Lactase persistence versus lactose intolerance: Is there an intermediate phenotype?

BACKGROUND

According to the prevailing theory about the genetic background to lactose intolerance, there are three genotypes but only two adult physiological phenotypes: lactase persistence in individuals with the CT and TT genotypes and lactase non-persistence in individuals with the CC genotype. However, analysis of lactase activity from intestinal biopsies has revealed three distinct levels of activity, suggesting that an intermediate physiological phenotype may exist.

AIM

To assess possible disparities between different genotypes with regard to biomarkers of lactase activity and physical symptoms during an oral lactose load test.

METHODS

A retrospective study using an oral lactose load test (n=487). Concentrations of hydrogen in exhaled air and blood glucose were measured. Afterwards, subjects were asked to provide oral mucosa samples for genotyping and answer a questionnaire (participation rate 56%, n=274).

RESULTS

Mean hydrogen levels in exhaled air at 120min were significantly higher in the CT genotype than in the TT genotype. There was no significant difference in blood glucose levels between the two groups. Reported symptoms, with the possible exception of abdominal pain, were equally prevalent in both groups.

CONCLUSIONS

Subjects with the CT and TT genotypes, hitherto classified as lactase-persistent, differ in their physiological response to lactose intake, indicating differences in phenotype which could have clinical significance.

Lactose Intolerance in Adults: Biological Mechanism and Dietary Management

Lactose intolerance related to primary or secondary lactase deficiency is characterized by abdominal pain and distension, borborygmi, flatus, and diarrhea induced by lactose in dairy products. The biological mechanism and lactose malabsorption is established and several investigations are available, including genetic, endoscopic and physiological tests. Lactose intolerance depends not only on the expression of lactase but also on the dose of lactose, intestinal flora, gastrointestinal motility, small intestinal bacterial overgrowth and sensitivity of the gastrointestinal tract to the generation of gas and other fermentation products of lactose digestion. Treatment of lactose intolerance can include lactose-reduced diet and enzyme replacement. This is effective if symptoms are only related to dairy products; however, lactose intolerance can be part of a wider intolerance to variably absorbed, fermentable oligo-, di-, monosaccharides and polyols (FODMAPs). This is present in at least half of patients with irritable bowel syndrome (IBS) and this group requires not only restriction of lactose intake but also a low FODMAP diet to improve gastrointestinal complaints. The long-term effects of a dairy-free, low FODMAPs diet on nutritional health and the fecal microbiome are not well defined. This review summarizes recent advances in our understanding of the genetic basis, biological mechanism, diagnosis and dietary management of lactose intolerance.

The Interrelationships between Lactose Intolerance and the Modern Dairy Industry: Global Perspectives in Evolutional and Historical Backgrounds

Humans learned to exploit ruminants as a source of milk about 10,000 years ago. Since then, the use of domesticated ruminants as a source of milk and dairy products has expanded until today when the dairy industry has become one of the largest sectors in the modern food industry, including the spread at the present time to countries such as China and Japan. This review analyzes the reasons for this expansion and flourishing. As reviewed in detail, milk has numerous nutritional advantages, most important being almost an irreplaceable source of dietary calcium, hence justifying the effort required to increase its consumption. On the other hand, widespread lactose intolerance among the adult population is a considerable drawback to dairy-based foods consumption. Over the centuries, three factors allowed humans to overcome limitations imposed by lactose intolerance: (i) mutations, which occurred in particular populations, most notably in the north European Celtic societies and African nomads, in which carriers of the lactose intolerance gene converted from being lactose intolerant to lactose tolerant; (ii) the ability to develop low-lactose products such as cheese and yogurt; and (iii) colon microbiome adaptation, which allow lactose intolerant individuals to overcome its intolerance. However, in a few examples in the last decade, modern dairy products, such as the popular and widespread bio-cultured yogurts, were suspected to be unsuitable for lactose intolerant peoples. In addition, the use of lactose and milk-derived products containing lactose in non-dairy products has become widespread. For these reasons, it is concluded that it might be important and helpful to label food that may contain lactose because such information will allow lactose intolerant groups to control lactose intake within the physiological limitations of ~12 g per a single meal.

