectively recruited between February 2018 and October 2019. Individuals with a potential new diagnosis of CD (positive IgA-EMA/IgA-TTG) or established CD had a duodenal biopsy to assess for lactose malabsorption (Lactose Intolerance Quick Test [LIQT], BIOHIT Oyj, Helsinki, Finland) at time of gastroscopy. Subsequent to this, individuals had a lactose hydrogen breath test (LHBT). Symptoms around the time of gastroscopy were assessed, to allow assessment of symptom correlation with lactose malabsorption (e.g. abdominal pain, bloating, diarrhoea, borborygmi). Results 97 patients were prospectively recruited; out of these 24 had a LHBT suggestive of small intestinal bacterial overgrowth (SIBO) and were excluded. Of the remaining 73 patients (n= 54 female, median age = 47 years), 50 patients had a potential new diagnosis of CD and 23 had established CD. The total prevalence of a positive duodenal lactase test was 43.8%, compared to 15.1% for a positive LHBT. The prevalence of lactose malabsorption was significantly higher in individuals with villous atrophy compared to those without, when using the duodenal lactase test (p Conclusions The prevalence of lactose malabsorption was higher in individuals with CD using the lactase test compared to the LHBT. The prevalence of lactose malabsorption was significantly higher in those with villous atrophy (VA) compared to those without. Although symptom correlation was poor there may be value in using LIQT when assessing CD patients with persisting symptoms.

Background: Sheep milk (SM) is a possible alternate dairy source for those who experience digestive symptoms with cow milk (CM). While both the milks contain lactose, one of the causes for self-reported intolerance to CM, the composition of SM and CM also differs across proteins and fats, which have been shown to impact digestive processes.Objective: To compare the acute digestive comfort and lactose malabsorption of SM to CM in female dairy avoiders.Method: In a double-blinded, randomized cross over trial, 30 dairy-avoiding females (aged 20–30 years) drank 650 mL of SM or CM (each reconstituted from spray dried powder) following an overnight fast, on two separate occasions at least 1 week apart. Blood samples were collected for glucose and insulin assessment, and single nucleotide polymorphisms of the lactase (LCT) gene (C/T13910 and G/A22018). Breath H2 and visual analog scale (VAS) digestive symptom scores were recorded at fasting and regular intervals over 4 h after ingestion.Results: Eighty percentage of study participants were lactase non-persistent (LNP; CC13910 and GG22018 genotype). Digestive symptoms, including abdominal cramps, distension, rumbling, bloating, belching, diarrhea, flatulence, vomiting, and nausea, were similar in response to SM and CM ingestion (milk × time, P > 0.05). Breath H2 was greater after CM than SM (72 ± 10 vs. 43 ± 6 ppm at 240 min, P < 0.001), which may be due to greater lactose content in CM (33 vs. 25 g). Accordingly, when corrected for the lactose content breath H2 did not differ between the two milks. The response remained similar when analyzed in the LNP subset alone (n = 20).Conclusions: Despite a higher energy and nutrient content, SM did not increase adverse digestive symptoms after ingestion, relative to CM, although there was a reduced breath H2 response, which could be attributed to the lower lactose content in SM. The tolerability of SM should be explored in populations without lactose intolerance for whom underlying trigger for intolerance is unknown.

Lactose intolerance (LI) is characterized by the presence of symptoms, mainly gastrointestinal, due to the colonic fermentation of lactose not absorbed by lactase enzyme deficiency. Lactase deficiency can be primary, congenital, or adult type lactase deficiency, and secondary to other pathologies that involve a loss of enzyme activity. The prevalence of adult type lactose malabsorption varies depending on ethnicity and geographic location. In Europe it is related to the presence of two single nucleotide polymorphisms (SNP C / T-13910 and G / A-22018). What is the best technique for its diagnosis, especially with what dose the provocation should be done and for how long it should be performed, is still under discussion. The clinical symptomatology in lactose intolerance is modified by the load of the lactose substrate, the activity of the lactase enzyme, the speed of intestinal transit, the rate of gastric emptying and colonic compensation. Some LI do not present symptoms after usual amounts of milk intake, mainly of yogurt and cheese. In addition, the intestinal microbiota will also modify the presence and severity of symptoms. So the modification of this with biotics could be a possibility of treatment and to promote dairy products consumption.

