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

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

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

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

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

Intestinal integrity, digestive enzyme activity, nutrient utilization, and egg quality of laying hens at different ages were evaluated and compared in this study. A total of 192 Hy-line Brown laying hens at 195-d-old (D195 group), 340-d-old (D340 group), and 525-d-old (D525 group) were allocated into one of 3 groups in accordance with their ages. Each group had 8 replicates of 8 birds each, and all birds were fed a maize-soybean meal basal diet for a 2-wk experiment. Compared with the D195 group, intestinal villus height and ratio of villus height to crypt depth, as well as serum D-lactate content increased in the D525 group (P < 0.05). The sucrase and maltase activities in the jejunal mucosa, amylase activity in the pancreas, and trypsin activity in the jejunal chyme of 525-d-old hens were lower than their 195-d-old counterparts (P < 0.05). In addition, there was a decline of trypsin and lipase activities in the ileal chyme of hens from D525 group in comparison with D195 or D340 group (P < 0.05). Apparent retention of dry matter and crude protein of birds in D340 and D525 group decreased when compared with the D195 group (P < 0.05). Moreover, birds in the D525 group exhibited a lower level of ether extract retention, and higher contents of several excreted amino acids than those in the D195 group (P < 0.05). Compared with the D195 group, eggs harvested from D525 group exhibited lower albumen height, eggshell strength and thickness, and a higher egg weight (P < 0.05). In conclusion, increased intestinal permeability (higher serum D-lactate content), compromised digestive function (lower digestive enzyme activities and apparent nutrient retention, and higher concentrations of excreted amino acids), and poor egg quality (lower albumen height, eggshell strength, and thickness) were observed with increasing age in the laying hens.

Carbohydrate intolerance or malabsorption has been suggested as a cause of chronic abdominal pain (CAP) in a subset of patients. We aimed to evaluate disaccharidase deficiencies in children with functional CAP and to correlate deficiencies with clinical features.

Patients presenting to the gastroenterology clinic at Children's Hospital of Wisconsin with abdominal pain prospectively completed a detailed demographic, history, and symptom questionnaire. The CAP cohort included those with at least 1 month of symptoms. Data on disaccharidase activity and histology of endoscopic biopsies were collected retrospectively. Only patients with normal histology were included in the study. The association between groups with low disaccharidases and clinical features was examined.

A total of 203 pediatric patients with CAP were included. The mean (SD) age was 11.5 (3.1) years, and 32.5% were male. The percentages of abnormally low disaccharidase levels using the standard laboratory cutoffs were lactase, 37%; sucrase, 21%; glucoamylase, 25%; and palatinase, 8%. Thirty-nine percent of the patients with low lactase also had low sucrase, and 67% of the patients with low sucrase had low lactase. There was no significant difference in the activities of any of the disaccharidases or sucrase/lactase ratio in relation to age. Also, no association was found between stool consistency, stool frequency, or location of pain and low disaccharidase activity.

A large proportion of patients with CAP have deficiencies in disaccharidases. Bowel frequency, vomiting, or location of pain was no different between groups, suggesting that these clinical features cannot be used to predict disaccharidase deficiencies.

