Lactose malabsorption and intolerance: a systematic review on the diagnostic value of gastrointestinal symptoms and self-reported milk intolerance

The Effect of A2 Milk on Gastrointestinal Symptoms in Comparison to A1/A2 Milk: A Single-center, Randomized, Double-blind, Cross-over Study

β-Casein, a major protein in cow's milk, is divided into the A1 and A2 type variants. Digestion of A1 β-casein yields the peptide β-casomorphin-7 which could cause gastrointestinal (GI) discomfort but A2 milk containing only A2 β-casein might be more beneficial than A1/A2 (regular) milk. The aim of this study was to evaluate the differences in GI discomfort after ingestion of A2 milk and A1/A2 milk. A randomized, double-blind, cross-over human trial was performed with 40 subjects who experienced GI discomfort following milk consumption. For each intervention period, either A2 milk first (A2→A1/A2) or A1/A2 milk was first consumed for 2 weeks (A1/A2→A2) following a 2-week washout period. GI symptom rating scale (GSRS) scores, questionnaire for digestive symptoms, and laboratory tests including fecal calprotectin were evaluated. For symptom analysis, generalized estimating equations gamma model was used. A2 milk increased bloating (P = 0.041) and loose stools (P = 0.026) compared to A1/A2 milk in GSRS. However, A2 milk caused less abdominal pain (P = 0.050), fecal urgency (P < 0.001) and borborygmus (P = 0.007) compared to A1/A2 milk in questionnaire for digestive symptoms. In addition, fecal calprotectin also decreased or less increased after consumption of A2 milk compared to A1/A2 milk (P = 0.030), and this change was more pronounced in males (P = 0.005) than in females. There were no significant adverse reactions during the trial. A2 milk alleviated digestive discomfort in Koreans following A2 milk consumption (ClinicalTrials.gov NCT06252636 and CRIS KCT0009301).

Oat milk analogue versus traditional milk: Comprehensive evaluation of scientific evidence for processing techniques and health effects

Milk, enriched with high-quality protein, is a healthy and nutritious food that meets people's needs. However, consumers are turning their attention to plant-based milk due to several concerns, such as lactose intolerance, allergies and some diseases caused by milk; carbon emission from cattle farming; economical aspects; and low access to vitamins and minerals. Oat milk, which is produced from whole grain oats, is lactose free and rich in a variety of nutrients and phytochemicals. With the significant development of food processing methods and advancement in milk simulation products, the production of plant-based milk, such as cereal milk, has greatly progressed. This review described some features of oat milk analogue versus traditional milk and compared the properties, processing technologies, health effects, environmental friendliness, and consumer acceptance of these products. It is expected to provide a reference for evaluating development trends and helping consumers choose between oat milk and traditional milk.

Testing for lactase non-persistence in a Dutch population: Genotyping versus the hydrogen breath test

BACKGROUND

Lactose intolerance is defined as the presence of gastrointestinal symptoms, such as bloating, abdominal pain or diarrhoea, after consumption of lactose in individuals with lactose malabsorption. Most cases involve primary lactose intolerance, caused by a loss of activity of the enzyme lactase, needed for digestion of lactose. A traditional method of establishing lactose intolerance is the hydrogen breath test (HBT), accompanied by a questionnaire to document complaints experienced by the patient during the test. Due to knowledge on lactase-persistent alleles, DNA genotyping has become available for the diagnostic work-up for lactose intolerance. Both methods are currently in use. The aim of this study is to provide a definite diagnostic approach for patients suspected of lactose intolerance in a Dutch population.

METHODS

In this retrospective, observational study, patients aged 15 years or older were included after presenting to their treating physician with symptoms suggestive of lactose intolerance. HBT, including a questionnaire to document complaints and DNA genotyping of LCT-13,910 C/T was performed for each patient as part of a routine diagnostic work-up.

RESULTS

1101 patients were included (29% men). Positive and negative predictive value, sensitivity and specificity of HBT versus DNA genotyping were 80% (CI 75-84), 97% (CI 96-98), 89% (CI 84-92) and 94% (92-96) respectively. The use of the questionnaire added little diagnostic value.

CONCLUSIONS

In a population with a high prevalence of lactase-persistent alleles, we advise to exclude HBT from the diagnostic route for suspected lactose intolerance, and replace it with genotyping of lactase-persistent alleles.

Fecal Calprotectin in Self-Reported Milk Intolerance: Not Only Lactose Intolerance

The hypothesis is that inflammatory/allergic conditions should be considered in self-reported milk intolerance (SRMI) patients who test negative and/or are asymptomatic at Lactose Hydrogen Breath Test (LHBT). We analyzed fecal calprotectin (FCP) values in SRMI patients to investigate the frequency of a "positive" intestinal inflammation marker and its correlation with lactose tolerance/intolerance. Data from 329 SRMI patients were retrospectively analyzed; according to the positive/negative results (maldigester/digester) and the presence/absence of symptoms reported during LHBT (intolerant/tolerant), patients were divided into: 'lactose tolerants' (n. 104), 'maldigesters/intolerants' (n. 187), 'digesters/intolerants' (n. 38). FCP values were analyzed in all three subgroups. A percentage of SRMI patients complained of constipation (>15%), extraintestinal symptoms (>30% including anemia), multiple food hypersensitivity (7.6%) and had intraepithelial lymphocytic infiltration at duodenal biopsy (>50%). Over 50.0% showed FCP values above the normal limit. Lactose tolerants and maldigesters/intolerants had higher positivity frequencies (p < 0.0001, for both) and absolute values (p = 0.04, for maldigesters/intolerants) of FCP compared to digesters/intolerants. FCP was not useful to differentiate tolerant from intolerant subjects (AUC 0.58). Our data suggest the existence of an allergic/inflammatory pathogenetic mechanism in a subset of SRMI subjects. FCP results are in keeping with this hypothesis, even if they cannot differentiate lactose tolerant from intolerant patients.

Lactase Deficiency Diagnosed by Endoscopic Biopsy-based Method is Associated With Positivity to Glucose Breath Test

Background/Aims

Lactase deficiency, which has many similarities with small intestinal bacterial overgrowth (SIBO), causes various gastrointestinal symptoms. We estimate the prevalence of SIBO in patients with intestinal symptoms from dairy products and investigate the association between lactase deficiency (LD) and SIBO.

