Detection of malabsorption of low doses of carbohydrate: accuracy of various breath H2 criteria

Dose-response efficacy of mulberry fruit extract for reducing post-prandial blood glucose and insulin responses: randomised trial evidence in healthy adults

Extracts of mulberry have been shown to reduce post-prandial glucose (PPG) and insulin (PPI) responses, but reliability of these effects and required doses and specifications are unclear. We previously found that 1·5 g of a specified mulberry fruit extract (MFE) significantly reduced PPG and PPI responses to 50 g carbohydrate as rice porridge, with no indications of intolerance. The trials reported here aimed to replicate that work and assess the efficacy of lower MFE doses, using boiled rice as the carbohydrate source. Two separate randomised controlled intervention studies were carried out with healthy Indian males and females aged 20-50 years (n 84 per trial), with PPG area under the curve over 2 h as the primary outcome. Trial 1 used doses of 0, 0·37, 0·75, 1·12 and 1·5 g MFE in boiled rice and 0 or 1·5 g MFE in rice porridge. Trial 2 used doses of 0, 0·04, 0·12, 0·37 g MFE in boiled rice. In trial 1, relative to control, all MFE doses significantly decreased PPG (-27·2 to -22·9 %; all P ≤ 0·02) and PPI (-34·6 to -14·0 %, all P < 0·01). Breath hydrogen was significantly increased only at 1·5 g MFE (in rice porridge), and self-reported gastrointestinal symptoms were uniformly low. In trial 2, only 0·37 g MFE significantly affected PPG (-20·4 %, P = 0·002) and PPI (-17·0 %, P < 0·001). Together, these trials show that MFE in doses as low as 0·37 g can reliably reduce PPG and PPI responses to a carbohydrate-rich meal, with no apparent adverse effects.

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Background: Dairy products are frequently considered responsible for post-prandial symptoms and are withdrawn from the diet, even against medical advice.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.

European guideline on indications, performance, and clinical impact of hydrogen and methane breath tests in adult and pediatric patients: European Association for Gastroenterology, Endoscopy and Nutrition, European Society of Neurogastroenterology and Motility, and European Society for Paediatric Gastroenterology Hepatology and Nutrition consensus

INTRODUCTION

Measurement of breath hydrogen (H2 ) and methane (CH4 ) excretion after ingestion of test-carbohydrates is used for different diagnostic purposes. There is a lack of standardization among centers performing these tests and this, together with recent technical developments and evidence from clinical studies, highlight the need for a European guideline.

METHODS

This consensus-based clinical practice guideline defines the clinical indications, performance, and interpretation of H2 -CH4 -breath tests in adult and pediatric patients. A balance between scientific evidence and clinical experience was achieved by a Delphi consensus that involved 44 experts from 18 European countries. Eighty eight statements and recommendations were drafted based on a review of the literature. Consensus (≥80% agreement) was reached for 82. Quality of evidence was evaluated using validated criteria.

RESULTS

The guideline incorporates new insights into the role of symptom assessment to diagnose carbohydrate (e.g., lactose) intolerances and recommends that breath tests for carbohydrate malabsorption require additional validated concurrent symptom evaluation to establish carbohydrate intolerance. Regarding the use of breath tests for the evaluation of oro-cecal transit time and suspected small bowel bacterial overgrowth, this guideline highlights confounding factors associated with the interpretation of H2 -CH4 -breath tests in these indications and recommends approaches to mitigate these issues.

CONCLUSION

This clinical practice guideline should facilitate pan-European harmonization of diagnostic approaches to symptoms and disorders, which are very common in specialist and primary care gastroenterology practice, both in adult and pediatric patients. In addition, it identifies areas of future research needs to clarify diagnostic and therapeutic approaches.

Induced volatolomics of pathologies

Volatolomics allows us to elucidate cell metabolic processes in real time. In particular, a volatile organic compound (VOC) excreted from our bodies may be specific for a certain disease, such that measuring this VOC may afford a simple, fast, accessible and safe diagnostic approach. Yet, finding the optimal endogenous volatile marker specific to a pathology is non-trivial because of interlaboratory disparities in sample preparation and analysis, as well as high interindividual variability. These limit the sensitivity and specificity of volatolomics and its applications in biological and clinical fields but have motivated the development of induced volatolomics. This approach aims to overcome issues by measuring VOCs that result not from an endogenous metabolite but, rather, from the pathogen-specific or metabolic-specific enzymatic metabolism of an exogenous biological or chemical probe. In this Review, we introduce volatile-compound-based probes and discuss how they can be exploited to detect and discriminate pathogenic infections, to assess organ function and to diagnose and monitor cancers in real time. We focus on cases in which labelled probes have informed us about metabolic processes and consider the potential and drawbacks of the probes for clinical trials. Beyond diagnostics, VOC-based probes may also be effective tools to explore biological processes more generally.

Small Intestinal Bacterial Overgrowth Syndrome: A Guide for the Appropriate Use of Breath Testing

The increased availability of noninvasive breath tests, each with limitations, has led to widespread testing for small intestinal bacterial overgrowth (SIBO) in patients with non-specific gastrointestinal complaints. The lactulose breath test (LBT) is based upon an incorrect premise and therefore incorrect interpretations which has resulted in the over-diagnosis of SIBO and the excessive use of antibiotics in clinical practice. Despite limitations, the glucose breath test (GBT) should be exclusively employed when considering SIBO in appropriately chosen patients. This review suggests guidelines for the optimal use and appropriate interpretation of the GBT for suspected SIBO. The LBT should be discarded from future use, and the literature based upon the LBT should be discounted accordingly.

Lactose tolerance test as an alternative to hydrogen breath test in the study of lactose malabsorption

Objectives

Lactose malabsorption is generally assessed by hydrogen breath testing (HBT). However, this test is not recommended in patients with high baseline hydrogen concentrations (H₂B). In addition, breath testing is not recommended in the current situation created by the COVID-19 pandemic, due to the potential infectiveness of the samples. The objective is to assess concordance between HBT and lactose tolerance test (LTT) depending on H₂B concentrations.

Methods

A total of 430 patients (40 years, Q1-Q3 = 28-54 years; 66.7% women) suspected of lactose malabsorption were included in the study. Breath and heparinized blood samples were collected at baseline and sequentially after the intake of 50 g of lactose, to measure hydrogen in breath and glycemia in blood, respectively.

Results

H₂B was <10 ppm in 69.5% of subjects; 10-20 ppm in 14.7%; and >20 ppm in 15.8% of subjects. In patients with H₂B <20 ppm, concordance between HBT and LTT was moderate and consistently improved when the cut-off in LTT was set at 15 mg/dL. The increase in hydrogen and glucose correlated negatively (r=-0.389; p<0.05). The increase in glycemia during LTT was not influenced by H₂B levels obtained in HBT.

Conclusions

LTT emerges as an alternative to HBT to assess lactose malabsorption in the presence of high H₂B levels or when breath testing is not recommended by the circumstances. The best concordance was obtained when the cut-off for LTT was set at 15 mg/dL.

The effect of 8 plant extracts and combinations on post-prandial blood glucose and insulin responses in healthy adults: a randomized controlled trial

BACKGROUND

Lower post-prandial glucose (PPG) and insulin (PPI) responses to foods are associated with reduced diabetes risk and progression. Several plant extracts have been proposed to reduce PPG or PPI by inhibiting enzymes or transporters involved in carbohydrate digestion and uptake. This study evaluates a range of such extracts, consumed with a carbohydrate load, for their effects on PPG, PPI and indicators of (gastrointestinal) tolerance.