The study was designed to examine whether feeding soy protein isolate as partial replacement of casein (CN) affects glucose metabolism in young goats and whether effects may be ameliorated by supplementation of those AA known to be lower concentrated in soy than in CN. Goat kids (d 20 of age) were fed comparable milk protein diets, in which 50% of the crude protein was either CN (control, CON), soy protein isolate (SPI), or soy protein isolate supplemented with AA (SPIA) for 43 d (n=8 per group). On d 62 of age, a single bolus dose of d-[(13)C6]glucose (10mg/kg of BW) was given with the morning diet, and simultaneously, a single bolus dose of d-[6,6-(2)H2]glucose (5mg/kg of BW) was injected into a jugular vein. Blood samples were collected between -30 and +420 min relative to the tracer administration to measure the (13)C and (2)H enrichments of plasma glucose and the (13)C enrichment of blood CO2. Glucose first-pass uptake by the splanchnic tissues was calculated from the rate of appearance of differentially labeled glucose tracer in plasma. Glucose oxidation was calculated from (13)C enrichment in blood CO2. In addition, plasma concentrations of triglycerides, nonesterified fatty acids, glucose, insulin, and glucagon were measured. On d 63 of age, kids were killed and jejunal mucosa and liver samples were collected to measure lactase mRNA levels and lactase and maltase activities in the jejunum and activities of pyruvate carboxylase and phosphoenolpyruvate carboxykinase (PEPCK) in the liver. Basal plasma glucose concentration tended to be higher in the CON than the SPIA group, whereas basal insulin was higher in the CON group than the SPI and SPIA groups, and glucagon was higher in the CON than the SPIA group. Plasma glucose and insulin concentrations increased during the first hour after feeding, whereas plasma glucagon increased immediately after feeding and after 1h of feeding. First-pass uptake and glucose oxidation were not affected by diet. Maltase activities in proximal and mid jejunum and lactase activities in mid jejunum were lower in the CON than in the SPIA group. Activities of PEPCK were higher in the SPIA than in the SPI group. In conclusion, feeding milk diets with soy protein isolate seems to affect glucose status in kids, but has no effect on first-pass uptake and oxidation of glucose. The highest activities of lactase and maltase were observed after supplementation with AA. Higher PEPCK activities in the liver may point at elevated gluconeogenic activities after AA supplementation in soy-fed kids.

The "gold standard" for the diagnosis of celiac disease (CD) is the small intestinal biopsy. A significant number of biopsies are inadequate for interpretation. Furthermore, the labeling of a biopsy as a Marsh I or II is somewhat subjective and may vary with the experience of the pathologist. Our hypothesis is that patients with intact villi undergoing biopsies frequently have associated disaccharidase deficiencies (DSD).

We reviewed 220 charts of pediatric patients with CD and selected those with a duodenal biopsy Marsh score of I/II. The disaccharidase (DS) levels of these patients were compared with a randomly selected, age-matched control group. DSD is defined as levels below the lower limits of normal.

Lactase (mean lactase = 18.8 in the control group vs. 4.2 in the diseased group, p = 0.004); sucrase (mean sucrase = 46.4 in the control group vs. 21.4 in the diseased group, p = 0.001); maltase (mean maltase = 138 in the control group vs. 52.5 in the diseased group, p = 0.001); palatinase (mean palatinase = 9.6 in the control group vs. 3.3 in the diseased group, p < 0.001).

There is a profound deficiency of DS levels in pediatric patients with CD who have intact villi.

At upper gastrointestinal endoscopy to investigate unexplained diarrhea and iron deficiency anemia, duodenal biopsies are often taken to exclude a diagnosis of coeliac disease. While histology remains the gold standard for this diagnosis, recent developments in serological testing may overtake this as a first line test and biopsy restricted to confirming the diagnosis. Established coeliac disease on biopsy is straightforward, but early lesions may pose a challenge. Newer endoscopic procedures such as push-pull enteroscopy (balloon enteroscopy) with biopsy allow access to the small bowel beyond the second part of the duodenum. Controversy remains as to what constitutes the normal histology of the duodenum, and small bowel. Lymphocytic duodenosis (increased intraepithelial lymphocytes with normal villous architecture) in patients with negative coeliac serology can be associated with Helicobacter pylori, drugs, autoimmune and other diseases including food allergy. Full thickness small intestinal biopsies can aid in investigation of enteric neuropathies in severe dysmotility disorders. Biopsies are also taken to investigate malabsorption due to suspected infectious and metabolic disorders. Despite highly active anti-retroviral therapy (HAART), immunosuppressed patients may be affected by duodenal pathogens. The histology of duodenal mucosa in acid related disorders reflects the damage seen at endoscopy. Although the prevalence of duodenal ulcer disease is decreasing, drugs causing ulceration remain an important disease entity. Recent observations in functional bowel disorders suggest that the duodenum may be a key site for pathology. In functional dyspepsia, patients with early satiety may have excess eosinophil infiltration, and the mast cell is probably a key player in the irritable syndrome in the small intestine.

