Does Oral Enzyme Replacement Therapy Reverse Intestinal Lactose Malabsorption?

The effects of oral enzyme replacement therapy on breath hydrogen excretion and symptoms after milk ingestion were studied in lactase-deficient patients. Sixteen symptomatic patients underwent interval hydrogen breath tests using whole milk as substrate. Each study was repeated with the addition of 250 mg of β-D-galactosidase derived from Aspergillus oryzae (Lactrase) given orally with the milk. Subsequently seven of those 11 patients who did not normalize their hydrogen excretion with 250 mg of Lactrase were available to be restudied with a 500-mg dose. Mean cumulative and peak hydrogen excretions were calculated for the baseline (milk alone), 250 mg, and 500 mg Lactrase groups. Significant (p ≤ 0.05) decreases in cumulative and peak hydrogen excretion were noted between the 500 mg Lactrase versus the baseline group, but not between the 250 mg versus baseline group. Five of the 16 (31%) symptomatic lactase-deficient patients normalized their hydrogen excretion after 250 mg of Lactrase; four of seven (57%) who bad not normalized on 250 mg, normalized their hydrogen excretion with 500 mg of Lactrase. A different pattern was observed in the incidence of symptoms. Five of the nine patients (56%) whose hydrogen excretion normalized with the addition of Lactrase at either dosage became asymptomatic after milk ingestion; in addition, three patients who did not normalize their hydrogen also became asymptomatic. We conclude that oral Lactrase in sufficient dosage temporarily reverses lactose malabsorption in some patients.     

Assessment of lactose absorption by measurement of urinary galactose

Individuals with sufficient intestinal lactase hydrolyze ingested lactose to galactose and glucose and these monosaccharides are absorbed. Lactose is not digested completely when intestinal lactase activity is low and the disaccharide is malabsorbed. Breath hydrogen excretion after lactose ingestion is used commonly to diagnose lactose malabsorption. However, no direct tests are currently used to assess lactose absorption. We tested a new method of assessing lactose absorption in 26 healthy individuals. Each subject ingested 50 g of lactose. Participants were evaluated for lactose malabsorption using a standard 3-h breath hydrogen test. In addition, the urinary excretions of galactose, lactose, and creatinine were quantitated for 3-5 h after lactose ingestion. On the basis of breath hydrogen analysis after lactose ingestion, 12 individuals were lactose malabsorbers (defined as a rise in the breath hydrogen concentration of greater than 20 parts per million above the baseline value). The 14 subjects who did not malabsorb lactose by breath hydrogen testing (defined as a rise in the breath hydrogen concentration of less than or equal to 20 parts per million above the baseline value), had significantly more galactose in their urine 1, 2, and 3 h after lactose ingestion than lactose malabsorbers. The ratio of excreted lactose to excreted galactose was significantly decreased in lactose absorbers compared with lactose malabsorbers (p less than 0.001). Determination of the ratio of urinary galactose to urinary creatinine separated lactose absorbers from lactose malabsorbers completely (p less than 0.001). We conclude from this study that the determination of urinary galactose, urinary lactose/galactose ratio, and urinary galactose/creatinine ratio may be used to assess lactose digestion and absorption in healthy adults.     

Intestinal Gas Production from Bacterial Fermentation of Undigested Carbohydrate in Irritable Bowel Syndrome

The relationship between abdominal pain and bowel gas from bacterial fermentation of undigested carbohydrate was investigated in nine patients with irritable bowel syndrome (IBS), six lactose malabsorbers, and 11 asymptomatic controls. All subjects took breath samples and marked analog scales for abdominal pain, bloating, and psychological stress hourly during all waking hours for 7 days. Breath samples were analyzed for hydrogen concentration within 3 days, and the concentration was corrected for storage time. Symptoms of pain and bloating were significantly more common in IBS patients than in lactose malabsorbers or normal controls, and pain was significantly correlated with bloating in IBS patients. Breath hydrogen concentration was similar in all three groups, and breath hydrogen was not correlated with pain ratings in IBS patients. Thus, abdominal pain may be related to bloating from gastrointestinal gas, but bacterial fermentation cannot be the cause of such gas. The most likely source is swallowed air. This study also demonstrates the feasibility of monitoring hydrogen production in the bowel in field studies by having subjects collect hourly breath samples.     

