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Summary Background Fructose malabsorption, lactose malabsorption and an early rise in breath hydrogen after lactulose (ERBHAL) may play roles in induction of symptoms in gastrointestinal conditions. Aim To compare prevalence and interactions of fructose malabsorption, lactose malabsorption and ERBHAL among healthy subjects and those with chronic intestinal disorders using consistent breath hydrogen testing methodologies. Methods Consecutive series of Caucasian patients with Crohn’s disease (n = 91), ulcerative colitis (56), functional gastrointestinal disorders (FGID) (201), coeliac disease (136) and 71 healthy volunteers underwent breath hydrogen testing using lactulose, fructose and lactose. Results Early rise in breath hydrogen after lactulose occurred more commonly in healthy controls (39%) than in Crohn’s disease (20%) and untreated coeliac disease (14%; P

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.

Adult‑type hypolactasia (lactase nonpersistence or lactase deficiency) is the most common enzyme deficiency leading to lactose intolerance and primary lactose malabsorption. Clinical presentation of the condition includes symptoms resulting from bacterial fermentation of undigested lactose in the colon, which gives rise to gas bloat, increased motility, and loose stools. Diagnosis of the disease is based on clinical symptoms, biochemical, functional, histochemical and genetic tests. Treatment includes dietary restrictions, namely, use of low‑lactose milk, in which lactose has been prehydrolyzed, or non‑lactose milk.

As decreased bone mineral density (BMD) is a common problem in cystic fibrosis (CF) and milk products may have pivotal dietary role affecting BMD, we aimed to assess the potential influence of adult-type hypolactasia (ATH) and lactose malabsorption (LM) on BMD in adolescent and young adult patients. In 95 CF pancreatic-insufficient patients aged 10–25 years (without liver cirrhosis, steatosis and cholestasis, diabetes mellitus, systemic glucocorticoid therapy), lumbar BMD, the nutritional status, pulmonary function, vitamin D3 concentration, calcium intake and single-nucleotide polymorphism upstream of the lactase gene were assessed. In subjects with the −13910 C/C genotype predisposing to ATH, the presence of LM was determined with the use of a hydrogen–methane breath test (BT). BMD and calcium intake were significantly lower in patients with the C/C genotype (P

Summary Background & aims Lactose malabsorption (LM) is a frequent condition in adults and is often associated with bowel symptoms. Although the diagnostic gold standard is represented by assessment of the tissue lactase activity, LM diagnosis is currently made non-invasively by hydrogen breath test. Alternatively, an accurate clinical and anamnestic evaluation of symptoms can suggest LM in many cases. The aim of the study was to evaluate the diagnostic accuracy of clinical variables for the diagnosis of LM when compared to the hydrogen breath test. Methods Forty consecutive patients with suspected LM performed a hydrogen breath test after oral load of lactose (25 g). Patients were requested to answer five questions on a visual-analogical scale (0–4): subjective correlation milk/symptoms; abdominal pain; bloating; soft stools; response after milk exclusion. Statistical analysis was performed by using the Mann–Whitney U-test and Cohen's k of agreement. Also, a ROC curve was constructed to identify the best diagnostic cut-off for the resulting clinical-anamnestic score. Results Breath test was positive in 16 out of 40 patients (40%). The mean clinical score was significantly higher in patients with LM (14 vs 8.5; p 10 showed a sensitivity of 91%, a specificity of 95%, positive and negative predictive values of 91% and of 95% for LM diagnosis. Additionally, a score >10 presented high concordance with the result of the breath test (k = 0.92). Conclusions Accurate evaluation of five clinical-anamnestic variables, with the use of a simple scoring system, is almost equivalent to the hydrogen breath test for the diagnosis of lactose malabsorption and could avoid breath testing in many cases.