Intestinal disaccharidase activities were measured in 199 individuals with autism to determine the frequency of enzyme deficiency. All patients had duodenal biopsies that were evaluated morphologically and assayed for lactase, sucrase, and maltase activity. Frequency of lactase deficiency was 58% in autistic children ≤ 5 years old and 65% in older patients. As would be expected, patients with autism at age 5 > years demonstrated significant decline in lactase activity (24%, p = .02) in comparison with ≤ 5 years old autistic patients. Boys ≤ 5 years old with autism had 1.7 fold lower lactase activity than girls with autism (p = .02). Only 6% of autistic patients had intestinal inflammation. Lactase deficiency not associated with intestinal inflammation or injury is common in autistic children and may contribute to abdominal discomfort, pain and observed aberrant behavior. Most autistic children with lactose intolerance are not identified by clinical history.

Lactase non-persistence (adult-type hypolactasia) is present in more than half of the human population and is caused by the down-regulation of lactase enzyme activity during childhood. Congenital lactase deficiency (CLD) is a rare severe gastrointestinal disorder of new-borns enriched in the Finnish population. Both lactase deficiencies are autosomal recessive traits and characterized by diminished expression of lactase activity in the intestine. Genetic variants underlying both forms have been identified. Here we review the current understanding of the molecular defects of human lactase deficiencies and their phenotype-genotype correlation, the implications on clinical practice, and the understanding of their function and role in human evolution.

In celiac disease (CD), abnormalities of brush border enzyme activities have been detected in the course of the disease activity. There are conflicting results on intestinal mucosal enzyme activities and its correlation to mucosal injury in CD. The aim of the present study was to evaluate the brush border enzyme activities (disaccharidases and alkaline phosphatase) in the duodenal mucosa of North Indian children with CD and to examine their correlation to duodenal mucosal morphological alterations.

This prospective study included 71 children with CD and 29 controls (patients with gastroesophageal reflux disease) in whom upper gastrointestinal endoscopy was performed and distal duodenal biopsies were taken for histological assessment, and estimation of disaccharidases and alkaline phosphatase activities. Each biopsy sample was classified according to the modified Oberhuber classification. Lactase, sucrase, maltase and alkaline phosphatase activities were estimated in duodenal biopsy homogenates from patients with CD and from controls. The association between enzyme activities and duodenal morphology was examined.

The mean age of the 71 patients with CD (M:F, 43:28) was 6.0 +/- 0.3 years and mean age of onset of symptoms was 2.7 +/- 0.4 years. Sixty-four of 71 (90.1%) CD patients showed type 3 (destructive) lesion, whereas it was grade 0 in all patients with gastroesophageal reflux disease. In CD and patients with gastroesophageal reflux disease, the mean level (IU/g protein) of lactase was 12.1 +/- 0.9 versus 24.4 +/- 1.0 (P < 0.001), mean level of sucrase was 25.9 +/- 1.9 versus 42.5 +/- 1.9 (P < 0.001), mean level of maltase was 56.6 +/- 3.5 versus 76.1 +/- 13.0 (NS), and mean level of alkaline phosphatase was 602.8 +/- 56.2 versus 1359.3 +/- 51.2 (P < 0.001), respectively. The mean disaccharidases and alkaline phosphatase levels were not significantly different in patients with milder lesions (type 2 and type 3a) compared with those of control. However, mean lactase, sucrase and alkaline phosphatase levels were significantly lower (P < 0.001) in CD patients with moderate (type 3b) and severe (type 3c) lesions compared with control.

A generalized decrease of disaccharidases and alkaline phosphatase activity was seen in the duodenal mucosa of children with CD. The depressed activities of lactase, sucrase and alkaline phosphatase were well correlated with the histological grade of duodenal mucosal lesions in children with CD.

There is uncertainty regarding disaccharidase activity (DA) in infants. In this study, values for DA in infants were established and compared with symptoms and intestinal mucosal histological appearance.

