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PubMed1993

Correlation of lactose maldigestion, lactose intolerance, and milk intolerance.

Lactose digestion and tolerance were evaluated in 164 African Americans ranging in age from 12 to 40 y who claimed intolerance to one cup (240 mL) or less of milk. With use of a breath-hydrogen test with 25 g lactose as test dose and the presence or absence of symptoms, 50% of the subjects were classified as lactose maldigesters and intolerant, 8% were maldigesters but tolerant, 15% were digesters but intolerant, and 27% were digesters and tolerant. Forty-five subjects from the lactose maldigesting and intolerant group were further tested for milk intolerance in a double-blind study. Sixty-seven percent of the subjects reacted appropriately to the presence or absence of lactose in ingested milk whereas 33% reported symptoms to both low-lactose milk and milk containing lactose. The results suggest that the cause of milk intolerance in as many as one-third of African Americans claiming symptoms after ingestion of a moderate amount of milk cannot be its lactose content.

Adolescent↗

PubMed1988

Effect of milk and lactose on zinc absorption in lactose-intolerant postmenopausal women.

We evaluated the effect of lactose intolerance on intestinal zinc absorption under various test conditions in a group of postmenopausal women. Fractional zinc absorption was studied with a dual-isotope technique using 65Zn and 51Cr (as nonabsorbable fecal markers). We performed four absorption tests on sixteen subjects with water (control), whole cow milk, lactose-free cow milk and lactose alone. Mean (+/- SEM) fractional zinc absorption was 0.558 +/- 0.032 with water, 0.276 +/- 0.031 with milk, 0.246 +/- 0.028 with lactose-free milk and 0.564 +/- 0.051 with lactose. No significant differences in zinc absorption were found under any of the test conditions between lactose-tolerant and lactose-intolerant subjects. Milk and lactose-free milk significantly reduced zinc absorption in both groups.

Aged↗

PubMed1982

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

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

Adolescent↗

PubMedDate not supplied

Lactose digestion and clinical tolerance to milk, lactose-prehydrolyzed milk and enzyme-added milk: a study in undernourished continuously enteral-fed patients.

We investigated: (1) the capacity to digest and tolerate the lactose administered by continuous infusion of intact milk to undernourished tube-fed patients, and (2) the effectiveness of lactose-prehydrolyzed milk, and of the addition of exogenous lactase to milk at infusion time, to reduce lactose maldigestion and increase clinical tolerance. Carbohydrate digestion was evaluated in 10 subjects with the hydrogen breath analysis test during 8 hr of observation. Lactose intolerance was determined by evaluation of subject's symptoms. With the infusion of intact milk (IM), none of the subjects were able to efficiently digest the lactose infused (5.6 +/- 0.35 g/hr, mean +/- SEM) and 86% of them experienced major symptoms of intolerance. With the infusion of lactose-prehydrolyzed milk (HM) and enzyme-added milk (EM) there was a highly significant reduction in lactose maldigestion. More importantly, major symptoms were present in only 10% of subjects with EM, and were completely eliminated with HM. Lactose maldigestion and intolerance represent a major limitation for the application of milk-based polymeric formula for liquid diets in undernourished subjects. The use of exogenous beta-galactosidases represents an alternative to avoid such reactions.

Adult↗

PubMed1997

Improvement of lactose digestion by humans following ingestion of unfermented acidophilus milk: influence of bile sensitivity, lactose transport, and acid tolerance of Lactobacillus acidophilus.