OBJECTIVES: Sheep milk (SM) is compositionally different from cow milk (CM), but maintains the nutritional benefits of CM, making it a potential alternative for CM avoiders. While dairy avoidance is often due to intolerance to lactose, which is also found in SM, there are consumer anecdotal reports that SM is better tolerated than CM. Thus, this clinical trial was undertaken to assess acute digestive comfort and lactose malabsorption comparing SM and CM in female dairy avoiders. METHODS: In a double-blinded, randomized cross over trial, 30 dairy avoiding females (aged 20–30 years) drank 650 mL of SM or CM (reconstituted from spray dried powder) following an overnight fast, on separate occasions at least one week apart. Blood samples were collected for single nucleotide polymorphisms of the LCT gene (lactase gene; C/T(13910) and G/A(22018)). Breath H(2) and visual analog scale (VAS) digestive symptom scores were recorded at fasting and regular intervals over 4 h after ingestion. RESULTS: Genotyping showed 80% of the dairy avoiders were lactase non-persistent (CC(13910) and GG(22018) genotype), hence lactose malabsorbers. Digestive symptoms were similar in response to SM and CM, with increased symptoms; abdominal cramps, rumbling, bloating, belching, flatulence, and nausea, after the ingestion of either milk (P

Background Lactose malabsorption is a common condition that affects a broad segment of the population. Clinical diagnosis based on symptom recall can be unreliable and conventional testing can be inconvenient, requiring expensive laboratory-based equipment and conduction of the testing in a clinical setting. Objective The aim of this study is to assess the performance of a digital handheld hydrogen breath monitor (GIMate) in diagnosing lactose malabsorption compared to a US Food and Drug Administration (FDA)–cleared device (H2 Check) for the same indication. Methods An interventional crossover study was performed in adult participants with a prior confirmed diagnosis of lactose malabsorption or a suspected history of lactose intolerance. Results A total of 31 participants (mean age 33.9 years) were enrolled in the study. There was 100% positive percent agreement and 100% negative percent agreement between the GIMate monitor and the H2 Check. Correlation between gastrointestinal symptoms and hydrogen values was positive at 0.82 (P Conclusions The digital handheld GIMate breath monitor achieved equivalent diagnostic performance to that of an FDA-cleared device in the diagnosis of lactose malabsorption. Trial Registration ClinicalTrials.gov NCT04754724; https://clinicaltrials.gov/ct2/show/NCT04754724

Additional File 2: Figure S1. Pre and postprandial concentration of A) breath H2, B) plasma glucose and C) urinary galactose/creatinine between lactase persistent and lactase non-persistent individuals following ingestion of lactose, CON milk, and A2M. A) and B) show the timecoure change in breath H2 and plasma glucose respectively pre and post lactose and milk ingestion. C) shows the urinary galactose/creatinine concentration pre and post lactose and milk ingestion. Comparisons computed by generalised linear mixed model. Interaction between group and time are shown on each plot. * p

Additional File 3: Figure S2. The receiver operating characteristic (ROC) curve for breath H2, plasma glucose, and urinary galactose/creatinine ratio.

Additional File 1: Table S1. Response to lactose and milk ingestion. Table showing group means (lactase persistent and lactase non-persistent) means of breath H2 concentration, plasma glucose concentration, and urinary galactose/creatinine ratio following lactose (50 g), conventional milk (750 mL), or a2 Milk™ (750 mL).