All Lactase Preparations Are Not the Same: Results of a Prospective, Randomized, Placebo-Controlled Trial

Objective: To compare the efficacy of three commercially available oral lactase preparations in adults with lactose intolerance. Methods: Design—Prospective, randomized, placebo-controlled trial. Setting—Outpatient study in a General Clinical Research Center. Subjects—Ten lactose-intolerant healthy volunteers were challenged with ice cream containing 18 g of lactose. Lactase or placebo was given immediately prior to challenge. Measurements—Symptoms and breath hydrogen excretion were recorded for 3 h following lactose challenge. Results: The three products differed in their abilities to influence symptoms and breath hydrogen excretion. Only Lactaid reduced the breath hydrogen excretion with lactose (mean peak, area under the curve and cumulative breath hydrogen excretion) ( P < 0.05). Lactrase and Dairy Ease influenced symptoms: Lactrase reduced pain, bloating and total symptomatic scores ( P < 0.05), whereas Dairy Ease only reduced pain ( P < 0.05). Lactaid administration did not reduce symptoms. Conclusion: In lactose-intolerant subjects, the available lactase preparations differ in their ability to improve both breath hydrogen excretion and symptoms. Lactrase may be the product of choice for achieving symptomatic improvement.     

Interval sampling of breath hydrogen (H2) as an index of lactose malabsorption in lactase-deficient subjects

Interval sampling of breath hydrogen content was used in lactose malabsorbers: (1) to compare hydrogen responses following increasing oral doses of lactose in milk and aqueous solutions; (2) to determine the reproducibility of interval breath sampling, and (3) to compare carbohydrate malabsorption following ingestion of either regular milk or milk containingLactobacillus acidophilus. Significant differences in breath hydrogen responses due to increasing amounts of lactose in milk and aqueous solutions were observed. The individual breath hydrogen responses were reproducible using the same lactose dose on different days. There was no significant difference in breath hydrogen responses or symptoms following administration of either regular milk or milk containingLactobacillus acidophilus. Breath hydrogen sampling at intervals, as performed in these studies, provides a sensitive and reproducible index of lactose malabsorption.Supported by the Oklahoma Agricultural Experiment Station, Stillwater, Oklahoma, and the Veterans Administration.     

Comparison of abdominal bloating severity between irritable bowel syndrome patients with high and low levels of breath hydrogen excretion in a lactulose breath test

BackgroundThere is growing evidence that gut flora plays a role in the development of Irritable Bowel Syndrome (IBS). Abdominal bloating is a common symptom in these patients and the severity of this symptom could be related to the variations in their fermentative profiles, obtained by measuring the levels of breath hydrogen excretion after lactulose ingestion.AimsOur objective was to determine the difference in abdominal bloating severity between IBS patients with high vs low levels of breath hydrogen excretion after lactulose administration.MethodsLactulose breath tests were carried out on IBS patients in our institution between July 2009 and August 2010. Patients were requested to fill out a validated questionnaire to assess the severity of their symptoms. Abdominal bloating severity score was compared among patients with high and low breath hydrogen levels.ResultsA total of 234 patients were enrolled. There was a statistically significant difference in the abdominal bloating severity score between groups: 7.0 (5.7-8.0) vs 6.5 (5.0-7.5), p=0.001. The comparison among IBS patients with constipation (IBS-C) in both groups also showed a statistically significant difference: 7.5 (6.0-8.5) vs 5.8 (3.5-7.2), p=0.0051.ConclusionsThose patients with a low level of breath hydrogen excretion after lactulose ingestion presented with significantly greater abdominal bloating than those with a high level of breath hydrogen excretion.     

Efficacy of Addition of Exogenous Lactase to Milk in Adult Lactase Deficiency

The efficacy of lactase by Kluyveromyces lactis in hydrolyzing milk lactose and reducing milk intolerance symptoms was tested in 52 proved lactose malabsorbers. The enzyme was added to milk administered to the patients, and H2 breath excretion (as an index of carbohydrate malabsorption), was determined by gas chromatograph technique, and milk intolerance symptoms were recorded. H2 mean excretion was 78.3 +/- 5.49 ppm after administration of intact whole milk 500 ml (test A), 43.5 +/- 4.99 ppm when lactase 2000 U was added to milk 500 ml immediately before administration (test B); 36.7 +/- 5.01 ppm when milk 500 ml was incubated for 12 h with lactase 1000 U (test C), and 29.7 +/- 4.35 ppm when the incubation was prolonged for 24 h (test D). Symptoms score was: test A = 5.85 +/- 0.56, test B = 3.71 +/- 0.45, test C = 2.77 +/- 0.63, test D = 1.7 +/- 0.68. A correlation index of r = 0.44 (p less than 0.01) was obtained between reduction in H2 mean excretion and reduction in symptoms score of a single individual. The addition of this lactase to milk seems to be effective in correcting lactose malabsorption, thus representing a convenient approach in milk intolerance.     

