Comparative effects of exogenous lactase (beta-galactosidase) preparations on in vivo lactose digestion

Innovative concepts in diet therapies in disorders of gut-brain interaction

Diet therapy in disorders of gut-brain interaction (DGBI) is rapidly advancing, with accumulating evidence to support two innovative therapies-manipulation of dietary fibers and enzyme supplementation-that target specific DGBI pathophysiology and modulate digestion. Dietary fibers escape digestion in the upper gastrointestinal tract and can influence gut function by impacting digestion, improving laxation, and interacting with the microbiota. A more nuanced understanding of different fiber types and their ability to impact gut function in highly specific ways has shown that fibers can impact distinct gut symptoms and pathophysiology. By considering their functional characteristics of bulking, gel-forming, and fermentability, restriction or supplementation of specific fibers can offer clinical value in DGBI. Similarly to fiber specificity, emerging evidence suggests that supplemental digestive enzymes may be targeted to known food triggers with consideration that enzymes are substrate specific. Limited evidence supports use of lactase to target lactose, and α-galactosidase to target galacto-oligosaccharides. Application of enzymes during manufacturing of food products may prove to be an additional strategy, although evidence is scant. Both innovative therapies may be utilized in isolation or in combination with other diet and nondiet therapies. Implementation can be guided by the principles that fiber modulation can be targeted to specific symptomology or requirement for alterations to gut function, and digestive enzymes can be targeted to known food triggers. This review aims to summarize recent literature of these two innovative concepts and provide practical suggestions for their implementation in clinical practice.

Exploring Therapeutic Digestive Enzyme Landscape in India: Current Evidence, Profit Motives, Regulations, and Future Perspectives

This analysis critically examines the profit-driven marketing of digestive enzymes as over-the-counter (OTC) supplements in the context of India, expressing ethical concerns regarding pharmaceutical companies prioritizing financial gain over genuine public health needs within the lucrative OTC supplement market. The review delves into various enzymes, their mechanisms of action, uses, adverse drug reactions, and provides evidence from various studies. The research method involves the exploration of profit-driven strategies employed by pharmaceutical companies, addressing regulatory challenges, investigating the gap between dietary supplements and pharmaceutical drugs, and emphasizing the impact of direct-to-consumer advertising on self-diagnosis and overuse. Additionally, the study reviews various e-pharmacy platforms in India, assessing formulations and pricing. Key findings highlight the diverse formulations on these platforms, exposing insights into cost variations and indicating a regulatory gap that necessitates a comprehensive re-evaluation by Indian and international authorities. The analysis emphasizes the influence of direct-to-consumer advertising on behavior and potential health risks, raising ethical concerns about oversimplified health claims that overlook the necessity for individualized treatment plans. In conclusion, the study underscores the ethical complexity of prioritizing profit over public health and advocates for regulatory re-evaluation, exploring broader implications such as cultural influences and alternative therapies. The evolving landscape, featuring plant-based and microbe-derived alternatives, is presented as transformative, particularly in conditions like celiac disease.

Fungal digestive enzymes promote macronutrient hydrolysis in the INFOGEST static in vitro simulation of digestion

The objective of this study was to test the hydrolytic efficacy of 6 fungal enzymes in the INFOGEST static in vitro simulation of gastrointestinal (GI) digestion. First, the INFOGEST protocol was adapted for testing of exogenous enzymes. Second, a dose-response study of 3 individual fungal proteases, a lipase, and an amylase with glucoamylase demonstrated improved dietary protein, lipid, and carbohydrate hydrolysis, respectively, from an oral nutritional supplement (ONS) under simulated gastric or GI conditions, compared to pepsin and pancreatin-based control conditions. Third, a combination of the 6 enzymes (BC-006) improved macronutrient digestion, including enhanced release of individual amino acids from ONS and mixed meal substrates. Finally, we validated digestive models of aging and proton pump inhibitor (PPI) use, and showed that BC-006 improved gastric digestion under these compromised digestive conditions. The INFOGEST static simulation is a feasible tool to rapidly screen and profile exogenous enzymes for digestive efficacy in vitro.

Fermented foods and probiotics: An approach to lactose intolerance

The aim of this review was to present various topics related to lactose intolerance with special attention given to the role of fermented foods and probiotics in alleviating gastrointestinal symptoms. Lactose intolerance is a common digestive problem in which the human body is unable to digest lactose, known as milk sugar. Lactose intolerance can either be hereditary or a consequence of intestinal diseases. Recent work has demonstrated that fermented dairy products and probiotics can modify the metabolic activities of colonic microbiota and may alleviate the symptoms of lactose intolerance. We suggest that, lactose free dairy products could be recommended as alternatives for the alleviation of lactose intolerance and for the promotion of human health and wellness.