[THE CERTAIN CLINICAL CHARACTERISTICS OF BLOOD IN PATIENTS WITH FAMILY MEDITERRANEAN FEVER OF ARMENIAN POPULATION]

The study was carried out to evaluate erythrocyte sedimentation rate, glucose level, rheumatoid factor and C-reactive protein in blood of patients with periodic peritonitis at the stage of remission. Also, effect of colchicine on activity of lactase was analyzed. It is demonstrated that frequency of increase of levels of erythrocyte sedimentation rate and C-reactive protein during period of remission differed depending on gender while at the same time indicators of rheumatoid factor were within limits of normality in all patients. Despite research literature data establishing effect of colchicine on lactose assimilability, no significant inhibition of lactose activity was established in examined volunteers.

Lactose-hydrolyzed milk is more prone to chemical changes during storage than conventional ultra-high-temperature (UHT) milk

The enzymatic hydrolysis of lactose to glucose and galactose gives rise to reactions that change the chemistry and quality of ambient-stored lactose-hydrolyzed ultra-high-temperature (UHT) milk. The aim of the present study was to investigate and compare chemical changes in lactose-hydrolyzed and conventional UHT milk during a 9 month ambient storage period. Several complementary analyses of volatiles, free amino acids, acetate, furosine, and level of free amino terminals were concluded. The analyses revealed an increased level of free amino acids and an increased formation rate of specific compounds such as furosine and 2-methylbutanal in lactose-hydrolyzed UHT milk compared to conventional UHT milk during storage. These observations indicate more favorable conditions for Maillard and subsequent reactions in lactose-hydrolyzed milk compared to conventional UHT milk stored at ambient temperature. Furthermore, it is postulated that proteolytic activity from the lactase-enzyme preparation may be responsible for the observed higher levels of free amino acids in lactose-hydrolyzed UHT milk.

Genetic origins of lactase persistence and the spread of pastoralism in Africa

In humans, the ability to digest lactose, the sugar in milk, declines after weaning because of decreasing levels of the enzyme lactase-phlorizin hydrolase, encoded by LCT. However, some individuals maintain high enzyme amounts and are able to digest lactose into adulthood (i.e., they have the lactase-persistence [LP] trait). It is thought that selection has played a major role in maintaining this genetically determined phenotypic trait in different human populations that practice pastoralism. To identify variants associated with the LP trait and to study its evolutionary history in Africa, we sequenced MCM6 introns 9 and 13 and ~2 kb of the LCT promoter region in 819 individuals from 63 African populations and in 154 non-Africans from nine populations. We also genotyped four microsatellites in an ~198 kb region in a subset of 252 individuals to reconstruct the origin and spread of LP-associated variants in Africa. Additionally, we examined the association between LP and genetic variability at candidate regulatory regions in 513 individuals from eastern Africa. Our analyses confirmed the association between the LP trait and three common variants in intron 13 (C-14010, G-13907, and G-13915). Furthermore, we identified two additional LP-associated SNPs in intron 13 and the promoter region (G-12962 and T-956, respectively). Using neutrality tests based on the allele frequency spectrum and long-range linkage disequilibrium, we detected strong signatures of recent positive selection in eastern African populations and the Fulani from central Africa. In addition, haplotype analysis supported an eastern African origin of the C-14010 LP-associated mutation in southern Africa.