Disaccharidase activity and histological appearance of endoscopically obtained intestinal mucosal biopsy specimens from 131 infants (75 males; mean age 180 days; range 20-364 days) obtained during an 8-year period were reviewed. Patients were divided into 2 groups on the basis of absence (group 1; n = 56) or presence (group 2; n = 75) of failure to thrive (FTT) and/or diarrhea. These groups were subdivided into 3 subgroups on the basis of histological findings: normal histological appearance (A), mild histological abnormalities (B), and moderate to severe histological abnormalities (C).

The DA from patients in group 1A represent values in infants who were free of diarrhea/FTT and who had normal intestinal mucosal histological appearance. The geometric means (95% CI) in units of DA were as follows: lactase 33.7 (normal range 29.0-39.1), sucrase 48.9 (normal range 44.2-54.1), maltase 160.5 (normal range 144.4-178.3), and palatinase 11.2 (normal range 9.7-12.9). Differences in DA were not related to symptoms, in the absence of histological abnormalities (1A vs 2A), but rather on the presence of histological abnormalities even in the absence of symptoms (1A vs 1B). Differences were also found when patients with FTT and/or diarrhea with abnormal histological appearance (2B and 2C) were compared with patients with no FTT and/or diarrhea with a normal brush border (1A).

We outline DA values in a large cohort of infants. DA in infants, as in children, relates to intestinal mucosal histological appearance rather than to symptoms.

Adult-type hypolactasia (lactase non-persistence; primary lactose malabsorption) is characterized by the down-regulation of the lactase enzyme activity in the intestinal wall after weaning. The down-regulation is genetically determined and a mutation has occurred that has made part of mankind tolerate milk (lactase persistence). A DNA-variant, single nucleotide polymorphism C/T-13910 located 13 910 base pairs (bp) upstream of the lactase gene (LCT) at chromosome 2q21-22 has been shown to associate with the lactase persistence/non-persistence trait both in family and case-control studies. The C/T-13910 variant is located in a non-coding region in the genome in intron 13 of the minichromosome maintenance type 6 gene (MCM6). Significant correlation between the C/T-13910-variant and lactase activity in the intestinal biopsy specimens has been demonstrated. Molecular epidemiological studies on the prevalence of the C/C-13910 genotype associated with low lactase activity are in agreement with the prevalence figures for adult type hypolactasia in>70 diverse ethnic groups studied. Recent functional studies have suggested that this variant has an enhancer effect over the lactase gene. Based on the biochemical, functional, genetic and molecular epidemiological studies of the C/T-13910 variant, genetic testing for adult type hypolactasia has been introduced into clinical practice in Finland. Identification of the genetic change has highlighted the role of non-coding variants in the regulation of common genes and created new tools to study the mechanism of lactase enzyme activation.

Often a cause for chronic non-specific diarrhea (> or =3 stools per day for more than 4 weeks) is not identified. Small bowel bacterial overgrowth (SBO) can occur without morphological damage and remains difficult to diagnose. Often diarrhea is treated empirically with antibiotics with a good response. The aims of the present study were first to investigate the prevalence of SBO in a consecutive series of patients with chronic diarrhea and second to compare the utility of duodenal fluid culture and (14)C-d-xylose breath/lactulose test in diagnosing SBO.

In the first study, the cause of chronic diarrhea was prospectively diagnosed in 87 subjects. In the second study, tests of SBO were compared in 18 subjects with chronic diarrhea and 15 subjects with reflux oesophagitis used as control subjects. Duodenal fluid was aspirated at endoscopy and cultured and later a (14)C-d-xylose breath/lactulose test was performed.

In the first study, SBO was present in 48% of those with chronic diarrhea. In the second study, the diarrhea group had an average (range) stool frequency of 5.5 (3-10) per day and had normal duodenal biopsies. A total of 33%, 50%, 67% of subjects had SBO by duodenal culture alone, by a (14)C-d-xylose breath/lactulose test alone and by a combination of both tests, respectively. In the control group, 0%, 13% and 13% had SBO by duodenal culture alone, by (14)C-d-xylose breath/lactulose test alone and by combination of tests, respectively.