The influence of bile sensitivity, lactose transport, and acid tolerance of Lactobacillus acidophilus on in vivo digestion of lactose was investigated. Four strains of L. acidophilus exhibiting varied degrees of lactose transport, beta-galactosidase activity, and bile sensitivity were used to prepare unfermented acidophilus milks. Lactose malabsorption was evaluated by measuring breath H2 excretion off 11 lactose maldigesting subjects following ingestion of four acidophilus test milks. Test meals were fed in a randomized double-blind protocol. Consumption of acidophilus milk (2% fat) containing strains B, N1, and E significantly reduced mean total H2 production compared with that of the control reduced-fat (2% fat) milk, but milk containing strain ATCC 4356 did not differ from the control. Acidophilus milk containing L. acidophilus N1 was the most effective of the four acidophilus milks in improving lactose digestion and tolerance. Strain N1 exhibited the lowest beta-galactosidase activity and lactose transport but the greatest bile and acid tolerance of the four strains. The results indicated that bile and acid tolerance may be important factors to consider when L. acidophilus strains are selected for improving lactose digestion and tolerance.

Adult↗

PubMed1992

Effect of a single dose of lactase on symptoms and expired hydrogen after lactose challenge in lactose-intolerant subjects.

The effect of a single dose or oral lactase on symptoms, breath hydrogen concentration, and glucose absorption in lactose-intolerant subjects challenged with lactose was studied. Volunteers underwent a lactose challenge test; those whose breath hydrogen concentrations increased 20 ppm or more and who met other criteria were admitted as subjects. After fasting, the subjects were given three chewable lactase tablets (total lactase dose, 9900 FCC units) or placebo tablets in a randomized, double-blind, crossover manner. The subjects also consumed 8 oz of whole milk in which 37.5 g of lactose powder was dissolved (total lactose content, 50 g). The washout period between lactose challenges was at least one week. Breath hydrogen and plasma glucose concentrations were measured before and at intervals after the challenges, and the subjects completed symptom-evaluation questionnaires every eight hours for four days. Twenty-four subjects completed the study. The maximum mean breath hydrogen concentration was significantly lower after lactase treatment than after placebo treatment. In 21 subjects, the area under the hydrogen concentration-time curve (AUC) was lower after lactase than after placebo; three subjects had hydrogen AUCs more than 300 ppm.hr lower. There were no significant differences in plasma glucose levels. Subjective ratings of the severity of abdominal cramping, belching, flatulence, and diarrhea were lower during the first eight hours after challenge in lactase-treated subjects; ratings for bloating were lower during the next eight hours. Single doses of a chewable lactase tablet reduced the concentration of expired hydrogen and symptoms of lactose intolerance after a lactose challenge.

Abdominal Muscles↗

PubMed1981

Stimulation of Escherichia coli adenylate cyclase by lactose in strains carrying mutations in lactose permease.

When a wild-type strain of Escherichia coli contains lactose permease, the accumulation of cyclic AMP (cAMP) by intact cells is inhibited by lactose. This inhibitory effect of lactose is observed in a strain with a mutant cAMP phosphodiesterase and therefore involves a regulation of adenylate cyclase activity. Some E. coli strains carrying mutations in lactose permease show an effect opposite to that of the wild-type strain; the accumulation of cAMP by intact cells is stimulated by lactose, but only when the mutant permease is present. Insertion of lactose permease into the membrane of cells can produce a change in the specific activity of adenylate cyclase; induction of the wild-type transporter is correlated with a decrease in the specific activity, while implantation of a mutant form of lactose permease can lead to an increase in the specific activity. From these data, it is suggested that the state of the lactose transporter in the cell membrane influences the activity of adenylate cyclase.

Adenylyl Cyclases↗

PubMed1989

Plasma lactose after weaning and its relationship with lactose content of milk, post-weaning plasma oestradiol-17 beta and weaning to mating interval in sows.

