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PubMed2000

Lactose does not enhance calcium bioavailability in lactose-tolerant, healthy adults.

BACKGROUND: 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. OBJECTIVE: 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. DESIGN: 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. RESULTS: 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. CONCLUSIONS: Lactose does not have a beneficial effect on calcium bioavailability in lactose-tolerant adults.

Adult↗
PubMed1997

Effects of milk viscosity on gastric emptying and lactose intolerance in lactose maldigesters.

The possibility of delaying gastric emptying and improving lactose digestion and tolerance by increasing milk viscosity was studied in 13 lactose maldigesters who ingested three test milks with different viscosities (range: 33-1892 mPa.s) in random order at intervals of 1 wk. Each test portion was 500 mL and provided approximately equal to 1900 kJ and 18 g lactose. The different viscosities were obtained by adding varying proportions of rice starch and maltodextrin to a basic milk formula. A combined [13C]glycine-hydrogen breath test was used to measure gastric emptying and lactose digestion simultaneously. Participants reported their gastrointestinal symptoms by using a four-grade scale. Mean (+/- SEM) gastric-emptying half times were 78 +/- 5.7 min for low-viscosity milk (30 mPa.s), 86 +/- 5.0 min for moderate-viscosity milk (80 mPa.s), and 78 +/- 4.5 min for high-viscosity milk (1.9.10(3) mPa.s). Mean orocecal transit times (180 +/- 24, 163 +/- 23, and 180 +/- 24 min, respectively) were not significantly different. There were no milk-dependent differences in breath-hydrogen excretion or in the severity of gastrointestinal symptoms. The milks were well tolerated; > 50% of the subjects reported nondisturbing symptoms or none. We conclude that gastric emptying, orocecal transit time, and lactose digestion and tolerance were not affected by altering milk viscosity. This may have been due to the high energy content of the test milks, which in itself led to slow gastric emptying.

Adult↗
PubMed1975

Carbohydrate digestion and absorption in the equine small intestine.

Dietary carbohydrates, which constitute a most important source of equine nutrition, are digested and absorbed by a series of complex processes principally in the small intestine, beginning with intraluminal starch hydrolysis by the action of pancreatic amylase. The continuous secretion of a copious volume of pancreatic juice, low in enzyme activity, presumably releases sufficient oligosaccharides for further hydrolysis at the intestinal cell surface by brush border enzymes. Active carrier mediated mechanisms then transport the final hexose products across the intestinal cell for uptake in the hepatic portal system. Brush border disaccharidase activities in the equine small intestine are of the same order of magnitude, and have a similar distribution pattern, to those reported in omnivorous and carnivorous species. The disaccharidase development patterns are characteristic and reflect the ability of the horse to digest the major nutrient sources adequately at various stages of life. The efficiency of the mucosal disaccharidases and the monosaccharide transport systems in the equine small intestine have been established by a series of oral disaccharide and monosaccharide tolerance tests. Horses older than three years of age are unable to hydrolyse lactose, but young and adult horses are fully capable of rapidly hydrolysing sucrose and maltose loads. Several tests have clinical application for assessing small intestinal dysfunction in the investigation of diarrhoea and malabsorption. The deficient digestion or absorption of carbohydrate, whether primary or secondary, can almost always be localized to a defect in the enzymic or transport capacity of the small intestinal surface cell. The continued ingestion of lactose could be detrimental in severely diarrhoeic foals.

Animals↗
PubMed1995

In vitro tolerability of human nasal mucosa: histopathological and scanning electron-microscopic evaluation of nasal forms containing Sandostatin.

An in vitro human nasal model was developed as a tool to study the local tolerability of nasal powder forms using excised nasal mucosa in a diffusion chamber. The suitability of this model was tested using Sandostatin (SMS) an octapeptide analog of somatostatin, as a reference drug enhanced by Avicel (microcrystalline cellulose) or lactose (100 mesh). The standard nasal spray vehicle was taken as a harmless control and 1% chenodeoxycholate (CDC) as a harmful control in terms of local tolerability. The extent of peptide permeation was determined by measuring SMS concentration in the receiving chamber. The labeling of SMS was detected by immunoperoxidase staining on cross sections. The local tolerability for all tested forms was assessed by histopathological examination and scanning electron microscopy. The apparent permeation coefficient allowed us to rank the absorption of the tested drug forms as Avicel > spray = lactose > 1%CDC. For all formulations, SMS was detected in the epithelium. No changes of the nasal mucosa could be observed with Avicel, lactose or nasal spray vehicle in the presence or absence of SMS. 1%CDC with or without drug showed an immediate destruction of the nasal epithelium. The validation of this in vitro model using human nasal mucosa will be further discussed as a tool for assessing the local tolerability of intranasally applied test substances.