Methods

This prospective study included patients with functional intestinal symptoms from dairy product indigestion. A questionnaire on gastrointestinal symptoms, a hydrogen (H₂)-methane glucose breath test (GBT) for SIBO, and lactose intolerance quick test (LQT) for LD using upper gastrointestinal endoscopy were performed.

Results

A total of 88 patients, 29 (33.0%) with severe and 36 (40.9%) with mild LD were included. Sixteen patients (18.2%) were GBT positive. Patients with LQT negativity indicating severe LD showed a higher positivity to GBT or GBT (H₂) than the historic controls (27.6% vs 6.7%, P = 0.032). There was no difference in the items on the symptom questionnaire according to the presence of LD or SIBO, except for higher symptom scores for urgency in GBT-positive patients. There were more LQT-negative patients in the GBT (H₂)-positive group than in the other groups (27.6% vs 10.2%, P = 0.036). Moreover, only GBT (H₂)-positivity was significantly associated with a higher risk of LQT negativity in multivariate analysis (OR, 4.19; P = 0.029).

Conclusions

SIBO producing H₂ is common in patients with severe LD suspected lactose intolerance. SIBO may be a new therapeutic target for managing intestinal symptoms in patients with lactose intolerance.

Relationships of Intestinal Lactase and the Small Intestinal Microbiome with Symptoms of Lactose Intolerance and Intake in Adults

BACKGROUND

Approximately two-thirds of adults are genetically predisposed to decreased lactase activity after weaning, putting them at risk of lactose intolerance. However, symptoms are a poor marker of lactose maldigestion.

AIMS

We assessed association between self-reported lactose intolerance and intestinal lactase, lactose intake, and the small intestinal microbiome.

METHODS

Patients 18-75 years presenting for upper endoscopy were recruited prospectively. Observational study participants completed a lactose intolerance symptom questionnaire and reported lactose intake. Post-bulbar biopsies were obtained to measure lactase activity and assess the small intestinal mucosal microbiome. We compared intestinal lactase between patients with and without lactose intolerance. We assessed associations between lactose intolerance symptoms and lactase and lactose intake. We examined associations of small bowel microbial composition with self-reported lactose intolerance and symptoms.

RESULTS

Among 34 patients, 23 (68%) reported lactose intolerance. Those with lactose intolerance had higher total symptom scores, more frequent bowel urgency, and more bowel movements after consuming dairy. The proportion of individuals with abnormal lactase activity did not differ by lactose intolerance status. Median lactase levels were correlated with total lactose intolerance symptom scores (p = 0.038) and frequency of bowel urgency (p = 0.012). Daily lactose intake did not differ between groups. In 19 patients, we observed significant associations of small intestinal microbiome beta diversity with stool consistency after consuming dairy (p = 0.03).

CONCLUSIONS

Intestinal lactase is associated with lactose intolerance symptoms and bowel urgency in adults but does not distinguish the clinical phenotype entirely. Studying other contributing factors (microbiota, diet) may further clarify the pathophysiology of lactose intolerance.

Benefits of Flavored Lactose-Free Milk for Korean Adults with Lactose Intolerance

Although lactose-free dairy products for the clinical management of lactose intolerance (LI) are widely available, scientific evidence on their efficacy is still lacking. This study comparatively analyzed the efficacy of flavored lactose-free milk (LFM) and whole milk (WM) in reducing symptoms in South Korean adults with LI. This prospective study was conducted in adults suspected of LI. All screened participants underwent the hydrogen breath test (HBT) using 570 mL of chocolate-flavored WM (20 g of lactose) and responded to a symptom questionnaire. LI was confirmed when the ΔH₂ peak exceeded 16 ppm above baseline values and with the occurrence of symptoms after WM consumption. The participants who were diagnosed with LI underwent the HBT again with 570 mL of chocolate-flavored LFM (0 g of lactose), followed by the symptom questionnaire survey after 1 week. After excluding 40 participants who did not meet the diagnostic criteria for LI and 2 who were lost to follow-up, a total of 28 lactose-intolerant individuals were enrolled in the study. The ΔH₂ values in the first HBT were significantly higher than those in the second HBT (33.3 ± 21.6 ppm vs. 8.6 ± 6.3 ppm, P < .001). Similarly, there was a significant reduction in the total symptom score in the second HBT (4.18 ± 1.51 vs. 0.61 ± 0.98, P < .001). Flavored LFM is well tolerated in South Korean adults diagnosed with LI based on the HBT and symptom questionnaire results. Therefore, LFM may be a viable alternative to WM.

Analysis of correlation between the consumption of beverages and the risk of radiographic knee osteoarthritis in Korean people: A cross-sectional study using the Fifth Korea National Health and Nutrition Examination Survey (KNHANES V-1, 2)

The purposes were to analyze correlations between the frequency of beverage drinking (coffee, green tea, milk, and soft drinks) and the presence of radiographic knee osteoarthritis (OA) in relation to sex. We performed this study using the Korea National Health and Nutrition Examination Survey (KHANES V-1, 2). We examined data from 5503 subjects after exclusion. We utilized the food frequency questionnaires from KHANES, and reorganized them into 2 or 3 groups according to the frequency of beverage consumption. We analyzed the relationship between radiographic knee OA and beverage consumption statistically after adjusting confounding factors with multivariable logistic regression analysis. Knee OA was inversely associated with coffee consumption only in women (P < .05). The odds ratio of knee OA was lower in those who drank at least a cup of coffee than in those who did not drink coffee in women (P for trend < .05). However, there was no significant linear trend of the odds ratio of each group in both sexes for drinking other beverages. As the coffee consumption increased, the radiographic knee OA group showed decreasing linear trend only in women. However, other beverages did not show a significant relation to the radiographic knee OA in both sexes.

The Perception of Lactose-Related Symptoms of Patients with Lactose Malabsorption

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.