Preparation of novel poly(hydroxyethyl methacrylate-co-glycidyl methacrylate)-grafted core-shell magnetic chitosan microspheres and immobilization of lactase

Poly(hydroxyethyl methacrylate-co-glycidyl methacrylate)-grafted magnetic chitosan microspheres (HG-MCM) were prepared using reversed-phase suspension polymerization method. The HG-MCM presented a core-shell structure and regular spherical shape with poly(hydroxyethyl methacrylate-co-glycidyl methacrylate) grafted onto the chitosan layer coating the Fe₃O₄ cores. The average diameter of the magnetic microspheres was 10.67 μm, within a narrow size distribution of 6.6–17.4 μm. The saturation magnetization and retentivity of the magnetic microspheres were 7.0033 emu/g and 0.6273 emu/g, respectively. The application of HG-MCM in immobilization of lactase showed that the immobilized enzyme presented higher storage, pH and thermal stability compared to the free enzyme. This indicates that HG-MCM have potential applications in bio-macromolecule immobilization.

Lactose intolerance: from diagnosis to correct management

This review discusses one of the most relevant problems in gastrointestinal clinical practice: lactose intolerance. The role of lactase-persistence alleles the diagnosis of lactose malabsorption the development of lactose intolerance symptoms and its management. Most people are born with the ability to digest lactose, the major carbohydrate in milk and the main source of nutrition until weaning. Approximately, 75% of the world's population loses this ability at some point, while others can digest lactose into adulthood. Symptoms of lactose intolerance include abdominal pain, bloating, flatulence and diarrhea with a considerable intraindividual and interindividual variability in the severity. Diagnosis is most commonly performed by the non invasive lactose hydrogen breath test. Management of lactose intolerance consists of two possible clinical choice not mutually exclusive: alimentary restriction and drug therapy.

Anti-hyperglycemic effects and mechanism of traditional Chinese medicine Huanglian Wan in streptozocin-induced diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Huanglian Wan (HLW) is a prescription of traditional Chinese medicine (TCM), which has been used to treat diabetes mellitus for thousands of years in China. In this study we provide experimental evidence for the clinical use of HLW in the treatment of diabetes mellitus.

MATERIALS AND METHODS

HLW extract was prepared and the main components (namely berberine and catalpol) contained in the extract were assayed with high performance liquid chromatography (HPLC), and diabetic model rats were induced by intraperitoneal injection of streptozotocin (STZ). After grouped randomly, diabetic rats were administered low or high dose of HLW extract, acarbose and vehicle for 33 days, respectively. Body weight, food intake, urine volume, urine sugars, fasting plasma glucose and fasting plasma insulin were monitored to evaluate its antidiabetic effects in diabetic rats. Intestinal mucosa homogenate was prepared and the activities of intestinal disaccharidases were assayed. Moreover, oral sucrose tolerance test (OSTT) was performed and the inhibitory effect of HLW extract on the maltase and sucrase in vitro was evaluated.

RESULTS

After the treatment of HLW extract, the body weight and the fasting plasma insulin level were found to be increased while food intake, urine volume, urine sugars and fasting plasma were decreased. OSTT showed that HLW extract could lower the postprandial plasma glucose level of diabetic rats. Furthermore, HLW extract could inhibit the activities of sucrase and maltase in vitro.

CONCLUSIONS

According to our present findings, the TCM prescription HLW possessed potent anti-hyperglycemic effect on STZ-induced diabetic rats. And HLW extract exerted anti-hyperglycemic effect partly via inhibiting the increased activities of intestinal disaccharidases and elevating the level of plasma insulin in diabetic rats induced by streptozotocin.

