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PubMed1991

[Lactose--a potential dietary fiber. The regulation of its microecological effect in the intestinal tract. 2. The nutrient effect of lactose].

In the small intestine lactose is subjected to the hydrolytic impact of beta-galactosidase originating mainly from the mucosa. In rats about two thirds of the enzyme activity are located in the first part of the small intestine, and one third in the second one. A part of the mucosal enzyme does not remain in the mucosa. It becomes detached and can be determined in the chymus. The ratio of the transient to the resident proportion amounts to 1.8: 1 in germfree and 0.23: 1 in conventional rats. Bacterial settlement causes an increase in the mucosal mass resulting in higher total activity whereas the specific activity of the mucosal enzyme remains unchanged. Microorganisms occurring close to the small intestine mucosa take part in lactose degradation. Lactose-containing diet leads to an increase in both the bacterial and the mucosal activity, the latter one to varying degrees. Lactose concentration in the ileal chymus rises with increasing intake of lactose and decreasing protein and phosphate intake. Following a saturation kinetics the velocity of lactose hydrolysis is correlated with the lactose concentration of the diet. alpha-lactose is hydrolysed more rapidly in the small intestine of both human sucklings and rats than beta-lactose. As the results of a mathematical model show lactose mutarotation does not effect on the degree of lactose degradation in the small intestine. Depending on the intake of lactose and the food composition the rate of lactose hydrolysis amounts to: --max. 50% after small intestine perfusion in human sucklings, --max. 80% after small intestine perfusion in rats, --max. 60% in rats with ileostomata.

Animals↗
PubMed2003

Breath testing to evaluate lactose intolerance in irritable bowel syndrome correlates with lactulose testing and may not reflect true lactose malabsorption.

OBJECTIVES: An increased prevalence of lactose intolerance is seen in irritable bowel syndrome (IBS). Recently, we demonstrated a high prevalence of abnormal lactulose breath test results in IBS suggesting bacterial overgrowth. Because symptoms of lactose intolerance result from bacterial fermentation, the purpose of this study was to determine whether an abnormal lactose breath test is reflective of malabsorption or early presentation to bacteria. METHODS: Subjects with diarrhea-predominant IBS were enrolled. On day 1, subjects underwent a lactulose breath test after an overnight fast. Within 1 wk, subjects returned after fasting for a lactose breath test with simultaneous blood glucose measurements every 15 min to complete a lactose tolerance test (LTT). Symptoms were evaluated 3 h after lactose administration. RESULTS: Twenty subjects completed the study. One subject inadvertently received dextrose through the intravenous and was excluded. Of the remaining 19 subjects, three (16%) had an abnormal LTT suggesting malabsorption. In all, 10 subjects (53%) had an abnormal lactose breath test, 14 (74%) had an abnormal lactulose breath test, and 11 (58%) had symptoms after lactose administration. The agreement with symptoms was moderate (kappa = 0.47) and fair (kappa = 0.24) when compared to the lactose breath test and LTT, respectively. There was a fair correlation between lactose breath test and LTT (kappa = 0.29). However, lactose breath test hydrogen levels >166 ppm were universally predictive of abnormal LTT. Finally, a significant correlation was seen between the hydrogen production on lactose and lactulose breath test (r = 0.56, p = 0.01). CONCLUSIONS: Lactose breath testing in IBS subjects does not seem to reflect malabsorption; it may be an indicator of abnormal lactulose breath test, suggesting bacterial overgrowth.

Adult↗
PubMed2005

Maximum permissive dosage of lactose and lactitol for transitory diarrhea, and utilizable capacity for lactose in Japanese female adults.