The prevalence and duration of lactose malabsorption was studied in 64 Central Australian Aboriginal children requiring hospitalization for acute enteritis. Lactose malabsorption was determined by the breath‐hydrogen test. Sixty‐nine per cent were shown to malabsorb lactose, a figure similar to that for well nourished urban European children, hospitalized for acute enteritis. Whereas 90 per cent of the European children became lactose‐tolerant 1 month later, only three of 32 aboriginal children were lactose‐tolerant after 3 months. Lactose malabsorption was also associated with more frequent hospitalizations in affected children. Coronavirus‐like particles were the commonest agent isolated from Aboriginal children. The majority of the Aboriginal children were malnourished (< 80% standard weight for age) which may have been contributed to by their lactose malabsorption and explain why this failed to recover in the same way as European children. The possibility of lactose malabsorption must be taken into consideration when managing Aboriginal children with acute diarrhoeal disease and undernutrition. The use of the breath‐hydrogen test allows an accurate diagnosis of lactose malabsorption to be made in Aboriginal children with diarrhoea so that appropriate dietary management can be instituted.

Lactose malabsorption is a syndrome producing constellation of symptoms, including abdominal pain, bloating, flatulence, diarrhea, and sometimes nausea and/or vomiting. Primary causes of lactose malabsorption due to loss of intestinal lactase activity include genetic/racial lactase nonpersistence, congenital lactase deficiency, and developmental lactase deficiency. Secondary lactose malabsorption can be caused by any disorder that injures the small intestinal mucosa, such as viral gastroenteritis, celiac disease, allergic (eosinophilic) gastroenteritis, and radiation enteritis. The diagnosis depends on careful clinical evaluation and is customarily confirmed with a lactose breath hydrogen test. As the symptoms are nonspecific, many adults diagnosed with lactose malabsorption actually have irritable bowel syndrome. Treatment consists of a trial of eliminating lactose-containing dairy foods, with supplementation of alternative calcium and protein sources. Commercial enzyme products containing β-galactosidases can be prescribed to help patients digest dietary lactose. Long-term lactose restriction usually is not necessary and can lead to reduced bone mineral density.

Background: Lactose malabsorption (LM), the inability to break down lactose into glucose and galactose, is due to a deficiency in the small intestinal lactase phlorizin hydrolase enzyme. Ethnic and geographic variations of LM are known. Objective: The aim of this study was to compare the frequency of LM in healthy southern and northern Indian populations. Design: A total of 153 healthy volunteers (76 from southern and 77 from northern India) were evaluated for LM by using a lactose tolerance test (LTT), a lactose hydrogen breath test (lactose HBT), and polymerase chain reaction-restriction fragment length polymorphism to identify the lactase gene C/T-13910 polymorphism (confirmed by sequencing). Results: Volunteers from southern and northern India were comparable in age and sex. The LTT result was abnormal in 88.2% of southern Indians and in 66.2% of northern Indians (P = 0.001). The lactose HBT result was abnormal in 78.9% of southern Indians and in 57.1% of northern Indians (P = 0.003). The CC genotype was present in 86.8% and 67.5% (P = 0.002), the CT genotype was present in 13.2% and 26.0% (P = 0.036), and the TT genotype was present in 0% and 6.5% (P = 0.03) of southern and northern Indians, respectively. The frequency of symptoms after the lactose load (47.4% compared with 15.6%; P < 0.001) and peak concentrations of breath hydrogen (88.5 ± 71.9 compared with 55.4 ± 61.9 ppm; P = 0.003), both of which might indicate the degree of lactase deficiency, were higher in southern than in northern Indians. Conclusion: The frequency and degree of LM is higher in southern than in northern Indian healthy populations because of genetic differences in these populations.