The human lactase persistence-associated SNP -13910*T enables in vivo functional persistence of lactase promoter-reporter transgene expression

Lactase is the intestinal enzyme responsible for digestion of the milk sugar lactose. Lactase gene expression declines dramatically upon weaning in mammals and during early childhood in humans (lactase nonpersistence). In various ethnic groups, however, lactase persists in high levels throughout adulthood (lactase persistence). Genetic association studies have identified that lactase persistence in northern Europeans is strongly associated with a single nucleotide polymorphism (SNP) located 14 kb upstream of the lactase gene: -13910*C/T. To determine whether the -13910*T SNP can function in vivo to mediate lactase persistence, we generated transgenic mice harboring human DNA fragments with the -13910*T SNP or the ancestral -13910*C SNP cloned upstream of a 2-kb rat lactase gene promoter in a luciferase reporter construct. We previously reported that the 2-kb rat lactase promoter directs a post-weaning decline of luciferase transgene expression similar to that of the endogenous lactase gene. In the present study, the post-weaning decline directed by the rat lactase promoter is impeded by addition of the -13910*T SNP human DNA fragment, but not by addition of the -13910*C ancestral SNP fragment. Persistence of transgene expression associated with the -13910*T SNP represents the first in vivo data in support of a functional role for the -13910*T SNP in mediating the human lactase persistence phenotype.

High lactose tolerance in North Europeans: a result of migration, not in situ milk consumption

The main carbohydrate in milk is lactose, which must be hydrolyzed to glucose and galactose before the sugars can be digested. While 65% or more of the total human population are lactose intolerant, in some human populations lactase activity commonly persists into adulthood. Lactose tolerance is exceptionally widespread in Northern European countries such as Sweden and Finland, with tolerance levels of 74% and 82%, respectively. Theoretically, this may result either from a strong local selection pressure for lactose tolerance, or from immigration of lactose tolerant people to Northern Europe. We provide several lines of archaeological and historical evidence suggesting that the high lactose tolerance in North Europeans cannot be explained by selection from in situ milk consumption. First, fresh cow milk has not belonged to the traditional diet of Swedes or Finns until recent times. Second, not enough milk has been available for adult consumption. Cattle herding has been neither widespread nor productive enough in Northern Europe to have provided constant access to fresh milk. We suggest that the high prevalence of lactose tolerance in Finland in particular may be explained by immigration of people representing so-called Corded Ware Culture, an early culture representing agricultural development in Europe.

Milk consumption and lactose intolerance in adults

OBJECTIVE

To investigate relations between milk consumption and lactose intolerance (LI) in adults and to explore the effect of milk consumption on lactase activity.

METHODS

Total of 182 subjects aged 20-70 years were recruited and interviewed by questionnaires, and their accumulative cow's milk intake (AMI) was calculated. LI was evaluated by hydrogen breath test (HBT).

RESULTS

A negative correlation was found between AMI and severity of observed LI symptom (r=-0.2884; P<0.05). Binary logistic regression analysis showed a negative correlation between LI and duration and frequency of milk consumption (OR, 0.317 and 0.465, respectively; both P<0.05) and a positive correlation between LI and amount of milk consumed per sitting (OR, 6.337; P<0.05).

CONCLUSION

LI is related to various milk consumption behaviors. Most Chinese adults with LI may tolerate moderate milk consumption <160 mL.

Chemo-enzymatic synthesis of ester-linked docetaxel-monosaccharide conjugates as water-soluble prodrugs

Three new docetaxel prodrugs, i.e., 7-propionyldocetaxel 3''-O-β-D-glycopyranosides, which contain ester-linked monosaccharides, were synthesized by a chemo-enzymatic procedure involving enzymatic transglycosylations with lactase, β-galactosidase, or β-xylosidase. The water-solubility of 7-propionyldocetaxel 3''-O-β-D-glucopyranoside was 52-fold higher than that of docetaxel. 7-Propionyldocetaxel 3''-O-β-D-glucopyranoside and 7-propionyldocetaxel 3''-O-β-D-xylopyranoside were effectively hydrolyzed by the relevant enzyme(s) of human cancer cells to release docetaxel, whereas 7-propionyldocetaxel 3''-O-β-D-galactopyranoside was relatively resistant under similar conditions. 7-Propionyldocetaxel 3''-O-β-D-glucopyranoside and 7-propionyldocetaxel 3''-O-β-D-xylopyranoside showed in vitro cytotoxic activity against human cancer cells, whereas 7-propionyldocetaxel 3''-O-β-D-galactopyranoside exerted low cytotoxicity.

