Yogurt--an autodigesting source of lactose

Parental management of childhood diarrhea

The objective was to determine the prevalence of therapies used by parents to manage acute diarrhea in their children and determine extent of parental adherence to current management guidelines and utilization of functional foods. Parents (N=623) of children with diarrhea were surveyed in a tertiary care pediatric emergency department. Most (53%) treated their child's diarrhea with appropriate fluids, including oral rehydration solution (52%), but 14% used treatments not recommended in current guidelines (antidiarrheals, 8%; fluids high in simple sugars, 6%). In addition, 13% used functional foods (yogurt, 11%; probiotics, 4%). Children whose parents did not adhere to guidelines were older (OR 1.02; 95% CI 1.01-1.02 years) and Hispanic (OR 2.1; 95% CI 1.1-3.9). Although most parents use appropriate fluids to treat their children's diarrhea, functional foods and antidiarrheal medications were also frequently administered. Further data on effectiveness of functional foods and education regarding avoidance of potentially harmful medications are needed.

Clinical indications for probiotics: an overview

Probiotic bacteria are used to treat or prevent a broad range of human diseases, conditions, and syndromes. In addition, there are areas of medical use that have been proposed for future probiotic applications. Randomized double-blind studies have provided evidence of probiotic effectiveness for the treatment and prevention of acute diarrhea and antibiotic-induced diarrhea, as well as for the prevention of cow milk-induced food allergy in infants and young children. Research studies have also provided evidence of effectiveness for the prevention of traveler's diarrhea, relapsing Clostridium difficile-induced colitis, and urinary tract infections. There are also studies indicating that probiotics may be useful for prevention of respiratory infections in children, dental caries, irritable bowel syndrome, and inflammatory bowel disease. Areas of future interest for the application of probiotics include colon and bladder cancers, diabetes, and rheumatoid arthritis. The probiotics with the greatest number of proven benefits are Lactobacillus rhamnosus strain GG and Saccharomyces boulardii.

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.

Effects of yogurt and bifidobacteria supplementation on the colonic microbiota in lactose-intolerant subjects

AIMS

Colonic metabolism of lactose may play a role in lactose intolerance. We investigated whether a 2-week supplementation of Bifidobacterium longum (in capsules) and a yogurt enriched with Bifidobacterium animalis could modify the composition and metabolic activities of the colonic microbiota in 11 Chinese lactose-intolerant subjects.

METHODS AND RESULTS

The numbers of total cells, total bacteria and the Eubacterium rectale/Clostridium coccoides group in faeces as measured with fluorescent in situ hybridization and the faecal beta-galactosidase activity increased significantly during supplementation. The number of Bifidobacterium showed a tendency to increase during and after supplementation. With PCR-denaturing gradient gel electrophoresis, in subjects in which B. animalis and B. longum were not detected before supplementation, both strains were present in faeces during supplementation, but disappeared after supplementation. The degree of lactose digestion in the small intestine and the oro-caecal transit time were not different before and after supplementation, whereas symptom scores after lactose challenge decreased after supplementation.

CONCLUSIONS

The results suggest that supplementation modifies the amount and metabolic activities of the colonic microbiota and alleviates symptoms in lactose-intolerant subjects. The changes in the colonic microbiota might be among the factors modified by the supplementation which lead to the alleviation of lactose intolerance.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides evidence for the possibility of managing lactose intolerance with dietary lactose (yogurt) and probiotics via modulating the colonic microbiota.

Bovine milk in human nutrition--a review

Milk and milk products are nutritious food items containing numerous essential nutrients, but in the western societies the consumption of milk has decreased partly due to claimed negative health effects. The content of oleic acid, conjugated linoleic acid, omega-3 fatty acids, short- and medium chain fatty acids, vitamins, minerals and bioactive compounds may promote positive health effects. Full-fat milk has been shown to increase the mean gastric emptying time compared to half-skimmed milk, thereby increasing the gastrointestinal transit time. Also the low pH in fermented milk may delay the gastric emptying. Hence, it may be suggested that ingesting full-fat milk or fermented milk might be favourable for glycaemic (and appetite?) regulation. For some persons milk proteins, fat and milk sugar may be of health concern. The interaction between carbohydrates (both natural milk sugar and added sugar) and protein in milk exposed to heat may give products, whose effects on health should be further studied, and the increasing use of sweetened milk products should be questioned. The concentration in milk of several nutrients can be manipulated through feeding regimes. There is no evidence that moderate intake of milk fat gives increased risk of diseases.

