Malabsorption of fructose-sorbitol mixtures. Interactions causing abdominal distress

Carbohydrate malabsorption in anorexia nervosa: a systematic review

OBJECTIVES

Anorexia nervosa (AN) is an eating disorder accompanied by a low body mass index and (self-) restricted food intake. Nutritional limitations can cause complaints of the digestive system, because of a disturbed absorption of food components. The absorption of carbohydrates may be seriously affected and reduced to a minimum. On this basis, a possible connection between AN, and the prevalence of gastrointestinal symptoms due to malabsorption was examined.

METHODS

For the systematic literature research with the aim of a better understanding of the topic the databases PubMed, Web of Science, Cochrane Library, Livivo and Google Scholar were used.

RESULTS

After the manual selection process of 2215 retrieved studies, 89 full texts were read and according to the predetermined eligibility criteria, finally 2 studies on the monosaccharide fructose and disaccharide lactose were included in this review.

CONCLUSION

Malabsorption is often observed in patients with AN. It may contribute to the gastrointestinal complaints reported by patients and hamper body weight regain. Among others, mucosal atrophy and duodenal transporter dysfunction are discussed as main reasons. In the future more studies on carbohydrate malabsorption related to low body weight as observed in AN are warranted and may be conducted rather in an outpatient setting.

Carbohydrate Maldigestion and Intolerance

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

Glucose transporters in the small intestine in health and disease

Absorption of monosaccharides is mainly mediated by Na+-D-glucose cotransporter SGLT1 and the facititative transporters GLUT2 and GLUT5. SGLT1 and GLUT2 are relevant for absorption of D-glucose and D-galactose while GLUT5 is relevant for D-fructose absorption. SGLT1 and GLUT5 are constantly localized in the brush border membrane (BBM) of enterocytes, whereas GLUT2 is localized in the basolateral membrane (BLM) or the BBM plus BLM at low and high luminal D-glucose concentrations, respectively. At high luminal D-glucose, the abundance SGLT1 in the BBM is increased. Hence, D-glucose absorption at low luminal glucose is mediated via SGLT1 in the BBM and GLUT2 in the BLM whereas high-capacity D-glucose absorption at high luminal glucose is mediated by SGLT1 plus GLUT2 in the BBM and GLUT2 in the BLM. The review describes functions and regulations of SGLT1, GLUT2, and GLUT5 in the small intestine including diurnal variations and carbohydrate-dependent regulations. Also, the roles of SGLT1 and GLUT2 for secretion of enterohormones are discussed. Furthermore, diseases are described that are caused by malfunctions of small intestinal monosaccharide transporters, such as glucose-galactose malabsorption, Fanconi syndrome, and fructose intolerance. Moreover, it is reported how diabetes, small intestinal inflammation, parental nutrition, bariatric surgery, and metformin treatment affect expression of monosaccharide transporters in the small intestine. Finally, food components that decrease D-glucose absorption and drugs in development that inhibit or downregulate SGLT1 in the small intestine are compiled. Models for regulations and combined functions of glucose transporters, and for interplay between D-fructose transport and metabolism, are discussed.

[Importance of functional diagnostics in gastroenterology]

In this review article important and frequently used investigation methods for gastrointestinal functional diagnostics are presented. Some other rarely used special investigations are also explained. The hydrogen breath test is simple to carry out, ubiquitously available and enables the detection of lactose, fructose and sorbitol malabsorption. Furthermore, by the application of glucose, the test can be carried out when there is a suspicion of abnormal intestinal bacterial colonization and using lactulose for measuring small intestinal transit time. The ¹³C urea breath test is applied for non-invasive determination of Helicobacter pylori infections and assessment of gastrointestinal transit time, liver and exocrine pancreas functions. The secretin cholecystokinin test was the gold standard for the detection of exocrine pancreas insufficiency. However, measurement of pancreatic elastase in stool is less invasive but also less sensitive. Scintigraphy and capsule investigations with pH and temperature probes constitute important methods for determination of gastric emptying, intestinal and colon transit times. For evaluation of constipation panoramic abdominal images are taken after intake of radiologically opaque markers (Hinton test). For the diagnosis of functional esophageal diseases manometry is indispensable. In addition, manometry is only occasionally used for diagnosing a dysfunction of the sphincter of Oddi, due to the danger of inducing pancreatitis. A 24 h pH-metry is applied for the detection of non-erosive gastroesophageal reflux disease and, if necessary, with impedance measurements. Recent investigation procedures, e. g. specific MRI sequences, sonographic determination of gall bladder ejection fraction, analysis of gastric accomodation or real-time lumen imaging, require further evaluation prior to clinical application.

Snack selection influences glucose metabolism, antioxidant capacity and cholesterol in healthy overweight adults: A randomized parallel arm trial

Including carbohydrate/fructose-rich foods (predominantly fruit) in the diets of overweight individuals can improve chronic disease risk factors. We hypothesized dried plums (DP) would improve nutrient consumption, total antioxidant capacity (TAC), lipid and adipokine profiles, and would decrease adiposity and inflammation. To test this, we studied the effects of 8-weeks of twice-daily snacking of macronutrient-matched 100kcal servings of DP or refined carbohydrate-rich snack (low-fat muffins: LFM) on daily energy and nutrient consumption, and chronic disease risk factors in overweight adults. Body weight/composition, waist circumference, blood pressure, plasma glucose, insulin, c-peptide, lipids, TAC, adipokines and inflammation were measured at baseline and throughout the study. Postprandial glucose and insulin were assessed following assigned test foods at baseline and 8-weeks. Repeated measures ANOVAs were undertaken to examine group and time differences. Post-hoc independent and paired samples t-tests were conducted where necessary. DP increased (P<.05) overall intake of dietary fiber and potassium, and TAC, from baseline to 8-weeks. Baseline postprandial glycemia tended (P=.09) to be lower with DP versus LFM, while both groups had a decreased response after 8-weeks. Postprandial insulinemia was lower (P<.05) for DP at both time-points. No differences in body weight/composition, blood pressure, or fasting glucose, insulin, triglycerides, total cholesterol, HDL-C, inflammation or adipokines were detected. Low-density lipoprotein cholesterol (LDL-C) increased (P<.05) throughout the trial following LFM. Overall, DP lessened postprandial insulinemia, improved nutrient consumption and plasma TAC, and maintained plasma LDL-C compared to a macronutrient-matched refined carbohydrate snack, which could decrease chronic disease risk.