[Effect of zinc deficiency on intestinal mucosal morphology and digestive enzyme activity in growing rat]

OBJECTIVE

In this study, a growing rat model of zinc deficiency was established to investigate the effect of zinc deficiency on intestinal mucosal morphology and digestive enzyme activity as well as to provide a scientific basis for zinc supplementation therapy in patients with diarrhea.

METHOD

Three-week-old weaned Sprague-Dawley male rats (n = 30) were randomly divided into 3 groups with 10 in each: rats in the control group (ZA) were fed with a normal diet containing 30 µg/g zinc; rats in the zinc deficient group (ZD) were fed with a zinc-deficient diet containing 0.4 µg/g zinc (refer to AIN-76 formula); and rats in the paired fed group (PF) were fed with a normal diet, but the food intake was limited to intake of rats in ZD group in the previous day. All rats were provided with deionized water for drinking. Their body weight was measured and the food intake during the previous day was recorded early in the morning of the following day. Symptoms of zinc deficiency, such as anorexia, diarrhea, dermatitis, and growth retardation, were observed. Two weeks later, the rats were sacrificed and serum zinc concentration was measured. Jejunal mucosa was taken for biopsy and was stained with hematoxylin and eosin (HE). The height ratio of the jejunal mucosal villi and crypts was measured. In addition, the activity of lactase in the jejunal mucosal brush border, γ-glutamyl peptidase (GGT), and aminopeptidase N (APN) were measured.

RESULT

The average weight of the rats in the ZA, ZD, and PF groups at the beginning of the experiment was (67.4 ± 5.3) g, (64.7 ± 4.8) g, and (66.5 ± 4.1) g, respectively, and the average daily food intake was (11.2 ± 1.0) g, (11.6 ± 1.6) g, and (11.2 ± 1.4) g, respectively. The intergroup differences were not significant. On the 7(th) day of experiment, no significant differences in average food intake were observed between the ZD group and the ZA and PF groups, but the average body weight in the ZD group was significantly lower than that in the ZA and PF groups (P < 0.01). At the end of the experiment (2 weeks), the average weight in the ZD group (112.0 ± 11.5) g was significantly lower than that in the ZA (164.0 ± 15.9) g and PF groups (137.5 ± 16.2) g. The average food intake in the ZD group (13.4 ± 5.1) g was significantly lower than that in the ZA group (18.2 ± 2.4) g (P < 0.01). Serum zinc level in the ZD group (733 ± 231) µg/L was significantly lower than that in the ZA (1553 ± 159) µg/L and PF groups (1457 ± 216) µg/L (P < 0.01). The height ratio of jejunal mucosa villus and crypt in the ZA, ZD, and PF groups was 2.98 ± 0.5, 2.77 ± 0.5, and 2.81 ± 0.7, respectively, and lactase activity was (26.1 ± 15.0) U/mg, (27.4 ± 12.8) U/mg, and (40.8 ± 18.5) U/mg, respectively, without significant intergroup differences. The GGT activity in the jejunal mucosa in the ZD group (12.7 ± 6.5) U/g was significantly lower than that in the ZA (19.1 ± 10.4) U/g and PF groups (18.5 ± 7.7) U/g, but the difference was not significant. The activity of APN in the jejunal mucosa in the ZD group (25.5 ± 7.5) U/g was significantly lower than that in the ZA (48.7 ± 16.8) U/g and PF groups (43.9 ± 14.5) U/g (P < 0.01).

CONCLUSION

Zinc deficiency can cause loss of appetite, weight loss, and decreased activity of peptidase in the jejunal mucosal brush border. Zinc deficiency has little effect on the height ratio of the villus and crypt and lactase activity, thereby indicating that zinc deficiency may first affect protein digestion and absorption.