BACKGROUND: The hydrogen breath test (H2BT) is the most widely used procedure in the diagnostic workup of lactose malabsorption and lactose intolerance.AIM: To establish whether a simplified two-or three-sample test may reduce time, costs and staff resources without reducing the sensitivity of the procedure.PATIENTS AND METHODS: Data from 1112 patients (292 men, 820 women) with a positive 4 h, nine-sample H2BT were retrospectively analyzed. Patients were stratified according to the degree of lactose malabsorption, the occurrence and type of symptoms. Loss of sensitivity in the procedure was evaluated taking into account two-sample tests (0 min and 120 min or 0 min and 210 min) or three-sample tests (0 min, 120 min and 180 min or 0 min, 120 min and 210 min).RESULTS: Using a two-sample test (0 min and 120 min or 0 min and 210 min) the false-negative rate was 33.4% and 22.7%, respectively. With a three-sample test (0 min, 120 min and 180 min or 0 min, 120 min or 210 min), lactose malabsorption was diagnosed in 91.2% (1014 of 1112) patients and in 96.1% (1068 of 1112) patients, respectively. Of 594 patients with abdominal symptoms, 158 (26.6%) and 73 (12.2%) would have false-negative results with 0 min and 120 min or 0 min and 210 min two-sample tests, respectively. The three-sample tests, 0 min, 120 min and 180 min or 0 min, 120 min and 210 min, have a false-negative rate of 5.9% and 2.1%, respectively.CONCLUSIONS: A three-sample H2BT is time-and cost-sparing without significant loss of sensitivity for the diagnosis both of lactose malabsorption and lactose intolerance.

Background Adult-type hypolactasia is a widespread condition throughout the world, causing lactose malabsorption. The lactose breath test is a simple tool for diagnosis but the need for prolonged monitoring of hydrogen excretion has led to a genetic test proposal. The aim of this study was to compare the genetic test with the lactose breath test in order to give some insights into the clinical value of genetic testing. Methods Thirty-two consecutive functional patients underwent lactose breath test and lactase genetic polymorphism analysis (C/T 13910 and G/A 22018). Intolerance symptoms after lactose load were also monitored. Results All patients with positive lactose breath test showed homozygosis for both polymorphisms. Among the nine patients with a negative breath test result, six showed heterozygosis while three showed homozygosis. Intolerance symptoms were present in 16 homozygotic patients but also in one heterozygotic patient. The k value for the agreement between the genetic test and the lactose breath test was 0.74. Conclusion A positive genetic test for lactase non-persistence indicates whether lactase activity decline may represent a clinical problem for the patient, but does not give information on actual patient symptoms. On the contrary, this information is already available by combining the lactose breath test with intolerance symptom evaluation. Lactose absorption phenotype may be not yet evident until young adult age.

Background and Aim Lactase non-persistence is common in India. We evaluated: (i) frequency of lactase gene (C/T-13910 and G/A-22018) polymorphisms in irritable bowel syndrome (IBS) and healthy controls (HC), (ii) association between these polymorphisms and IBS-subtypes and symptoms. Methods A total of 150 IBS patients (Rome-III criteria) and 252 age and gender-matched HC were evaluated for C/T-13910 and G/A-22018 genotypes using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results Totals of 79 (52%), 52 (35%) and 19 (13%) patients had diarrhea-predominant IBS (D-IBS), constipation predominant IBS (C-IBS) and alternating diarrhea and constipation IBS (A-IBS), respectively (Rome-III). Frequency of C/T-13910 [genotypes: CC 102 (68%), CT 43 (29%), TT 5 (3%) vs CC 155 (61%), CT 83 (33%), TT 14 (6%), P > 0.05] and G/A-22018 [GG 97 (65%), GA 41 (27%), AA 12 (8%) vs GG 154 (61%), GA 78 (31%), AA 20 (8%), P > 0.05] were similar among IBS and HC. Patients with D-IBS more often had C/T-13910 and G/A-22018 genotypes than C-IBS (CC 71 [90%], CT 6 [8%], TT 2 [2%]) versus (24 [46%], 25 [48%], 3 [6%]), A-IBS (7 [39%], 12 [63%], 0, [0%]) and HC (155 [61%], 83 [33%], 14 [6%]), P