Twenty first-liter sows were used to investigate the relationship between plasma lactose concentrations following weaning and milk production, total milk content of lactose, post-weaning plasma oestradiol-17beta (E2) concentration and weaning to mating interval. Milk production was estimated from 6 out of 8 hourly successive "weighing-suckling-weighing" of piglets on day 21 of a 28-day lactation. Sows were cannulated in the jugular vein and sampled at 8-h intervals from 2 h to 66 h after weaning. Plasma lactose concentrations (means +/- SE) after weaning increased from 52 +/- 4 microM at the beginning of sampling to a peak value of 183 +/- 23 microM 40 h later and then decreased to 91 +/- 11 microM 66 h after weaning (P less than 0.001). Milk production on day 21 (7.5 +/- 0.3 kg) and the corresponding milk content of lactose (400.5 +/- 0.2 g) were not related (P greater than 0.10) to area under the curve, timing, amplitude and spreading of the lactose peak in plasma. Similarly, none of the characteristics of the lactose peak were related (P greater than 0.10) to weaning to mating interval. There was a linear increase (P less than 0.0001) in mean plasma E2 concentrations (means +/- SE) from 5.6 +/- 0.3 pg/ml, 2 h after weaning, to 12.9 +/- 1.2 pg/ml at the end of the sampling period. On a within-sow basis, there was a correlation (r = 0.28; P less than 0.01) between post-weaning plasma lactose and E2 concentrations. Results showed the existence of the post-weaning peak of plasma lactose in sows.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

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↗

PubMed1996

Efficacy of traditional rice-lentil-yogurt diet, lactose free milk protein-based formula and soy protein formula in management of secondary lactose intolerance with acute childhood diarrhoea.

Secondary lactose intolerance is often a cause of prolongation of diarrhoeal episodes. As appropriate management of lactose intolerance is elimination of lactose from diet, expansive lactose free formulae are often prescribed in acute childhood diarrhoea without establishing diagnosis of lactose intolerance. Since cheap weaning diets made from locally available cereals have been found effective in management of persistent diarrhoea, we postulated that same weaning diet made of rice lentil and yogurt (K-Y diet) could be effectively used in management of acute childhood diarrhoea associated with secondary lactose intolerance. We compared this K-Y diet with milk protein-based lactose free and soy-protein formula. Thirty children between 3-18 months of age completed dietary trial for 72 h. Of these nine children received K-Y diet (Group A), four children received milk protein-based formula (Group B) and 11 children received soy protein formula (Group C). Stool frequency was significantly reduced in children in Group A (13 +/- 6 on day 1 to 6 +/- 5 on day 3) and in Group B (13 +/- 5 on day 1 to 7 +/- 4 on day 3), but not in Group C (13 +/- 4 on day 1 to 10 +/- 8 on day 3). No significant difference was observed in intake of diet, total calories intake, and fluid intake among the three groups. It is concluded that cheap weaning diet made of locally available cereals and yogurt can be used effectively in management of secondary lactose intolerance associated with acute childhood diarrhoea.

Child↗

PubMed1978

Transport by the lactose permease of Escherichia coli as the basis of lactose killing.

Lactose killing is a peculiar phenomenon in which 80 to 98% of the Escherichia coli cells taken from a lactose-limited chemostat die when plated on standard lactose minimal media. This unique form of suicide is caused by the action of the lactose permease. Since uptake of either lactose or galactose by the lactose permease caused death, the action of rapid transport across the membrane must be the cause of the phenomenon. Alternative causes of lactose killing, such as accumulation of toxic metabolic intermediates or action of the beta-galactosidase, have been eliminated. It is proposed that rapid uptake of sugars by the lactose permease disrupts membrane function, perhaps causing collapse of the membrane potential.

Biological Transport↗

PubMed1995

Effects of pelleting, lactose level, polyethylene glycol 4000, and guar gum compared to pectin on growth performances, energy values, and losses of lactose, lactic acid, and water in chickens.