Cloning, expression, and bioinformatics analysis and characterization of a β-galactosidase from Bacillus coagulans T242

The activities of β-galactosidases from bacteria and molds are affected by temperature, pH, and other factors in the processing of dairy products, limiting their application, so it is necessary to find alternative lactases. In this study, the β-galactosidase gene from Bacillus coagulans T242 was cloned, co-expressed with a molecular chaperone in Escherichia coli BL21, and subjected to bioinformatic and kinetic analyses and lactase characterization. The results show that the enzyme is a novel thermostable neutral lactase with optimum hydrolytic activity at pH 6.8 and 50°C. The thermal stability and increased lactose hydrolysis activity of β-galactosidase in the presence of Ca²⁺ indicated its potential application in the dairy industry.

Lactose Intolerance, Dairy Avoidance, and Treatment Options

Lactose intolerance refers to symptoms related to the consumption of lactose-containing dairy foods, which are the most common source for this disaccharide. While four causes are described, the most common is the genetically-determined adult onset lactose maldigestion due to loss of intestinal lactase governed by control of the gene by a 14,000 kb promoter region on chromosome 2. Gastrointestinal symptoms from lactose have expanded to include systemic effects and have also been confounded by other food intolerances or functional gastrointestinal disorders. Partly because lactose maldigestion is often interpreted as lactose intolerance (symptoms), focus of therapy for these symptoms starts with lactose restriction. However, withholding of dairy foods completely is not appropriate due to a more favorable impact on health. Industrial efforts to substitute with plant-based products is not completely successful at this time. This narrative article reviews the complexities of the perception of lactose intolerance, its epidemiology, and pathogenesis. Treatments are discussed, including the inappropriateness of dairy avoidance. In conjunction, effects of dairy products on 19 common diseases are reviewed. Different methods of treatment, lactose-reduced products, plant-based dairy substitutes, adaptation, prebiotics, exogenous lactase, probiotics, and some other dietary interventions are further discussed.

Increasing Symptoms in Irritable Bowel Symptoms With Ingestion of Galacto-Oligosaccharides Are Mitigated by α-Galactosidase Treatment

OBJECTIVES

Galacto-oligosaccharides (GOS) are dietary FODMAPs (fermentable carbohydrates) associated with triggering gastrointestinal symptoms in patients with irritable bowel syndrome (IBS). This randomized, double-blind, placebo-controlled, cross-over trial aimed to assess whether oral α-galactosidase co-ingestion with foods high in GOS and low in other FODMAPs would reduce symptoms.

METHODS

Patients meeting the Rome III criteria for IBS who were hydrogen-producers on breath testing were recruited. Participants were treated with full-dose (300 GALU (galactosidic units) α-galactosidase) and half-dose enzyme (150 GALU α-galactosidase), and placebo (glucose) in a random order with ≤14 days washout between arms. Following a 3-day low FODMAP run-in period, participants consumed provided diets high in GOS for a further 3-days. Gastrointestinal symptoms were measured daily using a 100 mm visual-analogue-scale, and breath samples taken hourly on the second last day with hydrogen content analysed as area-under-the-curve.

RESULTS

Thirty-one patients with IBS (20 IBS-D, 4 IBS-C, 7 IBS-M) completed the study. The addition of high GOS foods resulted in a significant increase in overall symptoms with 21 patients exhibiting GOS-sensitivity (>10 mm increase for overall symptoms). Of those, full-dose enzyme reduced overall symptoms (median 24. 5(IQR 17.5-35.8) vs. 5.5(1.5-15.0) mm; P=0.006) and bloating (20.5(9.5-42.0) vs. 6.5(2.0-15.8); P=0.017). Breath hydrogen production was minimal with no differences seen between placebo and full-dose (P=0.597).

CONCLUSIONS

Oral α-galactosidase taken with high GOS foods provides a clinically significant reduction in symptoms in GOS-sensitive individuals with IBS. This strategy can be translated into practice to improve tolerance to high GOS foods as an adjunct therapy to the low FODMAP diet.

Effect of probiotic strain Lactobacillus acidophilus (LBKV-3) on fecal residual lactase activity in undernourished children below 10 years

Clinically proven Lactobacillus acidophilus strain LBKV-3 intended as probiotic for humans was used to test its effect on fecal residual lactase activity in undernourished children below 10 years of age. The children were selected from malnutrition-declared area of Maharashtra (India). One of the major causes of malnutrition is lactose intolerance which leads to diarrhea. The basic consideration in selecting the probiotic strain of L. acidophilus (LBKV-3) in this investigation was the fact that the organism is isolated from human vaginal surface swab and it was found extensively studied for probiotic characteristic. LBKB₃ is tested by several workers as probiotic for hypocholesterolemic activity, implantation ability, therapeutic effects on gastrointestinal (GI) and related ailments. The results of present investigation have shown that the fecal residual lactase activity significantly increased than its initial value (which was almost zero). It appeared that the fecal residual β-galactosidase activity is an indication of positive implementation abilities of the cultures under investigation. These trends were compared with the control and blank group of children receiving Dahi and buffalo milk (BM). It was observed that both these products failed to exert any significant impact on increase in residual lactase activity.