The prevalence of lactose malabsorption (LM) is increased in the elderly, although the mechanisms responsible are still a matter of speculation. The objective of this study was to investigate the possible roles of reduced functional small intestinal absorptive area, lactase deficiency and small intestinal bacterial overgrowth (SIBO).Twenty Caucasian (Anglo-Celtic), asymptomatic, well-nourished, elderly volunteers (median age 79 years, range 70-94 years) with no clinically apparent predisposition to SIBO underwent a 50 g lactose breath hydrogen test (LBHT) and mannitol absorption test, the latter as an index of functional small intestinal absorptive area. Those with LM additionally underwent bacteriological assessment of small intestinal secretions and mucosal biopsy, to assess the contribution of SIBO and lactase deficiency, respectively, to the pathogenesis of LM in individual cases. The prevalence of SIBO was also determined in elderly subjects without LM. Twenty asymptomatic younger subjects (median age 29 years, age range 18-35 years) served as controls. All subjects were "hydrogen producers" in response to lactulose.LM was evident in 10/20 (50%) elderly subjects and 1/20 (5%) younger subjects (p=0.003). Mannitol absorption did not differ significantly in elderly and younger subjects or in elderly subjects with and without LM. SIBO was documented in 9/10 (90%) elderly subjects with LM; eradication was associated with resolution of LM. Lactase deficiency was evident in only one elderly subject with LM. SIBO was evident in 2/10 (20%) elderly subjects without LM (p=0.005 compared to those with LM). Lactulose breath hydrogen test identified only 2/11 (18%) elderly subjects with SIBO.Increased prevalence of LM in the elderly is mostly due to clinically non-apparent SIBO, rather than mucosal factors. The lactulose breath hydrogen test cannot be relied upon to identify elderly subjects with SIBO, even in those without an anatomical predisposition.

Introduction: A large portion of the world’s population undergoes a genetically programmed decrease in lactase synthesis and may experience symptoms of lactose intolerance (LI) after dairy consumption. Aim: The aim of the present study was to assess the effect of the same dose of lactose consumed by LI subjects in the form of different dairy products. Material and methods: Fifteen healthy young adults with LI were enrolled in the study. All subjects were symptomatic homozygotes –13910 C/C in the lactase promoter gene. The hydrogen-methane breath test was performed in each subject after a load of 400 ml of milk, kefir and yogurt. Clinical symptoms were assessed within the 12 h after each product consumption. Results: The excretion of gases was lower after ingestion of kefir and yogurt in comparison to milk. All examined subjects reported symptoms. After milk consumption, abdominal pain and intestinal rumbling were perceived as more severe. The number of stools was higher and their consistency was more liquid. Conclusions: Young adults with LI are not able to tolerate the typical dose of different dairy products as assessed by subjective and objective measures. The tolerance of kefir and yogurt is significantly better than that of milk. Streszczenie Wstep: U znacznej cześci ludności świata produkcja laktazy podlega genetycznie zaprogramowanej redukcji, co moze prowadzic do wystepowania objawow klinicznych nietolerancji laktozy (NL) po spozyciu produktow mlecznych. Cel: Ocena wplywu spozycia takiej samej dawki laktozy przez osoby z NL, podawanej w postaci roznych produktow mlecznych. Material i metody: Badaniem objeto 15 mlodych doroslych z objawową NL. Wszyscy badani byli homozygotami –13910 C/C w zakresie genu promotorowego dla laktazy. U kazdej osoby wykonano wodorowo-metanowy test oddechowy po obciązeniu 400 ml mleka, kefiru i jogurtu. Objawy kliniczne oceniano przez 12 godz. po spozyciu kazdego produktu. Wyniki: Wydalanie gazow bylo mniejsze po spozyciu kefiru i jogurtu niz mleka. Wszyscy badani zglaszali objawy kliniczne. Po spozyciu mleka bole brzucha i przelewania byly bardziej nasilone, stwierdzono wiekszą liczbe stolcow, a ich konsystencja byla bardziej plynna. Wnioski: Mlodzi dorośli z NL nie tolerują typowych porcji produktow mlecznych, co potwierdzono w ocenie subiektywnej i obiektywnej. Tolerancja kefiru i jogurtu jest znacząco lepsza niz mleka.

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.