METHODS

Interventions were extracts of mulberry fruit (MFE, 1.5 g), mulberry leaf (MLE, 1.0 g), white bean (WBE, 3.0 g), apple (AE, 2.0 g), elderberry (EE, 2.0 g), turmeric (TE, 0.18 g), AE + TE, and EE + TE. Each of these 8 individual extracts or combinations were added to a rice porridge containing ~ 50 g available carbohydrate (control). In a within-subject (randomised, balanced incomplete block) design, individual subjects received the control and a subset of 4 of the 8 extracts or combinations. Participants were 72 apparently healthy adults (mean [SD] age 31.2 [5.5] yr, body mass index 22.1 [2.0] kg/m2). The primary outcome was the percentage change in 2-h PPG (positive incremental area under the curve) relative to control. Secondary measures were the 2-h PPI response, 7-h breath hydrogen, measures of gastrointestinal discomfort, and urine glucose.

RESULTS

In the 65 subjects who completed the control and at least one intervention treatment, additions of AE, MFE and MLE produced statistically significant reductions in PPG vs control (p < 0.05; mean effect - 24.1 to - 38.1%). All extracts and combinations except TE and WBE significantly reduced PPI (p < 0.01; mean effect - 17.3% to - 30.4%). Rises in breath hydrogen > 10 ppm were infrequent, but statistically more frequent than control only for MLE (p = 0.02). Scores for gastrointestinal discomfort were extremely low and not different from control for any treatment, and no glucosuria was observed.

CONCLUSIONS

Additions of AE, MFE and MLE to rice robustly reduced PPG and PPI. EE significantly reduced only PPI, while TE and WBE showed no significant efficacy for PPG or PPI. Breath hydrogen responses to MLE suggest possible carbohydrate malabsorption at the dose used, but there were no explicit indications of intolerance to any of the extracts.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT04258501. Registered 6 February 2020 - Retrospectively registered.

Congruency of Genetic Predisposition to Lactase Persistence and Lactose Breath Test

The physiological decline of lactase production in adulthood, in some individuals, is responsible for the so-called “Lactose Intolerance.” This clinical syndrome presents with gastrointestinal and non-gastrointestinal symptoms following the consumption of dairy containing food. Lactose intolerance can be evaluated by means of the Lactose Breath Test (phenotype) and/or genetic evaluation of lactase-gene polymorphism (genotype). A comparison of the two tests was carried out in a large number of symptomatic adult subjects, which are selected and not representative of the general population. Congruency was as high as 88.6%. Among lactase non-persistent (genotype C/C), 14 subjects showed a negative Lactose Breath Test (LBT), possibly due to young age. Among lactase-persistent (genotype C/T), four subjects showed a positive LBT, which helps to diagnose secondary lactose intolerance. Symptoms, both gastrointestinal and extra-gastrointestinal, were reported by 90% of patients during the breath test. Clinical use of both tests in the same patients could be taken into consideration as a sharp diagnostic tool. We suggest considering the use of the genetic test after LBT administration, when secondary hypolactasia is suspected, for completion of diagnostic procedures.

Assessment of intestinal malabsorption

Significant efforts have been made in the last decade to either standardize the available tests for intestinal malabsorption or to develop new, more simple and reliable techniques. The quest is still on and, unfortunately, clinical practice has not dramatically changed. The investigation of intestinal malabsorption is directed by the patient's history and baseline tests. Endoscopy and small bowel biopsies play a major role although non-invasive tests are favored and often performed early on the diagnostic algorithm, especially in paediatric and fragile elderly patients. The current clinically available methods and research tools are summarized in this review article.

Small intestinal bacterial overgrowth as an uncommon cause of false positive lactose hydrogen breath test among patients with diarrhea-predominant irritable bowel syndrome in Asia

BACKGROUND AND AIM

It has been reported that small intestinal bacterial overgrowth (SIBO) may lead to false positive diagnoses of lactose malabsorption (LM) in irritable bowel syndrome patients. The aim of this study was to determine the influence of SIBO on lactose hydrogen breath test (HBT) results in these patients.

METHODS

Diarrhea-predominant irritable bowel syndrome patients with abnormal lactose HBTs ingested a test meal containing (99m) Tc and lactose. The location of the test meal and the breath levels of hydrogen were recorded simultaneously by scintigraphic scanning and lactose HBT, respectively. The increase in hydrogen concentration was not considered to be caused by SIBO if ≥ 10% of (99m) Tc accumulated in the cecal region at the time or before of abnormal lactose HBT.

RESULTS

LM was present in 84% (31/37) of irritable bowel syndrome patients. Twenty of these patients agreed to measurement of oro-cecal transit time. Only three patients (15%) with abnormal lactose HBT might have had SIBO. The median oro-cecal transit time between LM and lactose intolerance patients were 75 min and 45 min, respectively (Z=2.545, P=0.011).

CONCLUSIONS

Most of irritable bowel syndrome patients with an abnormal lactose HBT had LM. SIBO had little impact on the interpretation of lactose HBTs. The patients with lactose intolerance had faster small intestinal transit than LM patients.

Hydrogen breath test in patients with severe constipation: the interference of the mixing of intestinal content

BACKGROUND

The diagnostic accuracy of the hydrogen (H2 ) breath test might be reduced by the release of preformed H2 , trapped in hard stools. Test solution ingestion might induce the mixing of colonic content and a false positive result. We studied severely constipated patients, at diagnosis and after the normalization of bowel function, to clarify whether this mechanism affects test results.

METHODS

Twenty functional constipated patients, 10 consecutive patients with functional diarrhea and 10 healthy volunteers underwent (i) a H2 breath test after lactulose, to exclude differences among the groups in fermenting capacity; (ii) breath H2 excretion monitoring after non-absorbable, non-fermentable PEG-electrolyte solution, to exclude the role of the delivery to the colon of preexisting fermentable substrates or of the release of preformed H2 entrapped in the feces; (iii) H2 measurement during a 7-h fasting period, to exclude the role of spontaneous variations of breath gas excretion; and (iv) breath H2 excretion monitoring after PEG, after normalization of bowel function.

KEY RESULTS

All the subjects excreted similar amounts of H2 after lactulose. After PEG, only severely constipated patients showed significant breath H2 excretion, theoretically able to induce a false positivity of the lactose breath test in 70% of patients and a false positivity of glucose breath tests in 50% of patients. Breath H2 excretion after PEG disappeared if fecal consistency improved after therapy.

CONCLUSIONS & INFERENCES

Severely constipated patients may harbor preformed gas in hard stools which can be released when mixing of the intestinal content is induced. This mechanism may interfere with breath test results.

Simultaneous non-invasive measurement of liquid gastric emptying and small bowel transit by combined 13C-acetate and H2-lactulose breath test

The 13C-acetate breath test (13C-ABT) allows noninasive measurement of liquid gastric emptying time (LGET), the H2-lactulose breath (H2-LBT) measures orocecal transit time (OCTT). Because of different test principles, both tests can generally be combined. This would not only spare time and resources but may also deliver additional information on the integrated regulation of gastrointestinal motor functions. Our aim was to define an adequate test protocol and to generate normal values for the combined 13C-ABT/H2-LBT. Twenty two healthy volunteers participated (HV, 12 females, age: 26.5  ±  4.7 years, BMI: 22  ±  2.1 kgm(-2). Fasting subjects received 200 ml of an aequous solution containing 150 mg 13C-acetate and 10 g lactulose. Breath samples for H2 measurements were collected before ingestion of the test solution and afterwards at 5 min intervals for 180 min, for 13C measurements sampling intervals were prolonged to 15 min after the first hour. LGET was defined as time of maximal 13C-exhalation, OCTT as increase in H2 of ⩾ 20 ppm above basal. Small bowel transit time (SBTT) was calculated as the difference between OCTT and LGET. Mean [95% CI] values for LGET, OCTT and SBTT were 26 [23-30] min, 85 [68-102] min and 60 [44-76] min, respectively. Normal values for LGET and OCTT corresponded with published data. SBTT was not correlated with LGET (R2 = 0.019; p = 0.546). By contrast, there was a very tight and highly significant correlation between SBTT and OCTT (R2 = 0.933; p < 0.001). Multivariate linear regression analyses confirmed that age, sex and BMI had no significant effects on OCTT or SBTT while LGET was weakly correlated with BMI (R2 = 0.240; p = 0.021). In conclusion, the combined 13C-ABT/H2-LBT allows simultaneous measurement of LGET and OCTT as well as calculation of SBTT.