Digestive Enzyme Supplementation in Gastrointestinal Diseases

BACKGROUND

Digestive enzymes are able to break down proteins and carbohydrates and lipids, and their supplementation may play a role in the management of digestive disorders, from lactose intolerance to cystic fibrosis. To date, several formulations of digestive enzymes are available on the market, being different each other in terms of enzyme type, source and origin, and dosage.

METHODS

This review, performed through a non-systematic search of the available literature, will provide an overview of the current knowledge of digestive enzyme supplementation in gastrointestinal disorders, discussion of the use of pancreatic enzymes, lactase (β-galactosidase) and conjugated bile acids, and also exploring the future perspective of digestive enzyme supplementation.

RESULTS

Currently, the animal-derived enzymes represent an established standard of care, however the growing study of plant-based and microbe-derived enzymes offers great promise in the advancement of digestive enzyme therapy.

CONCLUSION

New frontiers of enzyme replacement are being evaluated also in the treatment of diseases not specifically related to enzyme deficiency, whereas the combination of different enzymes might constitute an intriguing therapeutic option in the future.

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.

Enteric-coated capsule containing β-galactosidase-loaded polylactic acid nanocapsules: enzyme stability and milk lactose hydrolysis under simulated gastrointestinal conditions

In order to protect peroral β-galactosidase from being degraded and hydrolyse milk lactose efficiently in the environments of gastrointestinal tract, a double-capsule delivery system composed of enteric-coated capsule and polylactic acid (PLA) nanocapsules (NCs) was developed for encapsulation of β-galactosidase. β-galactosidase-loaded PLA NCs in the size range of 100–200 nm were prepared by a modified w1/o/w2technique. During the encapsulation process, dichloromethane/ethyl acetate (1 : 1, v/v) as the solvent composition, high-pressure homogenisation (150 bar, 3 min) as the second emulsification method and polyvinyl alcohol or Poloxamer 188 as a stabiliser in the inner phase could efficiently improve the activity retention of β-galactosidase (>90%). Subsequently, the prepared NCs were freeze-dried and filled in a hydroxypropyl methylcellulose phthalate (HP55)-coated capsule. In vitro results revealed that the HP55-coated capsule remained intact in the simulated gastric fluid and efficiently protected the nested β-galactosidase from acidic denaturation. Under the simulated intestinal condition, the enteric coating dissolved rapidly and released the β-galactosidase-loaded PLA NCs, which exhibited greater stability against enzymatic degradation and higher hydrolysis ratio (∼100%) towards milk lactose than the free β-galactosidase. These results suggest that this double-capsule delivery system represents promising candidate for efficient lactose hydrolysis in the gastrointestinal tract.

Fermentable oligosaccharides, disaccharides, monosaccharides and polyols: role in irritable bowel syndrome

Irritable bowel syndrome (IBS) was previously left poorly treated despite its high prevalence and cost. Over the past decade, significant research has been conducted providing new dietary strategies for IBS management. The 'low fermentable oligosaccharides, disaccharides, monosaccharides and polyols diet' has shown symptom improvement in 68-76% of patients. Randomized, controlled trials have now proven its efficacy. The diet, low in poorly absorbed and fermentable carbohydrates, uses dietary restriction and re-challenge to determine individual tolerance to various short-chain carbohydrates. However there may be potential detrimental effects of the diet in the long term, due to potential changes to the gastrointestinal microbiota. Appropriate dietary education and management of the diet is imperative. Future research should focus on the relevance of changes to the microbiota and ways to liberalize the dietary restrictions.

Treatment of both native and deamidated gluten peptides with an endo-peptidase from Aspergillus niger prevents stimulation of gut-derived gluten-reactive T cells from either children or adults with celiac disease

Celiac disease (CD) is characterized by an inappropriate immunological reaction against gluten driven by gluten-specific CD4+ T cells. We screened 25 proteases and tested 10 for their potential to degrade gluten in vitro. Five proteases were further tested for their ability to prevent the proliferative response by a gluten-specific CD4+ T cell clone and seven gluten-reactive T cell lines to protease-digested gluten peptides. A proline-specific endo-peptidase from Aspergillus niger (AnP2) was particularly efficient at diminishing proliferation after stimulation with cleaved antigen, and could completely block the response against both native and deamidated gluten peptides. We found that AnP2 was efficient down to a 1:64 protease:substrate ratio (w:w). When AnP2 was tested in assays using seven gluten-reactive T cell lines from individual CD patients (three adults and four children), the response to gluten was diminished in all cases. Our study indicates a therapeutic benefit of AnP2 to CD patients.