This study aims to estimate the tolerable lactose intake which can be utilized in the digestion by lactase and in the fermentation by intestinal microbes in Japanese female adults. The first, the maximum permissive dosage of lactose not to induce transitory diarrhea was estimated based on the oral ingestion of lactose at several dose levels in all the subjects, and compared with that of lactitol which is not hydrolyzed by digestive enzymes. A second lactose tolerance test involving 10 g and 30 g of lactose was carried out in 10 subjects showing resistance to diarrhea, and serum glucose and insulin levels and the amount of hydrogen excreted in the breath were measured for comparison with those of glucose and lactitol. Subjects were 43 Japanese female adults (average: age 20.5+/-2.1 y, weight 51.3+/-5.1 kg) who had not been diagnosed as having either hypolactasia or being lactose intolerant. Serum glucose and insulin levels were scarcely elevated following the ingestion of both 10 g and 30 g of lactose, while the amount of hydrogen excreted in the breath was greatly increased following the ingestion of 30 g of lactose, but these levels were less following the ingestion of 10 g of lactose. In contrast, the ingestion of 15 g of glucose significantly increased blood glucose and insulin levels, while no hydrogen was detected in the breath. The maximum permissive dosage of lactose not to induce transitory diarrhea was 0.72 g/kg of body weight and that of lactitol was 0.36 g/kg of body weight in Japanese adults. The digestive capacity of lactase is less than 10 g of lactose by single ingestion, while intestinal microflora are able to ferment approximately 20-30 g of lactose. In addition, the ingestion of more than 10 g of lactose might be contributed as prebiotics.

Adult↗
PubMed1980

[Effect of prolonged consumption of lactose or hydrolyzed lactose in rats--nutritive efficiency and anatomical changes (author's transl)].

Growing rats receive for 270 days well-balanced diets with 40 p. 100 of lactose or industrial hydrolyzed lactose. Whey and ultrafiltration permeate are used in crude state or after enzymic lactose hydrolysis. In lactose diets the ingesta and the food efficiency are considerably reduced as well as the growth. The water intake is greatly increased. The dry mater digestibility is not modified by the lactose after an experiment of 7 months. Hydrolyzed lactose provokes all these phenomena but with a weaker intensity. In a zootechnical point of view the lactose hydrolysis reduces the detrimental properties of lactose. After 270 days animals having received lactose show a high hypertrophy of small intestine and caecum tissues as well as a small renal hypertropy (dry matter/100 g of living weight). Hydrolyzed lactose involves the comparable modifications but with a less extent. Numerous facts attributed to lactose molecule are partially imputable to galactose molecule mainly the increase of water consumption. Only the growth of bone tissue (femur) is provoked by the lactose molecule itself and not to its components. When the diet is well-balanced the presence of whey proteins does not seem to modify the lactose effects.

Animals↗
PubMed2004

Randomized, double-blind clinical trial of a lactose-free and a lactose-containing formula in dietary management of acute childhood diarrhea.

BACKGROUND: Refeeding of artificially fed infants with lactose-containing formula after oral rehydration therapy in the treatment of acute diarrhea was concluded to be indifferent to non-lactose formula by a meta-analysis. In Thai as well as Asian infants and children with low lactase level from genetically determinant and with rotavirus infection, lactose malabsorption is most likely to occur and cause delayed recovery. The aim of this study was to compare the effect of a lactose-free and a lactose-containing formula in dietary management of acute childhood diarrhea. PATIENTS AND METHOD: A randomized, double-blind clinical trial of 80 male children, formula-fed, aged 3 to 24 months, admitted with acute watery diarrhea and mild or moderate dehydration, was carried out. All children received oral rehydration therapy for the first 4 hours. After appropriate rehydration, they were fed either a lactose-free formula (Dumex Lactose-Free Formula; treatment group, n = 40) or a lactose-containing formula (Dumex Infant Formula; control group, n = 40) in adjunction with oral rehydration solution. In addition, the infants were fed rice gruel as tolerated. Comparisons of duration of diarrhea, weight gain, vomiting, biochemical changes, stool frequency and weight and unscheduled intravenous fluid were made. RESULTS: Three children (2 treatment, and 1 control) dropped out from the study. The total number of unscheduled intravenous infusions were 6 of 80 children (7.5%), including 2 (5.0%) in the treatment group and 4 (10.0%) in the control group. Three children in the control group did not resolve from diarrhea within 7 days of treatment. Rotavirus was identified in approximately 50% of the children in each group. Using survival analysis, the median duration of diarrhea was significantly shortened by 20.5 hours in the treatment group compared to the control group (77.0 hours in the treatment group vs 97.5 hours in the control group; P = 0.002). Significantly decrease in stool frequency and increase in percent weight gain were seen in the treatment group at 24 hours. Moderate acidosis cleared up to near normal at 24 hours in the treatment group but acidosis persisted in the control group. In the rotavirus diarrhea subgroup, moderate acidosis turned to be mild in treatment group, but acidosis was unchanged with increased plasma chloride level in the control at 24 hours thus suggesting that the children in the control group might have lactose malabsorption and osmotic diarrhea. Duration of rotavirus diarrhea was shortened 23.6 hours in treatment group compared to the control (P = 0.0034). CONCLUSIONS: In this study, lactose-free formula was shown to be effective in the dietary management of acute childhood diarrhea. Duration of diarrhea was shortened, weight gain was better, and stool frequency was less when compared to lactose-containing formula. Moderate acidosis cleared up spontaneously at 24 hours. Unscheduled IV could be decreased by 50%. Children receiving lactose-free formula tolerated it well. Data of subgroup analysis of rotavirus diarrhea revealed lactose-free formula scored higher than the control group for all parameters studied.