Lactose malabsorption (LM) may be secondary to several small bowel diseases, and small intestinal overgrowth (SIBO) may be one of them. We looked for a correlation between symptomatic diverticular disease of the colon and LM and assessed whether this correlation may be related to SIBO. Ninety consecutive patients (pts; 39 males, 51 females; mean age, 67.2 years; range, 32–91 years) affected by symptomatic uncomplicated diverticular disease of the colon were evaluated to assess orocecal transit time (OCTT), SIBO, and LM by lactulose and lactose H2 breath test (H2-BT) at entry and after 8 weeks of treatment. OCTT was delayed in 67 of 90 pts (74.44%). Fifty-three of 90 pts (58.88%) showed SIBO, and OCTT was normal in 23 of 90 pts (25.56%). LM was diagnosed in 59 of 90 pts (65.55%): 49 of 59 (71.74%) were simultaneously affected by SIBO and delayed OCTT (and thus 49 of 53 pts [92.45%] with delayed OCTT and SIBO were affected by LM); 3 of 59 pts (5.09%) showed only delayed OCTT; 7 of 59 pts (11.86%) did not show either SIBO or delayed OCTT. The association of LM and SIBO was statistically significant (P < 0.001). Seventy-nine of 86 pts (91.86%) showed normal OCTT, while OCTT remained prolonged but shorter in the remaining 7 pts (8.14%). SIBO was eradicated in all pts completing the study, while a new lactulose H2-BT showed persistence of SIBO in one pt with recurrence of symptomatic diverticular disease. Forty-seven of 59 pts (79.66%) had a normal lactose H2-BT (P < 0.002), while 12 of 59 pts (20.34%) showed persistence of LM. LM disappeared in 46 of 49 pts (93.88%) concurrently with normalization of OCTT and eradication of SIBO (P < 0.002); it also disappeared in 1 of 3 pts (33.33%) previously affected by delayed OCTT (without SIBO) and LM concurrently with normalization of OCTT. On the contrary, it persisted in all pts with normal OCTT and absence of SIBO. Moreover, it persisted also in the pt with recurrence of symptomatic diverticular disease and persistence of SIBO. In conclusion, most pts affected by symptomatic uncomplicated diverticular disease of the colon showed LM, and in more than 70% of cases it disappeared after successful treatment of the colonic 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.

The aim of this study was to establish a retrospective evaluation and comparison of the hydrogen/methane (H2/CH4) breath test and genetic test (C/T-13910 polymorphism) results in lactose malabsorption testing. In total 263 consecutive patients with suspected lactose malabsorption were included in this study. They underwent the H2/CH4 breath test following the ingestion of 50 g lactose and were tested for the C/T-13910 polymorphism. In total 51 patients (19.4%) had a C/C-13910 genotype, indicating primary lactose malabsorption. Only 19 patients (7.2%) also had a positive H2/CH4 breath test. All in all 136 patients (51.69%) had a C/T-13910 and 76 patients (28.91%) a T/T-13910 genotype, indicating lactase persistence. Four patients (1.5%) with the C/T-13910 genotype and one patient (0.4%) with the T/T-13910 genotype had a positive H2/CH4 breath test result, indicating secondary lactose malabsorption. Cohen's Kappa measuring agreement between the two methods was 0.44. Twenty patients (7.6%) with a positive H2/CH4 peak within 60 minutes after lactose ingestion were classified as patients with lactose-dependent small intestinal bacterial overgrowth (SIBO). In conclusion, only moderate agreement between the breath test and the genetic test was shown. Secondary lactose malabsorption as well as preanalytical limitations of the combined H2/CH4 breath test procedure can cause discrepant results. This trial is registered with K-42-13.