Clinical implications of lactose malabsorption versus lactose intolerance

The majority of the world's adult population and an estimated 80 million Americans are hypolactasic and hence malabsorb ingested lactose. Although lactose malabsorption is easily identified, less readily assessed is the clinically important question of how often does this malabsorption induce symptoms. This review summarizes: (1) knowledge concerning the etiology and diagnosis of hypolactasia and the pathophysiology of the symptoms of lactose malabsorption and (2) the results of well-controlled trials of the symptomatic response of lactose malabsorbers to varying dosages of lactose and the efficacy of therapeutic interventions to alleviate these symptoms. We conclude that the clinical significance of lactose malabsorption has been overestimated by both the lay public and physicians in that commonly ingested doses of lactose (ie, the quantity in a cup of milk) usually do not cause perceptible symptoms when ingested with a meal. Symptoms occur when the lactose dosage exceeds that in a cup of milk or when lactose is ingested without other nutrients. Simple dietary instruction, rather than the use of commercial products to reduce lactose intake, is recommended for the vast majority of lactose-malabsorbing subjects.

Beneficial effects of long-term consumption of a probiotic combination of Lactobacillus casei Shirota and Bifidobacterium breve Yakult may persist after suspension of therapy in lactose-intolerant patients

BACKGROUND

The efficacy of some probiotic strains for the management of lactose intolerance remains to be established.

AIM

To evaluate the effects of a 4-week consumption of a probiotic product containing Lactobacillus casei Shirota and Bifidobacterium breve Yakult (10(7)-10(9) CFU of each strain) on symptoms and breath hydrogen exhalation after a lactose load in lactose-intolerant patients and whether the beneficial results persisted after probiotic discontinuation.

METHODS

Twenty-seven patients with lactose maldigestion and intolerance participated in this study, which comprised 4 hydrogen breath tests: baseline condition (20 g lactose), after lactase ingestion (9000 FCC units), at the end of 4-week probiotic supplementation, and a follow-up test performed 3 months after probiotic discontinuation. For each test, the area under the breath hydrogen concentration vs time curve (AUC(180 min)) was calculated, and symptom scores were recorded.

RESULTS

The probiotic combination significantly reduced symptom scores (P < .01) and breath hydrogen AUC (P = .04) compared with the baseline condition. The comparison with the lactase test showed that symptom scores were similar (P > .05), despite the significantly higher (P = .01) AUC values after probiotic use. In the follow-up test, symptom scores and breath hydrogen AUC values remained similar to those found at the end of probiotic intervention.

CONCLUSION

Four-week consumption of a probiotic combination of L casei Shirota and B breve Yakult seems to improve symptoms and decrease hydrogen production intake in lactose-intolerant patients. These effects may persist for at least 3 months after suspension of probiotic consumption.

Targeted PLGA microparticles as a novel concept for treatment of lactose intolerance

BACKGROUND

Peroral β-galactosidase preparations for the management of lactose intolerance need to be administered in large doses (1500 to 6000 U) immediately before or together with a lactose-containing meal.

AIM

Therefore, this work aimed at developing an innovative long-acting formulation. For this purpose, biodegradable polymeric microcarriers were functionalized with β-galactosidase and targeted with wheat germ agglutinin (WGA) for bioadhesion and thus prolonged residence time in the small intestine.

METHODS

Spray-dried poly(D,L-lactide-co-glycolide) (PLGA) particles with 2.78±1.05µm in diameter were functionalized with β-galactosidase from Kluyveromyces lactis and WGA using different types of spacers (polyethyleneimine, hexamethylene diamine, 6-aminocaproic acid) and coupling methods (carbodiimide and glutaraldehyde). The particle-bound enzyme activity was determined, and the bioadhesive characteristics were assessed by interaction with mucin coatings and Caco-2 cell monolayers.

RESULTS

Up to 1470 U β-galactosidase per gram PLGA were immobilized. The best results were obtained with hexamethylene diamine as a spacer applying the carbodiimide method. Thereby, a nearly 6-fold increase in enzyme activity was obtained as compared to particles without spacer. Upon targeting with WGA, binding to artificial human intestinal epithelium was increased considerably.

CONCLUSIONS

For the delivery of β-galactosidase WGA-targeted PLGA microparticles were prepared, which represent promising candidates for a convenient biomimetic treatment regimen of lactose intolerance.

An acidophilic beta-galactosidase from Bispora sp. MEY-1 with high lactose hydrolytic activity under simulated gastric conditions

BgalA, a full-length gene (3,009 bp) that encodes a beta-galactosidase, was cloned from the meso-acidophilic fungus Bispora sp. MEY-1 and expressed in Pichia pastoris. The deduced amino acid sequence of BgalA shares highest identity (55.5%) with the beta-galactosidase from Aspergillus phoenicis, which belongs to the glycoside hydrolyase family 35. Purified recombinant BgalA is acidophilic, exhibiting maximum activity at pH 1.5, which is lower than that reported for other beta-galactosidases. The enzyme has high pH and thermal stability and is resistant to proteases and cations found in milk. The K(m) and V(max) of BgalA for 2-nitrophenyl-beta-D-galactopyranoside and lactose are 5.22 mM and 120.8 micromol/(min x mg), and 0.31 mM and 137.3 micromol/(min x mg), respectively. Under simulated gastric conditions, BgalA has greater stability ( approximately 100%) and hydrolysis ratio (>80%) toward milk lactose than the commercially available beta-galactosidase from Aspergillus oryzae (ATCC 20423). Thus, BgalA may be a better digestive supplement for alleviating symptoms associated with lactase deficiency.