Epigallocatechin-3-gallate inhibits lactase but is alleviated by salivary proline-rich proteins

Lactase phlorizin hydrolase is a small intestinal brush border enzyme that catalyzes the hydrolysis of the milk sugar, lactose, and also many flavonoid glucosides. We demonstrate that epigallocatechin-3-gallate (EGCG), the principal flavonoid from green tea, inhibits in vitro hydrolysis of lactose by intestinal lactase. We then tested the hypothesis that salivary proline-rich proteins (PRPs) could modulate this inhibition and stabilize EGCG. Inhibition by EGCG of digestive enzymes (α-amylase>chymotrypsin>trypsin>lactase≫pepsin) was alleviated ∼2-6-fold by PRPs. Furthermore, PRPs appeared stable to proteolysis and also stabilized EGCG under digestive conditions in vitro. This is the first report on EGCG inhibition of lactase, and it quantifies the protective role of PRPs against EGCG inhibition of digestive enzymes.

Longitudinal cell formation in the entire human small intestine is correlated with the localization of Hath1 and Klf4

BACKGROUND

Double balloon endoscopy (DBE) enables the observation and collection of viable specimens from the entire intestine, thereby allowing more detailed investigation of how the structure and function of the human small intestine are regulated. The present study aimed to elucidate the regulation of cell formation in the human small intestine using biopsy specimens collected from an entire individual small intestine by DBE.

METHODS

The expression and the localization of representative genes for the differentiation program were analyzed in the entire small intestine of 10 patients. The functional correlation between Hath1 and Klf4 was analyzed in an intestinal cell line by using a Tet-On system.

RESULTS

In longitudinal cell formation in the small intestine, it was shown that goblet cells, but not Paneth cells, increased toward the ileum in each individual small intestine. Immunohistochemistry showed that Hath1-expressing cells migrated from the base of the crypt to the top of the villi in the terminal ileum, while Klf4-expressing cells migrated from the top of the villus, resulting in the colocalization of Hath1 and Klf4 in the terminal ileum. Coexpression of Hath1 and Klf4 upregulated the expression of phenotypic genes for goblet cells following the downregulation of those for Paneth cells.

CONCLUSIONS

Using mapping biopsy by DBE, we have demonstrated, for the first time, the molecular basis of the villus structure in the entire human small intestine in vivo. The present study showed that longitudinal cell formation was regulated by the colocalization of Hath1 and Klf4 that converted Paneth cell differentiation into goblet cell differentiation.

Theodore E. Woodward Award: lactase persistence SNPs in African populations regulate promoter activity in intestinal cell culture

Lactase-phlorizin hydrolase, lactase, is the intestinal enzyme responsible for the digestion of the milk sugar lactose. The majority of the world's human population experiences a decline in expression of the lactase gene by late childhood (lactase non-persistence). Individuals with lactase persistence, however, continue to express high levels of the lactase gene throughout adulthood. Lactase persistence is a heritable autosomal dominant condition and has been strongly correlated with several single nucleotide polymorphisms (SNPs) located ∼14 kb upstream of the lactase gene in different ethnic populations: -13910*T in Europeans and -13907*G, -13915*G, and -14010*C in several African populations. The coincidence of the four SNPs clustering within 100 bp strongly suggests that this region mediates the lactase non-persistence/persistence phenotype. Having previously characterized the European SNP, we aimed to determine whether the African SNPs similarly mediate a functional role in regulating the lactase promoter. Human intestinal Caco-2 cells were transfected with lactase SNP/promoter-reporter constructs and assayed for promoter activity. The -13907*G and -13915*G SNPs result in a significant enhancement of lactase promoter activity relative to the ancestral lactase non-persistence genotype. Such differential regulation by the SNPs is consistent with a causative role in the mechanism specifying the lactase persistence phenotype.