Carbohydrate Maldigestion and Intolerance

This review summarizes dietary carbohydrate intolerance conditions and recent advances on the possible role of carbohydrate maldigestion and dietary outcomes in patients with functional bowel disease. When malabsorbed carbohydrates reach the colon, they are fermented by colonic bacteria, with the production of short-chain fatty acids and gas lowering colonic pH. The appearance of diarrhoea or symptoms of flatulence depends in part on the balance between the production and elimination of these fermentation products. Different studies have shown that there are no differences in the frequency of sugar malabsorption between patients with irritable bowel disease (IBS) and healthy controls; however, the severity of symptoms after a sugar challenge is higher in patients than in controls. A diet low in 'Fermentable, Oligo-Di- and Monosaccharides and Polyols' (FODMAPs) is an effective treatment for global symptoms and abdominal pain in IBS, but its implementation should be supervised by a trained dietitian. A 'bottom-up' approach to the low-FODMAP diet has been suggested to avoid an alteration of gut microbiota and nutritional status. Two approaches have been suggested in this regard: starting with only certain subgroups of the low-FODMAP diet based on dietary history or with a gluten-free diet.

Whole Cow's Milk but Not Lactose Can Induce Symptoms in Patients with Self-Reported Milk Intolerance: Evidence of Cow's Milk Sensitivity in Adults

BACKGROUND

Lactose intolerance is the most frequent food intolerance, but many subjects with self-reported milk intolerance (SRMI) are asymptomatic at lactose hydrogen breath test (LHBT). The aim of this study was to evaluate the frequency of lactose intolerance in SRMI patients and their clinical characteristics.

METHODS

In a retrospective study, the clinical records of 314 SRMI patients (259 females, mean age: 39.1 ± 13.5 years) were reviewed; 102 patients with irritable bowel syndrome (IBS) served as controls. In a prospective study, 42 SRMI patients, negatives at the LHBT, underwent a double-blind, placebo-controlled (DBPC) whole cow's milk challenge.

RESULTS

In the retrospective study, only 178 patients (56%) were lactose maldigesters and intolerant at LHBT; 68% of the subjects with SRMI were suffering from IBS; 74% reported dyspepsia (p = 0.0001 vs. IBS controls); and weight loss was recorded in 62 SRMI patients (20%) (p = 0.01 vs. IBS controls). Duodenal histology showed intra-epithelial lymphocytosis in about 60% of cases. In the prospective study, 36 patients (86%) experienced symptoms during the DBPC cow's milk challenge, and only 4 patients (9%) reacted to placebo (p = 0.0001).

CONCLUSIONS

A percentage of SRMI patients were not suffering from lactose intolerance. DBPC revealed that SRMI patients had clinical reactions when exposed to whole cow's milk.

Evaluation of a Digital Handheld Hydrogen Breath Monitor to Diagnose Lactose Malabsorption: Interventional Crossover Study

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<.001).

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 costs of lactose-reduced diets: lactose-free dairy product substitutes are a cost-effective alternative for people with lactose intolerance

OBJECTIVE

People with lactose intolerance have to limit their consumption of lactose-containing dairy products which are a main source of Ca. In particular, for low-income people it is of interest which alternative diet form rich in Ca leads to the lowest additional costs. This study aims to calculate the additional costs of lactose-reduced diets and to show which of different options represent the most cost-effective alternative within a lactose-reduced diet.

DESIGN

Using linear programming, food baskets with different lactose contents were calculated and were compared to a basic model, reflecting a normal diet without a limitation of lactose. By comparing the costs and the composition of the food baskets, recommendations for a lactose-reduced diet were derived.

SETTING

Germany.

PARTICIPANTS

A consumer panel dataset representative for Germany is used for the calculations. Information on prices and nutrients is derived from the 9429 adult households without children, and information on consumed food quantities from the 3046 single households.

RESULTS

The minimum additional food costs depend on the severity of lactose intolerance and range from 0·2 % to 6·1 % per month. It was found that the greatest adjustments due to lactose reduction could be observed within the dairy product group. In this group, with a rising lactose limit, normal milk was increasingly replaced by lactose-free milk.

CONCLUSION

It was shown that a lactose-reduced diet is generally associated with higher food costs. When suffering from lactose intolerance, switching to lactose-free milk seems to be the most cost-effective way to cover nutrient requirements.

Lactose Intolerance: A Concise Review to Skim the Surface

Lactose intolerance is a common but poorly understood cause of gastrointestinal symptoms. Contrary to popular belief, there is much more to its diagnosis beyond symptoms with exposure and management beyond milk- and dairy-product avoidance. In this article, we review definitions, genetic basis, pathogenesis, clinical signs, as well as diagnostic and management strategies.

Evaluation of breath, plasma, and urinary markers of lactose malabsorption to diagnose lactase non-persistence following lactose or milk ingestion

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 < 0.70) after milk ingestion. The specificity of breath H2 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.

Lactose Intolerance: What Your Breath Can Tell You

Lactose intolerance has seen recognized as a clinical syndrome characterized by pain, abdominal distention, flatulence, and diarrhea after the consumption of lactose. Lactose is a common disaccharide found in dairy that requires lactase-phlorizin hydrolase (LPH) to break down into glucose and galactose. A deficiency in this enzyme results in flora bacteria further along in the gastrointestinal tract (GI) tract to metabolize the excess lactose to numerous gases, including H₂. Recent studies show that the risk of symptoms after lactose ingestion depends on the dose of lactose, LPH expression, intestinal flora, and sensitivity of the gastrointestinal tract. Currently, there are several diagnostic tests that investigate the biological mechanism of lactose intolerance such as blood, biopsy, genetic, and breath tests. Due to its relatively low cost, availability, and non-invasiveness, the hydrogen breath test (HBT) has become a popular technology to aid in the diagnosis of many gastroenterological diseases, specifically lactose intolerance. Additionally, while administering the HBT there seems to be a lack of uniform criteria amongst the various studies, with many using their own guidelines, which may in turn cause inconsistency with the analysis of the results. With ever improving nanotechnology, novel approaches to expedite and lower the costs of the HBT has become an area of research with significant advancements.

The importance of lactose intolerance in individuals with gastrointestinal symptoms

Lactose intolerance is a condition with an elevated prevalence worldwide, especially in Latin American, Asian, and African countries. The aim of the present narrative review was to highlight the importance of accurately diagnosing lactose intolerance to prevent self-diagnosis that results in the unnecessary elimination of milk and dairy products from the diet and the consequent deprivation of nutrients that could be essential at certain stages of life. The pathophysiologic mechanism of deficient lactose absorption in the intestine can be primary, secondary to other enteropathies, or coexistent with other intestinal diseases with similar symptoms, such as irritable bowel syndrome, bacterial overgrowth syndrome, or celiac disease, causing confusion in relation to diagnosis and treatment. Lactose intolerance consists of a set of symptoms attributed to the consumption of milk and dairy products that are assumed to be due to deficient digestion of that disaccharide. A wide range of tests have been validated to detect deficient digestion that include blood tests, genetic mutation analyses, breath tests, and recently, a urine test, all of which are described in the present article. Nevertheless, there are few validated questionnaires for symptom evaluation and measurement, partly due to the heterogeneity of concepts and the subjectivity of each of the symptoms.