A Systematic Review of the Effects of Polyols on Gastrointestinal Health and Irritable Bowel Syndrome

Polyols are sugar alcohols found in certain fruits, vegetables, and sugar-free sweeteners. They make up a component of the diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols, which is gaining popularity in the treatment of patients with irritable bowel syndrome (IBS). We conducted a systematic review to evaluate the effects of polyols on the gastrointestinal tract in healthy men and women and in patients with IBS. Utilizing PubMed, Ovid, and Embase databases, we conducted a search on individual polyols and each of these terms: fermentation, absorption, motility, permeability, and gastrointestinal symptoms. Standard protocols for a systematic review were followed. We found a total of 1823 eligible articles, 79 of which were included in the review. Overall, available work has shown that polyol malabsorption generally occurs in a dose-dependent fashion in healthy individuals, and malabsorption increases when polyols are ingested in combination. However, studies in patients with IBS have shown conflicting results pertaining to polyol malabsorption. Polyol ingestion can lead to intestinal dysmotility in patients with IBS. Regarding the microbiome, moderate doses of polyols have been shown to shift the microbiome toward an increase in bifidobacteria in healthy individuals and may therefore be beneficial as prebiotics. However, data are limited regarding polyols and the microbiome in patients with IBS. Polyols can induce dose-dependent symptoms of flatulence, abdominal discomfort, and laxative effects when consumed by both healthy volunteers and patients with IBS. Further research is needed to better understand the effects of specific polyols on gastrointestinal function, sensation, and the microbiome in health and gastrointestinal disorders such as IBS.

The Science, Evidence, and Practice of Dietary Interventions in Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a highly prevalent disorder that is characterized by symptoms of abdominal pain, bloating, constipation, and/or diarrhea. The diagnosis can be made using Rome III criteria or published guidelines after taking a thoughtful history, excluding warning signs, and performing a careful physical examination. Limited testing (ie, complete blood count and C-reactive protein level) may be useful in appropriate patients. A number of pharmacologic options are available, although many patients fail to respond to pharmacologic therapy. Although several IBS diets frequently are recommended, data supporting their use are limited. This article provides a rationale as to why specific diets might improve IBS symptoms and evaluates published trials.

Review article: the aetiology, diagnosis, mechanisms and clinical evidence for food intolerance

BACKGROUND

Food intolerance is non-immunological and is often associated with gastrointestinal symptoms.

AIM

To focus on food intolerance associated with gastrointestinal symptoms and critically appraise the literature in relation to aetiology, diagnosis, mechanisms and clinical evidence.

METHODS

A search using the terms and variants of food intolerance, lactose, FODMAP, gluten, food chemicals within Pubmed, Embase and Scopus was carried out and restricted to human studies published in English. Additionally, references from relevant papers were hand searched for other appropriate studies.

RESULTS

Food intolerance affects 15-20% of the population and may be due to pharmacological effects of food components, noncoeliac gluten sensitivity or enzyme and transport defects. There have been significant advances in understanding the scientific basis of gastrointestinal food intolerance due to short-chain fermentable carbohydrates (FODMAPs). The most helpful diagnostic test for food intolerance is food exclusion to achieve symptom improvement followed by gradual food reintroduction. A low FODMAP diet is effective, however, it affects the gastrointestinal microbiota and FODMAP reintroduction to tolerance is part of the management strategy.

CONCLUSIONS

There is increasing evidence for using a low FODMAP diet in the management of functional gastrointestinal symptoms where food intolerance is suspected. Exclusion diets should be used for as short a time as possible to induce symptom improvement, and should be followed by gradual food reintroduction to establish individual tolerance. This will increase dietary variety, ensure nutritional adequacy and minimise impact on the gastrointestinal microbiota.

Significance of hydrogen breath tests in children with suspected carbohydrate malabsorption

BACKGROUND

Hydrogen breath tests are noninvasive procedures frequently applied in the diagnostic workup of functional gastrointestinal disorders. Here, we review hydrogen breath test results and the occurrence of lactose, fructose and sorbitol malabsorption in pediatric patients; and determine the significance of the findings and the outcome of patients with carbohydrate malabsorption.

METHODS

We included 206 children (88 male, 118 female, median age 10.7 years, range 3-18 years) with a total of 449 hydrogen breath tests (lactose, n = 161; fructose, n = 142; sorbitol, n = 146) into a retrospective analysis. Apart from test results, we documented symptoms, the therapeutic consequences of the test, the outcome and the overall satisfaction of the patients and families.

RESULTS

In total, 204 (46%) of all breath tests were positive. Long-term follow-up data could be collected from 118 patients. Of 79 patients (67%) who were put on a diet reduced in lactose, fructose and/or sorbitol, the majority (92%, n = 73) reported the diet to be strict and only 13% (n = 10) had no response to diet. Most families (96%, n = 113) were satisfied by the test and the therapy. There were only 21 tests (5%) with a borderline result because the criteria for a positive result were only partially met.

CONCLUSIONS

Hydrogen breath tests can be helpful in the evaluation of children with gastrointestinal symptoms including functional intestinal disorders. If applied for a variety of carbohydrates but only where indicated, around two-third of all children have positive results. The therapeutic consequences are successfully relieving symptoms in the vast majority of patients.

Short-chain carbohydrates and functional gastrointestinal disorders

Carbohydrates occur across a range of foods regularly consumed including grains such as wheat and rye, vegetables, fruits, and legumes. Short-chain carbohydrates with chains of up to 10 sugars vary in their digestibility and subsequent absorption. Those that are poorly absorbed exert osmotic effects in the intestinal lumen increasing its water volume, and are rapidly fermented by bacteria with consequent gas production. These two effects alone may underlie most of the induction of gastrointestinal symptoms after they are ingested in moderate amounts via luminal distension in patients with visceral hypersensitivity. This has been the basis of the use of lactose-free diets in those with lactose malabsorption and of fructose-reduced diets for fructose malabsorption. However, application of such dietary approaches in patients with functional bowel disorders has been restricted to observational studies with uncertain efficacy. As all dietary poorly absorbed short-chain carbohydrates have similar and additive effects in the intestine, a concept has been developed to regard them collectively as FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) and to evaluate a dietary approach that restricts them all. In patients with irritable bowel syndrome, there is now an accumulating body of evidence, based on observational and comparative studies, and on randomized-controlled trials that supports the notion that FODMAPs trigger gastrointestinal symptoms in patients with functional bowel disorders, and that a diet low in FODMAPs offers considerable symptom relief in the majority of patients who use it.

Follow-up of coeliac disease with the novel one-hour 13C-sorbitol breath test versus the H2-sorbitol breath test

BACKGROUND

We recently developed a (13)C-sorbitol breath test ((13)C-SBT) as an alternative to the H(2)-sorbitol breath test (H(2)-SBT) for coeliac disease. In this study we compared the diagnostic properties of the H(2)-SBT and the (13)C-SBT in follow-up of coeliac disease.