Semiquantitative assessment of breath hydrogen testing

BACKGROUND AND AIM

A major use of breath hydrogen testing is to assess absorptive capacity for sugars to assist dietary design for management of gut symptoms. Qualitative reporting takes no account of the vigor of hydrogen response and provides little insight into degrees of malabsorption. This study aimed to describe a semiquantitative reporting method and to compare results with those reported qualitatively.

METHODS

In consecutive Caucasian patients with Crohn's disease (n = 87), ulcerative colitis (59), functional gastrointestinal disorders (FGID) (162), and healthy controls (76), area under the curve was calculated for lactulose (15 g). This was compared with that for lactose (50 g) and fructose (35 g). Degree of malabsorption was categorized into arbitrary groups.

RESULTS

Semiquantitative results for ≥ 30% (designated "convincing") malabsorption was most similar to those using a qualitative cutoff value of 20 ppm, but in 38% and 21% of patients, the classification of malabsorption (nil or clinically significant) changed for fructose and lactose, respectively. Using a cutoff of 10 ppm, 49% and 5% were classified differently. Crohn's disease had a higher prevalence (42%) of convincing fructose malabsorption than controls (24%) or patients with FGID (33%) (P < 0.02). Highest prevalence of convincing lactose malabsorption (38%) was in ulcerative colitis, greater than controls (18%) and FGID (18%) (P < 0.02).

CONCLUSIONS

Semiquantitative assessment provides different results with different clinical implications in more than one third of patients, but disease-related alterations in prevalence are similar to those defined qualitatively. This method may be preferable because it lessens the confounding influence of the vigor of the hydrogen response.

A proprietary alpha-amylase inhibitor from white bean (Phaseolus vulgaris): a review of clinical studies on weight loss and glycemic control

Obesity, and resultant health hazards which include diabetes, cardiovascular disease and metabolic syndrome, are worldwide medical problems. Control of diet and exercise are cornerstones of the management of excess weight. Foods with a low glycemic index may reduce the risk of diabetes and heart disease as well as their complications. As an alternative to a low glycemic index diet, there is a growing body of research into products that slow the absorption of carbohydrates through the inhibition of enzymes responsible for their digestion. These products include alpha-amylase and glucosidase inhibitors. The common white bean (Phaseolus vulgaris) produces an alpha-amylase inhibitor, which has been characterized and tested in numerous clinical studies. A specific and proprietary product named Phase 2^® Carb Controller (Pharmachem Laboratories, Kearny, NJ) has demonstrated the ability to cause weight loss with doses of 500 to 3000 mg per day, in either a single dose or in divided doses. Clinical studies also show that Phase 2 has the ability to reduce the post-prandial spike in blood glucose levels. Experiments conducted incorporating Phase 2 into food and beverage products have found that it can be integrated into various products without losing activity or altering the appearance, texture or taste of the food. There have been no serious side effects reported following consumption of Phase 2. Gastro-intestinal side effects are rare and diminish upon extended use of the product. In summary, Phase 2 has the potential to induce weight loss and reduce spikes in blood sugar caused by carbohydrates through its alpha-amylase inhibiting activity.

MALDI-TOF MS characterization of glycation products of whey proteins in a glucose/galactose model system and lactose-free milk

The major modifications induced by thermal treatment of whey proteins α-lactalbumin (α-La) and β-lactoglobulin (β-Lg) in a model system mimicking lactose-free milk (L(-) sugar mix) were investigated by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). The analysis of the intact α-La revealed species with up to 7 and 14 adducts from lactose and sugar mix, respectively, whereas for β-Lg 3 and up to 5 sugar moieties were observed in the case of lactose and sugar mix experiments, respectively. A partial enzymatic hydrolysis with endoproteinase AspN prior to mass spectrometric analysis allowed the detection of further modifications and their localization in the amino acid sequence. Using α-cyano-4-chlorocinnamic acid as MALDI matrix, it could be shown that heating α-La and β-Lg with glucose or galactose led to the modification of lysine residues that are not glycated by lactose. The higher glycation degree of whey proteins in a lactose-free milk system relative to normal milk with lactose reflects the higher reactivity of monosaccharides compared to the parent disaccharide. Finally, the analysis of the whey extract of a commercial lactose-free milk sample revealed that the two whey proteins were present as three main forms (native, single, and double hexose adducts).

Effect of carbohydrate digestibility on appetite and its relationship to postprandial blood glucose and insulin levels

BACKGROUND/OBJECTIVES

'Slowly digestible' carbohydrates have been claimed to reduce appetite through their effects on postprandial glucose and insulin levels, but literature is inconsistent. The inconsistencies between studies might be explained by factors other than glycemic effects per se, for example, nutritional or physical properties. We tested this possibility by examining postprandial glucose, insulin and appetite responses to drinks differing only in rate and extent of digestibility of carbohydrates. This was accomplished by comparing different glucose polymers: maltodextrin (rapidly digestible) versus medium-chain pullulan (slowly but completely digestible) versus long-chain pullulan (indigestible).

SUBJECTS/METHODS

In a randomized double-blind balanced crossover design, 35 subjects received drinks with 15 g test carbohydrate polymers. Key outcome measures were appetite scores, digestibility (in vitro test and breath hydrogen), and (in a subset) glucose and insulin levels.

RESULTS

Digestibility, glucose and insulin data confirmed the rapid, slow and nondigestible nature of the test carbohydrates. Despite its low digestibility, only long-chain pullulan reduced appetite compared with the maltodextrin control, whereas the medium-chain pullulan did not.

CONCLUSIONS

We conclude that glycemic responses per se have minimal effects on appetite, when tested in products differing in only carbohydrate digestibility rate and extent.

Influence of colectomy on hydrogen excretion in breath

INTRODUCTION

Hydrogen breath test is the most commonly used method to analyze carbohydrate absorption and diagnose carbohydrate malabsorption. The result of the H(2) breath test is influenced by different factors, which are mostly related to quantitative or qualitative aspects of colonic flora. A scarcely studied variable is the effect of colonic anatomical integrity on H(2) excretion in breath.

PURPOSE

The present study aims to determine whether loss of colonic integrity reduces H(2) excretion capacity after an oral load of an unabsorbable carbohydrate.

METHODS

An observational study was conducted in three patient groups: controls with preserved colon, patients with partial colectomy, and patients with complete colectomy and ileostomy. H(2) concentration in breath was measured by gas chromatography every 10 min for 3 h after oral lactulose administration.

RESULTS

Twenty-two patients with partial colectomy, 18 controls with preserved colon, and seven patients with ileostomy were included. H(2) excretion after lactulose did not differ between patients with partial colectomy and controls (basal excretion = 8.5 vs 4 ppm; delta increase = 50.0 vs 47.5 ppm; area under the curve = 4,480.0 vs 4,710.5 ppm/min). In contrast, H(2) excretion was significantly lower in the ileostomy group.