Prospective Study of Lactose Intolerance as a Potential Cause of Gas Bloat Syndrome in Patients Treated Surgically for Gastroesophageal Reflux

Introduction. The high incidence of lactose intolerance leads us to consider that many of our patients could suffer from this alteration. Therefore, as its main sign (even when asymptomatic) is increased intestinal gas, patients recovering from a Nissen fundoplication have a significant probability of suffering from gas bloat syndrome. Materials and Methods. This prospective study was conducted from November 2012 to January 2017, we included all the patients who had been treated by the Nissen technique for gastroesophageal reflux disease with gas bloat syndrome detected during follow-up and tested positive for lactose intolerance. The study participants were then prescribed a lactose-poor diet to be followed for 3 months. The patients were asked to complete quality of life and symptomatology questionnaires before and after diet. The pre- and post-diet results were then compared. Results. The pre- and post-diet results showed statistically significant improvements in both questionnaires. Conclusion. Lactose intolerance may account for the symptoms presented by a significant number of patients with gas bloat syndrome following antireflux surgery; these patients could benefit from consuming a lactose-free diet, which we expect to alleviate or, in some cases, eliminate the above symptoms.

Roles of Lactose and Fructose Malabsorption and Dietary Outcomes in Children Presenting with Chronic Abdominal Pain

Intolerance to lactose or fructose is frequently diagnosed in children with chronic abdominal pain (CAP). However, the causal relationship remains a matter of discussion. A cohort of 253 patients, aged 7–12 years, presenting with unexplained CAP received standardized diagnostics. Additional diagnostic tests were performed based on their medical history and physical and laboratory investigations. Fructose and lactose hydrogen breath tests (H₂BT) as well as empiric diagnostic elimination diets were performed in 135 patients reporting abdominal pain related to the consumption of lactose or fructose to evaluate carbohydrate intolerance as a potential cause of CAP. Carbohydrate malabsorption by H2BT was found in 55 (41%) out of 135 patients. An abnormal increase in H2BT was revealed in 30% (35/118) of patients after fructose consumption and in 18% (20/114) of patients after lactose administration. Forty-six percent (25/54) reported pain relief during a diagnostic elimination diet. In total, 17 patients had lactose malabsorption, 29 fructose malabsorption, and nine combined carbohydrate malabsorption. Carbohydrate intolerance as a cause of CAP was diagnosed at follow-up in only 18% (10/55) of patients with malabsorption after the elimination of the respective carbohydrate. Thus, carbohydrate malabsorption appears to be an incidental finding in children with functional abdominal pain disorders, rather than its cause. Therefore, testing of carbohydrate intolerance should only be considered in children with a strong clinical suspicion and with the goal to prevent long-term unnecessary dietary restrictions in children suffering from CAP.

Maternal Lactase Polymorphism (rs4988235) Is Associated with Neural Tube Defects in Offspring in the National Birth Defects Prevention Study

BACKGROUND

The risk of neural tube defect (NTD)-affected pregnancies is reduced with adequate folic acid intake during early pregnancy. However, NTDs have been observed among offspring of women with adequate folic acid intake. Some of these women are possibly not absorbing enough folic acid. Because lactase deficiency can lead to poor nutrient absorption, we hypothesized that lactase-deficient women will be at increased risk of having offspring with NTDs.

OBJECTIVE

We examined the association between maternal rs4988235 (a lactase deficiency genetic marker) and NTDs in offspring.

METHODS

We conducted a case-control study using data from the National Birth Defects Prevention Study, United States, 1997-2009, restricting to non-Hispanic white (NHW) and Hispanic women. Cases were women with an offspring with an NTD (n = 378 NHW, 207 Hispanic), and controls were women with an offspring without a birth defect (n = 461 NHW, 165 Hispanic). Analyses were conducted separately by race/ethnicity, using logistic regression. Women with the CC genotype were categorized as being lactase deficient. To assess potential effect modification, analyses were stratified by lactose intake, folic acid supplementation, dietary folate, and diet quality.

RESULTS

Among NHW women, the odds of being lactase deficient were greater among cases compared with controls (OR: 1.37; 95% CI: 1.02, 1.82). Among Hispanic women, the odds of being lactase deficient were significantly lower among cases compared with controls (OR: 0.50, 95% CI: 0.33, 0.77). The association differed when stratified by lactose intake in NHW women (higher odds among women who consumed ≥12 g lactose/1000 kcal) and by dietary folate in Hispanic women (opposite direction of associations). The association did not differ when stratified by folic acid supplementation or diet quality.

CONCLUSIONS

Our findings suggest that maternal lactase deficiency is associated with NTDs in offspring. However, we observed opposite directions of effect by race/ethnicity that could not be definitively explained.

Lactose intolerance: what is a correct management?

SUMMARY Individuals with Lactose Intolerance (LI) tend to exclude milk from their diet since this behavior seems to relieve the symptoms caused by the disease. However, milk is a food of high nutritional value, and complete exclusion of dairy products may favor the development of bone diseases such as osteopenia and osteoporosis. The objective of this review was to evaluate the scientific evidence on the adequate management of patients with LI. This study was carried out from the review of the scientific literature in PubMed and SciELO databases. Complete exclusion of conventional dairy products is not necessary since most individuals with LI can tolerate up to 12 grams of lactose daily in a single dose. Yogurts and cheeses matured for having low amounts of lactose are part of the strategy that allows consumption of dairy products by patients with LI. Currently, there is a diversity of products considered as “milk substitutes” and supplements aimed at individuals with LI. However, these strategies still require better-designed studies.