Irritable bowel syndrome and bloating

Gaseous symptoms in irritable bowel syndrome (IBS) including eructation, flatulence, and bloating occur as a consequence of excess gas production, altered gas transit, abnormal perception of normal amounts of gas within the gastrointestinal tract, or dysfunctional somatic muscle activity in the abdominal wall. Because of the prominence of gaseous complaints in IBS, recent investigations have focussed on new insights into pathogenesis and novel therapies of bloating. The evaluation of the IBS patient with unexplained gas and bloating relies on careful exclusion of organic disease with further characterisation of the underlying condition with directed functional testing. Treatment of gaseous symptomatology in IBS should be targeted to pathophysiologic defects whenever possible. Available therapies include lifestyle alterations, dietary modifications, enzyme preparations, adsorbents and agents which reduce surface tension, treatments that alter gut flora, and drugs that modulate gut transit.

Counseling parents on feeding their children

PURPOSE OF REVIEW

The high-nutrient needs of children for normal growth and development are matched by ready access to low-nutrient high-energy foods. Parents are often confused by new and at times conflicting information. This review discusses three recently published papers that offer specific and important dietary information for school-aged children.

RECENT FINDINGS

Lactose intolerance is common in some populations and there are misconceptions about dairy intake. Most lactose-intolerant children can consume some dairy products without symptoms. Fruit-juice intake can predict increased weight gain in children, especially those who are already overweight or at risk for being overweight. Hypertension is a serious disease with onset likely in childhood. This paper discusses the importance of dietary sodium as a contributor to the development of hypertension, and the sodium content of children's diets.

SUMMARY

Advice to parents on feeding children should be based on the food pyramid and include information on exercise. Recent publications suggest that children consume dairy products, even if lactose intolerant, restrict juice intake, remove sweetened beverages from their diets and reduce sodium consumption.

Genes involved in obesity: Adipocytes, brain and microflora

The incidence of obesity and related metabolic disorders such as cardiovascular diseases and type 2 diabetes, are reaching worldwide epidemic proportions. It results from an imbalance between caloric intake and energy expenditure leading to excess energy storage, mostly due to genetic and environmental factors such as diet, food components and/or way of life. It is known since long that this balance is maintained to equilibrium by multiple mechanisms allowing the brain to sense the nutritional status of the body and adapt behavioral and metabolic responses to changes in fuel availability. In this review, we summarize selected aspects of the regulation of energy homeostasis, prevalently highlighting the complex relationships existing between the white adipose tissue, the central nervous system, the endogenous microbiota, and nutrition. We first describe how both the formation and functionality of adipose cells are strongly modulated by the diet before summarizing where and how the central nervous system integrates peripheral signals from the adipose tissue and/or the gastro-intestinal tract. Finally, after a short description of the intestinal commensal flora, rangingfrom its composition to its importance in immune surveillance, we enlarge the discussion on how nutrition modified this perfectly well-balanced ecosystem.

Lactose intolerance in infants, children, and adolescents

The American Academy of Pediatrics Committee on Nutrition presents an updated review of lactose intolerance in infants, children, and adolescents. Differences between primary, secondary, congenital, and developmental lactase deficiency that may result in lactose intolerance are discussed. Children with suspected lactose intolerance can be assessed clinically by dietary lactose elimination or by tests including noninvasive hydrogen breath testing or invasive intestinal biopsy determination of lactase (and other disaccharidase) concentrations. Treatment consists of use of lactase-treated dairy products or oral lactase supplementation, limitation of lactose-containing foods, or dairy elimination. The American Academy of Pediatrics supports use of dairy foods as an important source of calcium for bone mineral health and of other nutrients that facilitate growth in children and adolescents. If dairy products are eliminated, other dietary sources of calcium or calcium supplements need to be provided.