Lactose malabsorption in Greek adults: correlation of small bowel transit time with the severity of lactose intolerance.

Using breath hydrogen analysis after 139 mmol (50 g) oral lactose load, we investigated the prevalence of lactose malabsorption in 200 Greek adults and examined the relationship between symptoms and small bowel transit time. One hundred and fifty subjects had increased breath hydrogen concentrations (greater than 20 ppm) after the lactose load. In these individuals peak breath hydrogen concentration was inversely related to small bowel transit time (r = 0.63, 6 = 6.854, p less than 0.001) and the severity of symptoms decreased with increasing small bowel transit time. Lactose malabsorbers with diarrhoea during the lactose tolerance test had a small bowel transit time of 51 +/- 22 minutes (x +/- SD; n = 90) which was significantly shorter than the small bowel transit time of patients with colicky pain, flatulence, and abdominal distension (74 +/- 30, n = 53; p less than 0.001) and both groups had significantly shorter small bowel transit time than that of asymptomatic malabsorbers (115 +/- 21 n:7; p less than 0.001). When the oral lactose load was reduced to 33 mmol (12 g), the small bowel transit time increased five-fold and the overall incidence of diarrhoea and/or symptoms decreased dramatically. These results indicate that the prevalence of lactase deficiency in Greece may be as high as 75% and suggest that symptom production in lactose malabsorbers is brought about by the rapid passage down the small intestine of the malabsorbed lactose.     

Respiratory methane excretion in children with lactose intolerance

Two evaluate the relationship between colonic methane production and carbohydrate malabsorption, we measured end-expiratory methane levels in 70 normal and 40 lactose-intolerant children. Time-dependent excretion of hydrogen and methane was determined every 30 min for 120 min following a fasting oral lactose challenge (2 g/kg). Mean breath hydrogen levels in normals (lactose-tolerant) equaled 3.7 parts per million (ppm) throughout the study, but increased to >10 ppm by 60 min and remained elevated in lactose-intolerant subjects. Breath methane in normal children averaged 1.6 ppm from 0 to 120 min. In contrast, CH₄ excretion by lactose-intolerant children averaged 5.1 ppm at 90 min; and, by 120 min levels increased significantly compared with control. Breath methane levels in lactose-intolerant subjects following a lactose load continued to increase, however, despite the coingestion of exogenous lactase in amounts calculated to result in complete hydrolysis of the disaccharide. These data demonstrate that lactase-deficient children manifest significant increases in breath methane excretion following lactose ingestion and that enhanced methane production may be a consequence of several factors, including altered fecal pH and increased methanogenic substrates provided by colonic lactose fermentation. Further studies are required to determine the clinical significance of elevated methane production in lactose intolerance.     

Effects of age on lactose malabsorption in Oklahoma Native Americans as determined by breath H2 analysis

Breath H₂ excretion was used to determine lactose malabsorption in 30 healthy females and 30 healthy males between the ages of 3 and 64 yr who were at least 7/8 Native American. The test meal consisted of 5 ml reconstituted nonfat dry milk (0.25 g lactose) per kg of body weight. On the basis of breath H₂ tests in 15 control subjects with normal oral lactose tolerance tests, a response factor of 20 ppm was selected as the upper limit for lactose absorbers. Of the 60 subjects in the study group, 36 (60%) were classified as lactose malabsorbers since they had a response factor of 20 ppm or greater of breath H₂. Only 3 of 20 children (15%) who were under the age of 12 yr were nondigesters of the small lactose dose used in this study. Approximately 82 percent (82.5%) of subjects who were 13 yr and older were lactose malabsorbers. Adolescence appears to be the period in which malabsorption of lactose becomes evident in Native North Americans.Supported by the Nutrition Foundation, Inc., New York, New York; Biomedical Sciences Support Grant (USPH) 5-S05-RR7077 to The Research Foundation, Oklahoma State University.     