Acute Disease↗
PubMed2003

Tolerance of symptomatic lactose malabsorbers to lactose in milk chocolate.

OBJECTIVE: To study tolerance to lactose in milk chocolate among symptomatic lactose maldigesters. DESIGN: Randomized cross-over study. SUBJECTS: Twenty-seven adult lactose maldigesters with symptomatic lactose intolerance. METHODS: A 100 g chocolate sample prepared with whole milk (12 g lactose), whole-milk powder (12 g lactose), low-lactose milk powder (2 g lactose) or lactose-free milk powder was eaten after an overnight fast. Gastrointestinal symptoms (flatulence, abdominal bloating, abdominal pain, borgorygmi and nausea) were recorded in a questionnaire during the following 8 h. Bowel movements and stool consistency were also registered during the test day. RESULTS: The numbers of persons reporting different gastrointestinal symptoms or any of the symptoms did not differ significantly after eating the chocolate samples. No statistical differences were found in the estimated strength of the different symptoms or the total strength of all symptoms combined. Differences in the bowel frequency and stool consistency were also non-significant. CONCLUSIONS: Lactose malabsorbers with self-reported lactose intolerence did not differ in their response to milk chocolate samples containing different amounts of lactose.

Cacao↗
PubMed1995

Lactose malabsorption and irritable bowel syndrome. Effect of a long-term lactose-free diet.

Lactose malabsorption may induce abdominal symptoms indistinguishable from those of the irritable bowel syndrome (IBS), however the exact relationship between the two conditions and the optimal differential diagnostic workup are still to be defined. We prospectively studied the prevalence of lactose malabsorption (by means of a hydrogen breath test) and the clinical effect of a long-term lactose-free diet in 230 consecutive patients with a suggested diagnosis of irritable bowel syndrome, no organic disease of the GI tract, and no history of milk intolerance. Lactose malabsorption was diagnosed in 157 patients (68.2%). In 48 (43.6%) of the 110 patients who complied with the diet symptoms subsided, in 43 they were somewhat reduced and in 17 they remained unchanged. Symptoms never fully subsided in lactose malabsorbers non-compliant with the diet or in normal lactose absorbers who adhered to a lactose-free regimen. Partial improvement was observed in 20% of these subjects. No relation was demonstrated between pre-trial symptoms and the outcome of the diet. The occurrence of symptoms during the lactose breath test strongly suggested a favorable response to diet, but did not help in predicting whether symptoms would subside or be reduced. Conversely, their absence during the test was not associated with an acceptable negative predictive value. The high prevalence of lactose malabsorption in the patients under study suggests that in Italy IBS and lactose malabsorption are frequently associated. A test for diagnosing lactose malabsorption should always be included in the diagnostic workup for IBS and a long-term lactose-free regimen recommended if the test is positive.