Five mash and two pelleted diets were tested in broiler chickens (7 to 19 d). Mash diets consisted of a basal fraction diluted with either .5% pectin or .5% guar gum. Mash pectin and guar gum diets contained either 3% lactose (PL3m and GL3m diets, respectively) or 6% lactose (PL6m and GL6m diets, respectively). Compositions of pelleted diets (PL3p and GL3p) were those of PL3m and GL3m diets, respectively. All diets contained .5% polyethylene glycol 4000 (PEG) except the PL3m0 diet. The latter diet differed from PL3m diet by the PEG content, only. The real applied viscosities of pectin and guar gum diets were 1.48 and 4.94 mL/g, respectively, No effect of PEG was detected on growth performances, and excreta losses of lactose, lactic acid, and water. No negative effect of guar gum compared to pectin was observed on body weight (19 d), except with pelleted diets (P < .05). Feed:gain ratios for guar gum diets were 7% higher (P < or = .001) that those of pectin diets. The AMEn values of guar gum diets were 4% lower (P < or = .001) than those of pectin diets. For mash diets, lactose digestibilities were lower (P < .05) with guar gum than with pectin. Increasing lactose level from 3 to 6% did not affect (P > .05) AMEn values, feed: gain ratios, and body weights (19 d) but reduced (P > .001) lactose digestibilities from 78 to 64%. The positive effects of pelleting on body weights (19 d) were much less pronounced with guar gum than with pectin (P < .05). The AMEn values of pelleted diets (PL3p) and GL3p) were, on average, 2.5% lower (P = .005) than their mash counterparts (PL3m and GL3m). Water losses related to feed intake were greater with guar gum than with pectin (P < .001) and with 6% lactose than with 3% (P = .001) but were not affected (P > .05) by pelleting. Lactic acid losses related to feed intake were increased by guar gum compared with pectin (P < .001), with more pronounced effects induced by high lactose level (P < .05) and pelleting (P < .05). In many respects, the effects of guar gum seemed similar to those observed in an acid liquid diarrhea.

Animal Feed↗

PubMed1977

Gastric emptying of lactose and milk in subjects with lactose malabsorption.

Six lactose absorbers (LA) and 5 lactose malabsorbers (LM) had tests of gastric emptying with 750-ml meals of glucose in water, lactose in water, plain milk, and chocolate milk. The glucose and lactose meals emptied in a similar fashion in LA and LM subjects with a significant decrease in gastric emptying as the osmolarity of the meals was doubled. If the data are normalized by dividing lactose emptying by the emptying of glucose meals of twice the osmolality in each individual, the lactose malabsorbers empty significantly more lactose. Both LA and LM subjects emptied comparable amounts of milk meals having similar osmolarity. Chocolate milk, which had a higher osmolality than plain milk, emptied more slowly than plain milk in both groups, and this difference was significant in the LM group.

Adult↗

PubMed1997

Fecal hydrogen production and consumption measurements. Response to daily lactose ingestion by lactose maldigesters.

The alteration of hydrogen (H2) metabolism, which accounts for the large decrease in breath H2 excretion following prolonged ingestion of malabsorbed carbohydrate (lactulose, lactose in lactose maldigesters) was studied in six lactose-maldigesting adults. Metabolic inhibitors of the three main H2-consuming reactions (methanogenesis, sulfate reduction, and acetogenesis) were used to independently measure H2 production and consumption in fecal samples obtained after 10 days of either dextrose or lactose feeding. Absolute fecal H2 production (net of production minus consumption) after 3 hr of incubation with lactose was approximately threefold lower after lactose adaptation (242 +/- 54 microliters) compared to dextrose adaptation (680 +/- 79 microliters, P = 0.006). Fecal H2 consumption was not affected by either feeding period. We conclude that decreased absolute H2 production, rather than increased H2 consumption, is responsible for the decrease in breath H2 observed with lactose feeding.

Adult↗

PubMed2001

Relationship between lactose digestion, gastrointestinal transit time and symptoms in lactose malabsorbers after dairy consumption.

BACKGROUND: The relationship of symptoms with objective measurements, as well as some of the mechanisms involved in lactose tolerance after yoghurt consumption, remain unclear. METHODS: The trial had a double-blind design in which 22 lactose malabsorbers received 25 g daily lactose in fresh (living bacteria > 108 cfu/g) yoghurt or heated (< 102 cfu/g) yoghurt for 15 days, followed by a cross-over (15 days) after a wash-out period (14 days). The lactose digestion was determined by the breath H2 test, the gastric emptying (GE) with a 13C-acetate breath test and the revealed transit time (OCTT) by 15N-lactose-ureide test. Subjects reported their gastrointestinal symptoms (GIS) in a validated questionnaire. RESULTS: Breath H2 test indicated more effective lactose digestion after fresh yoghurt intake. The OCTT was shorter after heated yoghurt ingestion as compared with the fresh. There was lower severity of GIS (P < 0.05) after fresh yoghurt intake, and this showed an inverse correlation with OCTT (P < 0.05). CONCLUSIONS: Delayed orocoecal transit time was associated with fewer gastrointestinal symptoms. The improved lactose digestion and tolerance of fresh yoghurt should be mainly attributed to the presence of living bacteria.