Lactose Intolerance, Dairy Avoidance, and Treatment Options

Lactose intolerance refers to symptoms related to the consumption of lactose-containing dairy foods, which are the most common source for this disaccharide. While four causes are described, the most common is the genetically-determined adult onset lactose maldigestion due to loss of intestinal lactase governed by control of the gene by a 14,000 kb promoter region on chromosome 2. Gastrointestinal symptoms from lactose have expanded to include systemic effects and have also been confounded by other food intolerances or functional gastrointestinal disorders. Partly because lactose maldigestion is often interpreted as lactose intolerance (symptoms), focus of therapy for these symptoms starts with lactose restriction. However, withholding of dairy foods completely is not appropriate due to a more favorable impact on health. Industrial efforts to substitute with plant-based products is not completely successful at this time. This narrative article reviews the complexities of the perception of lactose intolerance, its epidemiology, and pathogenesis. Treatments are discussed, including the inappropriateness of dairy avoidance. In conjunction, effects of dairy products on 19 common diseases are reviewed. Different methods of treatment, lactose-reduced products, plant-based dairy substitutes, adaptation, prebiotics, exogenous lactase, probiotics, and some other dietary interventions are further discussed.

Phase IV noninferiority controlled randomized trial to evaluate the impact on diagnostic thinking and patient management and the test-retest reproducibility of the Gaxilose test for hypolactasia diagnosis

BACKGROUND

The diagnostic accuracy of the Gaxilose test (GT) for hypolactasia diagnosis has already been proved. The objectives of this clinical trial were to demonstrate the noninferiority of the GT compared to the hydrogen breath test (HBT) on the impact on diagnostic thinking and patient management, to evaluate the GT reproducibility with urine accumulated from 0 to 4 hours and from 0 to 5 hours and to assess test safety.

METHODS

We conducted a randomized, parallel, noninferiority clinical trial. Patients with clinical symptoms suggestive of lactose intolerance were screened for inclusion and randomly assigned to the GT arm or the HBT arm of the study. The impact on diagnostic thinking and patient management was analyzed with pretest and posttest questionnaires in which the investigators indicated their estimated probability of hypolactasia diagnosis and the intended management before and after the GT or the HBT (noninferiority margin: -10%). The primary outcome of the study was the impact on diagnostic thinking, expressed as the mean of the absolute values of the differences between the pretest and posttest probabilities of hypolactasia diagnosis. Patients randomized to the GT arm performed also the retest to evaluate the reproducibility of the GT.

RESULTS

A total of 147 patients were included in the intend-to-treat (ITT) population. Among them, 74 performed the HBT and 73 performed the GT. The results proved the noninferiority of the GT compared to the HBT on the impact on diagnostic thinking (ImpactGT = 31.74 ± 23.30%; ImpactHBT = 24.28 ± 19.87%; ΔGT-HBT = 7.46%; 95% confidence interval of ΔGT-HBT: 1.55%, infinite) and on patient management. The test-retest reproducibility was better for the GT with urine accumulated from 0 to 5 h: the intraclass correlation coefficient (ICC) was 0.5761, and the Kappa coefficient was 0.7548, indicative of substantial agreement between both tests. No serious adverse events were reported during the study.

CONCLUSIONS

The GT has an impact on diagnostic thinking and patient management noninferior to that of the HBT, is reproducible and well tolerated. These results prove the clinical benefit of its use in the clinical practice (ClinicalTrials.gov identifier: NCT02636413).

Does primary lactase deficiency reduce bone mineral density in postmenopausal women? A systematic review and meta-analysis

Postmenopausal osteoporosis is a significant cause of morbidity and mortality. The role of primary lactase deficiency (PLD) in its development is not clear. This meta-analysis showed that PLD is a risk factor for osteoporosis in postmenopausal women. These women need special attention in terms of screening for osteoporosis and its prevention.

INTRODUCTION

Postmenopausal osteoporosis is an important predictor of bone fractures. The purpose of the study was to conduct a systematic review and meta-analysis of association of PLD and bone mineral density (BMD) in postmenopausal women.

METHODS

The electronic databases PubMed, Scopus, and Web of Science were searched over the course of July 2017 for any date of publication without language limitation. Studies were included in the meta-analysis if the diagnosis of PLD was made by genetic testing or H-2 breath tests and the diagnosis of osteoporosis was made by a modern reliable method for BMD measurement. Two investigators conducted a comprehensive, independent review of all the papers. Five of the studies initially identified met the inclusion criteria. We used MOOSE guidelines for abstracting data and assessing data quality and validity. Meta-analysis was performed using the random effects model.

RESULTS

Five case-control studies with 2223 participants and 763 lactase-deficient cases fulfilled the inclusion criteria. Meta-analysis showed a significantly higher bone density Z-score in absorbers (mean difference 0.20, CI (0.14-0.27), P = 0.000), with no significant heterogeneity among the studies. Moreover, the Z-score in the vast majority of the measured sites (femoral head, femoral neck, lumbar spine, radius, and Ward's triangle) was significantly higher in absorbers. There was no significant overall difference in BMD in g/cm² between absorbers and non-absorbers, but a significantly higher BMD using g/cm² was observed in absorbers in the total hip site.

CONCLUSIONS

Postmenopausal women with PLD had lower Z-scores at most anatomic sites compared to healthy controls.

The association between adult-type hypolactasia and symptoms of functional dyspepsia

Functional dyspepsia and lactose intolerance (adult-type hypolactasia, ATH) are common conditions that may coexist or even be confounded. Their clinical presentation can be similar, however, lactose intolerance does not form part of the diagnostic investigation of functional dyspepsia. Studies on the association between functional dyspepsia and ATH are scarce. This study aimed to evaluate whether ATH is associated with symptoms of functional dyspepsia. Patients fulfilling the Rome III diagnostic criteria for functional dyspepsia underwent genetic testing for ATH. Dyspeptic symptoms were evaluated and scored according to a validated questionnaire. The diagnostic criteria for ATH was a CC genotype for the -13910C/T polymorphism, located upstream of the lactase gene. The mean scores for dyspeptic symptoms were compared between patients with ATH and those with lactase persistence. A total of 197 functional dyspeptic patients were included in the study. Mean age was 47.7 years and 82.7% patients were women. Eighty-eight patients (44.7%) had a diagnosis of ATH. Abdominal bloating scores were higher in ATH patients compared to the lactase persistent patients (P=0.014). The remaining dyspeptic symptom scores were not significantly different between the two groups. The study results demonstrate an association between ATH and bloating in patients with functional dyspepsia.