Review article: lactose intolerance in clinical practice--myths and realities

BACKGROUND

Approximately 70% of the world population has hypolactasia, which often remains undiagnosed and has the potential to cause some morbidity. However, not everyone has lactose intolerance, as several nutritional and genetic factors influence tolerance.

AIMS

To review current clinical practice and identify published literature on the management of lactose intolerance.

METHODS

PubMed was searched using the terms lactose, lactase and diet to find original research and reviews. Relevant articles and clinical experience provided the basis for this review.

RESULTS

Lactose is found only in mammalian milk and is hydrolysed by lactase in the small intestine. The lactase gene has recently been identified. 'Wild-type' is characterized by lactase nonpersistence, often leading to lactose intolerance. Two genetic polymorphisms responsible for persistence have been identified, with their distribution concentrated in north Europeans. Symptoms of lactose intolerance include abdominal pain, bloating, flatulence and diarrhoea. Diagnosis is most commonly by the lactose hydrogen breath test. However, most people with hypolactasia, if given appropriate advice, can tolerate some lactose-containing foods without symptoms.

CONCLUSION

In clinical practice, some people with lactose intolerance can consume milk and dairy foods without developing symptoms, whereas others will need lactose restriction.

Purification and properties of a β-galactosidase with potential application as a digestive supplement

Functional-based screening of crude beta-galactosidase activities from 42 yeast strains resulted in the selection of a single enzyme of potential interest as a digestive supplement. beta-Galactosidase produced by Kluyveromyces marxianus DSM5418 was purified to homogeneity by a combination of gel filtration, ion-exchange, and hydroxylapatite chromatographies. The denatured (123 kDa) and native molecular masses (251 kDa) suggest that the enzyme is a homodimer. The optimum pH and temperature of the purified enzyme were 6.8 and 37 degrees C, respectively. The unpurified beta-galactosidase in particular displayed a high level of stability when exposed to simulated intestinal conditions in vitro for 4 h. Matrix-assisted laser desorption ionization mass sectrometry analysis revealed that the enzyme's trypsin-generated peptide mass fingerprint shares several peptide fragment hits with beta-galactosidases from Kluyveromyces lactis. This confirms the enzyme's identity and indicates that significant sequence homology exists between these enzymes.

Management and treatment of lactose malabsorption

Lactose malabsorption is a very common condition characterized by intestinal lactase deficiency. Primary lactose malabsorption is an inherited deficit present in the majority of the world’s population, while secondary hypolactasia can be the consequence of an intestinal disease. The presence of malabsorbed lactose in the colonic lumen causes gastrointestinal symptoms. The condition is known as lactose intolerance. In patients with lactase nonpersistence, treatment should be considered exclusively if intolerance symptoms are present. In the absence of guidelines, the common therapeutic approach tends to exclude milk and dairy products from the diet. However, this strategy may have serious nutritional disadvantages. Several studies have been carried out to find alternative approaches, such as exogenous β-galactosidase, yogurt and probiotics for their bacterial lactase activity, pharmacological and non pharmacological strategies that can prolong contact time between enzyme and substrate delaying gastrointestinal transit time, and chronic lactose ingestion to enhance colonic adaptation. In this review the usefulness of these approaches is discussed and a therapeutic management with a flow chart is proposed.

Effect of exogenous beta-galactosidase in patients with lactose malabsorption and intolerance: a crossover double-blind placebo-controlled study

OBJECTIVE

To evaluate the efficacy of the addition to milk, 5 min and 10 h before its consumption, of a lactase obtained from Kluyveromyces lactis in lactose malabsorbers with intolerance.

DESIGN

Double-blind, placebo-controlled, crossover study.

SETTING

University Hospital.

SUBJECTS

In total, 11 male and 19 female (aged from 18 to 65 y, mean age 43.3 y) lactose malabsorbers with intolerance participated.

INTERVENTIONS

Each patient underwent three H(2) breath tests, in a random order. We used 400 ml of cow's semiskimmed milk as substrate and a beta-galactosidase obtained from K. lactis. The test A was carried out adding to the milk the enzyme (3000 UI), 10 h before its consumption; the test B was performed adding the beta-galactosidase (6000 UI) 5 min before milk ingestion and the test C was made using placebo. We evaluated the maximum breath H(2) concentration, the cumulative H(2) excretion and a clinical score based on intolerance symptoms (bloating, abdominal pain, flatulence and diarrhoea).