MATERIAL AND METHODS

Twenty-seven coeliac patients on a gluten-free diet (GFD) performed the breath tests. All had been tested before treatment in the initial study of the (13)C-SBT, in which 39 untreated coeliac patients, 40 patient controls, and 26 healthy volunteers participated. Five gram sorbitol and 100 mg (13)C-sorbitol were dissolved in 250 ml tap water and given orally. H(2), CH(4) and (13)CO(2) were measured in end-expiratory breath samples every 30 min for 4 h. Increased H(2) concentration ≥20 ppm from basal values was used as cut-off for the H(2)-SBT. Sixty minutes values were used as diagnostic index in the (13)C-SBT.

RESULTS

(13)CO(2) levels at 60 min increased in 20/26 treated coeliac patients (77%) after GFD, but were significantly lower than in control groups. Out of 20 patients who had a positive H(2)-SBT before GFD, 12 had a negative H(2)-SBT after GFD. Peak H(2) concentrations were not correlated with (13)C-SBT results.

CONCLUSION

The study confirms the sensitivity of a one-hour (13)C-SBT for small intestinal malabsorption. The (13)C-SBT has superior diagnostic properties compared with the H(2)-SBT in follow-up of coeliac disease.

Fructose malabsorption: true condition or a variance from normality

Fructose exists in food naturally or as a sweetening additive. It has been thought that fructose malabsorption may cause the gastrointestinal symptoms seen in patients with irritable bowel syndrome. However, fructose malabsorption is still poorly understood, and clinicians are still uncertain of its role. This review attempts to clarify the relation between fructose malabsorption and symptoms in normal individuals and patients with irritable bowel syndrome. The main problem lies in the diagnosis. First, there is no definite cut off value for the breath tests. Second, we are unsure of the normal absorptive capacity of fructose in normal individuals. Normal individuals will have a degree of fructose malabsorption with or without symptoms depending on the dose of fructose used. From earlier studies, 25 g of fructose seems to be the cut-off dose to investigate fructose malabsorption, with a positive breath test at this dose suggesting abnormally low capacity to absorb fructose. This low level may be difficult to exclude from the daily diet, resulting in symptoms of fructose malabsorption.

Type of snack influences satiety responses in adult women

The effect of different snack foods on satiety and plasma glucose and hormone responses was assessed. Nineteen fasted adult women (mean age: 39.2 + or - 0.7 years, mean BMI: 26.1 + or - 0.8 kg/m(2)) consumed test foods including dried plums, low-fat cookies, white bread and water only on separate days. The test foods (with the exception of water) provided 238 kcal and were similar in total carbohydrate, fat and protein content but differed in fiber and sugar content. Subjects rated their feelings of hunger using satiety index scales prior to snack consumption and again every 15 min for 2h following initiation of intake. Blood samples were collected at baseline and 15, 30, 45, 60, 90, and 120 min following intake. At the end of the 120-min test period, subjects were presented with a meal to be consumed until satisfied. The satiety index AUC was greater for the dried plum trial versus the low-fat cookie trial (p < or = 0.05). There was no difference in post-snack consumption between the dried plums and cookie trials. The dried plums trial elicited lower plasma glucose and insulin AUC than the low-fat cookie trial (p < or = 0.05) and tended to promote a greater plasma ghrelin AOC (p = 0.056). These results demonstrate that consuming dried plums as a snack suppresses hunger relative to a low-fat cookie as evidenced by lower glucose and/or satiety-regulating hormone concentrations.

A novel one-hour 13C-sorbitol breath test versus the H2-sorbitol breath test for assessment of coeliac disease

OBJECTIVE

The H(2)-sorbitol breath test (H(2)-SBT) has previously been suggested as a screening tool for coeliac disease. We developed an alternative (13)C-sorbitol breath test ((13)C-SBT). The aim of the study was to compare the diagnostic properties of the H(2)-SBT and the (13)C-SBT in a clinical setting.

MATERIAL AND METHODS

Thirty-nine coeliac patients, 40 patient controls (mainly patients with irritable bowel syndrome) and 26 healthy volunteers underwent the breath tests. The patients were given an oral load of 5 g sorbitol and 100 mg (13)C-sorbitol dissolved in 250 ml tap-water. H(2), CH(4) and (13)CO(2) concentrations were measured in end-expiratory breath samples every 30 min for 4 h. Increased H(2) concentration > or =20 ppm from basal values was used as the cut-off for the H(2)-SBT.

RESULTS

The H(2)-SBT had a sensitivity of 71%, a specificity of 46% versus healthy controls, and a specificity of 25% versus patient controls. Individuals with methane-producing intestinal flora had significantly lower peak H(2) concentrations than non-methane producers. The (13)C-SBT reached maximal combined sensitivity/specificity (74%/85%) for both control groups after 1 h. A diagnostic algorithm which stratified patients into high-, moderate- and low risk for coeliac disease was proposed. Following the algorithm, 62% of coeliac patients were detected with 100% specificity. The (13)C-SBT, but not the H(2)-SBT, correlated with age and serum IgA tissue-transglutaminase antibody levels in coeliac patients.

CONCLUSIONS

The novel (13)C-SBT has superior diagnostic properties compared to the H(2)-SBT, which has unsatisfactory specificity in clinical practice. The 1-h (13)C-SBT may be a useful supplemental test when investigating for coeliac disease.

Fructose-sorbitol malabsorption

Important dietary carbohydrates such as fructose and sorbitol are incompletely absorbed in the normal small intestine. This malabsorption is sometimes associated with abdominal complaints and diarrhea development, symptoms indistinguishable from those of functional bowel disease. Recently, polymerized forms of fructose (fructans) also were implicated in symptom production in patients with irritable bowel syndrome (IBS). Evidence from uncontrolled and controlled challenge studies suggests that malabsorbed sugars (fructose, sorbitol, lactose) and fructans may act as dietary triggers for clinical symptoms suggestive of IBS. Further placebo-controlled studies are needed to obtain definite conclusions about the role of dietary sugar malabsorption in functional bowel disease.

Fructose intolerance in children presenting with abdominal pain

OBJECTIVES

We determined the occurrence of fructose malabsorption in pediatric patients with previous diagnoses of abdominal pain caused by a functional bowel disorder, whether the restriction of fructose intake changes the reporting of symptoms, the role of fructose dosage, and the severity of resultant symptoms.

PATIENTS AND METHODS

We administered a fructose breath test to children presenting with persistent unexplained abdominal pain. Patients randomly received 1, 15, or 45 g fructose, and breath hydrogen was measured for 3 hours after ingestion. Test results were positive when breath hydrogen was 20 ppm greater than baseline and was accompanied by gastrointestinal symptoms.