Food lactose and lactose intolerance are today hot topics in the field of food and nutrition. About 70% of the adult world population is lactose-intolerant, due to low levels of intestinal lactase, also called lactase-phlorizin hydrolase (LPH), a β-d-galactosidase found in the apical surface of the intestinal microvilli. This may be due to the loss of intestinal lactase in adulthood, a condition transmitted by an autosomal recessive gene, which differs in humans according to race. According to the cultural-historical hypothesis, the mutation that allows the metabolization of lactose appeared about 10 000 years ago in the inhabitants of Northern Europe where mammalian milk continued in the diet after weaning, and lactase-persistent populations were genetically selected in some areas. Many intolerant individuals can tolerate low levels of lactose in their daily diet. Probiotics have also been proposed as an alternative that could avoid some symptoms of lactose intolerance. Many products are marketed nowadays as alternatives to dairy products for lactose-intolerant individuals. However, the rules for low-lactose foods are currently not harmonised in the European Union. As scientific knowledge on lactose intolerance has notably advanced in recent decades, the aim of this work was to review the current state of the knowledge on lactose and lactose intolerance, its diagnosis and clinical management, and the various food products that are offered specifically for non-tolerant individuals.

Lactose is the main source of calories in milk, an essential nutriedigestion, patients with visceral hypersensitivity nt in infancy and a key part of the diet in populations that maintain the ability to digest this disaccharide in adulthood. Lactase deficiency (LD) is the failure to express the enzyme that hydrolyses lactose into galactose and glucose in the small intestine. The genetic mechanism of lactase persistence in adult Caucasians is mediated by a single C→T nucleotide polymorphism at the LCTbo -13'910 locus on chromosome-2. Lactose malabsorption (LM) refers to any cause of failure to digest and/or absorb lactose in the small intestine. This includes primary genetic and also secondary LD due to infection or other conditions that affect the mucosal integrity of the small bowel. Lactose intolerance (LI) is defined as the onset of abdominal symptoms such as abdominal pain, bloating and diarrhoea after lactose ingestion by an individual with LM. The likelihood of LI depends on the lactose dose, lactase expression and the intestinal microbiome. Independent of lactose digestion, patients with visceral hypersensitivity associated with anxiety or the Irritable Bowel Syndrome (IBS) are at increased risk of the condition. Diagnostic investigations available to diagnose LM and LI include genetic, endoscopic and physiological tests. The association between self-reported LI, objective findings and clinical outcome of dietary intervention is variable. Treatment of LI can include low-lactose diet, lactase supplementation and, potentially, colonic adaptation by prebiotics. The clinical outcome of these treatments is modest, because lactose is just one of a number of poorly absorbed carbohydrates which can cause symptoms by similar mechanisms. ispartof: GUT vol:68 issue:11 pages:2080-2091 ispartof: location:England status: published

Consumption of foods can be suppressed by two feeding system defense mechanisms: conditioned taste aversion (CTA) or taste avoidance learning (TAL). There is a debate in the literature about which form of intake suppression is caused by various aversive stimuli. For instance, illness-inducing stimuli like lithium chloride are the gold standard for producing CTA and external (or peripheral) painful stimuli, such as footshock, are the traditional model of TAL. The distinction between CTA and TAL, which have identical effects on intake, is based on differential effects on palatability. That is, CTA involves a decrease in both intake and palatability, whereas TAL suppresses intake without influencing palatability. We evaluated whether lactose, which causes gastrointestinal pain in adult rats, produces CTA or TAL. Using lick pattern analysis to simultaneously measure intake and palatability (i.e., lick cluster size and initial lick rate), we found that pairing saccharin with intragastric infusions of lactose suppressed both the intake and palatability of saccharin. These results support the conclusion that gastrointestinal pain produced by lactose malabsorption produces a CTA, not TAL as had previously been suggested. Furthermore, these findings encourage the view that the CTA mechanism is broadly tuned to defend against the ingestion of foods with aversive post-ingestive effects.