RESULTS

Our study showed a significant reduction of the mean maximum H(2) concentration after both test A (12.07 +/- 7.8 p.p.m.) and test B (13.97 +/- 7.99 p.p.m.) compared with test C (51.46 +/- 16.12 p.p.m.) (ANOVA F = 54.33, P < 0.001). Similarly, there was a significant reduction of the mean cumulative H(2) excretion after both test A (1428 +/- 1156 p.p.m.) and test B (1761 +/- 966 p.p.m.) compared with test C (5795 +/- 2707 p.p.m.) (ANOVA F = 31.46, P < 0.001). We also observed a significant reduction of the mean clinical score after both test A (0.36 +/- 0.55) and test B (0.96 +/- 0.85) compared with test C (3.7 +/- 0.79) (ANOVA F = 106.81, P < 0.001). Moreover, with regard to the mean clinical score, there was a significant reduction after test A with respect to test B (Bonferroni's P = 0.03).

CONCLUSIONS

Our study shows that in lactose malabsorbers with intolerance, the lactase obtained from K. lactis can represent a valid therapeutic strategy, with objective and subjective efficacy and without side effects.

Genetic variation and lactose intolerance: detection methods and clinical implications

The maturational decline in lactase activity renders most of the world's adult human population intolerant of excessive consumption of milk and other dairy products. In conditions of primary or secondary lactase deficiency, the lactose sugars in milk pass through the gastrointestinal tract undigested or are partially digested by enzymes produced by intestinal bacterial flora to yield short chain fatty acids, hydrogen, carbon dioxide, and methane. The undigested lactose molecules and products of bacterial digestion can result in symptoms of lactose intolerance, diarrhea, gas bloat, flatulence, and abdominal pain. Diagnosis of lactose intolerance is often made on clinical grounds and response to an empiric trail of dietary lactose avoidance. Biochemical methods for assessing lactose malabsorption in the form of the lactose breath hydrogen test and direct lactase enzyme activity performed on small intestinal tissue biopsy samples may also be utilized. In some adults, however, high levels of lactase activity persist into adulthood. This hereditary persistence of lactase is common primarily in people of northern European descent and is attributed to inheritance of an autosomal-dominant mutation that prevents the maturational decline in lactase expression. Recent reports have identified genetic polymorphisms that are closely associated with lactase persistence and nonpersistence phenotypes. The identification of genetic variants associated with lactase persistence or nonpersistence allows for molecular detection of the genetic predisposition towards adult-onset hypolactasia by DNA sequencing or restriction fragment length polymorphism analysis. The role for such genetic detection in clinical practice seems limited to ruling out adult-onset hypolactasia as a cause of intolerance symptoms but remains to be fully defined. Attention should be paid to appropriate interpretation of genetic detection in order to avoid potentially harmful reduction in dairy intake or misdiagnosis of secondary lactase deficiency.

Kefir improves lactose digestion and tolerance in adults with lactose maldigestion

OBJECTIVE

Kefir is a fermented milk beverage that contains different cultures than yogurt. The objective of this study was to determine whether kefir improves lactose digestion and tolerance in adults with lactose maldigestion.

DESIGN

Randomized block design.

SUBJECTS

Fifteen healthy, free-living adults with lactose maldigestion.

MAIN OUTCOME MEASURES

Breath hydrogen excretion and lactose intolerance symptoms were monitored hourly for 8 hours after each test meal.

INTERVENTION

Subjects were fed test meals consisting of 20 g lactose portions of milk (2% reduced fat), plain and raspberry flavored kefir, and plain and raspberry flavored yogurt, each following an overnight (12 hour) fast.

STATISTICAL ANALYSIS

Mixed model ANOVA was performed on raw or transformed data, followed by Tukey HSD post hoc tests (when appropriate). Significance was defined as P<.05.

RESULTS

The breath hydrogen area under the curve (AUC) for milk (224+/-39 ppm x h) was significantly greater than for the plain yogurt (76+/-14 ppm x h, P<.001), the plain kefir (87+/-37 ppm x h, P<.001), and the flavored yogurt (76+/-14 ppm x h, P=.005). The flavored kefir had an intermediate response (156+/-26 ppm x h). The yogurts and kefirs all similarly reduced the perceived severity of flatulence by 54% to 71% relative to milk. Abdominal pain and diarrhea symptoms were negligible among the five treatments.

APPLICATIONS/CONCLUSION

Because kefir improved lactose digestion and tolerance in this study, its use may be another potential strategy for overcoming lactose intolerance. Further studies of other types of kefir for improving lactose digestion are warranted.

Improved lactose digestion and intolerance among African-American adolescent girls fed a dairy-rich diet

OBJECTIVE

To determine whether African-American adolescent girls who were fed a dairy-rich diet for 21 days could adapt to lactose, experiencing an overall improvement in lactose tolerance as well as a decrease in hydrogen gas production.

DESIGN

Twenty-one-day dietary intervention study.

SUBJECTS/SETTING

Seventeen of 21 African-American girls (aged 11 to 15 years) enrolled in a calcium metabolism study chose to participate in the lactose tolerance study. Subjects were screened for any diseases, conditions, or medications that might alter calcium metabolism or colonic fermentation. Subjects were housed in a fraternity on the Purdue University, West Lafayette, Ind, campus, and were supervised 24 hours a day.