RESULTS

A total of 32 patients was enrolled, and none of the 9 who received 1 g had positive results. Three of 10 who received 15 g and 8 of 13 who received 45 g had positive results. All patients with positive test results restricted their fructose intake. Among the group with positive results, 9 of 11 had rapid improvement of their gastrointestinal symptoms. After 2 months, all 9 patients continued to report improvement.

CONCLUSIONS

We concluded that fructose malabsorption may be a significant problem in children and that management of dietary intake can be effective in reducing gastrointestinal symptoms.

Effect of nonabsorbed amounts of a fructose-sorbitol mixture on small intestinal transit in healthy volunteers

Although malabsorption of small amounts of fructose-sorbitol mixtures occurs frequently in healthy humans, insights into their effects on gastrointestinal motility are poor. The present study addresses the hypothesis that malabsorption of a fructose-sorbitol challenge changes the small intestinal transit rate. Eleven healthy volunteers participated in a double-blind crossover investigation. In random order, the subjects ingested 30 g glucose or a mixture of 25 g fructose and 5 g sorbitol as 10% solutions. As a radiolabeled marker, (99m)Tc-diethylenetriaminepentaacetic acid was added to each test solution. Breath hydrogen and methane concentrations and gastrointestinal progress of the radiolabeled marker were followed for the next 6-hr period. Malabsorption of small amounts of the fructose-sorbitol mixture was evident in all subjects. The area under the gastric radioactivity-time curve after ingestion of glucose did not differ from that after ingestion of the fructose-sorbitol mixture (P = 0.7897). However, the mouth-to-cecum transit of the radiolabeled marker was faster (P = 0.0033) and the percentage content of the marker in colon was higher after ingestion of the fructose-sorbitol mixture than after ingestion of glucose (P = 0.0128). In healthy humans, malabsorption of small amounts of a fructose-sorbitol mixture accelerates small bowel transit.

Dietary fructose and gastrointestinal symptoms: a review

It has been proposed that fructose may cause or aggravate symptoms in patients with functional gastrointestinal disorders. Fructose is commonly used to sweeten processed foods, and the prevalence of incomplete fructose absorption (25 g, 10%) in healthy subjects is as high as 50%. The only controlled study that has been performed did not demonstrate a higher prevalence of fructose-induced gastrointestinal symptoms or incomplete fructose absorption in patients with functional gastrointestinal disorders. The amount and concentration of fructose used to evaluate absorption by breath testing has varied among studies. Moreover, dietary sources of fructose usually contain glucose, which increases fructose absorption in healthy subjects. Thus, breath testing with fructose alone may not reflect fructose ingestion under normal circumstances. Given these limitations, we suggest that a practical, empirical approach to testing in patients with suspected incomplete fructose absorption is to restrict fructose ingestion. Additional controlled studies are needed to clarify the relation between incomplete fructose absorption and symptoms, assess the effects of co-ingestion of other sugars on fructose absorption, and evaluate the effects of eliminating sugars from the diet on gastrointestinal symptoms.

Management of the irritable bowel syndrome

Irritable bowel syndrome (IBS) is the most common disorder diagnosed by gastroenterologists and one of the more common ones encountered in general practice. The overall prevalence rate is similar (approximately 10%) in most industrialized countries; the illness has a large economic impact on health care use and indirect costs, chiefly through absenteeism. IBS is a biopsychosocial disorder in which 3 major mechanisms interact: psychosocial factors, altered motility, and/or heightened sensory function of the intestine. Subtle inflammatory changes suggest a role for inflammation, especially after infectious enteritis, but this has not yet resulted in changes in the approach to patient treatment. Treatment of patients is based on positive diagnosis of the symptom complex, limited exclusion of underlying organic disease, and institution of a therapeutic trial. If patient symptoms are intractable, further investigations are needed to exclude specific motility or other disorders. Symptoms fluctuate over time; treatment is often restricted to times when patients experience symptoms. Symptomatic treatment includes supplementing fiber to achieve a total intake of up to 30 g in those with constipation, those taking loperamide or other opioids for diarrhea, and those taking low-dose antidepressants or infrequently using antispasmodics for pain. Older conventional therapies do not address pain in IBS. Behavioral psychotherapy and hypnotherapy are also being evaluated. Novel approaches include alosetron; a 5-HT(3) antagonist, tegaserod, a partial 5-HT(4) agonist, kappa-opioid agonists, and neurokinin antagonists to address the remaining challenging symptoms of pain, constipation, and bloating. Understanding the brain-gut axis is key to the eventual development of effective therapies for IBS.

Effect of gastric myoelectric activity on carbohydrate absorption of fruit juice in children

Juices have a different rate of gastric emptying than other foods. This may alter the rate of delivery of carbohydrates to the small bowel for absorption. The aim of the study is to demonstrate that faster gastric emptying is associated with greater production of hydrogen through a randomized, crossover study of 39 healthy children. The electrogastrography (indicator of the gastric myoelectric activities) and breath hydrogen tests (indicator of carbohydrate malabsorption) were performed at baseline and after ingestion of 240 to 330 mL of grape or pear juice given in a random order. The cutaneous electrogastrogram was analyzed by running spectral analysis to compute pre- and postprandial period dominant power (PDP) and running spectrum total power (RSTP). Postprandial PDP and RSTP were higher (p < 0.02) in the pear juice group than in the grape juice group, suggesting higher antral myoelectric activities. Twenty three percent of the subjects had significant movement artifacts that suggested discomfort after drinking pear juice compared to 5% after grape juice (p < 0.03). Breath hydrogen test was more frequently positive (increase >20 part per million [ppm] above baseline) after pear juice (52.2%; mean, 36 +/- 33 ppm) than after grape juice (4.3%, 6 +/- 6 ppm). In a multiple regression analysis, the most predictive independent variable of hydrogen concentration was found to be either postprandial PDP (r2 = 0.24; p < 0.002), or RSTP (r2 = 0.37; p < 0.001). Juices affect gastric myoelectric activity. Grape juice induces lower antral myoelectric activities and is better absorbed. The malabsorption of carbohydrates of juices is in part related to their effect on the gastric physiology.

Carbohydrate absorption from fruit juices in infants

OBJECTIVE

To compare the absorption of carbohydrate in particular from a lower (10 mL/kg(-1)) quantity than that previously tested, of white grape juice and pear juice after a single feeding and after ingestion twice daily for 2 weeks, and determine their respective effects on stool water content, in healthy infants.

STUDY PARTICIPANTS

Twelve healthy, well-nourished infants, 5 to 9 months of age, who were recruited from the general population.