Background. Insufficient vitamin D and calcium intake associated with the restricted intake of milk and dairy products can lead to poor health outcomes like malnutrition and abnormal bone mineralization. The aim of the study was to estimate the prevalence of primary and secondary lactose intolerance in children with IBD. Methods. The study included 107 patients (mean age 14.07±3.58 years; 46.7% boys) which includes 43 patients with Crohn’s disease (CD), 31 with ulcerative colitis (UC), and 33 children with functional abdominal pain (AP-FGID). We analysed the result of the hydrogen breath test with lactose loading, two single nucleotide polymorphisms of the LCT gene (LCT-13910CC and LCT-22018GG). The results were analysed with MedCalc Statistical Software. Results. Adult-type hypolactasia (ATH) was found in 31% of patients with IBD and 42.4% of AP-FGID (p=0.2). Lactose malabsorption (LM) was found in 27.9% of patients with CD, in 22.6% with UC, and in 24.2% with AP-FGID (p=0.8). Lactose intolerance (LI) was diagnosed in a similar percentage of patients in each group (p=0.9). Secondary LI in IBD patients does not depend on the location, duration, and activity of the disease and the number of relapses (p>0.05). The median time of lactose-free diet in CD was 10 months and in CU 24 months. Conclusions. The incidence of LI, LM, and ATH does not differ among children with IBD from the population.

SummaryPatients with anomalies of the inferior vena cava (IVC) are rare, are usually asymptomatic and this developmental anomaly is detected during radiologic evaluation of deep vein thrombosis or incidentally during abdominal radiologic evaluation. We report on time resolved three-dimensional magnetic resonance angiography (4D MRA) in a patient with congenital anomaly of the IVC and nonspecific abdominal complaints. 4D MRA is shown for evaluation and detailed diagnosis in vascular venous anatomy. However, due to continuing bloating and irregular bowel movements we investigated carbohydrate malabsorption and a lactose malabsorption was diagnosed. The nonspecific abdominal complaints in this patient with IVC anomaly were due to lactose malabsorption and were treated successfully with a lactose-free diet.@Supplementary material online: www.phlebologieonline.de: http://dx.doi.org/10.12687/phleb2285-1-2016

Background Current literature proposes associations between homocysteine (HCY), folic acid (FA), vitamin B12 metabolism and depression. However, the exact underlying biological mechanisms remain unclear. This study aimed at evaluating a possible link between primary adult-type lactose malabsorption (PALM), HCY, FA and vitamin B12 metabolism and depressive disorder. Methods Plasma levels of HCY, FA and vitamin B12 were determined in 78 patients with PALM and 160 individuals with lactase persistence sub-grouped by the presence or absence of major depression. Results In 78 patients with PALM, the subgroup of 22 individuals with major depression showed significantly higher median (interquartile range) HCY (10.10 [8.46–12.03] vs. 8.9 [7.54–9.86] μmol/L, p = 0.029) and lower plasma FA levels (5.7 [4.68–9.14] vs. 6.95 [5.24–10.56] μmol/L, p = 0.272) compared to the subgroup of 56 individuals without depression, respectively. No such associations could be observed for those 160 individuals without PALM (i.e., lactase persistence) Plasma HCY levels were positively correlated with depressive symptoms (p = 0.052), and showed negative correlations with FA (p = < 0.001) and vitamin B12 (p = 0.029), respectively. Conclusion Depressed individuals with PALM were found with significantly higher HCY and lower FA levels compared to non-depressed individuals with PALM, however, this association was absent in the subgroup of lactase persistent individuals. These findings suggest an association between increased HCY levels, lactose malabsorption and depression.

Background Lactase deficiency may lead to gastrointestinal symptoms after milk ingestion, known as lactose intolerance. Studies showed that lactose intolerant individuals avoid milk consumption, but they eat other dairy. Most of these studies were conducted on healthy people. Aim The aim of present study was to evaluate the impact of lactose malabsorption and lactose intolerance on dairy consumption in children with gastrointestinal diseases. Material and methods Hydrogen breath test was conducted on pediatric patients aged from 2 to 19 years. Data regarding consumption of milk, plain fermented dairy products (FDP), flavored FDP, cheese and cottage cheese were collected. Differences in dairy consumption were analyzed between lactose absorbers and lactose malabsorbers, as well as between lactose intolerant and lactose tolerant individuals. Results Two hundred and three children were selected to the study (82 males, mean age 11.39 years). There was no relationship between dairy products consumption and age. However, the frequency of lactose intolerance increased significantly with age. The type of gastrointestinal disease influenced only the cottage cheese consumption. Lactose intolerance decreased significantly milk consumption, but not other dairy products consumption. Lactose intolerants consumed dairy products (excluding milk) more often than lactose tolerants (38.2% and 23.6% respectively). Positive relationship between milk consumption and the consumption of FDP and cottage cheese was observed only in lactose absorbers and lactose tolerants. Conclusions Lactose intolerance decreases milk consumption, but does not affect other dairy consumption. Dietary preferences play a key role in dairy consumption in lactose absorbers and lactose tolerant children.