Small bowel bacterial overgrowth is a common (33-67%) cause of chronic diarrhea.

To establish reference values for disaccharidase activities in Belgian children and to compare enzyme activities with those of non-Belgian Caucasian children.

Data from Belgian children who had undergone endoscopic jejunal biopsies (1994-2000) for suspected malabsorption were reviewed. The patients were divided into three groups based on histology: (A) normal (n = 201), (B) moderate changes (n = 58) and (C) (sub)total atrophy (n = 14). The 95% reference limits for disaccharidase activities (U/g protein) were calculated for group A after exclusion of patients with a positive hydrogen breath test, a history of lactose intolerance or coeliac disease (final population: n = 151, 0.1-12 y). Values were compared with those of 34 non-Belgian Caucasian children with normal histology (28 of Mediterranean origin).

The reference limits (90% confidence interval) were 86 (65-111)-423 (366-494) for maltase, 9 (6-12)-91 (78-122) for lactase and 24 (18-30)-155 (120-184) for sucrase. No gender-related differences in enzyme activities were found. Lactase levels showed a slight decrease with increasing age. Disaccharidase activities of children with histologically confirmed mucosal injury were significantly lower than those of children with normal histology: median values for groups A, B and C were 208, 181 and 96, respectively, for maltase, 40, 28 and 7, respectively, for lactase and 69, 54 and 25, respectively, for sucrase. Median disaccharidase activities in biopsies with normal histology were lower in non-Belgian children, the difference being only statistically significant for lactase, 33 versus 40.

The reference values for Belgian children are well in line with other reported values from Caucasian children. Although enzyme activities are lower in children with histologically confirmed mucosal damage, they do not allow differentiation between histology groups. Lower lactase values were found in non-Belgian children.

The development of immune-mediated diabetes in BB rats may involve a defect of the gastrointestinal tract (GI), as suggested by increased gut permeability. This study aimed at measuring invertase, maltase, lactase, and peroxidase activities in the duodenum of diabetesprone BioBreeding (BBdp) rats and control BioBreeding rats (BBc) given free access to NIH-07 diet up to the time of killing at 60 66 d of age. After washing the entire small intestine, the duodenal mucosa was scraped off in the first 5-cm segment from the pylorus and frozen in distilled water. Invertase, maltase, and lactase activities were measured by monitoring the conversion of [U-(14)C]sucrose, [U-(14)C]maltose, and [D-[1-(14)C]glucose] lactose to radioactive hexoses, which were phosphorylated in the presence of adenosine triphosphatase and yeast hexokinase and then separated from their precursor by ion-exchange chromatography. Peroxidase activity was measured by a spectrophotometric procedure. In the BBdp rats, the activity of invertase, maltase, and lactase averaged, respectively, 70.2 +/- 4.4, 81.2 +/- 4.3, and 75.7 +/- 4.1% (n = 16 and p < 0.001 in all cases) of the control values found in BBc rats of the same sex. Inversely, after exclusion of two female BBc rats with abnormally high plasma D-glucose concentration, the activity of peroxidase in the BBdp rats averaged 157.4 +/- 20.0% (n = 16; p < 0.02) of the mean control value recorded in BBc rats of the same sex (100.0 +/- 9.3%; n = 14). These findings are compatible with the view that a proinflammatory state of the GI associated with compromise function may precede the occurrence of pancreatic insulitis in BBdp rats and, possibly, human subjects with type 1 diabetes.

The relationship between lactose intolerance and post-infectious irritable bowel syndrome (IBS) in adults is uncertain. Bowel symptoms may persist after bacterial gastroenteritis and as post-infectious IBS. Acquired lactose intolerance may follow viral enteric infections in children. We compared the frequency of lactose intolerance after bacterial gastroenteritis in adults with and without symptoms of IBS or functional diarrhoea at 3-6-months' follow-up.