CONCLUSIONS

Partial colectomy does not influence the capacity for H(2) excretion after oral unabsorbable carbohydrate administration.

Genetic test for lactase non-persistence and hydrogen breath test: is genotype better than phenotype to diagnose lactose malabsorption?

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.

Therapeutic antioxidant medical gas

Medical gases are pharmaceutical gaseous molecules which offer solutions to medical needs and include traditional gases, such as oxygen and nitrous oxide, as well as gases with recently discovered roles as biological messenger molecules, such as carbon monoxide, nitric oxide and hydrogen sulphide. Medical gas therapy is a relatively unexplored field of medicine; however, a recent increasing in the number of publications on medical gas therapies clearly indicate that there are significant opportunities for use of gases as therapeutic tools for a variety of disease conditions. In this article, we review the recent advances in research on medical gases with antioxidant properties and discuss their clinical applications and therapeutic properties.

Beneficial effects of oral tilactase on patients with hypolactasia

BACKGROUND

A lactose-free diet is commonly prescribed to subjects with hypolactasia. We tested the effectiveness of a single ingestion of tilactase (a beta-D-galactosidase from Aspergillus oryzae) in adults with hypolactasia, previously assessed by lactose H(2)-breath test.

MATERIALS AND METHODS

After measurement of orocecal transit time (OCTT, by lactulose H(2)-breath test) and lactose H(2)-breath testing plus placebo, a total of 134 subjects were positive to hypolactasia and underwent lactose H(2)-breath testing plus either low (6750 U) or standard (11,250 U) doses of tilactase. The appearance of gastrointestinal symptoms during the tests was monitored.

RESULTS

OCTT was longer in malabsorbers (subjects without bloating, abdominal pain and/or diarrhoea, n = 25) than in intolerants (bloating, abdominal pain and/or diarrhoea, n = 109, P < 0.02). Malabsorbers had longer time to H(2) peak (P < 0.03), lower H(2) peak levels (P < 0.002) and smaller integrated H(2) excretion levels (P < 0.005) than intolerants. After tilactase ingestion, integrated H(2) levels were decreased by 75% (low dose) and 87% (standard dose) in malabsorbers, and by 74% (low dose) and 88% (standard dose) in intolerants. In the latter group, total symptom score were decreased by 76% (low dose) and by 88% (standard dose) (P < 0.0001).

CONCLUSION

A single oral administration of tilactase is highly effective in decreasing symptoms and hydrogen excretion of hypolactasia assessed by lactose H(2)-breath test. If confirmed by long-term observations, ingestion of tilactase might be a better option than exclusion diets in intolerant subjects with hypolactasia.

The small bowel flora in individuals with cecoileal reflux

BACKGROUND: The observation of cecoileal reflux to barium enema is not rare; however, its causes and consequences have not been widely investigated. Considering that ileocecal junction exerts a function as barrier to invasion of bacteria from colon to small bowel, it seems interesting to study the intestinal microflora in subjects carrying cecoileal reflux. AIMS: This study aims at evaluating the ileal flora in individuals with cecoileal reflux. METHODS: A group of 36 subjects comprising 30 females and 6 males with a mean age of 54 years was assessed. Twenty-five individuals with cecoileal reflux and 11 without cecoileal reflux were submitted to small intestine contamination evaluation through the breath test with lactulose-H2 and measurement of the orocecal transit time by means of alternate current biosusceptometry. Small intestine bacterial overgrowth was characterized by orocecal transit time-H2 shortening. RESULTS: Comparison of basal H2, orocecal transit time-H2 and orocecal transit time-alternate current biosusceptometry measurements did not statistically differ between the groups with and without cecoileal reflux. Orocecal transit time-H2 was significantly smaller than orocecal transit time-alternate current biosusceptometry, particularly in individuals with cecoileal reflux. A significant correlation between the two methods was observed only in relation to control, not existing in relation to cecoileal reflux group. CONCLUSIONS: Smaller orocecal transit time-H2 and the loss of correlation with orocecal transit time-alternate current biosusceptometry observed in the individuals with cecoileal reflux suggest a differentiated behavior for such group relative to control, which could be associated with small intestine bacterial overgrowth.

Comparison of breath testing with fructose and high fructose corn syrups in health and IBS

Although incomplete fructose absorption has been implicated to cause gastrointestinal symptoms, foods containing high fructose corn syrup (HFCS) contain glucose. Glucose increases fructose absorption in healthy subjects. Our hypothesis was that fructose intolerance is less prevalent after HFCS consumption compared to fructose alone in healthy subjects and irritable bowel syndrome (IBS). Breath hydrogen levels and gastrointestinal symptoms were assessed after 40 g of fructose (12% solution) prepared either in water or as HFCS, administered in double-blind randomized order on 2 days in 20 healthy subjects and 30 patients with IBS. Gastrointestinal symptoms were recorded on 100-mm Visual Analogue Scales. Breath hydrogen excretion was more frequently abnormal (P < 0.01) after fructose (68%) than HFCS (26%) in controls and patients. Fructose intolerance (i.e. abnormal breath test and symptoms) was more prevalent after fructose than HFCS in healthy subjects (25% vs. 0%, P = 0.002) and patients (40% vs. 7%, P = 0.062). Scores for several symptoms (e.g. bloating r = 0.35) were correlated (P < or = 0.01) to peak breath hydrogen excretion after fructose but not HFCS; in the fructose group, this association did not differ between healthy subjects and patients. Symptoms were not significantly different after fructose compared to HFCS. Fructose intolerance is more prevalent with fructose alone than with HFCS in health and in IBS. The prevalence of fructose intolerance is not significantly different between health and IBS. Current methods for identifying fructose intolerance should be modified to more closely reproduce fructose ingestion in daily life.

Visceral hypersensitivity and intolerance symptoms in lactose malabsorption

Lactose malabsorption is not always associated with intolerance symptoms. The factors responsible for symptom onset are not yet completely known. As differences in visceral sensitivity may play a role in the pathogenesis of functional symptoms, we evaluated whether an alteration of visceral sensitivity is present in subjects with lactose intolerance. Thirty subjects, recruited regardless of whether they were aware of their capacity to absorb lactose, underwent an evaluation of intestinal hydrogen production capacity by lactulose breath test, followed by an evaluation of lactose absorption by hydrogen breath test after lactose administration and subsequently an evaluation of recto-sigmoid sensitivity threshold during fasting and after lactulose administration, to ascertain whether fermentation modifies intestinal sensitivity. The role of differences in gastrointestinal transit was excluded by gastric emptying and mouth-to-caecum transit time by (13)C-octanoic and lactulose breath tests. Lactulose administration induced a significant reduction of discomfort threshold in subjects with lactose intolerance but not in malabsorbers without intolerance symptoms or in subjects with normal lactose absorption. Perception threshold showed no changes after lactulose administration. Severity of symptoms in intolerant subjects was significantly correlated with the reduction of discomfort thresholds. Visceral hypersensitivity should be considered in the induction of intolerance symptoms in subjects with lactose malabsorption.