Background Recurrent abdominal pain (RAP) is common among school-age children. Previous studies found that lactose malab- sorption has an important role in RAP in children. Up to date, data on the prevalence of lactose malabsorption in children with RAP in Indonesia has not been available. Objective To elicit the prevalence of RAP and lactose malabsorption in children with RAP, and to determine associated foods that cause RAP in children with and without lactose malabsorption, the frequency of lactose intolerance during breath hydrogen test (BHT), and also the onset and duration of the symptoms after a lactose load. Methods This was a cross-sectional study conducted on junior high school students who suffered from recurrent abdominal pain. Results Of 1054 students screened, 157 (14.9%) fulfilled the Apley’s criteria for RAP. Of 157, 85 children were enrolled and underwent BHT. Fifty five of them (65%) were girls. Lactose malabsorption was found in 68 (80%) subjects. Milk and yogurt were the most frequent products that cause symptoms of RAP in our subjects who mostly (80%) were malabsorber. Lactose intolerance during BHT was found in 69 (81%) children. Symptoms appeared in 30 minutes after lactose ingestion, and the most frequent symptom was abdominal pain (44%). Lactose intolerance symptoms disap- peared in about 15 hours. Conclusions The prevalence of RAP in children aged 12-14 years was 14.9%. The prevalence of lactose malabsorption in children with RAP was 80%. Milk and yogurt were the most frequent products that cause symptoms of RAP in our subjects who mostly were malabsorbers. The frequency of lactose intolerance during BHT was 81%, and the symptoms lasted within approximately 15 hours

Summary Background Studies have shown wide variation in the prevalence of lactose malabsorption across the world, but no systematic reviews or meta-analyses have recently assessed the prevalence of lactose malabsorption in different geographical areas. We aimed to present an updated systematic review and meta-analysis on the prevalence of lactose malabsorption in adults, by countries and regions, and to assess the variation between different testing methods. Methods Studies reporting on prevalence of lactose malabsorption and lactase persistence were identified by searching MEDLINE and Embase from database inception to Nov 2, 2016. We evaluated studies presenting lactose malabsorption or lactase persistence prevalence data in adults and children aged 10 years or older, including cross-sectional and prospective studies, using genotyping, hydrogen breath tests, lactose tolerance tests, and other testing methods. We excluded studies in children younger than 10 years, studies using self-reported data, and studies including inpatients and outpatients at gastroenterological wards. Studies were screened by two authors (CLS and SKF) and data values were extracted by two authors (CLS and SKF) independently. The primary outcome was the prevalence of lactose malabsorption. This study is registered with PROSPERO, number CRD42017064802. Findings We screened 2665 records, and 306 study populations from 116 full-text articles were included (primary sources); data for 144 additional study populations from 59 articles were obtained from review articles, because full-text primary articles could not be obtained (secondary sources). Of the 450 study populations included, 231 were assessed by genotyping, 83 by hydrogen breath tests, 101 by lactose tolerance tests, and 35 by other methods or methods that were not described sufficiently. The studies included 62 910 participants from 89 countries (covering 84% of the world's population). When standardising for country size, the global prevalence estimate of lactose malabsorption was 68% (95% CI 64–72), ranging from 28% (19–37) in western, southern, and northern Europe to 70% (57–83) in the Middle East. When assessing the global prevalence using genotyping data only, the estimate was 74% (69–80), whereas prevalence was 55% (46–65) using lactose tolerance test data, and 57% (46–67) using hydrogen breath test data. Risk of bias was assessed based on ten indicators; 12 of the articles had a score of ten, indicating low risk of bias, 76 had a score of nine, 26 a score of eight, and two articles a score of seven (indicating higher risk of bias). There was substantial heterogeneity between studies within most of the assessed countries. Interpretation Lactose malabsorption is widespread in most of the world, with wide variation between different regions and an overall frequency of around two-thirds of the world's population. Acknowledging regional patterns of lactose malabsorption is important to guide management of gastrointestinal symptoms. Funding None.