DESIGN/METHODS

Infants underwent a breath hydrogen test after a serving of pear juice. Three to 5 days later, the test was repeated after a serving of white grape juice. Infants were randomly assigned to receive a 10 mL/kg(-1) serving of grape juice or pear juice twice daily for 2 weeks. The breath tests were repeated after the ingestion of the juices in the same sequence. With the second breath test with pear juice, a charcoal marker and 20 mg (13)C fructose, a stable, nonradioactive isotope, were mixed with the juice. Water content of the stools was compared before and after the 2-week feeding of the juice, and fecal samples were analyzed for (13)C enrichment by mass spectrometry.

RESULTS

After the ingestion of the fruit juices, only 1 infant had an abnormal peak hydrogen (H(2); >/=10 ppm), which followed the pear juice. That same infant was the only one who had H(2) levels >/=10 ppm after grape juice. There was no significant difference in the peak breath H(2) levels after grape juice and pear juice either at the beginning of the study or 2 weeks after taking the juice assigned (2.8 ppm +/- 2.9 vs 6.2 ppm +/- 9, respectively). The difference in breath H(2) response before and after the 2 weeks of fruit juice intake was not significant. Mean (+/-standard deviation) fecal (13)C enrichment at baseline was 3.0 Delta%o (+/-2.4), which was not significantly different from after 2 weeks of juice intake (2.4 Delta%o [+/-1.5]), regardless of the juice assigned: 2.7 Delta%o (+/-1.6) for grape juice and 2.2 Delta%o (+/-1.5) for pear juice. Mean (+/-standard deviation) percentage of fecal water at baseline was 24.1% (+/-5.1), which was not significantly different from after 2 weeks of juice (22.5% [+/-6]), regardless of the juice received: 21.8% (+/-5.8) for grape juice and 23.2% (+/-6.7) for pear juice.

CONCLUSION

When either grape or pear juice is administered in a dosage of 10 mL/kg/day, the carbohydrate is well absorbed, produces no adverse gastrointestinal symptoms, and has no effect on stool water in healthy infants.

Children's growth parameters vary by type of fruit juice consumed

BACKGROUND

Excessive fruit juice consumption in young children has been associated with nonorganic failure to thrive and short stature in some children and with obesity in others.

OBJECTIVE

To evaluate, in a sample of healthy young children, whether the associations between fruit juice intakes and growth parameters differ by the type of fruit juice consumed.

DESIGN

Cross-sectional study.

SETTING

General primary care health center in upstate New York.

PARTICIPANTS

One hundred sixteen two-year-old children and one hundred seven five-year-old children, who were scheduled for a nonacute visit, and their primary care-takers or parents were recruited over a two-year period.

METHODS

For 163 children (73% of total), 14 days of dietary records were available. The dietary records were entered and analyzed using the Nutrition Data System (NDS). Type of fruit juice was classified according to Nutrition Coordinating Center food codes. Height was measured using a Harpenden Stadiometer. Weight was measured using a standard balance beam scale.

RESULTS

The children consumed, on average, 5.5 fluid oz/day of fruit juices, which were classified by the NDS software as 35% apple juice, 31% orange juice, 25% grape juice and 9% other types and/or mixtures of fruit juice. Children with higher fruit juice intakes had lower total fat, saturated fat and cholesterol intakes. Child height was inversely related to apple juice intake (p=0.007) and grape juice intake (p=0.02), after adjustment for child age, gender and energy intake (excluding fruit juice) and maternal height. Apple juice intake was correlated with child body mass index (p<0.05) and ponderal index (p<0.005), after adjustment for the above covariates. Total cholesterol, LDL-cholesterol, triglyceride and lipoprotein(a) levels were not related to intakes of any of the fruit juices examined. The children's ratios of total cholesterol to HDL cholesterol were correlated with grape juice intakes, while HDL-cholesterol levels were inversely related to grape juice intakes. There were no significant relationships between fruit juice intake and measures of anemia (hematocrit or mean corpuscular volume).

CONCLUSIONS

The previously reported associations between short stature and high intakes of fruit juice were observed for intakes of both apple juice and grape juice. The associations between high fruit juice intakes and obesity were observed with apple juice intakes only. Because most of the fruit juice mixtures were classified as single fruit juices, the findings, especially those with grape juice, need to be cautiously interpreted. High intakes of fruit juice, however, appear to be associated with growth extremes in young children. Thus, it would seem prudent for parents and caretakers to moderate the fruit juice intakes of their young children.

Fructose-sorbitol malabsorption and symptom provocation in irritable bowel syndrome: relationship to enteric hypersensitivity and dysmotility

BACKGROUND

Fructose-sorbitol (F-S) mixtures can provoke symptoms in irritable bowel syndrome (IBS) patients, and a proportion of IBS patients also have enteric hypersensitivity to distension. We hypothesized, therefore, that sugar malabsorption and fermentation to produce hydrogen gas may provoke symptoms to a greater extent in IBS patients hypersensitive to distension than in those patients without such hypersensitivity. Our aims were therefore to compare, in IBS patients, symptoms and breath hydrogen responses after F-S, on the basis of jejunal sensitivity and jejunal motor function.

METHODS

Fifteen female IBS patients (44 +/- 15 years) underwent, on separate occasions, 3-h breath hydrogen analyses after ingesting 10 g lactulose and 25 g fructose with 5 g sorbitol. Jejunal sensitivity and motor function were determined by balloon distension and 24-h manometry studies, respectively. Cumulative symptom scores and breath hydrogen production were analysed on the basis of the presence or absence of jejunal hypersensitivity and dysmotility.

RESULTS

Four and seven patients had jejunal hypersensitivity for initial perception and pain, respectively. Eleven, nine, and nine patients had jejunal dysmotility for fasting phase 3, phase 2, and fed motor activity, respectively. Of the patients with symptom provocation after F-S (n = 8 within 3 h, n = 12 within 12 h) or with F-S malabsorption (n = 10), the relative proportion did not differ on the basis of the presence or absence of jejunal hypersensitivity or of motor dysfunction. Symptom scores and hydrogen production also were not different in these subgroups.

CONCLUSIONS

Although carbohydrate malabsorption can provoke symptoms in some IBS patients, there is no consistent association between such a phenomenon and the presence of either jejunal hypersensitivity or dysmotility.

Carbohydrate absorption from one serving of fruit juice in young children: age and carbohydrate composition effects

OBJECTIVES

To test the hypotheses that: the efficiency of carbohydrate absorption in childhood increases with age, and decreased carbohydrate absorption occurs more frequently with juices containing more fructose than glucose and/or sorbitol than with juices which contain equal amounts of fructose and glucose and are sorbitol-free.