Fructose malabsorption may be gender dependent and fails to show compensation by colonic adaptation

Fructose malabsorption is linked to gastrointestinal and other unusual symptoms. Polymers of fructose are also recognized prebiotics. While some prebiotics can self-adapt when consumed regularly (resulting in decreased breath hydrogen and symptoms), we wondered whether self-adaptation occurs with basic fructose. We evaluated 90 subjects (61 females). Each completed a diet questionnaire and underwent a fructose challenge. Breath hydrogen and quantified symptom scores were recorded. Group comparisons for sum of breath hydrogen and total symptom scores were evaluated with the Mann-Whitney U test. Spearman's correlation coefficient and chi(2) or Fisher's exact test were used as appropriate. Malabsorption occurred in 29 patients (32.2%) and low-grade symptoms without malabsorption in 30 (33%). Women complained of symptoms more frequently (p = 0.04) and exhibited more fructose malabsorption (p = 0.0527). Breath hydrogen correlated with symptoms (r = 0.516, p = 0.0037). Adaptation with increasing pretest fructose intake was absent. We conclude that gender may influence fructose malabsorption and there is no adaptation to regular consumption.

Efficacy of rifaximin, a nonabsorbed oral antibiotic, in the treatment of small intestinal bacterial overgrowth

INTRODUCTION

Rifamixin is an orally administrated, nonabsorbed antibiotic whose utility in eradication of small intestinal bacterial overgrowth (SIBO) is currently being evaluated.

PURPOSE

The aim of this study was to investigate efficacy and safety of rifaximin in relieving symptoms and normalizing the glucose breath test (GBT) in patients with SIBO.

METHODS

Symptom score assessment, consisting of frequency and severity of bloating, gas, abdominal pain, and bowel movements and the GBT were performed before and after treatment with rifaximin 800 mg/d for 4 weeks.

SUBJECTS

Twenty consecutive symptomatic patients (16 women and 4 men; mean age, 47.8 years; range, 19 to 85 years) who had a positive GBT were prospectively studied in an open-labeled fashion. Fourteen patients (70.0%) presented with diarrhea, 3 (15.0%) with bloating and gas, and 3 (15.0%) with constipation as the dominant symptom.

RESULTS

: Eleven patients were hydrogen producers, 8 exclusively methane, and 1 patient produced both gases by the GBT. Among patients with diarrhea, 12 of 14 (85.7%) reported improvement in symptom scores of more than 50%; 1 between 25% and 50%, 1 had no response after 4 weeks of rifamixin. Among patients with bloating and gas or constipation as the main symptom: 2 of 6 (33.3%) had improvement between 50% and 75%; 3 (50%) had 25% to 50% improvement, and 1 (16.7%) had no response. Repeat GBT at the end of the 4 weeks showed that 54.5% of hydrogen formers and 50.0% of methane producers were eradicated, and there was a significant reduction (P <0.05) in the area under the concentration-time curve and peak values. No adverse effects were observed.

CONCLUSIONS

Rifaximin in a dose of 800 mg per day for 4 weeks: 1) was safe and effective treatment in reducing symptoms in patients with SIBO of multiple etiologies, especially when diarrhea was the dominant symptom; and 2) normalized the GBT in approximately 50% of patients. Data support a future therapeutic role for rifaximin in SIBO.

Comparison of a real-time polymerase chain reaction assay for lactase genetic polymorphism with standard indirect tests for lactose maldigestion

BACKGROUND & AIMS

There is a discrepancy in outcome between the lactose tolerance and breath hydrogen tests for lactose maldigestion. The availability of a validated genetic test for lactase polymorphism allows a reevaluation of these tests.

METHODS

Thirty healthy adults participated in a 50-g lactose challenge test at a university clinic. Blood was drawn for genetic and timed blood glucose testing (2 hours), and breath hydrogen was measured (4.5 hours). Lactase genetic polymorphism was assessed by a real-time polymerase chain reaction assay. Participants completed a diet questionnaire, and symptoms were recorded during the lactose challenge. Sensitivity and specificity were calculated for each indirect test. The 2-way kappa coefficient between these tests was evaluated. Student t test and Wilcoxon rank sum test were used to compare variables.

RESULTS

The lactose tolerance test as a standard had an 87.5% sensitivity and 92.7% specificity for genetic status. Only a moderate agreement between lactose tolerance test and breath hydrogen test was observed (2-way kappa coefficient, .53; 95% confidence interval, .22-.83). When genetic status was used as standard, symptoms had a moderate sensitivity and specificity. Lactose tolerance test had very good sensitivity, and the breath test had excellent specificity.

CONCLUSIONS

Both indirect tests independently have good to very good sensitivities and specificities for genetic lactase status. The noted disagreement likely reflects variables that affect the tests independently of intestinal lactase status. The value of these tests in the light of the availability of genetic testing is discussed.

An extract of black, green, and mulberry teas causes malabsorption of carbohydrate but not of triacylglycerol in healthy volunteers

BACKGROUND

In vitro studies suggest that extracts of black, green, and mulberry teas could interfere with carbohydrate and triacylglycerol absorption via their ability to inhibit alpha-amylase, alpha-glucosidase, sodium-glucose transporters, and pancreatic lipase.

OBJECTIVE

We measured breath hydrogen and 13CO2 to investigate the ability of an extract of black, green, and mulberry tea leaves to induce malabsorption of carbohydrate and triacylglycerol in healthy volunteers.

DESIGN

In a crossover design, healthy adult volunteers randomly ingested test meals with a placebo beverage or a preparation containing an extract of black (0.1 g), green (0.1 g), and mulberry (1.0 g) teas. One test meal contained 50 g carbohydrate as white rice, 10 g butter, and 0.2 g [13C]triolein, and the beverages contained 10 g sucrose. The calorie content of the second test meal consisted entirely of lipid (30 g olive oil and 0.2 g [13C]triolein). Breath-hydrogen and 13CO2 concentrations were assessed hourly for 8 h, and symptoms were rated on a linear scale.

RESULTS

With the carbohydrate-containing meal, the tea extract resulted in a highly significant increase in breath-hydrogen concentrations, which indicated appreciable carbohydrate malabsorption. A comparison of hydrogen excretion after the carbohydrate-containing meal with that after the nonabsorbable disaccharide lactulose suggested that the tea extract induced malabsorption of 25% of the carbohydrate. The tea extract did not cause triacylglycerol malabsorption or any significant increase in symptoms.

CONCLUSION

This study provides the basis for additional experiments to determine whether the tea extract has clinical utility for the treatment of obesity or diabetes.

Gamma-Cyclodextrin Lowers Postprandial Glycemia and Insulinemia without Carbohydrate Malabsorption in Healthy Adults

OBJECTIVE

Preliminary in vitro and animal studies have shown that gamma-cyclodextrin (GCD) is a slowly and completely digestible carbohydrate. The objective of this study was to determine the glycemic and insulinemic responses to GCD in humans. Breath hydrogen excretion was measured simultaneously to evaluate carbohydrate malabsorption.

METHODS

Healthy adult subjects (N = 32) received 50 g of carbohydrate from GCD or a rapidly digested maltodextrin (MD) in a double-masked, randomized, crossover design. Plasma glucose (fingerstick) and serum insulin (venous) concentrations were measured at baseline and at 15, 30, 45, 60, 90, 120, 150, and 180 min postprandially. Breath hydrogen excretion was monitored hourly for 8 h postprandially. The severity of gastrointestinal symptoms (nausea, cramping, distension, flatulence) was rated by the subjects on a ranked scale for two 24-h periods postprandially.

RESULTS

The mean baseline-adjusted peak plasma glucose concentration was 47% lower (P < 0.001), and the mean baseline-adjusted peak serum insulin concentration was decreased by 45% (P < 0.001) after subjects consumed GCD compared with MD. Positive incremental area under the curve (0-120 min) was reduced 45% for plasma glucose and 49% for serum insulin by GCD compared with MD (P < 0.001 in each case). There were no differences between GCD and MD in the proportion of positive breath hydrogen tests and both carbohydrates were equally well tolerated.