During the last decade, lactose-free diets have become increasingly popular in the general population, either isolated or as a part of a cow's milk-free diet. However, health-related benefits from a lactose-free diet are only documented for individuals with clinical lactose intolerance due to decreased intestinal lactase activity and subsequent lactose malabsorption. In this paper we summarize the current knowledge of lactose intolerance regarding diagnostic procedures and treatment.

Background Lactase is an enzyme involved in the hydrolysis of lactose. Deficiency of the enzyme (hypolactasia) may be determined genetically or arise secondarily to disease of small intestine. Under this condition, lactose enters the colon where it is fermented by intestinal microflora and turns to gases and short-chain fatty acids, causing gastrointestinal symptoms known as lactose intolerance (LI). Objectives To investigate the incidence of lactose malabsorption (LM), LI and the coexistence of these two conditions in children with upper gastrointestinal tract diseases (UGTD), malabsorption syndrome, inflammatory bowel disease (IBD) and functional gastrointestinal disorders (FGID). Material and methods Hydrogen breath test (HBT) was conducted in 387 pediatric patients in years 2010-2013. Two hundred thirty two children with gastrointestinal tract diseases were selected and assigned to groups - UGTD, malabsorption syndrome, IBD or FGID. For each group the frequency of LM, frequency and severity of LI and the frequency of their co-occurrence were calculated. Results Lactose malabsorption was observed in 37.08% of patients with gastrointestinal diseases. Positive HBT result was the most common in children with malabsorption syndrome (52.50%) and less common in UGTD (30.85%), especially in ulcer disease (23.53%). Symptoms after lactose ingestion affected 36.64% of the subjects, and were more specific to lactose malabsorbers than to lactose absorbers (72.10% vs. 15.75%). The higher frequency of LI was noted in children with FGID, especially in irritable bowel syndrome (IBS) (65.22%). The lowest incidence of symptoms was obtained in children with UGTD, especially in those with ulcer disease (27.44%). The incidence of LM with LI was noted in 27.16% of all patients and was the highest in IBS (47.83%) and the lowest in ulcer disease (15.78%). Conclusions Lactose malabsorption is a common problem in children with gastrointestinal diseases, especially in children with bowel diseases. Lactose intolerance is related to LM, but does not affect all malabsorbers.

Background: Milk is the major food in the diet of the infant mammal and consequently has always attracted considerable interest from the physician, the industrialist and the mother. The concentration of lactose in milk varies from species to species. Main objective is to study the prevalence of malabsorption in malnutrition.Methods: Sixty-seven children ranged between ages of 6 months to 3 years, of both sex and varying grades of malnutrition, were studied. Study conducted between July 1979-December 1979. All children were grouped into 4 grades of malnutrition according to Indian Academy of Pediatrics recommendation.Results: Out of 67 cases, 50 were followed up. Severe malnutrition of grades III and IV (less than 60 percent of expected body weight) comprises 58.2 percent (39 out of 67) in first seen group, and 52 percent (26 out of 50) in follow up group. 59.7 percent Males and 40.3 percent females in first seen cases. 58 percent males and 42 percent females in follow up cases. 24 cases (53.33 percent) of lactose malabsorbers were males and 21 cases (46.67 percent) were females.Conclusions: Lactose malabsorption is common in protein-energy malnutrition. This can be determined by simple ward tests and abnormal lactose tolerance curve after oral lactose load. Lactose malabsorption increases with the severity of malnutrition. Malnutrition leads to lactose malabsorption and lactose malabsorption is an important contributory factor in production of malnutrition.