Adult↗

PubMed1987

Primary adult lactose malabsorption in Italy: regional differences in prevalence and relationship to lactose intolerance and milk consumption.

A study of regional differences in prevalence of primary adult lactose malabsorption in Italy was conducted on 205 subjects. Their origin was determined by their grandparents' birthplace, 89 from northern, 65 from central, and 51 from southern areas of Italy. Lactose malabsorption was diagnosed with standard oral lactose tolerance test and blood glucose determinations. Lactose malabsorbers showed symptoms more frequently than absorbers after the test load of lactose (p less than 0.01) they also reported milk intolerance more frequently (p less than 0.01). Prevalence of lactose malabsorption is significantly lower in the central sample (19%) than in the northern (52%) and southern (41%) samples (p less than 0.01). This finding contrasts with the hypothesis of a continuous increase in frequency of lactose malabsorption from northern to southern Europe and is probably due to the complex genetic history of the Italian population.

Adult↗

PubMed2004

Failure to improve parameters of lactose maldigestion using the multiprobiotic product VSL3 in lactose maldigesters: a pilot study.

Lactose maldigestion is a common genetic trait in up to 70% of the world's population. In these subjects, the ingestion of lactose may lead to prebiotic effects which can be confirmed by measurement of breath hydrogen. After a period of continuous lactose ingestion, colonic bacterial adaptation is measurable as improved parameters of lactose digestion. There may be inherent benefits in this process of adaptation which may protect against some diseases. We attempt to link therapeutically beneficial probiotics (VSL3, Seaford Pharmaceuticals Inc, Ontario) with improvement in parameters of lactose maldigestion. Two groups of five subjects with maldigestion were fed one or four packets of VSL3 (one packet containing 450 x 10(9) live bacteria) before testing and then 17 days later. A 50 g lactose challenge was carried out before and after feeding. While there was a trend toward increasing rather than reducing of summed breath hydrogen, no statistically significant changes were observed between results from before testing and those from testing 17 days later. The authors conclude that direct consumption of the probiotic VSL3 may not improve parameters of lactose maldigestion without metabolic activation. In its present format, therefore, the test for colonic adaptation cannot be used to demonstrate direct bacterial embedding with VSL3.

Adaptation, Physiological↗

PubMed1987

Effects in rats of dietary protein inadequacy on lactose production, milk volume and components of the lactose synthetase complex (EC 2.4.1.22).

Lactose synthetase (LS) is a complex of alpha-lactalbumin and N-acetylglucosamine galactosyl transferase (GT). LS is the rate-limiting enzyme in lactose biosynthesis. Lactose is the main osmotic component of milk and may thereby affect milk volume. Dietary protein inadequacy reduces milk volume and lactose content. The study investigates the role of LS activity in these phenomena. Lactating rats were fed adequate and inadequate amounts of protein of high (milk protein) and low (cereal protein) quality. After 14 days LS and GT activity of mammary tissue was measured. Milk volume and lactose content was determined. While GT activity was unaffected by diet, LS activity was reduced by low dietary protein quality. Addition of bovine alpha-lactalbumin to tissue incubates largely restored the reduced LS activities. Milk volume was affected in a parallel manner to LS activity. A highly significant positive correlation existed between LS activity and total lactose production (r = 0.794; p less than 0.001). Dietary protein inadequacy indirectly reduces milk volume by means of a direct effect on the lactalbumin part of the LS complex and, subsequently, lactose biosynthesis.

Animals↗