Prevalence of lactose intolerance in patients with diarrhea-predominant irritable bowel syndrome: data from a tertiary center in southern China

BACKGROUND

Symptoms associated with lactose intolerance (LI) and diarrhea-predominant irritable bowel syndrome (IBS-D) are almost the same. These disease entities are difficult to differentiate clinically. In practice, differential diagnosis depends on self-reported patient milk intolerance. However, there is limited data on the prevalence of LI in China. The aim of this study was to investigate the prevalence of LI in IBS-D patients and asymptomatic healthy controls.

METHODS

Lactose malabsorption (LM) was diagnosed by a lactose hydrogen breath test (HBT) and was defined by peak breath H₂ excretion over the baseline level of ≥ 20 ppm. LI-related symptoms were monitored for 8 h following lactose administration. LI was defined in LM patients with positive symptoms during the observation time. Patients with IBS-D were additionally asked if they were intolerant to milk.

RESULTS

A total of 109 eligible IBS-D patients (Rome III criteria) and 50 healthy controls were enrolled in this study. Except for hydrogen non-producers, the prevalence of LM did not differ between IBS-D patients and the control group (85%, 82/96 vs 72%, 34/47; P = 0.061). There was, however, a higher LI prevalence in IBS patients than in healthy subjects (45%, 43/96 vs 17%, 8/47; P = 0.002). Sensitivity, specificity, and positive and negative predictive values of self-reported milk intolerance for detecting LI were 58, 58, 53, and 63%, respectively.

CONCLUSIONS

Prevalence of LI is significantly higher in IBS-D patients than in healthy subjects. Self-reported milk intolerance is a poor diagnostic predictor of LI.

Country, regional, and global estimates for lactose malabsorption in adults: a systematic review and meta-analysis

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.

Type 1 diabetic patients with peripheral neuropathy have pan-enteric prolongation of gastrointestinal transit times and an altered caecal pH profile

AIMS/HYPOTHESIS

We hypothesised that type 1 diabetic patients with established diabetic sensorimotor polyneuropathy (DSPN) would have segmental and/or pan-enteric dysmotility in comparison to healthy age-matched controls. We aimed to investigate the co-relationships between gastrointestinal function, degree of DSPN and clinical symptoms.

METHODS

An observational comparison was made between 48 patients with DSPN (39 men, mean age 50 years, range 29-71 years), representing the baseline data of an ongoing clinical trial (representing a secondary analysis of baseline data collected from an ongoing double-blind randomised controlled trial investigating the neuroprotective effects of liraglutide) and 41 healthy participants (16 men, mean age 49 years, range 30-78) who underwent a standardised wireless motility capsule test to assess gastrointestinal transit. In patients, vibration thresholds, the Michigan Neuropathy Screening Instrument and Patient Assessment of Upper Gastrointestinal Symptom questionnaires were recorded.

RESULTS

Compared with healthy controls, patients showed prolonged gastric emptying (299 ± 289 vs 179 ± 49 min; p = 0.01), small bowel transit (289 ± 107 vs 224 ± 63 min; p = 0.001), colonic transit (2140, interquartile range [IQR] 1149-2799 min vs 1087, IQR 882-1650 min; p = 0.0001) and whole-gut transit time (2721, IQR 1196-3541 min vs 1475 (IQR 1278-2214) min; p < 0.0001). Patients also showed an increased fall in pH across the ileocaecal junction (-1.8 ± 0.4 vs -1.3 ± 0.4 pH; p < 0.0001), which was associated with prolonged colonic transit (r = 0.3, p = 0.001). Multivariable regression, controlling for sex, disease duration and glycaemic control, demonstrated an association between whole-gut transit time and total GCSI (p = 0.02).

CONCLUSIONS/INTERPRETATION

Pan-enteric prolongation of gastrointestinal transit times and a more acidic caecal pH, which may represent heightened caecal fermentation, are present in patients with type 1 diabetes. The potential implication of delayed gastrointestinal transit on the bioavailability of nutrition and on pharmacotherapeutic and glycaemic control warrants further investigation.

TRIAL REGISTRATION

EUDRA CT: 2013-004375-12.

[Efficacy of Lactose-free Milk in Korean Adults with Lactose Intolerance]

BACKGROUND/AIMS

Lactose-free milk (LFM) is available for nutrient supply for those with lactose intolerance (LI). However, there are no consistent results of the efficacy of LFM in LI subjects. We aimed to examine the changes of gastrointestinal (GI) symptoms and hydrogen breath test (HBT) values after ingestion of lactose contained milk (LCM) vs. LFM.

METHODS

From May 2015 to September 2015, thirty-five healthy adults with history of LCM-induced GI symptoms were recruited at a tertiary hospital. For the diagnosis of LI, HBT with LCM 550 mL (lactose 25 g) was performed every 20 minutes for 3 hours. The test was defined as "positive" when H2 peak exceeded 20 ppm above baseline values (ΔH2>20 ppm). When the subjects are diagnosed as LI, the second HBT using LFM 550 mL (lactose 0 g) was performed 7 days later. Subjects were asked to complete a questionnaire about the occurrence and severity of GI symptoms.

RESULTS

Among a total of 35 subjects, 31 were diagnosed with LI at first visit, and their LCM-related symptoms were abdominal pain (98.6%), borborygmus (96.8%), diarrhea (90.3%), and flatus (87.1%). The ΔH2 value in subjects taking LCM (103.7±66.3ppm) significantly decreased to 6.3±4.9 ppm after ingesting LFM (p<0.0001). There were also significant reduction in total symptom scores and the severity of each symptom when LCM was changed to LFM (p<0.0001).

CONCLUSIONS

This is the first report that LFM reduce LCM-related GI symptoms and H2 production in Korean adults. LFM can be an effective alternative for LCM in adults with LI.

The management of lactose intolerance among primary care physicians and its correlation with management by gastroenterologists: the SEPD-SEMG national survey

INTRODUCTION AND AIMS

The understanding of lactose intolerance (LI) is limited in some professional settings. Sociedad Española de Patología Digestiva (SEPD) and Sociedad Española de Medicina General (SEMG) have developed a survey in order to: a) Analyze primary care physicians (PCPs) knowledge and clinical management; and b) to compare results with those of a previous survey of Spanish gastroenterologists (GEs).