Background. The relationship between lactose malabsorption, irritable bowel syndrome and development of intestinal symptoms is unclear, especially when the ingested dose of milk is small. Thus, the role of hydrogen breath testing in the diagnostic work-up of patients with nonspecific intestinal symptoms is still debated. Aims. To establish the relationship between lactose malabsorption, severe self-reported milk intolerance, irritable bowel syndrome and related symptoms. Methods. The prevalence of lactose malabsorption was prospectively assessed by means of a hydrogen breath test in 839 patients (503 with irritable bowel syndrome, based on the Rome criteria, regularly consuming milk, and 336 subjects who identified themself as milk intolerant, after an oral load of 25 g lactose). The test was considered “positive” when a hydrogen peak exceeding 20 ppm over baseline values was observed in two or more samples. Attempts were also made to establish whether the predominant presenting symptom (diarrhoea, constipation, alternating diarrhoea and constipation, pain and gaseousness) might be helpful in predicting the outcome of the breath test. Results. The prevalence of a positive breath test was comparable in the two groups (337 patients with irritable bowel syndrome (66.9%) vs 240 patients with milk intolerance (71.4%)). The same holds true for the first peak of hydrogen excretion, total hydrogen output and prevalence of symptoms during, and in the four hours after, the test. The predominant presenting symptom was not useful for predicting outcome of the test either in regular milk users or in milk intolerant subjects. Conclusions. The almost identical results of the lactose breath test of patients with irritable bowel syndrome and subjects with self-reported milk intolerance suggests that the two conditions overlap to such an extent that the clinical approach should be the same. A lactose breath test should always be included in the diagnostic work-up for irritable bowel syndrome, as fermentation of malabsorbed lactose is likely responsible for triggering symptoms. Conversely, lactase deficiency is probably irrelevant in most subjects not affected by irritable bowel syndrome, within a moderate milk consumption.

Symptoms after intake of milk are common in persons with irritable bowel syndrome (IBS). The aims of this study were to compare the prevalence of lactose malabsorption (LM) and symptoms related to intake of milk and lactose in subjects with IBS with that of healthy volunteers, and to search for symptoms that are characteristic of LM.A case-control study in a Norwegian population was initiated. Subjects with IBS were asked for symptoms related to intake of milk and lactose, tested for LM, and compared with a group of healthy volunteers.The study comprised a total of 187 persons (82 with IBS and 105 volunteers), females/males: 138/49, mean age 47 years. In subjects with IBS and in healthy volunteers, LM was present in 3/74 (4.1%) and 4/105 (3.8%), respectively (ns), milk-related symptoms in 32/79 (40%) and 13/105 (12%), respectively (P0.001) and symptoms after intake of lactose in 28/74 (38%) and 21/104 (20%), respectively (P=0.01). Borborygmi starting within 5 h after intake of lactose and lasting for more than 2 h indicated LM (OR 61 (95% CI: 8-475), P0.001).IBS and LM are unrelated disorders in a Norwegian population. Milk-related symptoms and symptoms after intake of lactose are unreliable predictors for LM. Precise symptom-based criteria might enhance the diagnostic accuracy for LM.

Background: In clinical and field conditions, breath gas analysis has been widely used in evaluating carbohydrate digestion. A field study was performed to determine the prevalence of lactose malabsorption in Myanmar children and to evaluate the possibility of using breath methane excretion to indicate lactose malabsorption in a field situation. Methods: The study population consisted of 118 children aged 1 to 12 years. A hydrogen breath test after a lactose meal (2 g/kg, maximum 50 g) was used as a standard test. Results: Lactose malabsorption was detected in 16.7% of children aged 1 to 2.9 years, with the prevalence increasing with age from 40.5% of those aged 3 to 5.9 years to 88.5% of those aged 6 to 8.9 years and reaching 91.7% in those aged 9 to 11.9 years. Lactose malabsorption was more prevalent when children were weaned before 4 months of age (87.2 vs. 41.1%;p < 0.01). Compared with lactose-tolerant children, those with lactose malabsorption had significantly higher concentrations of breath hydrogen excretion 60 minutes after the lactose test meal. Breath methane excretion was also significantly higher in samples at 120 minutes in children with lactose malabsorption. Breath methane excretion of greater than or equal to 2 parts per million at 180 minutes as a diagnostic test for lactose malabsorption had a sensitivity of 61.5% and a specificity of 84.6%. Conclusion: The breath methane test for lactose malabsorption has a lower sensitivity and specificity than the breath hydrogen test and therefore does not replace the lactose breath hydrogen test.