A prospective cohort study was conducted.

All subjects with bacterial gastroenteritis confirmed by stool culture from the microbiology laboratory and without prior IBS or functional diarrhoea were eligible to participate. IBS and functional diarrhoea were diagnosed via self-completed Rome II modular questionnaires. Lactose intolerance was determined from a rise in breath hydrogen and plasma glucose and symptoms.

One hundred and twenty-eight subjects with bacterial gastroenteritis were followed prospectively, from which a smaller cohort of 42 subjects took part in this study. The cohort was comprised of 24/25 subjects who developed post-infectious IBS (n = 16) or functional diarrhoea (n = 8) (9 male, 15 female) and 18 random controls (8 male, 10 female) chosen from the group without IBS or functional diarrhoea. The mean age of the subjects was 44.4 years (range 25-76 years). In the group with functional diarrhoea or IBS, four subjects had failure of the plasma glucose to rise but none had abnormal glucose hydrogen breath tests. In the control subjects, one had a positive combined test and six had failure of plasma glucose to rise alone. No subject developed symptoms during the test.

Bacterial gastroenteritis did not cause persistent lactose intolerance in our study population. Lactose intolerance does not appear to be implicated in the aetiology of post-infectious bowel symptoms, including IBS. Advice to avoid dairy products in patients presenting with post-infectious IBS on the basis that they may have lactose intolerance appears unnecessary in patients from northern England.

In active coeliac disease, mucosal atrophy is associated with a marked decrease in intestinal disaccharidase enzyme activities. We investigated the value of duodenal mucosal disaccharidases to predict the severity of mucosal villous atrophy and its recovery in 50 patients with coeliac disease.

Duodenal mucosal histology and disaccharidase activities were studied at least twice with a mean interval of 9 months. Histology of specimens from all patients was examined by the same pathologist blinded to the data on disaccharidase activities. Mucosal damage was scored into four groups as follows: Grade 0 = normal mucosa; grade I = slight villous atrophy, that is, cryptic component 30%-50%; grade 2 = moderate villous atrophy, that is, cryptic component 50%-90%; grade 3 = severe villous atrophy, that is, cryptic component >90%. The enzyme activities of the disaccharidases were determined as U/g protein.

Duodenal mucosal disaccharidase activities were good predictors of the grade of mucosal villous atrophy. Positive predictive values for moderate or severe villous atrophy were 90% for maltase (maltase activity <150 U/g protein), 86% for sucrase (<40 U/g protein) and 71% for lactase (<20 U/g protein). Accordingly, negative predictive values, that is, none or only minimal villous atrophy (grades 0 or 1) with normal disaccharidase activities, were 71% for maltase, 70% for sucrase and 63% for lactase.

The increase in duodenal disaccharidase activities correlated with recovery of the mucosa based on histology. Besides the histological examination, measurement of disaccharidase activities offers an additional tool to evaluate response to a gluten-free diet in patients with coeliac disease.

The mechanism of gastrointestinal damage (mucositis) induced by cancer chemotherapy remains uncertain. The aims of this study were to define the time course and mechanism of small intestinal damage following chemotherapy in humans.

Patients receiving chemotherapy underwent upper gastrointestinal endoscopy (a maximum of two per patient) with duodenal biopsy prior to chemotherapy and again at 1, 3, 5, and 16 days after chemotherapy. Tissue was taken for morphometry, disaccharidase assays, electron microscopy, and for assessment of apoptosis using the Tdt mediated dUTP-biotin nick end labelling (TUNEL) method. Villus area, crypt length, and mitotic index were measured by a microdissection technique.

Apoptosis increased sevenfold in intestinal crypts at one day, and villus area, crypt length, mitotic count per crypt, and enterocyte height decreased at three days after chemotherapy. Disaccharidase activities remained unchanged. Electron microscopy showed increased open tight junctions of enterocytes at day 3, consistent with more immature cells. All indices improved by 16 days.

Small intestinal mucositis is associated with apoptosis in crypts that precedes hypoplastic villous atrophy and loss of enterocyte height.