MATERIAL AND METHODS

An online questionnaire was sent to SEMG members with 27 items on various issues: Demographics, occupational characteristics, outlook on LI, diagnostic tests, treatment, and follow-up. Results were compared to those from a survey of GEs.

RESULTS

A total of 456 PCPs responded, versus 477 GEs. PCPs had an older mean age and longer professional experience. Level of understanding of LI was similar, albeit a higher proportion of PCPs lacked epidemiological awareness (p < 0.01). GEs tended to consider LI a "minor" condition (71.3 vs. 40.1%; p > 0.001), and LI symptoms as overlapping those of irritable bowel syndrome (93.5 vs. 88.2%; p = 0.005), although symptoms perceived as suspicious of LI were similar in both groups. Dietary recommendations were recognized as the primary therapeutic approach.

CONCLUSION

This study reveals the outlook of PCPs on LI, and allows comparison with that of GEs, as a basis for the development of strategies aimed at improving LI understanding, approach and management in our setting.

Soybean and Lactose in Meat Products and Preparations Sampled at Retail

Food allergies and intolerances have increased during the last decades and regulatory authorities have taken different measures to prevent and manage consumers' adverse reactions, including correct labelling of foods. Aim of this work was to search for soybean and lactose in meat products and meat preparations taken from retail in some provinces of Campania Region (Southern Italy) and to evaluate the food labels compliance with Regulation (EU) n.1169/2011. Soybean and lactose were searched using commercial kits in n. 58 samples of meat products produced in or distributed by 19 establishments, and in n. 55 samples of meat products and n. 8 of meat preparations produced in 21 plants. All samples were selected on the basis of the absence of any information on the labels about the presence of the two searched allergens, with the exception of n. 5 samples tested for lactose. Traces of soybean were detected in 50 out of the 58 examined samples, at concentrations up to 0.93 mg kg-1. Only two samples contained levels above the detection limit of 0.31 mg kg-1. Lactose levels ranging from 0.11 to 2.95 g/100 g, i.e. above the detection limit, were found in all the tested samples (n. 63). The results of the present research underline the need for careful controls and planning by operators as part of the self-control plans, and deserve attention from the competent authorities considering not only the consumers' health but also the great attention media pay to regulations providing consumers with information on food.

Diagnosing lactose malabsorption in children: difficulties in interpreting hydrogen breath test results

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.

Primary hypolactasia diagnosis: Comparison between the gaxilose test, shortened lactose tolerance test, and clinical parameters corresponding to the C/T-13910 polymorphism

BACKGROUND & AIMS

There is no consensus on the most accurate method to diagnose primary hypolactasia. We aimed to compare the diagnostic accuracy of the new gaxilose test with 2 traditional tests (lactose tolerance test and clinical criteria) for the diagnosis of primary hypolactasia using the C/T-13910 polymorphism as a reference standard.

METHODS

Patients with a clinical suspicion of lactose intolerance were subjected to gaxilose tests, shortened lactose tolerance tests, and symptom questionnaires before and after overload with 50 g lactose and after a lactose-free diet. The diagnostic accuracy and degree of agreement and correlation were assessed using a genetic test (C/T-13910 polymorphism) as a reference standard and their respective 95% confidence intervals.

RESULTS

Thirty consecutive patients (70% women) participated in the study. The genetic test confirmed the C/T-13910 polymorphism in 11 patients (36.8%). The presence of diarrhoea and the symptom score after lactose overload, along with the tolerance test, were the variables with the highest degree of agreement (κ > 0.60). Area under the ROC curve was >0.82 (p < 0.05), with sensitivity and specificity values of >0.80. However, the gaxilose test obtained lower values: κ, 0.47; area under curve, 0.75 (0.57-0.94); sensitivity, 0.82 (0.55-1); and specificity, 0.68 (0.45-0.92). The multivariate analysis showed an association between the post-overload symptom questionnaire and the results of the genetic test (odds ratio: 1.17; 1.04-1.31; p < 0.01).

CONCLUSIONS

The presence of diarrhoea and the symptom score after overload with 50 g lactose showed a higher degree of agreement and diagnostic accuracy for primary hypolactasia than the gaxilose test when the genetic test is used as a reference standard.

Lactase persistence versus lactose intolerance: Is there an intermediate phenotype?

BACKGROUND

According to the prevailing theory about the genetic background to lactose intolerance, there are three genotypes but only two adult physiological phenotypes: lactase persistence in individuals with the CT and TT genotypes and lactase non-persistence in individuals with the CC genotype. However, analysis of lactase activity from intestinal biopsies has revealed three distinct levels of activity, suggesting that an intermediate physiological phenotype may exist.

AIM

To assess possible disparities between different genotypes with regard to biomarkers of lactase activity and physical symptoms during an oral lactose load test.

METHODS

A retrospective study using an oral lactose load test (n=487). Concentrations of hydrogen in exhaled air and blood glucose were measured. Afterwards, subjects were asked to provide oral mucosa samples for genotyping and answer a questionnaire (participation rate 56%, n=274).

RESULTS

Mean hydrogen levels in exhaled air at 120min were significantly higher in the CT genotype than in the TT genotype. There was no significant difference in blood glucose levels between the two groups. Reported symptoms, with the possible exception of abdominal pain, were equally prevalent in both groups.

CONCLUSIONS

Subjects with the CT and TT genotypes, hitherto classified as lactase-persistent, differ in their physiological response to lactose intake, indicating differences in phenotype which could have clinical significance.

Contribution of Colonic Fermentation and Fecal Water Toxicity to the Pathophysiology of Lactose-Intolerance

Whether or not abdominal symptoms occur in subjects with small intestinal lactose malabsorption might depend on differences in colonic fermentation. To evaluate this hypothesis, we collected fecal samples from subjects with lactose malabsorption with abdominal complaints (LM-IT, n = 11) and without abdominal complaints (LM-T, n = 8) and subjects with normal lactose digestion (NLD, n = 15). Lactose malabsorption was diagnosed using a ¹³C-lactose breath test. Colonic fermentation was characterized in fecal samples at baseline and after incubation with lactose for 3 h, 6 h and 24 h through a metabolomics approach using gas chromatography-mass spectrometry (GC-MS). Fecal water cytotoxicity was analyzed using a colorimetric assay. Fecal water cytotoxicity was not different between the three groups (Kruskall-Wallis p = 0.164). Cluster analysis of the metabolite patterns revealed separate clusters for NLD, LM-T and LM-IT samples at baseline and after 24 h incubation with lactose. Levels of 5-methyl-2-furancarboxaldehyde were significantly higher in LM-IT and LM-T compared to NLD whereas those of an unidentified aldehyde were significantly higher in LM-IT compared to LM-T and NLD. Incubation with lactose increased short chain fatty acid (SCFA) concentrations more in LM-IT and LM-T compared to NLD. In conclusion, fermentation patterns were clearly different in NLD, LM-IT and LM-T, but not related to differences in fecal water cytotoxicity.