INTERVENTION

Subjects consumed a dairy-based diet averaging 1,200 mg calcium and 33 g lactose per day for 21 days. Lactose digestion was assessed by an 8-hour breath hydrogen test on days 1 and 21, and symptoms of intolerance (abdominal pain, bloating, flatulence, and diarrhea) were evaluated hourly on a ranked scale during the breath hydrogen tests and once each evening during the 21-day feeding period.

MAIN OUTCOME MEASURES

A comparison of breath hydrogen production and gastrointestinal symptoms at the beginning and end of the study.

STATISTICAL ANALYSES PERFORMED

The Wilcoxon signed ranks test was used to compare the area under the curve for the 2 breath hydrogen tests. Spearman's p test for trend was used to determine whether there was a change in symptoms. All statistical analyses were 2-tailed and significance was set at P = .05.

RESULTS

Fourteen of the 17 subjects had lactose maldigestion. Breath hydrogen excretion decreased significantly (P < .03) from the beginning (148.3 +/- 27.0 ppm x hours) to the end (100.7 +/- 19.3 ppm x hours) of the 21-day period. Gastrointestinal symptoms were negligible during both the breath hydrogen tests as were symptoms during the 21-day period.

APPLICATIONS/CONCLUSIONS

The diet was well tolerated by the subjects. Furthermore, the decrease in breath hydrogen suggests colonic adaptation to the high-lactose diet. The results indicate that lactose maldigestion should not be a restricting factor in developing adequate calcium diets for this population. The existence of lactose maldigestion does not result in lactose intolerance in this population when it is fed a dairy-rich diet.

When to suspect lactose intolerance. Symptomatic, ethnic, and laboratory clues

Lactose intolerance is widespread, with adult-type hypolactasia being the predominant cause of lactose malabsorption. Daily ingestion of less than 240 mL of milk is well tolerated by most lactose-intolerant adults. Some persons with normal lactase activity may become symptomatic on consumption of products containing lactose. Lactose maldigestion may coexist in adults with irritable bowel syndrome and in children with recurrent abdominal pain. Management consists primarily of dietary changes. People who avoid dairy products should receive calcium supplementation and should be advised to read ingredient labels carefully. Several lactase replacement products are available, but their efficacy varies.

Allaying fears and fallacies about lactose intolerance

Public awareness and misunderstandings of lactose intolerance are at an all-time high. Many people erroneously believe they are lactose intolerant or develop gastrointestinal symptoms after intake of lactose. Consequently, lactose-containing foods such as milk and other dairy foods may be eliminated unnecessarily from the diet. Because these foods are a major source of calcium, low intake of them can compromise calcium nutriture. This, in turn, can increase the risk of major chronic diseases such as osteoporosis (porous bones) and hypertension. This review is intended to help dietetics professionals alleviate clients' fears about lactose intolerance and recommend dietary strategies to improve tolerance to lactose. Scientific findings indicate that the prevalence of lactose intolerance is grossly overestimated. Other physiologic and psychologic factors can contribute to gastrointestinal symptoms that mimic lactose intolerance. Scientific findings also indicate that people with laboratory-confirmed low levels of the enzyme lactase can consume 1 serving of milk with a meal or 2 servings of milk per day in divided doses at breakfast and dinner without experiencing symptoms. Several dietary strategies are available to help lactose maldigesters include milk and other dairy foods in their diet without experiencing symptoms.

[Lactose intolerance and consumption of milk and milk products]

The disaccharide lactose is present as a natural component of foods only in milk and dairy products. In the gastrointestinal tract, lactose is hydrolysed by the enzyme beta-galactosidase (lactase) into glucose and galactose. These components are absorbed. With the exception of the caucasian race, the lactase activity decreases in most people at an age of 4 to 6 years. Lactose intake can cause symptoms of bloating, flatulence, abdominal pain, and diarrhea due to the lactose reaching the large intestine. This phenomenon is called lactose intolerance. It is generally recommended to those persons that they refrain from the consumption of milk and dairy products. However, most lactose intolerant people are able to digest small amounts of milk. They can also consume cheese that contains no (hard and semi-hard) or only small amounts of lactose (present in only 10% of soft cheeses). These products are very important sources of calcium. Compared to milk, the lactose content of yogurt is usually lower by about one third. Studies during the last 10 years have shown that in spite of its lactose content yogurt is very well tolerated by lactose intolerant persons. This advantage is ascribed to the presence of living lactic acid bacteria in fermented dairy products which survive passage through the stomach and also to the lactase present in these products.

Recurrent abdominal pain and lactose maldigestion in school-aged children

Recurrent abdominal pain of childhood affects 10 to 15% of school-aged children and leads to disability and learning difficulties. Lactose maldigestion may be a causative or contributory factor that when identified may lead to improvement. Thus, formal diagnostic testing using breath hydrogen lactose challenge methods is encouraged. This review focuses on this important condition and management options.