CONCLUSIONS

GCD effectively lowers postprandial glycemia and insulinemia compared with MD, without resulting in appreciable carbohydrate malabsorption or gastrointestinal intolerance.

Inverse dose effect of pretest dietary lactose intake on breath hydrogen results and symptoms in lactase nonpersistent subjects

The aim of this study was to determine a relationship between pretest intake of lactose and outcome of lactose breath hydrogen test. Patients presented at a testing laboratory participated in the study. A 3-hour breath hydrogen, 50-g lactose challenge was carried out. Results were tabulated and patients completed a 3-day recall diet questionnaire. Daily lactose intake was independently calculated and was associated with breath hydrogen and total symptom score. Statistical analysis used Spearman's correlation, Mann-Whitney U-test and chi2 or Fisher exact test. Of 118 patients, 50% were lactose maldigesters. In these patients, measured breath hydrogen and symptom scores were significantly higher in the lowest intake group (< 5 g/d) than in the highest intake group (> 20 g/d) (P < .05). In the presumed lactose digesters, 59% experienced some symptoms during testing for unclear reasons. Pretest dietary intake of lactose inversely affects results of breath hydrogen.

Effects of a nutritional supplement containing Salacia oblonga extract and insulinogenic amino acids on postprandial glycemia, insulinemia, and breath hydrogen responses in healthy adults

OBJECTIVE

This study evaluated the postprandial glycemic, insulinemic, and breath hydrogen responses to a liquid nutritional product containing Salacia oblonga extract, an herbal alpha-glucosidase inhibitor, and two insulinogenic amino acids.

METHODS

In a randomized, double-masked, crossover design, 43 healthy subjects were fed the following meals on separate days after overnight fasting: control (C; 480 mL of a study beverage containing 82 g of carbohydrate, 20 g of protein, and 14 g of fat), control plus 3.5 g each of phenylalanine and leucine (AA), control plus 1000 mg of S. oblonga extract (S), and control plus S and AA (SAA). Postprandially, fingerstick capillary plasma glucose and venous serum insulin levels were measured for 180 min, and breath hydrogen excretion was measured for 480 min.

RESULTS

The baseline-adjusted peak glucose response was not different across meals. However, changes in plasma glucose areas under the curve (0 to 120 min and 0 to 180 min, respectively) compared with C were -9% and -11% for AA (P>0.05 each), -27% and -24% for S (P=0.035 and 0.137), and -27% and -29% for SAA (P<0.05 each). Changes in insulin areas under the curve were +5% and +5% for AA (P>0.05 each), -35% and -36% for S (P<0.001 each), and -6% and -7% for SAA (P>0.05 each). Breath hydrogen excretion was 60% greater (P<0.001) in the S-containing meals than in the C- and AA-containing meals and was associated with mild flatulence.

CONCLUSIONS

Salacia oblonga extract is a promising nutraceutical ingredient that decreased glycemia in this study. Supplementation with amino acids had no significant additional effect on glycemia.

Autonomic neuropathy may be associated with delayed orocaecal transit time in patients with cirrhosis

Orocaecal transit (OCT) time is delayed in patients with cirrhosis, but the reasons for this remain unclear. We hypothesized that autonomic neuropathy (AN) may explain the delay in OCT.

METHODS

We determined OCT and autonomic function tests (AFT) in 48 patients (Child A-15, B-27, C-6) with cirrhosis of various aetiologies. AFT were categorized as normal, borderline, or abnormal. OCT was measured using the lactulose hydrogen (H2) breath test. OCT was defined as the time from baseline when there was a rise in H2 levels of >20 ppm over baseline or >10 ppm over baseline sustained over 2 consecutive time points.

RESULTS

Based on OCT, patients were separated into those with delayed OCT (>90 min, group I) and normal OCT (< or = 90 min, group II). Mean OCT time of patients in group I was 169.7+/-49.7 min vs. 84.4+/-12.1 min in group II. Baseline clinical characteristics of patients with and without AN, and those with normal and delayed OCT were similar. Presence of mild encephalopathy did not have an effect on OCT. AN was seen more frequently in group I than group II [16/32 (50%) vs. 3/16 (19%), p=0.03]. Logistic regression analysis showed that the presence of AN was the only independent variable associated with delayed OCT (OR 7.3, CI 1.3-39.4, p=0.02).

CONCLUSION

Our study showed that the presence of AN was associated with delayed OCT in patients with cirrhosis.

Hydrogen breath test in the diagnosis of lactose malabsorption: accuracy of new versus conventional criteria

Increased hydrogen excretion in the breath after carbohydrate ingestion, an expression of carbohydrate malabsorption, represents the pathophysiologic basis of the hydrogen breath test, a simple, noninvasive, reproducible test for the diagnosis of this condition. Few data are available concerning the breath hydrogen response that most accurately identifies carbohydrate malabsorption. In this article we report our application for the first time in clinical practice of 2 recently described, more accurate criteria for the diagnosis of lactose malabsorption (ie, breath hydrogen excretion value > 6 parts per million (ppm) 6 hours after carbohydrate load and a sum greater than 15 ppm for the breath hydrogen values obtained 5, 6, and 7 hours after carbohydrate load). On 3 separate days, we subjected 84 consecutive patients with functional or organic gastrointestinal disease to measurement of hydrogen excretion in the breath after the administration of lactose to test for lactose malabsorption; after the administration of lactulose as a means of ruling out false-negative results resulting from hydrogen-nonproducer status; and after the administration of a nonabsorbable electrolyte solution as a means of ruling out false-positive results caused by the mixing of intestinal content and release of preformed hydrogen trapped in the feces. According to the conventional criterion, 51% of the subjects proved to be lactose malabsorbers. Positive results were obtained with the use of the 6th-hour criterion in 76% of patients, and positive results were found in 80% when the sum of the excretion at hours 5, 6, and 7 was used as the criterion (P < .05 for both comparisons). Ten of 21 and 11 of 25, respectively, showed intolerance symptoms. It was therefore possible for us to diagnose lactose malabsorption in 24% and 27% of patients, respectively, who tested negative according to the conventional criterion. The conventional criterion must be abandoned and these new criteria adopted.

Effects of a medical food containing an herbal α-glucosidase inhibitor on postprandial glycemia and insulinemia in healthy adults

OBJECTIVE

To determine the effect of different doses of Salacia oblonga extract, an herbal alpha-glucosidase inhibitor, on postprandial glycemic, insulinemic, and breath hydrogen responses in healthy adults.

DESIGN

Double-masked, randomized crossover design.

INTERVENTION

Subjects, after fasting for 12 hours, consumed four test meals consisting of 480 mL of study beverage (14 g fat, 82 g carbohydrate, and 20 g protein) with 0, 500, 700, or 1,000 mg of S oblonga extract on four separate occasions. Capillary finger-prick plasma glucose and venous serum insulin concentrations were measured at baseline and for 2 hours postprandially. Breath hydrogen excretion was measured at baseline and hourly for 8 hours postprandially.

SUBJECTS/SETTING

Thirty-nine healthy, nondiabetic adults (body mass index=23.7+/-0.4, age=25.7+/-0.9 years.

STATISTICAL ANALYSES PERFORMED

Repeated-measures analysis of variance was applied to the raw data or data that had been transformed (log, rank) when necessary due to nonnormality. The Tukey-Kramer post hoc test was used for pairwise comparisons.

RESULTS

Compared with the control, the 1,000-mg S oblonga extract dose reduced the plasma glucose and serum insulin incremental areas under the curve (0 to 120 minutes postprandial) by 23% ( P =.32) and 29% ( P =.01), respectively. The other doses of S oblonga extract did not impact glycemia or insulinemia. Breath hydrogen excretion increased linearly as the dose of S oblonga extract was advanced.