Additional Value of CH₄ Measurement in a Combined (13)C/H₂ Lactose Malabsorption Breath Test: A Retrospective Analysis

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 ¹³C/H₂ lactose breath test that measures breath ¹³CO₂ 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 ¹³C/H₂ lactose breath tests to assess the impact on the diagnostic accuracy of measuring breath CH₄ in addition to H₂ and ¹³CO₂. Based on the ¹³C/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 ¹³C/H₂ breath test to identify methanogenic subjects with lactose malabsorption or SIBO.

Self-reported lactose intolerance in clinic patients with functional gastrointestinal symptoms: prevalence, risk factors, and impact on food choices

BACKGROUND

Many patients complain of abdominal symptoms with dairy products; however, clinical and psychosocial factors associated with self-reported lactose intolerance (SLI) have not been assessed in large studies. In particular, data are lacking from lactase deficient populations. This prospective cohort study assessed the prevalence of, and risk factors for, SLI in Chinese patients attending a gastroenterology clinic.

METHODS

Consecutive patients completed questionnaires to assess digestive health (Rome III), psychological state (HADS), life event stress (LES), food intake, and quality-of-life (SF-8). A representative sample completed genetic studies and hydrogen breath testing (HBT) at the clinically relevant dose of 20 g lactose.

KEY RESULTS

SLI was present in 411/910 (45%) clinic patients with functional abdominal symptoms. The genotype in all subjects was C/C-13910. A small number of novel SNPs in lactase promoter region were identified, including C/T-13908 which appeared to confer lactase persistence. Over half of the patients (54%) completed the 20 g lactose HBT with 58% (285/492) reporting typical symptoms. Positive and negative predictive values of SLI for abdominal symptoms during HBT were 60% and 44%, respectively. Psychological state and stress were not associated with SLI in clinic patients. SLI impacted on physical quality-of-life and was associated with reduced ingestion of dairy products, legumes, and dried fruit (p ≤ 0.05).

CONCLUSIONS & INFERENCES

In a lactase deficient population, approximately half of patients attending clinic with functional gastrointestinal symptoms reported intolerance to dairy products; however, SLI did not predict findings on 20 g lactose HBT. Independent of psychosocial factors, SLI impacted on quality-of-life and impacted on food choices with restrictions not limited to dairy products.

Clinical, anthropometric and laboratory nutritional markers of pancreatic exocrine insufficiency: Prevalence and diagnostic use

Pancreatic exocrine insufficiency (PEI) frequently occurs secondary to exocrine pancreatic disease (e.g. chronic pancreatitis, cystic fibrosis, cancer) or pancreatic/gastrointestinal surgery, resulting in the maldigestion of nutrients and consequently malnutrition. Pancreatic enzyme replacement therapy (PERT) is the cornerstone of PEI management. Despite its clinical relevance, the diagnosis of PEI in clinical practice is challenging, as the current gold standard test is cumbersome, and alternatives have limited availability or accuracy. There is a need for accurate and easily applicable diagnostic modalities. We review the prevalence of clinical symptoms and changes in anthropometric measurements and laboratory nutritional markers indicative of malnutrition in patients with PEI, and the relevance of these findings in diagnosing PEI and monitoring PERT efficacy. Based on limited available evidence, assessment of clinical symptoms, body weight, body mass index and other anthropometric parameters are not sensitive methods for PEI diagnosis, owing to high variability and multiple confounding factors, but appear useful in monitoring PERT efficacy. Limited evidence precludes strong recommendations but suggests that serum levels of vitamin E, magnesium, and plasma proteins, notably retinol binding protein, albumin, and prealbumin, may have diagnostic utility in PEI. Studies show that assessment of changes in these and other nutritional parameters is helpful in monitoring PERT efficacy. Further research is needed to confirm the diagnostic accuracy of these parameters for PEI. Until such data are available, a nutritional evaluation including circulating vitamin E, magnesium, retinol binding protein, albumin, and prealbumin may be used to evaluate the probability of PEI in clinical practice when reliable pancreatic function tests are not available.

Prevalence of self-reported stomach symptoms after consuming milk among indigenous Sami and non-Sami in Northern- and Mid-Norway - the SAMINOR study

Objective

The main purpose of this work was to identify the prevalence of self-reported stomach symptoms after consuming milk among Sami and non-Sami adults.

Study design

A cross-sectional population-based study (the SAMINOR study). Data were collected by self-administrated questionnaires.

Method

SAMINOR is a population-based study of health and living conditions conducted in 24 municipalities in Northern Norway during 2003 and 2004. The present study included 15,546 individuals aged between 36 and 79, whose ethnicity was categorized as Sami (33.4%), Kven (7.3%) and Norwegian majority population (57.2%).

Results

Sami respondents had a higher prevalence of self-reported stomach symptoms after consuming milk than the Norwegian majority population. The reporting was highest among Sami females (27.1%). Consumption of milk and dairy products (yoghurt and cheese) was high among all the ethnic groups. However, significantly more Sami than non-Sami never (or rarely) consume milk or cheese, and individuals who reported stomach symptoms after consuming milk had an significant lower intake of dairy products than those not reporting stomach symptoms after consuming dairy products. Sami reported general abdominal pain more often than the majority population. The adjusted models show a significant effect of Sami ethnicity in both men and women on self-reported stomach symptoms after consuming milk. In females, the odds ratio (OR)=1.77 (p=0.001) and in males OR=1.64 (p=0.001).

Conclusion

Our study shows that the Sami population reported more stomach symptoms after consuming milk, suggesting a higher prevalence of milk intolerance among the Sami population than the Norwegian majority population.