Enzymatic synthesis and characterization of hydroquinone galactoside using Kluyveromyces lactis lactase

Hydroquinone galactoside (HQ-Gal) as a potential skin whitening agent was synthesized by the reaction of lactase (beta-galactosidase) from Kluyveromyces lactis, Aspergillus oryzae, Bacillus circulans, and Thermus sp. with lactose as a donor and HQ as an acceptor. Among these lactases, the acceptor reaction involving HQ and lactose with K. lactis lactase showed a higher conversion ratio to HQ-Gal (60.27%). HQ-Gal was purified using butanol partitioning and silica gel column chromatography. The structure of the purified HQ-Gal was determined by nuclear magnetic resonance, and the ionic product was observed at m/z 295 (C12H16O7Na)+ using matrix assisted laser desorption ionization time-of-flight mass spectrometry. HQ-Gal was identified as 4-hydroxyphenyl-beta-d-galactopyranoside. The optimum conditions for HQ-Gal synthesis by K. lactis determined using response surface methodology were 50 mM HQ, 60 mM lactose, and 20 U mL(-1) lactase. These conditions produced a yield of 2.01 g L(-1) HQ-Gal. The half maximal inhibitory concentration (IC50) of diphenylpicrylhydrazyl scavenging activity was 3.31 mM, indicating a similar antioxidant activity compared to beta-arbutin (IC50=3.95 mM). The Ki value of HQ-Gal (0.75 mM) against tyrosinase was smaller than that of beta-arbutin (Ki=1.97 mM), indicating its superiority as an inhibitor. HQ-Gal inhibited (23%) melanin synthesis without being significantly toxic to the cells, while beta-arbutin exhibited only 8% reduction of melanin synthesis in B16 melanoma cells compared with the control. These results indicate that HQ-Gal may be a suitable functional component in the cosmetics industry.

Determinants of geographic patterns of diseases: interaction of lactose/lactase status and sunshine exposure

Geographic patterns of diseases depend on multilayered causes. However, the division of the world's population into two phenotypes regarding lactose digestion and sunshine exposure to fixed areas of the globe are two relatively slow changing variables. It is hypothesized that it is a vectorial interaction between these two variables that provide a backbone to risk modification of many diseases. Lactase non persistence status tends to follow sunshine exposure particularly in Europe but Lactase persistence status is also been shown to be related to pastoral life styles in spotty regions of Africa, Middle East and China. Current emphasis of research favours the modifying role of vitamin D and sunshine. Nevertheless it was demonstrated that national digester/nondigester status has mathematical relationships to geographic distribution of some diseases. These relationships are also similar to that described for the effects of latitude through sunshine and vitamin D. This observation raises a question as to how each one affects disease outcome. In this paper lactose/lactase interactions are first reviewed for eight exemplary diseases. Based on population findings and corroborative meta-analyses gleaned from the literature 6 types of interactions may be classified. Then in a preliminary fashion lactose digester and maldigester status are related to relative annual sunshine exposure. Further the relative national annual sunshine exposure is evaluated to outcomes of the same exemplary diseases. The patterns related to sunshine reflect that obtained with national lactase status proportions and also corroborate a literature review. However, correlations are weak to moderate and only ovarian cancer reached conventional statistical significance. Because these comparisons are based on modest number of national data firm conclusions cannot be made. However, it is argued that evolutionary pressures exerted by regional sunshine exposure may have had influence on a number of relevant genetic polymorphisms in parallel with lactase status. Furthermore influences of ancestral herding and dairy food consumption also may have exerted independent influences on either lactose phenotype. As such both discussed variables are postulated to exert parallel as well as independent effects on modifying geographic disease patterns. These could partly explain both north to south and west to east directional changes.