CONCLUSIONS

The presence of S oblonga extract tended to lower postprandial glycemia and significantly reduced the postprandial insulin response. The increase in breath hydrogen excretion suggests a mechanism similar to prescription alpha-glucosidase inhibitors. Future studies of S oblonga extract in patients with diabetes are needed.

Hydrogen breath test with low-dose rice flour for assessment of exocrine pancreatic insufficiency

OBJECTIVES

The hydrogen (H2) breath test is widely used in the assessment of carbohydrate malabsorption. Severe exocrine pancreatic insufficiency markedly diminishes pancreatic amylase production and results in malabsorption of complex carbohydrates. Thus, the H2 breath test with low-dose rice flour starch was tested to determine its value in detecting exocrine pancreatic insufficiency by comparison with a direct measurement of pancreatic function.

METHODS

Ten patients with clinically suspected pancreatic insufficiency confirmed with a duodenal perfusion technique and measurement of trypsin and lipase output after cerulein stimulation were included. An H2-rice flour breath test was performed by orally administering 30 g of rice flour. End-alveolar breath samples were obtained before rice load and at 30-minute intervals thereafter for the next 5 hours.

RESULTS

The results are expressed as median (percentile 25-75). Patients included 8 men and 2 women with moderate to severe exocrine pancreatic insufficiency due to chronic pancreatitis, pancreatectomy, or cystic fibrosis. Stimulated duodenal output of lipase and trypsin was abnormally low in all patients (median release, 1.7; range, 0.5-4.5 and 0.8, range, 0.1-11.3 KU/h, respectively). Basal H2 excretion was 9 ppm (range, 7-17) and delta increase over basal H2 excretion was 4 ppm (range, 1-6). Correlation between H2-rice breath test and basal or stimulated duodenal output of lipase and trypsin was not significant.

CONCLUSION

In exocrine pancreatic insufficiency, an oral load of 30 g rice flour slightly raises H2 excretion in breath. This increase is not useful for detecting pancreatic insufficiency due to poor sensitivity and because it is influenced by extrapancreatic factors such as small bowel bacterial overgrowth.

Fermentation of endogenous substrates is responsible for increased fasting breath hydrogen levels in celiac disease

Fasting breath hydrogen (FBH) levels are frequently increased in celiac disease (CD). In this study we sought to determine whether the unknown source of the fermented substrates is endogenous glycoproteins shed or exuded through the damaged mucosa. To test the role of nonabsorbable exogenous substrates, we subjected 39 untreated and 23 treated CD patients and 37 healthy volunteers to the H(2) breath test after administration of lactulose after both an unrestricted and a restricted pretest meal. To test the relevance of endogenous substrates, we measured breath H(2) excretion during a 9-hour fast and after the administration of lactulose solution. To determine whether the luminal content of CD patients contains an increased amount of fermentable substrates, we incubated samples of jejunal juice from 7 untreated CD patients, 6 healthy volunteers, and 6 dyspeptic patients in vitro with a fecal homogenate obtained from a healthy H(2)-producer volunteer and measured the cumulative H(2) production. Untreated CD patients showed higher FBH levels than did treated patients and healthy volunteers. Only in untreated CD did FBH levels show no difference if a restricted or an unrestricted dinner was eaten the evening before the test. Nine-hour FBH levels were significantly higher in untreated CD than in healthy volunteers, whereas no difference was found after administration of lactulose. In vitro H(2) production was significantly higher in untreated CD patients than in controls. Increased FBH levels in CD do not depend on fermentation of malabsorbed exogenous substrates; endogenous substrates are increased in the lumens of CD patients and may be responsible for increased FBH levels.

Effects of a beverage containing an enzymatically induced-viscosity dietary fiber, with or without fructose, on the postprandial glycemic response to a high glycemic index food in humans

OBJECTIVE

Dietary supplementation with guar gum or fructose has been reported to reduce the postprandial glycemic response to an oral glucose challenge. As a result of the poor palatability of most foods containing guar gum, a novel low-viscosity beverage with guar gum was developed that becomes viscous in vivo through an enzymatic induction. The primary study objective was to determine the effect of an amylase-induced viscosity (I-V) product, with or without supplemental fructose, on the postprandial glycemic response to a high glycemic index test meal in healthy nondiabetic subjects.

DESIGN

The study was a four-treatment, placebo-controlled, double-blind, randomized block protocol.

SETTING

The study was performed at Glycaemic Index Testing, Inc., Toronto, Ontario, Canada.

SUBJECTS

A total of 30 healthy nondiabetic volunteers (13 male, 17 female, mean+/-s.e.m. age of 51+/-3 y and body mass index of 24.2+/-0.4 kg/m(2)) participated in the study.

INTERVENTION

In the morning after an overnight fast, subjects participated in four 3-h meal glucose tolerance tests on separate occasions. The test meals contained 50 g of available carbohydrate from maltodextrin and white bread (control) or the same meal with either 5 g of guar gum (3.6 g galactomannan), 5 g of fructose, or 5 g of guar gum +5 g of fructose.

RESULTS

Treatments containing guar gum had a reduced (P<0.01) baseline-adjusted peak glucose response and incremental area under the glucose curve. In contrast to previous studies, fructose increased (P<0.05) the baseline-adjusted peak glucose concentration.

CONCLUSIONS

Guar gum incorporated into an amylase I-V product provided a means to stabilize blood glucose levels by reducing the early phase excursion and then by appropriately maintaining the later phase excursion in healthy nondiabetic humans.

Kefir improves lactose digestion and tolerance in adults with lactose maldigestion

OBJECTIVE

Kefir is a fermented milk beverage that contains different cultures than yogurt. The objective of this study was to determine whether kefir improves lactose digestion and tolerance in adults with lactose maldigestion.

DESIGN

Randomized block design.

SUBJECTS

Fifteen healthy, free-living adults with lactose maldigestion.

MAIN OUTCOME MEASURES

Breath hydrogen excretion and lactose intolerance symptoms were monitored hourly for 8 hours after each test meal.

INTERVENTION

Subjects were fed test meals consisting of 20 g lactose portions of milk (2% reduced fat), plain and raspberry flavored kefir, and plain and raspberry flavored yogurt, each following an overnight (12 hour) fast.

STATISTICAL ANALYSIS

Mixed model ANOVA was performed on raw or transformed data, followed by Tukey HSD post hoc tests (when appropriate). Significance was defined as P<.05.

RESULTS

The breath hydrogen area under the curve (AUC) for milk (224+/-39 ppm x h) was significantly greater than for the plain yogurt (76+/-14 ppm x h, P<.001), the plain kefir (87+/-37 ppm x h, P<.001), and the flavored yogurt (76+/-14 ppm x h, P=.005). The flavored kefir had an intermediate response (156+/-26 ppm x h). The yogurts and kefirs all similarly reduced the perceived severity of flatulence by 54% to 71% relative to milk. Abdominal pain and diarrhea symptoms were negligible among the five treatments.

APPLICATIONS/CONCLUSION

Because kefir improved lactose digestion and tolerance in this study, its use may be another potential strategy for overcoming lactose intolerance. Further studies of other types of kefir for improving lactose digestion are warranted.

Small bowel bacterial overgrowth and rice malabsorption in healthy and physically disabled older adults

AIM

To determine whether there are differences in small bowel bacterial overgrowth (SBBO) and rice digestion between healthy and disabled older adults and to estimate the influence of physical activity on these nutritional statuses.