Objectives Recently, an intermediate lactose intolerance (LI) phenotype based on the lactase gene (LCT) C/T-13910 polymorphism was proposed. However, a multifactorial genesis of LI phenotypic variation including endogenous and exogenous factors cannot be ruled out. Therefore, this study was conducted to investigate a possible association between serum diamine oxidase (DAO) and LI phenotypes in individuals with lactose malabsorption (LM). Design and methods A total of 121 ambulatory patients with LM were included in this retrospective study. The lactose hydrogen breath test (LHBT) and serum DAO activity measurements were performed on the same day. A thorough anamnesis with respect to gastrointestinal symptoms was carried out at the initial consultation. Results In total, 44 (36.4%) patients with a serum DAO activity

Primary adult-type lactose malabsorption (PALM) is a widespread inherited autosomal recessive condition, which is considered to be associated with osteoporosis. This prospective study aimed at assessing the 25-hydroxy-vitamin D (25(OH)D) status and serum CrossLaps levels in individuals with PALM and normal controls.All participants (n=210) underwent genotyping for the LCT C/T-13910 polymorphism, 25(OH)D and CrossLaps measurements and clinical examinations. In addition, the anthropometric data (that is, height, weight and body mass index) were determined.Fifty-five individuals with PALM (that is, LCT C/C-13910 homozygotes) showed lower 25(OH)D (mean: 24.95±10.04 vs 28.59±9.56 ng/ml, P=0.018) and higher CrossLaps serum levels (mean: 0.46±0.31 vs 0.43±0.49 ng/ml, P=0.251) compared with 155 normal controls (that is, LCT C/T-13910 hetero- or T/T-13910 homozygotes). Anthropometric data were similar between PALM probands and controls.Individuals with PALM were found to have lower 25(OH)D and higher CrossLaps serum levels compared with normal controls. In order to preserve life-long bone health, routine 25(OH)D and CrossLaps serum measurements should be performed in individuals with PALM.

Background/Aims: Lactose malabsorption (LM) consists in the incomplete absorption of lactose, due to lactase deficiency. According to previous studies, headache can be triggered by food intolerance. We investigated the onset and severity of headache during the LBT and a correlation with LM. Patients and Methods: We enrolled 93 (74F/19M; mean-age 42 ± 16 yrs) outpatients who performed a LBT according to the guidelines. Patients reported on a Visual-Analogue-Scale the intensity of headache before and at the end of the test. We considered as significant an increase of headache in VAS peak >10mm. Results: 67/93 (72%) resulted LM, while 53% (49/93) referred a headache worsening. Within the group of LM headache worsened in 50.7%, compared to 57.7% in non-malabsorbers (p=0.36). In the subgroup of patients with habitual headaches there is a significant worsening compared to non-habitual ones (70.7% vs 38.5%; p=0.003) regardless of the LBT result. Conclusion: The present study denies the existence of an association between LM and headache. We found that headache significantly worsened in patients usually suffering from headache, regardless LM. We think that this data should be considered, since we suppose that the onset of headache during a LBT could affect the correct execution of the test.

AIM: To validate 4-sample lactose hydrogen breath testing (4SLHBT) compared to standard 13-sample LHBT in the clinical setting. METHODS: Irritable bowel syndrome patients with diarrhea (IBS-D) and healthy volunteers (HVs) were enrolled and received a 10 g, 20 g, or 40 g dose lactose hydrogen breath test (LHBT) in a randomized, double-blinded, controlled trial. The lactase gene promoter region was sequenced. Breath samples and symptoms were acquired at baseline and every 15 min for 3 h (13 measurements). The detection rates of lactose malabsorption (LM) and lactose intolerance (LI) for a 4SLHBT that acquired four measurements at 0, 90, 120, and 180 min from the same data set were compared with the results of standard LHBT. RESULTS: Sixty IBS-D patients and 60 HVs were studied. The genotype in all participants was C/C-13910. LM and LI detection rates increased with lactose dose from 10 g, 20 g to 40 g in both groups (P < 0.001). 4SLHBT showed excellent diagnostic concordance with standard LHBT (97%-100%, Kappa​​ 0.815-0.942) with high sensitivity (90%-100%) and specificity (100%) at all three lactose doses in both groups. CONCLUSION: Reducing the number of measurements from 13 to 4 samples did not significantly impact on the accuracy of LHBT in health and IBS-D. 4SLHBT is a valid test for assessment of LM and LI in clinical practice.