Hydrogen breath test for the diagnosis of lactose intolerance, is the routine sugar load the best one？

AIM： To evaluate the prevalence of lactose intolerance （LI） following a load of 12.5 g in patients diagnosed as high-grade malabsorbers using the hydrogen breath test （HBT）-25. METHODS： Ninety patients showing high-grade malabsorption at HBT-25 were submitted to a second HBT with a lactose load of 12.5 g. Peak hydrogen production, area under the curve of hydrogen excretion and occurrence of symptoms were recorded. RESULTS： Only 16 patients （17.77%） with positive HBT-25 proved positive at HBT-12.5. Hydrogen production was lower as compared to HBT-25 （peak value 21.55 parts per million （ppm） ± 29.54 SD vs 99.43 ppm ± 40.01 SD; P 〈 0.001）. Symptoms were present in only 13 patients. The absence of symptoms during the high-dose test has a high negative predictive value （0.84） for a negative low-dose test. The presence of symptoms during the first test was not useful for predicting a positive low-dose test （positive predictive value 0.06-0.31）. CONCLUSION： Most patients with a positive HBT-25 normally absorb a lower dose of lactose and a strict lactose restriction on the basis of a ＂standard＂ HBT is, in most instances, unnecessary. Thus, the 25 g lactose tolerance test should probably be substituted by the 12.5 g test in the diagnosis of LI, and in providing dietary guidelines to patients with suspected lactose malabsorption/intolerance.     

Activated charcoal: in vivo and in vitro studies of effect on gas formation

It has been reported that activated charcoal reduces intestinal gas production after ingestion of beans as evidenced by decreased breath hydrogen excretion and decreased passage of flatus. In the present study we assessed the ability of activated charcoal to reduce intestinal gas production by in vitro and in vivo methods. In vitro studies were performed using human fecal homogenates incubated with or without additional carbohydrate. In all studies hydrogen and carbon dioxide production and consumption occurred at similar rates in the charcoal-treated homogenate as compared with the untreated control. The influence of activated charcoal on gas production, in vivo, was studied by double-blind assessment of breath hydrogen excretion and flatus excretion after ingestion of a baked bean meal. No significant difference was observed in breath hydrogen concentration or number of passages of flatus in subjects who ingested 16 capsules of activated charcoal (4 g) as opposed to the placebo. We conclude that activated charcoal does not influence gas formation in vitro or in vivo.     

Development, Validation, and Applicability of a Symptoms Questionnaire for Lactose Malabsorption Screening

Lactase deficiency has a high prevalence worldwide. Thus, a valid symptom scale would be a useful tool for identifying patients with lactose malabsorption. Objective To develop, validate, and apply a symptoms questionnaire on lactose malabsorption to identify lactose malabsorbers diagnosed with the gold-standard hydrogen breath test. Methods In the first part of the study, 292 patients completed a questionnaire at the end of a 50-g lactose breath test. The questionnaire included five items (diarrhea, abdominal cramping, vomiting, audible bowel sounds, and flatulence or gas) scored on a 10-cm visual analogue scale. In the second part of the study, 171 patients completed the questionnaire twice: first, according to their opinion when consuming dairy products at home and second, after a 50-g lactose breath test. Patients were grouped as absorbers or malabsorbers according to the result of the breath test. Results Diarrhea, abdominal cramping, and flatulence were scored significantly higher in malabsorbers than in absorbers. Total score of the symptomatic questionnaire was significantly higher in malabsorbers (17.5 versus 3.0, P < 0.01). According to receiver operator characteristics (ROC) analysis, the most discriminant cut-off of the total score to identify lactose malabsorption was 6.5 (sensitivity 0.75, specificity 0.67). In 58 malabsorbers the effect size of the questionnaire to determine sensitivity to change was 1.32. In the second part of the study, scoring of the home questionnaire was higher than after the lactose-breath test. The lactose malabsorbers rate was higher according to the home questionnaire than after the lactose breath test (72% versus 52%). The home questionnaire had excellent sensitivity (0.82) but low specificity (0.35). Conclusion We developed and validated a five-item symptoms questionnaire for lactose malabsorption. This is a valid test that permits patients with a total score lower than 7 to be excluded from future studies.     