METHODS

One hundred and four healthy children were recruited from the Ambulatory Center at Maimonides Children's Center. They were assigned to one of three age groups: approximately 1, 3 and 5 years of age. Each child received one age-specific dose (by randomization) of one of four juices: a) pear juice which contains fructose in excess to glucose and a large amount of sorbitol; b) apple juice which is similar to pear juice in its fructose to glucose ratio but contains four times less sorbitol than pear juice; c) white grape juice or d) purple grape juice both of which contain equal amounts of fructose and glucose and are sorbitol-free. Breath hydrogen excretion (BH2) was utilized as the index of carbohydrate absorption. It was measured in fasting children and at 30-minute intervals for 3 hours after drinking the single serving of juice. Multiple breath hydrogen related parameters were quantified and results were expressed as: BH2 peak, area under the curve, and degree of carbohydrate malabsorption. After the test, parents completed a questionnaire and recorded signs and symptoms of intestinal malabsorption for 24 hours.

RESULTS

Pear juice related BH2 levels were significantly higher among children 1 and 3 years of age as compared to the levels achieved after the other juices. Apple juice related BH2 levels were significantly higher only among the youngest age group of children. There was no significant difference in carbohydrate absorption among the 5 year old children regardless of the juice consumed. Incomplete carbohydrate absorption (BH2 peak above 20 ppm) occurred more frequently after pear juice consumption (84%) than after apple juice (41%) or grape juice (white 20%, purple 24%) [p < 0.05]. Further outcome measures of BH2 excretion did not elicit differences beyond those detected by the above-mentioned parameters. Parents reported diarrhea in six children after pear juice, two after apple juice and two after purple grape juice and these children had the highest BH2 levels in their respective groups. No other symptoms were reported.

CONCLUSIONS

The data show that the efficiency of carbohydrate absorption of one age-specific serving of juice increases with advancing age of children. Decreased carbohydrate absorption occurs more often after ingestion of juices that contain more sorbitol, a nonabsorbable sugar and higher concentrations of fructose over glucose than after ingestion of juices which lack sorbitol and contain equal amounts of fructose and glucose.

Fruit juice consumption by infants and children: a review

The pattern of fruit juice consumption has changed over time. Fifty years ago, orange juice was the major juice produced and it was consumed primarily to prevent scurvy. Now, apple juice is the juice of choice for the under 5 age group. While fruit juice is a healthy, low-fat, nutritious beverage, there have been some health concerns regarding juice consumption. Nursing bottle caries have long been recognized as a consequence of feeding juice in bottles, using the bottle as a pacifier, and prolonged bottle feeding. Non-specific chronic diarrhea or "toddler's" diarrhea has been associated with juice consumption, especially juices high in sorbitol and those with a high fructose to glucose ratio. This relates to carbohydrate malabsorption, which varies by the type, concentration, and mixture of sugars present in different fruit juices. Fruit juice consumption by preschoolers has recently increased from 3.2 to about 5.5 fl oz/day. Consumption of fruit juice helps fulfill the recommendation to eat more fruits and vegetables, with fruit juice accounting for 50% of all fruit servings consumed by children, aged 2 through 18 years, and 1/3 of all fruits and vegetables consumed by preschoolers. Concomitant with the increase in fruit juice consumption has been a decline in milk intake. This is concerning as milk is the major source of calcium in the diet, and at present, only 50% of children, aged 1 through 5 years, meet the RDA for calcium. Studies of newborn infants and preschool-aged children have demonstrated a preference for sweet-tasting foods and beverages. Thus, it is not surprising that some children, if given the opportunity, might consume more fruit juice than is considered optimal. Eleven percent of healthy preschoolers consumed > or = 12 fl oz/day of fruit juice, which is considered excessive. Excess fruit juice consumption has been reported as a contributing factor in some children with nonorganic failure to thrive and in some children with decreased stature. In other children, excessive fruit juice consumption has been associated with an increased caloric intake and obesity. This paper reviews the role of fruit juice in the diets of infants and children and outlines areas for future research. Recommendations regarding fruit juice consumption based on current data are also given.

Digestion and absorption of fruit juice carbohydrates

As consumption of dietary fructose and sorbitol increases, the association between consumption of these sugars and gastrointestinal symptoms has been recognized. As a result, studies of fructose and sorbitol absorption and malabsorption have emerged with investigations relying largely on the use of breath hydrogen (H2) measurements. Since these sugars are prevalent in fruit juices, a major dietary staple in the first 5 years of life, an understanding of fructose and sorbitol absorption is particularly important to pediatric health care providers. This review examines fructose and sorbitol absorption in humans, reviewing as well the breath H2 method upon which studies of fructose and sorbitol absorption largely depend.

Facilitating effect of amino acids on fructose and sorbitol absorption in children

The facilitating effect of glucose on free fructose absorption has been suggested to be due to a sucrase-related transport mechanism. In contrast, the conditions influencing the absorption of sorbitol have hardly been investigated. As amino acids promote transcellular water flow, we investigated their effects on the absorption of fructose and sorbitol. We studied 15 healthy children using breath hydrogen tests following the ingestion of fructose and sorbitol, alone and in combination with glucose or amino acids. Similarly, the effect of acarbose pretreatment on sucrose and fructose-glucose absorption was investigated. The inhibition of sucrase isomaltase by acarbose impedes the absorption of sucrose but not of the fructose-glucose mixture. Fructose absorption is enhanced by glucose and by the amino acids L-alanine, L-glutamine, L-phenylalanine, and L-proline. Similarly, the absorption of sorbitol is facilitated by glucose and L-alanine. These results are not in concordance with a sucrase-related fructose-transport system and suggest another mechanism for glucose-induced enhancement of fructose (and sorbitol) absorption. We hypothesize that the absorption of fructose and sorbitol may be stimulated by the increased water flux induced by active absorption of glucose as well as amino acids.

Gastrointestinal gas formation and infantile colic

Gastrointestinal gas causes distress in many patients and their parents. Most often, patients do not have an actual increase in gastrointestinal gas volume, but rather their complaints derive from a misunderstanding of normal physiology, a misinterpretation of symptoms (colic), or an increase in intestinal sensitivity (irritable bowel syndrome). Symptoms from actual increases in intestinal gas volume are seen most frequently in children who swallow excessive amounts of air, have a dysmotility syndrome, or consume foods containing poorly absorbed carbohydrates. Although many therapies are used in the treatment of gas-related symptoms, under close scrutiny, the commonly recommended agents (e.g. simethicone) do not have proven efficacy. An understanding of the physiology of gas production and disposal is of practical use to pediatricians in determining the appropriate method of intervention for patients with these complaints.