Adult↗
PubMed1980

Comparative tolerance of adolescents of differing ethnic backgrounds to lactose-containing and lactose-free dairy drinks. II. Improvement of a double-blind test.

Using an improved double-blind test procedure, the relationship between lactose malabsorption and lactose intolerance was investigated in 87 healthy teenagers (14--19 years old) of differing ethnic backgrounds. Capillary blood glucose analysis after an oral dose of 50 g of lactose identified 45 lactose malabsorbers. A lactose-free (LF) chocolate dairy drink and one containing 4.5% lactose (LC) were administered under double-blind conditions on 4 consecutive mornings. As in a similar prior study, no statistically significant differences were found in the incidence of symptoms reported by malabsorbers and absorbers after drinking 240 ml of either the LF or the LC preparation. However, 12 lactose absorbers reported symptoms apparently not due to lactose, i.e., after 240 ml of LF, after this amount of both LF and LC, or after 240 ml (but not 480 ml) of LC. Such false-positive results would only be identified by the double-blind approach. It did not appear that any of the malabsorbers had symptoms due to the lactose in 240 ml of LC. However, 16% of the malabsorbers apparently reacted to the lactose in 480 ml of LC. Well designed, double-blind clinical trials are essential for evaluation of gastrointestinal responses to lactose or other ingredients in milk.

Adolescent↗
PubMed1997

The relationship between lactose tolerance test results and symptoms of lactose intolerance.

OBJECTIVE: A standard for the assessment of lactose malabsorption does not exist. As measured by lactose tolerance tests, insufficient increase in blood glucose or increased breath hydrogen (H2) excretion after lactose ingestion is regarded as pathological. In this study, we have tried to elucidate the relationship between lactose tolerance test results and symptoms after a lactose challenge. This relationship might be an indicator for the validity of the test. METHODS: In a prospective study, 309 consecutive patients with suspected lactose malabsorption underwent a lactose tolerance test. After consumption of 50 g of lactose, blood glucose and breath H2 concentrations were measured. During the test (240 min), the severity of bloating, flatulence, abdominal distention, and diarrhea were semiquantitatively scored as 0, 1, or 2. The individual sum of these four scores was calculated and denoted as the total symptom score (TSS). All subjects were classified according to their TSS to compare symptoms with peak breath-H2 concentration and change in blood glucose concentration, respectively. RESULTS: The glucose and breath H2 response were pathological in 51.1 and 39.5% of cases, respectively. A stepwise increase in TSS of 1 point was associated with a significant increase (p < 0.05) in mean peak H2 concentration. However, a significantly lower glucose increment compared with patients with a TSS of 0 was found only in patients with a TSS of 2 or 4. The mean symptom score differed significantly between the positive and negative breath tests (p < 0.001), but did not differ between the positive and negative glucose response results. CONCLUSIONS: This study shows that GI symptoms after a lactose challenge are strongly associated with the amount of H2 excretion. The relationship between the increase in glucose concentration and symptoms after a lactose load is less evident. Thus, the H2 breath test seems to be superior to the measurement of blood glucose increment as a diagnostic tool in lactose malabsorption, although the true predictive value of this test only can be determined after a period of dietary treatment.

Adult↗
PubMed2000

Lactose (mal)digestion evaluated by the 13C-lactose digestion test.