Probiotics are living microorganisms that exert scientifically proven health effects. The idea behind probiotics, prebiotics and synbiotics is to produce food or food supplements which, after ingestion, strengthen healthy intestinal microbiota, by either adding probiotic microorganisms, indigestible but fermentable prebiotic carbohydrates, or both constituents combined in synbiotics. This chapter offers a thorough review of evidence for uses of probiotics for a number of medical conditions: gastrointestinai disorders, Helicobacter eradication, lactose malabsorption and inflammatory bowel disease.

BACKGROUND Lactose intolerance is a frequent condition in certain populations. Different methods for diagnosis exist. There is scarce literature regarding Lactose Quick Test (LQT) and concordance with other methods for lactose intolerance diagnosis in children. METHODS Prospectively, we included children who underwent gastroduodenoscopy for evaluation of abdominal pain. We obtained a duodenal sample for LQT and blood sample for genetic test to evaluate LCT C>T-13910 variant. Later, patients underwent breath test with lactose, to evaluate malabsorption. We evaluated the concordance between the three different tests. KEY RESULTS We included 46 patients, 56.5% women. Mean age was 13.2 years (range 9-18 years). 66.6% of patients had lactose malabsorption according to breath test; 64.4% were homozygous CC; and 91.3% had hypolactasia (mild or severe) according to LQT. None of the patients with normolactasia had altered breath test. Genetic test had a substantial agreement (k = 0.675) with breath test and fair agreement (k = 0.301) with LQT. LQT had fair agreement (k = 0.348) with breath test. CONCLUSIONS & INFERENCES Genetic test had better concordance with breath test than LQT to diagnose lactose malabsorption, however, none of the patients with normal LQT had lactose malabsorption. In patients who undergo gastroduodenoscopy to study abdominal pain, it seems reasonable to perform LQT, and, in those with hypolactasia, to perform breath test.

Lactose malabsorption (LM) is caused by insufficient enzymatic degradation of the disaccharide by intestinal lactase. Although hydrogen (H2) breath tests (HBTs) are routinely applied to diagnose LM, false-negative results are not uncommon. Thirty-two pediatric patients (19 females, 13 males) were included in this prospective study. After oral lactose administration (1 g kg(-1) bodyweight to a maximum of 25 g), breath H2 was measured by electrochemical detection. HBT was considered positive if H2 concentration exceeded an increase of ⩾20 ppm from baseline. In addition to H2, exhaled methane (CH4), blood glucose concentrations and clinical symptoms (flatulence, abdominal pain, diarrhea) were monitored. A positive HBT indicating LM was found in 12/32 (37.5%) patients. Only five (41.7%, 5/12) of these had clinical symptoms during HBT indicating lactose intolerance (LI). Decreased blood glucose concentration increments (⩽20 mg dL(-1) (⩽1.1 mmol L(-1))) were found in 3/5 of these patients. CH4 concentrations ⩾10 ppm at any time during the test were observed in 5/32 (15.6%) patients and in 9/32 (28.1%) between 1 ppm and 9 ppm above baseline after lactose ingestion. In patients with positive HBT 10/12 (83.3%) showed elevated CH4 (>1 ppm) above baseline in breath gas, whereas in patients with negative HBT this figure was only 4/17 (23.5%). In addition to determining H2 in exhaled air, documentation of clinical symptoms, measurement of blood glucose and breath CH4 concentrations may be helpful in deciding whether in a given case an HBT correctly identifies patients with clinically relevant LM.