There is evidence from animal studies that lactose has a beneficial effect on intestinal calcium absorption. However, data concerning the effect of lactose on calcium absorption in lactose-tolerant adults are inconclusive.

Our objective was to investigate the effect of lactose on calcium bioavailability in humans by the use of a stable-strontium test under controlled metabolic conditions.

Eleven healthy, lactose-tolerant subjects (8 women, 3 men) randomly received a bolus of 2.27 mmol strontium alone (load A), the bolus with 35 g lactose (load B), or the bolus with 17.5 g glucose and 17.5 g galactose (load C). Blood samples were drawn at 0, 15, 30, 60, 90, 180, 240, and 300 min. Urine specimens were collected during the time intervals -2 to 0, 0-2, 2-4, 4-6, and 6-24 h.

Pharmacokinetic parameters of strontium bioavailability were comparable for all 3 loads. In detail, fractional absorption at 240 min for loads A, B, and C was 12.1 +/- 0.7%, 13.0 +/- 1.1%, and 12.2 +/- 0.7%, respectively. Areas under the curve for 0-240 min were 70.8 +/- 6.3, 69.6 +/- 3.5, and 65.8 +/- 5.1 micromol*h/L for loads A, B, and C, respectively (NS). Moreover, fractional strontium excretion values of 5.1 +/- 0.8% (load A), 5.8 +/- 0.4% (load B), and 5.2 +/- 0.8% (load C) were not significantly different.

Lactose does not have a beneficial effect on calcium bioavailability in lactose-tolerant adults.

Intestinal disaccharidase activities tend to be low in villous atrophy, but there are only a few reports of enzyme activities in children with normal villous architecture.

In the current study the data were reviewed on disaccharidase activities in duodenal biopsy specimens of normal villous structure in 223 children undergoing upper gastrointestinal endoscopy in 1997 and 1998. The ancestry was Finnish in 188 children (median age 8.0 years; range, 0.2-18 years), African in 27 children (median age 5.0 years; range, 1-13 years), and other in eight children.

The mean activities of lactase, sucrase, and maltase were significantly higher in Finnish children than in children of African origin (P < 0.0001, P < 0.002, and P < 0.02, respectively). Lactase activity decreased with increasing age (P < 0.001), but age had no significant effect on maltase and sucrase activities. Among Finnish children, 31% (59/188) had lactase activity below the established reference range of 20 units (units are micromoles of substrate hydrolyzed per minute at 37 degrees C per gram of protein) and one child had a probable sucrase-isomaltase deficiency. When these 60 children with low enzyme activities were excluded, the geometric means were lactase, 35.7 units (95% confidence interval [CI], 32.8-38.6 units); maltase, 241 units (95% CI, 225-258 units); and sucrase, 57.5 units (95% CI, 53.5-61.6 units). Among the children of African origin, lactase activity was decreased in 67% (18/27). All three enzyme activities were decreased in parallel more often among the African children (8/27) than among the Finnish children (9/188; P < 0.002).

Ethnicity has a strong effect on disaccharidase values in children with normal villous structure. African children have lower activities of lactase, sucrase, and maltase in duodenal specimens than do children of Finnish origin.

Trehalose is a disaccharide, the main dietary source being mushrooms. It has been approved as an additive in the preparation of dried food. Isolated intestinal trehalase deficiency is found in 8% of Greenlanders, but is rare elsewhere. The normal range of trehalase activity and the incidence of isolated trehalase deficiency in the UK have not been reported. Patients (n 400) were investigated for suspected malabsorption. Endoscopic distal duodenal biopsies were taken for histological assessment and maltase, sucrase, lactase and trehalase estimation. Disaccharidase activities were determined by Dahlqvist's technique (Dahlqvist, 1968). Most patients (n 369) had normal duodenal histology. In these, square root transformation of trehalase activity produced a normal distribution. The normal range (mean +/- 2 SD) was 4.79-37.12 U/g protein. One patient had an isolated borderline trehalase deficiency. The thirty-one patients with villous atrophy had significantly reduced disaccharidase activities. With ingestion of a gluten-free diet, maltase, sucrase and trehalase activities recovered to normal in most patients, whereas lactase activity did not. The normal range and very low incidence of isolated enzyme deficiency is comparable with that described in populations from the USA and mainland Europe. Activity is significantly reduced in untreated coeliac disease and recovers with treatment with a gluten-free diet. There is no place for routine determination of trehalase activity in the UK population and there should be no concern over the introduction of trehalose-containing dried foods.