Effects of asymptomatic Giardia intestinalis infection on carbohydrate absorption in well-nourished Mexican children

The aim of this study was to evaluate carbohydrate absorption in well-nourished children with asymptomatic giardiasis. Two groups were selected based on results of stool examination of 211 children attending pre-school centers in Hermosillo, Sonora, Mexico: a control group of six non-infected children, and an infected group of seven children harboring Giardia intestinalis, without gastrointestinal symptoms of disease. Carbohydrate absorption was determined in the control group, before and after drug therapy in the infected group by the hydrogen breath test. Hydrogen production after lactose ingestion was higher in children with giardiasis compared with control group and after anti-parasite treatment; however, hydrogen production was not high enough to classify children as lactose malabsorbers by the cut-off criteria. Similar results were obtained for xylose absorption. None of the children had hydrogen increments high enough to be considered xylose malabsorbers. In conclusion, children asymptomatically infected with G. intestinalis showed significantly higher hydrogen production. However, the biological relevance is questionable since they did not exceed cut-off criteria to classify them as carbohydrate malabsorbers.     

Fructose-induced breath hydrogen in patients with fruit intolerance

GOALS: To measure bloating score, flatus passage, and hydrogen production after oral fructose in patients with history of fruit intolerance and compare these parameters with those in normal controls. BACKGROUND: Some patients complain of abdominal distention and excessive flatus after ingesting certain fruits such as mango, persimmon, and grapes but not after eating apricots and melon. STUDY: We recorded breath hydrogen, flatus passage and bloating after 20 g fructose in 8 patients with history of fruit intolerance and 4 healthy controls. Breath hydrogen was measured every 15 minutes for 480 minutes using EC-60 gastrolyzer. Number of passage of flatus was recorded over 8 hours. Severity of abdominal distention on a scale of 1 to 10 was noted. RESULTS: The patients with fruit intolerance produced breath hydrogen 1745.2+/-7.8 parts per million, passed flatus 13.8+/-0.3 times, and had bloating score of 5.7+/-0.1. The healthy controls produced breath hydrogen 712.5+/-5.8 parts per million in 8 hours, passed flatus 7.2+/-0.5 time, and had bloating score of 2.7+/-0.2. CONCLUSIONS: After 20 g fructose, patients with history of fruit intolerance produce more breath hydrogen, pass flatus more frequently, and have a higher bloating score compared with healthy controls.     

Epidemiology of small bowel bacterial overgrowth and rice carbohydrate malabsorption in Burmese (Myanmar) village children.

Breath hydrogen tests were performed after a rice meal (3 g of cooked rice/kg of body weight, equivalent to 1 g of carbohydrate/kg of body weight) on 256 village children (age range 1-59 months) who were known hydrogen (H2) producers. Anthropometric measurements were made every three months and growth rates were calculated. A breath H2 excretion pattern that suggested small bowel bacterial overgrowth (SBBO), which was recognized as a transient maximum level of 10 ppm or more at 20-, 40-, or 60-min breath samples following the rice meal, was present in 53 (20.7%) children, and was more frequent in children 36-47 and 48-59 months old. This breath H2 excretion pattern was detected in 48 (33.3%) of 144 children who were rice malabsorbers (greater than 10 ppm H2 above baseline values in one of the breath samples taken between 90 and 240 min), and in only five (4.5%) of 112 rice absorbers. Children who had SBBO had a high relative risk (10.7) of being rice malabsorbers. Rice malabsorbers have a high relative risk (59.7) of having faltered growth, accompanied by a large etiologic fraction (94%). This same risk (6.68) and an etiologic fraction of 62% exist in children with untreated SBBO. These findings emphasize the need for interventions aimed at reducing the prevalence of SBBO or similar conditions as detected by the breath H2 excretion pattern to prevent rice malabsorption and growth faltering.     

Lactase deficiency and lactose intolerance-related symptoms in adult healthy subjects from western France]

The prevalence of lactase deficiency (LD) and lactose intolerance is not well known in France. Using breath hydrogen and methane analysis after 50 g oral lactose load, we investigated the prevalences of LD, lactose intolerance, and methane producer status in 102 healthy adults born in western France, and we examined the relationships between these parameters and the daily milk consumption. In 10 subjects with LD and lactose intolerance, we studied the reproducibility of the lactose hydrogen breath test results for the diagnosis of LD and lactose intolerance and estimated the quantity of lactose malabsorbed in comparison with the lactulose hydrogen breath test. The prevalence of LD was 23.4 percent and symptoms of lactose intolerance were observed in 50 percent of the 24 subjects with LD. The daily milk consumption was not significantly different in the 24 subjects with LD and in the 78 subjects without LD (281 +/- 197 vs 303 +/- 217 ml/24 h). The prevalence of methane producer status was 42.1 percent. The symptomatic group of lactose malabsorbers (n = 12) was characterized by a shorter lactose mouth to caecum transit time (39 +/- 20 vs 88 +/- 48 min; P less than 0.05), and more marked hydrogen production (6.1 +/- 2.3 vs 3.4 +/- 2.4 10(3) ppm.min; P less than 0.04). In the 10 subjects with LD and lactose intolerance, the hydrogen breath test was reproducible for diagnosis of LD and lactose intolerance, and for hydrogen production. The quantity of lactose malabsorbed was 60 percent. In France, symptoms of lactose intolerance are not severe and do not affect the daily consumption of milk and dairy products.     