METHOD

Fifteen disabled adults who commute to a day-care centre and 11 healthy older adults participated in this study. SBBO and rice absorption were judged using a breath hydrogen test. Physical activity was estimated using a pedometer.

RESULTS

The average number of steps taken per day by the disabled was 1056 +/- 243, which was statistically lower than that of the healthy, 6904 +/- 782 (P < 0.001). No SBBO-positive subject was seen in the healthy group, whereas five (33.3%) of 15 disabled older adults were SBBO-positive. After ingesting glucose solution, the triangle up H2 of disabled subjects was higher than that of the healthy subjects (7.6 +/- 2.7 versus 0.5 +/- 0.3 p.p.m., P < 0.05). Rice malabsorption was seen in one (9.1%) of 11 in the healthy and two (14.3%) of 14 in the disabled groups, which was not statistically significant.

CONCLUSIONS

Disabled older people who have a physically inactive lifestyle are at risk of SBBO, probably because of a reduction in their intestinal motility. SBBO has no influence on absorption of rice, and some older adults, independent of physical condition, can not absorb rice adequately.

Pullulan is a slowly digested carbohydrate in humans

Pullulan is an extracellular polysaccharide excreted by the fungus Aureobasidium pullulans. To evaluate the glycemic and breath hydrogen responses and gastrointestinal tolerance to pullulan, nondiabetic healthy adult subjects (n = 28) were studied in a randomized, double-masked, crossover design. After an overnight fast, subjects consumed beverages containing 50 g of carbohydrate from either maltodextrin (control) or pullulan. Capillary blood glucose response was determined for 180 min postprandially. Breath hydrogen response was determined for 8 h postprandially. Compared with control, incremental peak blood glucose concentration was reduced (P < 0.01) when subjects consumed pullulan (4.24 +/- 0.35 vs. 1.97 +/- 0.10 mmol/L). In addition, pullulan reduced (P < 0.01) the positive incremental area under the glucose curve by 50%. When subjects consumed pullulan, the incremental blood glucose excursions were reduced (P < 0.01) at 15, 30, 45, 60 and 90 min, but were maintained above basal glucose concentrations at 150 and 180 min. At 180 min, the blood glucose concentration was higher (P < 0.05) when subjects consumed pullulan compared with control, supporting the hypothesis that pullulan is digested slowly. Breath hydrogen concentrations were increased (P < 0.01) at 3, 4, 5, 6, 7 and 8 h postprandially when subjects consumed pullulan. In the first 24-h postprandial period, the frequency and intensity of flatulence was higher (P < 0.05) after subjects consumed pullulan compared with control. In conclusion, pullulan attenuated the postprandial glycemic excursion compared with an equivalent maltodextrin challenge. Pullulan also increased breath hydrogen excretion and the incidence of gastrointestinal intolerance symptoms, indicating that a portion of pullulan was malabsorbed.

Utilization of cornstarch in glycogen storage disease type Ia

OBJECTIVE

Uncooked cornstarch (UCCS) is used widely for the treatment of patients with glycogen storage disease type I (GSD-I). Previous studies suggested that glucose absorption may be impaired in GSD-I. In order to measure utilization of UCCS in young adults with GSD-Ia and healthy controls, we used a C-breath test based on the natural enrichment of C in UCCS.

DESIGN

Open, not randomized, prospective interventional study.

METHODS

Following 1 g/kg UCCS, we studied eight subjects with GSD-Ia (7 males, 1 female; mean age 28.3 years, range 16-42 years) and 15 healthy controls (10 males, 5 females; mean age 23.5 years, range 19-36 years). Breath samples for analysis of CO enrichment were collected at baseline and at 30-min intervals for 6 h or until hypoglycaemia occurred. Indirect calorimetry was used to measure respiratory gas exchange. Intermediate metabolites, lipids and glucose were measured in plasma. Breath H concentrations were measured as an indicator of malabsorption.

RESULTS

Cumulative utilization over 6 h was significantly higher in controls (18.35 +/- 6.2% of total carbohydrate intake) than in subjects with GSD-Ia (11.5 +/- 4.7%) (P < 0.02). However, utilization of UCCS was virtually identical up to 2.5 h. Two subjects with GSD-Ia fulfilled the criteria for malabsorption.

CONCLUSIONS

Starch digestion and absorption are not impaired in GSD-Ia. However, overall utilization of UCCS appears to be lower in GSD-Ia, which is most likely secondary to perturbed intermediary metabolism. There are important implications for treatment of this disorder. Ways to improve the efficacy of UCCS in GSD-I are needed.

Review article: lactose--a potential prebiotic

Lactose maldigestion, which affects a large majority of the world's population, has been mostly linked with uncomfortable symptoms. In addition, dairy consumption is variably blamed or recommended for a number of ill effects. There is, however, emerging evidence that certain lactic acid-producing bacteria, which selectively consume prebiotics, may be beneficial against some lower intestinal diseases. Lactose maldigestion and lactose should perhaps be re-evaluated as a potential provider of such a prebiotic. This historical and observational review discusses lactose and argues the opinion that it has prebiotic potential. Moreover, in maldigesters, natural ingestion or lack thereof may be relevant in the pathogenesis of diseases such as colorectal cancer and inflammatory bowel diseases.

Fructose prefeeding reduces the glycemic response to a high-glycemic index, starchy food in humans

The study objective was to determine whether a small dose of fructose administered before or simultaneously with a high glycemic index, starchy food decreases postprandial glycemic response. Nondiabetic healthy adults (n = 31; mean +/- SEM: age, 26 +/- 1 y; weight, 66.1 +/- 2.6 kg; body mass index, 23.3 +/- 0.6 kg/m(2)) were studied in a randomized crossover design. Treatments consisted of 50 g available carbohydrate from instant mashed potatoes fed alone (control) or with 10 g fructose fed 60, 30 or 0 min before the potato meal. Capillary finger-stick blood samples were analyzed for glucose concentration at -60, -30, 0, 15, 30, 45, 60, 90 and 120 min relative to the ingestion of the potato meal. Compared with the control, the positive incremental area under the glucose curve was reduced 25 and 27% (P < 0.01) when fructose was fed either 60 or 30 min before the meal, respectively. In contrast to previous studies demonstrating that immediate administration of a small amount of fructose lowers the glycemic response to a glucose solution, we found that fructose must be consumed before a starchy food to reduce postprandial glycemia.

Lactose malabsorption and intolerance and peak bone mass

BACKGROUND & AIMS

Lactose malabsorption per se is not associated with alterations of bone mineral density (BMD) or calcium intake, but when intolerance symptoms are present a lower calcium intake and reduction of BMD values are evident. The purpose of this study was to evaluate whether lactose intolerance interferes with the achievement of an adequate peak bone mass in young adults.

METHODS

Of 103 enrolled healthy subjects, 55 proved to be lactose malabsorbers with H(2) breath test after lactose administration, and 29 of them experienced intolerance symptoms (diarrhea, abdominal pain, bloating, flatulence). Lumbar and femoral BMD by dual-energy X-ray absorptiometry was measured, and calcium intake and biochemical indices of bone and mineral metabolism were evaluated.

RESULTS

Lumbar and femoral BMD, calcium intake, and mineral metabolism did not differ between malabsorbers and absorbers, although among malabsorbers, intolerant subjects showed significant alterations of all these parameters in comparison with tolerant subjects. A strict correlation was evident between BMD values and both severity of symptoms and calcium intake and between calcium intake and severity of symptoms.

CONCLUSIONS

Lactose intolerance prevents the achievement of an adequate peak bone mass and may, therefore, predispose to severe osteoporosis.