BACKGROUND: The prevalence of genetically determined lactase nonpersistence is based on the results of the lactose H2 breath test. This test, however, is an indirect test, which might lead to misinterpretation. DESIGN: We determined lactase activity in healthy Chinese and Dutch students using a novel 13C-lactose digestion test. The cut-off value of this test was established in a Chinese population with a homogenous genetic background of lactase nonpersistence and was compared with the results obtained in a Caucasian population. Twenty-five grams of a 13C-lactose solution was consumed by 12 known H2-positive and 5 H2-negative Chinese students and 48 Dutch students and, subsequently, 13C-glucose concentration in plasma and H2 excretion in breath were measured. RESULTS: A similar 13C-glucose response curve was found in all Chinese students. The mean response curve in the Dutch students was more pronounced (P < 0.01). The 1 h (peak) plasma 13C-glucose concentration was the best discriminator between lactose digesting and maldigesting subjects. The cut-off level of 2 mmol L-1 13C-glucose in plasma was defined in the H2-positive Chinese students group. Based on the 13C-glucose response the prevalence of lactose maldigestion in the Dutch subjects was 25%; based on the lactose H2 breath test 17%. CONCLUSIONS: Using the 13C-lactose digestion test the results demonstrate a higher prevalence of lactose maldigestion in a Caucasian population than indicated by the results of the H2 breath test. A moderate increase in the plasma 13C-glucose concentration after consumption of 13C-lactose in the young adult Chinese subjects indicates a residual lactase activity in that age group, even when a positive H2 breath test result is obtained. These results indicate that the 13C-glucose concentration in plasma more accurately reflects the small intestinal lactose digestion capacity than the lactose H2 breath test.

Adult↗
PubMed2003

Abdominal pain associated with lactose ingestion in children with lactose intolerance.

The causal relationship between lactose ingestion and gastrointestinal symptoms is questionable. The aim of this study was to assess symptoms associated with milk ingestion in children with lactose maldigestion. Thirty children (11 males) age 3 to 17 years with lactose maldigestion were studied. In a double-blind, crossover design, subjects ingested 240 mL daily of either lactose-hydrolyzed or lactose-containing milk for 14 days. Diaries were kept daily that recorded diet, medication use, and symptoms. There was a significant increase in abdominal pain experienced by study participants during the lactose ingestion period when compared to the lactose-free period. We conclude that ingestion of 12 g of lactose daily is associated with increased abdominal pain in susceptible children with lactose maldigestion. A trial of dietary lactose restriction may be beneficial in reducing abdominal pain in children with lactose maldigestion.

Abdominal Pain↗
PubMed1985

Hydrogen concentration in expired air analyzed with a new hydrogen sensor, plasma glucose rise, and symptoms of lactose intolerance after oral administration of 100 gram lactose.

A rapid breath hydrogen analyzer to detect lactose malabsorption is described. After ingestion of a lactose solution the patient expires into a mouthpiece attached to a hydrogen sensor at 30-min intervals for 3 1/2 h. The hydrogen of the expired air causes a voltage change that can be transformed into ppm from a calibration curve. A tolerance test with a load of 100 g lactose was performed in 43 consecutive patients with various gastrointestinal disturbances, referred to the laboratory for the commonly used lactose tolerance test based on plasma glucose measurements. Eleven patients developed symptoms of lactose intolerance during the test. Biopsy specimens from the distal duodenum or proximal jejunum showed partial villous atrophy in one, in whom celiac disease with lactose intolerance was diagnosed; the other 10 had normal specimens. In nine of them lactose intolerance was diagnosed and confirmed by observation for months on a lactose-poor diet. The 10th patient (H.P.L.) did not improve on such a diet. He also showed pronounced symptoms of intolerance during a test with monosaccharides (glucose + galactose). His intestinal disease remained undiagnosed. The 11 patients with symptoms of intolerance and 3 patients without symptoms during the lactose load showed a flat plasma glucose curve after drinking the lactose solution--that is, a maximum rise of the glucose concentration of 1.5 mmol/l. One of the symptom-free patients dropped out and could not be observed, another did not improve on a lactose-poor diet, and the third noticed a favorable effect of the diet on stool consistency but not on other abdominal symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1998

Effects of lactose intake on lactose digestion and colonic fermentation in preterm infants.