The purpose of this study was to assess the structure and function of the small intestine before and after enteral feeding given via a percutaneous feeding gastrostomy (PEG). It is not known whether this method of feeding provides a good luminal drive to the small intestine.

Studies were performed of patients at the time of PEG placement, in a cross-sectional group after a period of feeding and in a smaller longitudinal subgroup. Enteral feeds were adjusted in volume and caloric content for each patient. Duodenal biopsies were taken during endoscopy for quantitative morphometry, and lactulose-rhamnose permeability tests were performed during the next day. Duodenal fluid was cultured quantitatively in the first study, and disaccharidases determined in the second study.

The first study of 15 patients, who had enteral feeding for a median (range) period of 13 (8 to 104) weeks, showed partial villous atrophy with normal crypt length, no increase in duodenal bacteriology, and abnormal lactulose-rhamnose sugar permeability due to rhamnose malabsorption. These changes were also present in 38 similar patients before enteral feeding. A second study before enteral feeding showed lowered maltase activity (24 patients), and similar intestinal permeability findings (22 patients). Twelve of these patients were followed longitudinally for 3 months of enteral feeding that maintained but did not improve nutrition, as assessed by body mass index and mid-arm muscle circumference, and there was no change in duodenal morphometry (11 patients), rhamnose malabsorption (4 patients), or disaccharidases (11 patients).

These studies suggest villous atrophy was not due to an inflammatory enteropathy but resulted from a poor luminal "drive" associated with the enteral feeding. Enteral feeding maintained but did not improve nutrition status.

The relationship between disaccharidase activity, progression of human immunodeficiency virus (HIV) disease, and diarrhoea and weight loss was investigated.

Forty-six HIV-positive patients ingested a solution of lactose, palatinose, sucrose, and lactulose after 24 h of dietary exclusion and overnight fasting, after which urine was collected for 10 h. Urinary disaccharide (activity) ratios-lactose/lactulose (L/LL), palatinose/lactulose (P/LL), and sucrose/lactulose (S/LL)-were measured by thin-layer chromatography.

There was a significant decrease in disaccharidase activity (L/LL, P/LL, and S/LL) with advancing clinical stage of HIV disease (p < 0.05, Wilcoxon rank sum test) as well as decreasing CD4 count (p < 0.05, Spearman correlation). Patients with weight loss/diarrhoea also had significantly (p < 0.05) decreased disaccharidase activity compared with control but not as compared with AIDS patients. Anti-retroviral therapy did not influence disaccharidase activity.

Impairment of disaccharidase activity occurs with advancing HIV disease, but its role in HIV patients with weight loss and diarrhoea remains to be determined.

Selective adult-type hypolactasia, the main cause of primary malabsorption of lactose, shows considerable variation in terms of its symptoms, which mainly depend on the amount of milk consumption. The article discusses congenital lactase deficiency and familial lactose intolerance. Links between hypolactasia and non-specific abdominal complaints, coronary heart disease and cataract are presented. The decrease in lactase activity in the brush border of jejunal mucosa, associated with diseases of the mucosa or any other condition which damages the enterocytes, is discussed as a cause of secondary hypolactasia. It is shown that adult-type primary hypolactasia and selective lactose malabsorption represent a major problem in the everyday work of general practitioners, particularly in populations where hypolactasia is common. Therefore, the examination and treatment of non-selected patients with vague abdominal complaints is important in primary health care. As the need for calcium in humans is largely met by the intake of milk, the consumption of milk has to be in amounts that are tolerable for the individual.