Prediction of lactose malabsorption in referral patients

Two hundred forty-two patients referred for various gastrointestinal complaints were evaluated for clinical parameters that would predict findings of lactose malabsorption. Breath hydrogen and blood glucose lactose tests were performed after ingestion of 50 g lactose. Presenting complaints, duration of symptoms, and patient demographics such as age, sex, and ethnic heritage were not different between lactose malabsorbers and absorbers as defined by the breath hydrogen lactose test. Foodrelated symptoms in general and after specific foods such as milk, ice cream, cheese, and yogurt were also similar between groups. Prior to testing, 30% of malabsorbers (N=161) and 36% of absorbers (N=81) reported lactoserelated symptoms (P=NS). The blood glucose response to lactose was abnormal in 60% of malabsorbers and 15% of absorbers. This study confirmed our impression that it is difficult to predict lactose absorption status by clinical parameters. The majority of our lactose malabsorber patients were unaware of lactose-associated symptoms. Furthermore, symptom assessment, demographics, food history, and blood glucose testing did not predict abnormal hydrogen responses to lactose.The opinions and assertations expressed herein are those of the authors and are not to be construed as reflecting opinions of the United States Air Force or the Department of Defense.This work has been presented in part at the Annual Scientific Session of the American Gastroenterological Association, San Francisco, California, May 19, 1986, and published as an abstract (Gastroenterology 90:1562, 1986).     

Relationship between methane production and breath hydrogen excretion in lactose-malabsorbing individuals

Recent studies have shown reduced breath hydrogen (H₂) excretion in methane (CH₄)-producing healthy individuals following ingestion of lactulose. This questions the reliability of the breath hydrogen test (BHT) in CH₄ excretors, but the relationship between CH₄ and H₂ excretion in other clinical applications of the BHT is not known. We reviewed BHT results in two groups of subjects: (1) 385 children tested for lactose malabsorption in a hospital setting, and (2) 109 lactose-malabsorbing patients tested with a home kit. The percentage of lactose malabsorbers in group 1 (51%) was the same regardless of CH₄-producing status (P=0.97). The BHT data from group 2 showed a positive correlation (r=0.6, P<0.000001) between the magnitude of the rise in CH₄ and H₂ concentrations, and the H₂ excretion curves were significantly higher in the CH₄-producing individuals. We conclude that attention to CH₄-producing status is not necessary in the interpretation of the lactose BHT.     

Intestinal gas in plain abdominal radiographs does not correlate with symptoms after lactulose challenge

OBSERVATION: Intestinal gas production and abdominal discomfort can be triggered by the ingestion of carbohydrates such as lactulose. Using plain abdominal radiographs, we studied whether subjective complaints after a lactulose breath test would be quantitatively related to intestinal gas volumes. METHODS: Abdominal symptoms after the breath test were quantified by a written questionnaire and gas volumes were scored in plain abdominal radiographs, in 50 consecutive patients with unexplained, irritable bowel syndrome-like symptoms. Breath excretion of hydrogen and methane was determined in all patients. RESULTS: Forty-two (84%) of the patients claimed that their post-breath test symptoms were a true replicate of their customary discomfort. Total symptom scores (sum of scores for pain/discomfort, borborygmi, bloating, diarrhea, constipation) or any specific symptom score were not significantly correlated to gas volume scores (r=-0.04; P=0.8 for total symptom score). The 13 (26%) methane producers had significantly higher mean gas volume scores compared with nonproducers (0.38 vs. 0.24; P=0.0008), but fewer symptoms (total symptom score 11.9 vs. 18.2; P=0.17). CONCLUSION: Intestinal gas volume, as scored in plain abdominal radiographs, is not correlated with abdominal discomfort after lactulose challenge. Intestinal gas may not be the major cause of abdominal discomfort following carbohydrate ingestion in patients with functional gut disorders.