The purpose of this study was to determine whether doubling the lactose concentration in formula for preterm infants lowers the fraction of lactose digested and/or increases the fraction of lactose fermented. Six preterm infants, 31 to 36 weeks' postconceptional age, were fed a standard preterm formula (carbohydrate is 50% lactose and 50% glucose polymer)(SC) and/or the same volume of formula modified to contain lactose as the sole carbohydrate (LAC). Relative lactose digestion during the LAC formula feeding compared with SC formula feeding was measured by using a stable isotope approach for quantifying the fractional contribution of formula lactose to plasma glucose enrichment. Relative lactose digestion was 0.98 +/- 0.17 (range, 0.70 to 1.19). Fractional fermentation of lactose was estimated from breath H2 excretion (0.52 +/- 0.34 during LAC feeding and 0.23 +/- 0.22 during SC feeding, P = .11). The rate of breath H2 excretion was much higher with LAC (1.34 +/- 0.98 mL/h) than with SC (0.27 +/- 0.29, P = .029). In conclusion, doubling the lactose concentration had only modest effects on fractional lactose digestion. Increased breath H2 excretion with LAC may relate to fermentation of nonlactose sugar or to ill-defined changes in colonic physiology or motility, which could enhance colonic fermentation of malabsorbed sugar by H2-producing bacteria.

Bacteria↗
PubMed1997

Improved clinical tolerance to chronic lactose ingestion in subjects with lactose intolerance: a placebo effect?

BACKGROUND: Uncontrolled studies of lactose intolerant subjects have shown that symptom severity decreases after chronic lactose consumption. Adaptation of the colonic flora might explain this improvement. AIMS: To compare the effects of regular administration of either lactose or sucrose on clinical tolerance and bacterial adaptation to lactose. METHODS: Forty six lactose intolerant subjects underwent two 50 g lactose challenges on days 1 and 15. Between these days they were given 34 g of lactose or sucrose per day, in a double blind protocol. Stool samples were obtained on days 0 and 14, to measure faecal beta-galactosidase and pH. Symptoms, breath H2 excretion, faecal weight and electrolytes, and orofaecal transit time were assessed. RESULTS: Except for faecal weight, symptoms were significantly milder during the second challenge in both groups, and covariance analysis showed no statistical difference between them. In the lactose group, but not in the sucrose group, faecal beta-galactosidase activity increased, pH dropped, and breath H2 excretion decreased. CONCLUSION: Bacterial adaptation occurred when lactose intolerant subjects ingested lactose for 13 days, and all symptoms except diarrhoea regressed. Clinical improvement was also observed in the control group which displayed no signs of metabolic adaptation. This suggests that improved clinical tolerance may be just a placebo effect.

Adult↗
PubMed1981

The asynchronous hormonal induction of lactose synthetase components, alpha-lactalbumin and galactosyltransferase, in relation to lactose secretion by mouse mammary explants.

Hormonal induction of the lactose synthetase components, alpha-lactalbumin and galactosyltransferase, in relation to the induced levels of lactose synthetase activity and lactose secretion by mammary gland explants from mature virgin mice was examined. During 6 days of culture in the presence of insulin, cortisol, prolactin and triiodothyronine mammary explants accumulated progressively increasing amounts of alpha-lactalbumin. By contrast, galactosyltransferase and lactose synthetase activities were maximal on day 3, and then declined; the time course of lactose secretion was similar to that of galactosyltransferase and lactose synthetase activities. Cortisol concentration studies revealed the following dependencies on the steroid: alpha-lactalbumin content was maximal between 0.01 and 0.1 microgram and, at 10 microgram/ml fell below the baseline level observed without cortisol. On the other hand, galactosyltransferase, lactose synthetase and lactose secretion were only slightly increased at 0.01 microgram/ml, were maximal between 0.1 and 1.0 microgram/ml, and at 10 microgram/ml were still considerably above the baseline levels observed without cortisol. These results indicate that lactose formation and secretion by mammary explants from virgin mice correspond more closely to the hormone-induced activity of galactosyltransferase than to that of alpha-lactalbumin, and that asynchrony can arise between the induction of alpha-lactalbumin and the induction of lactose.

Animals↗