Absorption↗
PubMed1999

Lactitol tolerance in healthy Thai adults.

The hydrogen breath analysis test was performed in healthy Thai adults to determine lactitol tolerance. The study was conducted in 39 individuals (11 males and 28 females) aged 18-41 years. All volunteers agreed to participate in this study after the risks and benefits had been fully explained. Subjects were requested not to consume milk, milk products, or high-vegetable diets for a day and to fast from 10 p.m. of the day preceding the test day. After consumption of the test diet (12 and 20 g of lactose or lactitol, respectively, in 250 mL water), the subjects recorded the severity of symptoms for 24 hours. Breath samples were collected after fasting and after consumption of the test diet at 30 min intervals over the 7-hour study period. Breath samples were analyzed for hydrogen using gas chromatography. After consumption of 12 g lactose, the prevalence of lactose malabsorbers was established. The increment of a peak breath hydrogen level of > or = 20 ppm above the baseline level was used as an indicator of lactose malabsorption. The lactose malabsorbers were further classified as lactose tolerance or lactose intolerance according to the gastrointestinal symptoms observed. All 39 healthy Thai adults could be classified into 3 groups as follows: 9 (23%) lactose absorbers (LA), 15 (38.5%) lactose mal-absorber/tolerance (LMT), and 15 (38.5%) lactose mal-absorber/intolerance (LMI). Using the hydrogen breath test, 67% of the subjects were identified as lactitol intolerance after the consumption of 12 g lactitol. The lactitol intolerance comprised 53.8% of LMI, 34.6% of LMT, and 11.5% of LA. Among all subjects, one third of LA (33%), two thirds of LMT (60%), and 93% of LMI were lactitol intolerant. In addition, gastrointestinal symptoms such as flatulence and abdominal pain were most pronounced in LMI. Diarrhea was also a prominent manifestation after consumption of 12 g lactitol. Therefore, it was finally decided that 20 g lactose or lactitol were not given to LMI because of the risk of gastrointestinal symptoms. After high doses (20 g) of lactose and lactitol consumption, most LMT developed more symptoms than did LA and the main symptom was diarrhea. Consumption of 20 g lactose resulted in fewer symptoms than 20 g lactitol in both LA and LMT. On the basis of the hydrogen breath test, most LA tolerated 12 g lactitol without gastrointestinal symptoms except some flatulence whereas most LMT and LMI did not. Twenty g lactitol was not tolerated by both LA and LMT because there was diarrhea among the subjects, especially in LMT. Although the hydrogen breath analysis test is the best method for identification of lactose malabsorption, it is not the best method to identify lactitol intolerance. A hydrogen concentration of 15 ppm above the baseline level was found to be the best cut-off point to indicate lactitol intolerance although sensitivity was 85% and specificity only 38% in this study. It was further concluded that there is a greater susceptibility to lactitol in human lactose malabsorbers than in lactose absorbers. Our findings might be relevant for the limited use of lactitol in Thailand.

Absorption↗
PubMed1996

How much lactose is low lactose?

OBJECTIVE: To test the hypothesis that complete elimination of lactose is not necessary to ensure tolerance by lactose maldigesters. DESIGN: Double-blind, randomized protocol in which challenge doses of 0, 2, 6, 12, and 20 g lactose in water were fed to subjects after a 12-hour fast. SUBJECTS: 13 healthy, free-living adults who were lactose maldigesters. MAIN OUTCOME MEASURES: Breath hydrogen production (a measure of maldigestion) and symptom response to each challenge dose. STATISTICAL ANALYSIS: Analysis of variance was done to determine overall differences in mean hydrogen gas production (peak and sum of hours 1 through 8). Friedman's test was used to determine overall differences in the mean ranks for each symptom. Fisher's least significant difference test was used for multiple comparisons for hydrogen and symptom and data. RESULTS: Hydrogen production after consumption of the 0- and 2-g lactose doses was not significantly different. Hydrogen production increased with the 6-g dose. Intensity of abdominal pain increased when the dose of lactose was 12 g. Episodes of flatulence did not increase until the dose reached 20 g. No significant differences in the occurrence of diarrhea were observed after the five treatments. CONCLUSIONS: No significant increase in breath hydrogen production or intolerance symptoms occurred after consumption of a 2-g dose of lactose. Up to 6 g was tolerated, even though maldigestion could be measured at the 6-g dose. Thus, lactose maldigesters may be able to tolerate foods containing 6 g lactose or less per serving, such as hard cheeses and small servings (120 mL or less) of milk.

Abdominal Pain↗