[Nutrition and bone health. Lactose and bone]

Lactose, a disaccharide in milk or dairy products, is known to promote calcium absorption. The enzyme lactase is needed to digest lactose. Although lactase is secreted normally in childhood, the secretion is decreased with growth, and the activity becomes lower in adulthood. When the activity of lactase is low, lactose passes intact the small intestine and reaches the large intestine, could cause unpleasantness such as diarrhea and stomach ache. This is called lactose intolerance. In this paper, we discuss promotion of calcium absorption by lactose, lactose intolerance, and bone health.

Effect of aqueous leaf extract of Momordica charantia on intestinal enzyme activities in diarrhoeagenic mice

BACKGROUND

Momordica charantia (MC), an annual tropical plant has been reported to possess numerous medicinal properties. The aqueous extract of the plant had been earlier evaluated for its anti-diarrhoeal potential in castor oil-induced diarrhoea model.

OBJECTIVE

The objective of the present study is to evaluate the effect of aqueous leaf extract of M. charantia on the activities of the intestinal enzymes in castor oil-induced diarrhoeagenic mice for 48 h-duration.

METHODS

Diarrhoea was induced by oral administration of castor oil in mice. Mice in Group 1 were given distilled water; Group 2 received 0.2 ml of castor oil. Groups 3-4 received 100, 200 and 400 mg/kg body weight of the aqueous leaf extract respectively. The animals were sacrificed by cervical dislocation at 0, 2, 5, 7, 24, and 48 hours. Enzymatic activities and protein concentration in the intestinal mucosa homogenate were then analyzed at 0, 2, 5, 7, 24, and 48 hours.

RESULTS

Effect of graded doses (100-400 mg/kg) of M. charantia on intestinal alkaline phosphatase showed decrease in activity at 48 hours, while the reductive effect was significantly expressed in the castor oil than in the control and extract treated groups. Disaccharidases (lactase, maltase and sucrase) activities were significantly reduced in the castor oil group when compared with the extract treated groups and the control. The reduction in protein concentration was also observed in the castor oil group compared to the control and extract treated groups.

CONCLUSION

The aqueous leaf extract of MC increased enzymes activities (maltase, sucrase and lactase) in the extract treated diarrhoeagenic mice enhancing the absorptive role of these enzymes in the small intestine. This could prevent malnutrition and loss of these enzymes in diarrhoeal conditions.

Effects of galacto-oligosaccharide ingestion on the mucosa-associated mucins and sucrase activity in the small intestine of mice

BACKGROUND

Galacto-oligosaccharides (GOS) are non-digestible oligosaccharides with short galactosyl chain units produced by lactose fermentation which are considered as prebiotics. Only few studies have investigated the effects of GOS medium-term ingestion on the small intestinal epithelium characteristics.

AIM OF THE STUDY

In this study, we evaluated the consequences of GOS ingestion on small intestinal mucosal morphology, on brush-border membrane enzyme activities and on mucin content in BALB/c mice.

METHODS

Mice received the experimental diets for 4 weeks and then the small intestine was collected to measure sucrase, lactase and alkaline phosphatase activities, to study the villus heights in the jejunum mucosa and to determine mucosal mucin content as well as MUC-2 and MUC-4 mRNAs expression by qRT-PCR.

RESULTS

Our results showed that GOS has no detectable effect on the intestine villus height but increased the total protein content by twofold. Sucrase activity was significantly increased in the intestinal mucosa recovered from animals fed the GOS diet without any detectable modification of lactase and phosphatase activities. Interestingly, GOS was also able to increase sucrase activity in cultured Caco-2 cells raising the view that they likely act directly on these cells. Furthermore, GOS was found to markedly increase O-linked glycoproteins associated with the intestinal mucosa without modifying MUC-2, MUC-4 mRNAs expression. Lastly, TNF-alpha mRNA expression was also not modified after GOS ingestion.

CONCLUSIONS

These results suggest that, in BALB/c mice, 4-week GOS ingestion is able to increase the small intestinal mucosa-associated mucin content and enterocyte-associated sucrase activity without modifying villus height.