Improvement of lactose digestion in humans by ingestion of unfermented milk containing Bifidobacterium longum

Fifteen lactose malabsorbers were studied to evaluate the effects of consumption of milk containing different strains of Bifidobacterium longum on lactose digestion. Influences of different growth substrates, bile sensitivity, and lactose transport on lactose digestion by bifidobacteria were also investigated. Lactose malabsorption was determined by measuring breath hydrogen excretion of subjects fed four different test milks (three of which contained 5 x 10(8) cfu/ml of B. longum) on 4 different d using a randomized, double-blinded trial. Test milks included 1) 400 ml of lowfat milk (control), 2) 400 ml of milk containing B. longum B6 that had been grown with lactose, 3) 400 ml of milk containing B. longum B6 grown with lactose plus glucose, or 4) 400 ml of milk containing B. longum ATCC 15708 grown with lactose. beta-Galactosidase activity was highest in milk containing B6 grown with lactose but was extremely low in milk containing B6 grown with lactose and glucose. Consumption of milk containing B6 grown with lactose resulted in significantly less hydrogen production and flatulence than occurring after consumption of control milk or the milk containing B6 grown with both lactose and glucose. Hydrogen production after ingestion of 15708 was also significantly lower than hydrogen production after ingestion of the control milk. We concluded that milks containing B. longum might reduce breath hydrogen response and symptoms from lactose malabsorption when the culture is grown in a medium containing only lactose to induce a higher beta-galactosidase level and increase rate of lactose uptake.

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.

Review article: the treatment of lactose intolerance

While about 50 million Americans malabsorb lactose, the colonic metabolism of this disaccharide may prevent the symptomatic state known as lactose intolerance. Elucidation of the clinical importance of lactose malabsorption requires comparison of symptoms after ingestion of lactose with those following an identical appearing lactose-free control. This paper reviews the extensive literature concerning lactose-induced symptoms and the value of lactose digestive aids. Poorly controlled studies have suggested that a cup of milk results in appreciable symptoms in the majority of lactase-deficient subjects. In contrast, controlled trials in unselected lactose malabsorbers of subjects claiming severe lactose intolerance indicate that symptoms from a cup of milk are no greater than that with a lactose-hydrolyzed control. An increasing fraction of subjects experience symptoms as the lactose load is increased, with the majority having symptoms when the equivalent of 1 L of milk is ingested as a single dose. Further studies are required to determine the tolerance to several cups of milk taken throughout the day. Available digestive aids include pre-hydrolyzed milk and lactase preparations that can be added to milk (which is then incubated) or ingested with milk. While these products are effective in reducing symptoms, it should be emphasized that there appears to be no need for these preparations when the dosage of milk is limited to one cup per day.

Lactose maldigestion and recurrent abdominal pain in children

Our objectives were to evaluate children with recurrent abdominal pain for lactose maldigestion and to assess factors which might predict lactose absorption status. One hundred thirty-seven children were referred for specialty evaluation of recurrent abdominal pain of at least three months' duration. Study subjects were evaluated by history and physical examination, dietary interviews, hematologic and biochemical laboratory testing, stool parasite examination, and radiologic or endoscopic structural examinations, as indicated. Lactose hydrogen breath testing was performed after challenge with 1 g/kg lactose 10% aqueous solution). There were 53 males and 84 females, whose ages ranged from 6 to 18 years (9.64 +/- 2.9; mean +/- SD) Lactose maldigestion was detected in 33/137 patients (24%). The prevalence of abdominal pain, bloating, gas, flatulence, diarrhea, and constipation was similar in children with or without lactose maldigestion. The perception of symptoms related to the ingestion of dairy products was similar in both groups. No other clinical parameter predicted lactose maldigestion. However, children with lactose maldigestion had overall clinical improvement with a lactose-restricted diet. Clinical evaluation alone cannot adequately predict the presence of lactose maldigestion in children. Formal evaluation for lactose maldigestion using breath hydrogen testing methods should be considered in children with recurrent abdominal pain.

Intestinal brush border glycohydrolases: structure, function, and development

The hydrolytic enzymes of the intestinal brush border membrane are essential for the degradation of nutrients to absorbable units. Particularly, the brush border glycohydrolases are responsible for the degradation of di- and oligosaccharides into monosaccharides, and are thus crucial for the energy-intake of humans and other mammals. This review will critically discuss all that is known in the literature about intestinal brush border glycohydrolases. First, we will assess the importance of these enzymes in degradation of dietary carbohydrates. Then, we will closely examine the relevant features of the intestinal epithelium which harbors these glycohydrolases. Each of the glycohydrolytic brush border enzymes will be reviewed with respect to structure, biosynthesis, substrate specificity, hydrolytic mechanism, gene regulation and developmental expression. Finally, intestinal disorders will be discussed that affect the expression of the brush border glycohydrolases. The clinical consequences of these enzyme deficiency disorders will be discussed. Concomitantly, these disorders may provide us with important details regarding the functions and gene expression of these enzymes under specific (pathogenic) circumstances.