Chronic nonspecific diarrhea of childhood: pathophysiology and management

Chronic nonspecific diarrhea, or toddler's diarrhea, is a frequently encountered disorder of defecation in otherwise healthy children. Although the precise pathophysiology remains to be elucidated, evidence suggests that toddler's diarrhea primarily is a gut motility disorder, modulated by dietary factors. Although the role of low-fat diets has since long been established, the liberal consumption of fruit juices and soft drinks is considered an equally important factor. Normalization of the child's diet, especially with regard to fat, fiber, fluids, and fruit juices, usually suffices to attain resolution of the diarrhea.

Carbohydrate malabsorption: quantification by methane and hydrogen breath tests

BACKGROUND

Previous studies in small series of healthy adults have suggested that parallel measurement of hydrogen and methane resulting from gut fermentation may improve the precision of quantitative estimates of carbohydrate malabsorption. Systematic, controlled studies of the role of simultaneous hydrogen and methane measurements using end-expiratory breath test techniques are not available.

METHODS

We studied seven healthy, adult methane and hydrogen producers and seven methane non-producers by means of end-expiratory breath test techniques. Breath gas concentrations and gastrointestinal symptoms were recorded at intervals for 12h after ingestion of 10, 20 and 30 g lactulose.

RESULTS

In the seven methane producers the excretion pattern was highly variable; the integrated methane responses were disproportional and not reliably reproducible. However, quantitative estimates of carbohydrate malabsorption on the basis of individual areas under the methane and hydrogen excretion curves (AUCs) tended to improve in methane producers after ingestion of 20 g lactulose by simple addition of AUCs of methane to the AUCs of the hydrogen curves. Estimates were no more precise in methane producers than similar estimates in non-producers. Gastrointestinal symptoms increased significantly with increasing lactulose dose; correlation with total hydrogen and methane excretion was weak.

CONCLUSIONS

Our study suggests that in methane producers, simple addition of methane and hydrogen excretion improves the precision of semiquantitative measurements of carbohydrate malabsorption. The status of methane production should, therefore, be known to interpret breath tests semiquantitatively. The weak correlation between hydrogen and methane excretion and gas-related abdominal complaints suggests that other factors than net production of these gases may be responsible for the symptoms.

Symptom provocation in irritable bowel syndrome. Effects of differing doses of fructose-sorbitol

The role of fructose and sorbitol, when ingested together, in the aetiology of irritable bowel syndrome (IBS) is controversial. The aims of this study in IBS patients, therefore, were to compare differences in symptom provocation with various doses of fructose-sorbitol and to relate differences in the extent of colonic hydrogen production after each dose to such symptom provocation. Two different mixtures of fructose and sorbitol--20 g fructose plus 3.5 g sorbitol ('lower' dose) and 25 g fructose plus 5 g sorbitol ('higher' dose)--were administered to 15 patients with IBS and to 24 healthy controls. Breath hydrogen concentrations were determined at 10-min intervals for 3 h after ingestion of each mixture, and the presence and severity of a range of gastrointestinal symptoms were recorded on a standard form before, during, and after the study. Total symptom score in IBS patients, but not controls, was greater (p < 0.05) after the higher than after the lower dose of fructose-sorbitol mixture, and, for the higher dose, symptoms were significantly greater in IBS patients than in controls (p < 0.05). Moreover, the increase in total symptom score between the higher and lower dose mixtures was of a greater magnitude (p = 0.01) in IBS patients than in controls. No significant correlation was observed between the increase in symptom score and the increase in peak hydrogen concentration or the increase in integrated hydrogen response between lower and higher dose mixtures, although these latter increases were at times substantial.(ABSTRACT TRUNCATED AT 250 WORDS)

Fructose and related food carbohydrates. Sources, intake, absorption, and clinical implications

It is possible to point out subjects consuming considerable quantities of fructose and sorbitol, and the intake seems to be increasing both from added and natural sources. Studies of the absorption of fructose in animals are inconsistent, and the mechanisms of fructose uptake seem to vary in accordance with the species. In most species fructose absorption takes place by a specific carrier (facilitated transport), but it may be active in the rat. In vitro studies of human intestine are very scarce; there is no evidence of active intestinal fructose transport in the human intestine. By means of hydrogen breath tests, a very low absorption capacity for fructose given as the free monosaccharide has been found in humans. Fructose given as sucrose or in equimolar combinations with glucose is well absorbed, and only fructose in excess of glucose is malabsorbed. On this basis it is hypothesized that two different uptake mechanisms for fructose are present in the human intestine. One of these may be a disaccharidase-related uptake system. Sorbitol ingestion may aggravate malabsorption of fructose given as the monosaccharide; it is not known whether a specific mechanism is involved. In children and adults with functional bowel distress the absorption capacities for fructose may not differ from those of healthy individuals, but malabsorption of fructose and/or sorbitol may be the cause of or aggravate abdominal symptoms. Fructose polymers (fructans) are also subject to increasing nutritional interest. Fructans are not absorbed in the small intestine but are strongly fermented in the large bowel. Fructans may be of potential benefit for large-bowel function and blood glucose regulation.

Cost-effective treatment of constipation in the elderly: a randomized double-blind comparison of sorbitol and lactulose

PURPOSE

The purpose of this study was to evaluate the use of sorbitol as an inexpensive alternative to lactulose for treating constipation in the elderly.

PATIENTS AND METHODS

Thirty men aged 65 to 86 with chronic constipation were studied in a randomized, double-blind, cross-over trial in which lactulose and 70% sorbitol (0 to 60 mL daily) were each given for 4 weeks preceded by a 2-week washout period.

RESULTS

The average number of bowel movements per week was 6.71 with sorbitol and 7.02 with lactulose (95% confidence interval of the difference: -0.43 to 1.06), and the average number of days per week with bowel movements was 5.23 with sorbitol and 5.31 with lactulose (95% confidence interval of the difference: -0.32 to 0.48). Eleven patients stated a preference for sorbitol, 12 for lactulose, and seven had no preference. On a visual analogue scale measuring severity of constipation (0 to 100 mm), the average score for sorbitol was 35.6 mm versus 37.1 mm for lactulose (95% confidence interval of the difference: -6.4 to 9.3). The sorbitol and lactulose treatment periods were also similar in percent of bowel movements recorded as "normal," frequency and severity of symptoms such as bloating, cramping, and excessive flatulence, and overall health status as assessed by a previously validated five-category questionnaire. There were no significant differences between sorbitol and lactulose in any outcome measured except nausea, which was increased with lactulose (p less than 0.05).

CONCLUSION

These results support the hypothesis that sorbitol and lactulose have no clinically significant differences in laxative effect. Sorbitol can be recommended as a cost-effective alternative to lactulose for the treatment of constipation in the elderly.

Role of fructose-sorbitol malabsorption in the irritable bowel syndrome

Because even after low doses of fructose and sorbitol, fructose-sorbitol malabsorption has been found in a high number of patients with the irritable bowel syndrome, an etiological role of fructose-sorbitol malabsorption in the irritable bowel syndrome has been suggested. However, these studies have been uncontrolled. Therefore, a controlled study of fructose-sorbitol malabsorption in the irritable bowel syndrome compared with healthy controls was performed. Seventy-three patients, 23 men and 50 women with a mean age 43.1 +/- 1.7 years (range, 18-66 years) with the irritable bowel syndrome were compared with 87 age- and sex-matched control subjects. Fructose-sorbitol malabsorption was determined by a breath-hydrogen test (Lactoscreen, Hoek Loos, Schiedam, The Netherlands) following an oral load of 25 g fructose and 5 g sorbitol after a 10-hour fast. Fructose-sorbitol malabsorption, as shown by an H2 peak of 20 ppm over basal values, was found in 22 (30.1%) of the patients and 35 (40.2%) of the control subjects. With a lower peak level of 10 ppm over basal values, these percentages were 45.2% and 57.5%, respectively. Also, the highest H2 peak values (15.2 +/- 2.3 ppm vs. 21.5 +/- 2.6 ppm), time to reach peak levels (110.7 +/- 5.4 min vs. 107.1 +/- 5.9 min), and area under the H2 curve (1310 +/- 219 ppm.min vs. 1812 +/- 255 ppm.min) did not discriminate between patients and controls. During the test, symptoms developed in 31 of 70 patients and in 3 of 85 control subjects (P less than 0.0001). Symptomatic patients did not differ from asymptomatic patients regarding the presence or absence of fructose-sorbitol malabsorption, H2 peak values, and area under the curve. No differences could be identified between male and female patients or controls. In conclusion, fructose-sorbitol malabsorption is frequently seen in patients with irritable bowel syndrome, but this is not different from observations in healthy volunteers. Therefore, fructose-sorbitol malabsorption does not seem to play an important role in the etiology of irritable bowel syndrome.

Digestion and absorption in the human intestine of three sugar alcohols

The digestion and absorption of three sugar alcohols, consumed chronically in three identical daily postprandial doses, were evaluated in six volunteers during three 11-day periods. Each period included a 3-day adaptation period during which sugar alcohol doses were increased, a 4-day equilibration period, a 2-day stool collection period, and a 2-day intubation period. From day 4, the daily administered amounts were either 30 g pure sorbitol, 57 g maltitol containing 30 g sorbitol, or 69 g Lycasin 80/55 (Roquette, Lestrem, France), which is a hydrogenated glucose syrup also containing 30 g sorbitol. The distal ileal output of sugar alcohols and their components was determined by aspiration after a single meal. The mean percentage of sorbitol absorbed in the small intestine was significantly higher in pure sorbitol doses than in those containing maltitol and Lycasin 80/55 (79% +/- 4% vs. 64% +/- 4% and 64% +/- 5%, mean +/- SEM). The mean percentage of total maltitol digested was not different for pure maltitol and maltitol contained in Lycasin 80/55 (90% +/- 2% vs. 86% +/- 2%). Stool excretion of sugar alcohols was negligible, indicating that the sugar alcohols reaching the colon were almost completely digested by the colonic flora. The mean estimated energy values of the sugar alcohols ingested in kcal/g were 3.58 +/- 0.08 for sorbitol, about 3.50 +/- 0.07 for maltitol, and between 3.11 +/- 0.08 and 3.54 +/- 0.08 for Lycasin 80/55. Because the experimental conditions of this study mimicked the usual way of consumption of the three sugar alcohols, little calorie saving can be expected from the chronic consumption of these sugar alcohols in so-called sugar-free products.

Isolated fructose malabsorption

A patient with isolated fructose malabsorption presented with diarrhoea and colic during the first year of life and subsequently responded to a fructose free diet. Fructose malabsorption has been implicated in some cases of irritable bowel syndrome in adults and may also be an infrequently recognised cause of gastrointestinal symptoms in children.

Functional bowel disease: malabsorption and abdominal distress after ingestion of fructose, sorbitol, and fructose-sorbitol mixtures

Twenty-five patients with functional bowel disease were given fructose, sorbitol, fructose-sorbitol mixtures, and sucrose. The occurrence of malabsorption was evaluated by means of hydrogen breath tests and the gastrointestinal symptoms, if any, were recorded. One patient could not be evaluated because of lack of H2 production. Based on a cut-off level of 10 ppm rise of H2 concentration, malabsorption was apparent in 13 patients, in 7 of which the calculated absorption capacities were below 15 g. In contrast, in patients given 50 g of sucrose, malabsorption could not be detected. Ingestion of fructose caused marked abdominal distress in patients with demonstrable malabsorption. Ingestion of sucrose in these patients gave less pronounced symptoms of abdominal distress. Malabsorption of a 5-g dose of sorbitol could be detected in 8 of 13 patients. Mixtures of 25 g of fructose and 5 g of sorbitol caused significantly increased abdominal distress, and more than additive malabsorption was found in several cases. The present study shows that pronounced gastrointestinal distress may be provoked by malabsorption of small amounts of fructose, sorbitol, and fructose-sorbitol mixtures in patients with functional bowel disease. The findings may have direct influence on the dietary guidance given to a major group of patients with functional bowel disease and may make it possible to define separate entities in this disease complex.

Methodological aspects of breath hydrogen (H2) analysis. Evaluation of a H2 monitor and interpretation of the breath H2 test

The reliability of end-expiratory hydrogen (H2) breath tests were assessed and the significance of some important pitfalls were studied, using a compact, rapid H2-monitor with electrochemical cells. The H2 response was shown to be linear and stable. The reproducibility of the breath collection technique was determined in 20 patients following ingestion of lactulose. The increment between consecutive means of duplicate samples indicative of a significant rise of H2 concentration never exceeded 10 p.p.m., the mean coefficient of variation of the duplicate samples was below 5%. Fasting H2 levels were studied in 10 healthy adults during a 4-month period and they showed very marked inter- and intra-individual variability (16% above 40 p.p.m.). Initial peaks (early, short-lived H2 rises unrelated to carbohydrate malabsorption) were identified in 25% of the breath tests (in 4% above 20 p.p.m). It is concluded that the technique used for interval sampling of end-expiratory breath samples for H2 concentration gives reliable results. The biological significance of H2 concentration increments can only be evaluated if the limitations of the technical procedures and the individual ability to produce H2 is known.