Live bacterial cells as orally delivered therapeutics

Despite the swift escalation in research regarding the use of live bacterial cells for therapeutic purposes, the prophylactic and curative use of probiotic microorganisms still remains a wide and controversial field. In addition, the acknowledgement that live bacterial cells can be genetically engineered to synthesise products that have therapeutic potential has generated substantial interest among clinicians and health professionals. Clinical trials have increasingly provided an insightful scientific derivation for the use of live bacterial cells in medicinal practice in diseases such as diarrhoea, cancer, Crohn's disease, enhancement of the host's immune response, and numerous other diseases. A key constraint in the use of live bacterial cells, however, is the complexity of delivering them to the correct target sites. Oral delivery of free live cells, lyophilised cells and immobilised cells has been attempted, but with restricted success, chiefly because bacterial cells are unable to survive passage through the gastrointestinal tract in sufficient dosage. On many occasions, when given orally, these cells have been found to provoke immunogenic responses that are undesirable. Recent studies show that these problems can be overcome by delivering live bacterial cells using artificial cell microcapsules. This review abridges recent developments in the therapeutic use of live bacterial cells, addresses the potential and restrictions for their application in therapy, and provides insights into the future course of this emerging therapy.

Probiotics and the gastrointestinal tract: Where are we in 2005?

Probiotic agents are live microbes or components of microbes that have a positive effect on the host. They exert their action through interplay with the immune system of the host. Some of this effect is local and some is systemic. The full story is yet to be discovered. Probiotics have a definite positive effect on rotavirus diarrhea, post antibiotic diarrhea and pouchitis. Their exact role in inflammatory bowel disease, irritable bowel syndrome, other forms of infectious diarrhea, and prevention of cancer is yet to be determined. This review summarizes the data about probiotics in these conditions.

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.

Living drugs for gastrointestinal diseases: the case for probiotics

Nonpathogenic micro-organisms may contain or produce molecules of potential therapeutic interest. This led to the concept of using ingested living micro-organisms to produce and transport these molecules to targets in the proximal or distal intestine. Several characteristics of this pharmacological approach are very original: potential for in vivo production of active molecules, for targeting immune cells, for presenting immunogenic molecules in a microbial context, for duodenal delivery using bile sensitivity. Probiotics have been studied for some decades and more recently worm eggs have also received some interest. This paper summarizes facts (especially results of randomized controlled trials and pharmacokinetic studies), and ideas about the use of probiotics to treat or prevent gastrointestinal diseases. The safety of this approach (exceptional cases of infections have been observed), and the potential for using new agents or genetically modified micro-organisms (ongoing trials in humans with Crohn's disease) are also discussed.

[Benefits of a thickened infant formula with lactase activity in the management of benign digestive disorders in newborns]

This study aimed at evaluating the interest of a thickened infant formula with lactase activity by comparison with a standard infant formula in the management of benign digestive disorders in infants. Infants of both sex (N =109), ranging in age from 0 to 3 months, were included in a randomised double blind trial. Infants went to the paediatrician because of benign digestive disorders such as regurgitation, eructation or hiccup, colic, persistent crying and/or meteorism. Nine hundred and three infants were included and randomised in two parallel groups: they consumed daily either the thickened infant formula with lactase activity or a standard infant formula. There were no significant difference in the infants included in both groups. Both formula were well accepted and tolerated. Growth of the infants and compliance during the study were identical and good in the two groups. The efficiency of the formula tested was showed on digestive symptoms through: a decrease of the intensity of the digestive discomforts more important in the test than in the standard formula group; a decrease of the intensity of the gaz significantly more important in the test than in the standard formula group; significant decreases in frequency and intensity of the gaz in the test group while there were no significant diminution in the standard group; This study showed the good tolerance, acceptability and efficiency of a thickened infant formula with lactase activity on benign digestive disorders of young infants.

Probiotics and prebiotics: role in clinical disease states

Parents of pediatric patients are seeking alternatives to conventional therapy in the prevention and treatment of gastrointestinal disease states because of therapeutic failures caused by the increased incidence of antibiotic resistance. One such alternative is the use of probiotics and prebiotics to stimulate health-promoting indigenous flora to affect pathogen colonization and expression of disease. Probiotics are live flora given in oral quantities that allow for colonization of the colon. Probiotics are given as functional foods or dietary supplements, and function to activate the mucosal immune system and prevent pathogen colonization and translocation by strengthening the mucosal barrier, interfering with pathogen colonization, and in some instances, producing secretory antibacterial substances. Prebiotics are nondigestible carbohydrates, principally oligosoccharides, that are fermented by colonic commensals, stimulating their proliferation and producing short-chain fatty acids. Both protective nutrients have been shown to reduce the incidence and severity of infantile diarrhea, particularly rotaviral gastroenteritis, prevent antibiotic-induced diarrhea, and prevent and treat intestinal food allergy. With additional multicenter clinical trial confirmations, these substances may become routine in the care of infants and young children.

Probiotics and human health: a clinical perspective

There is unequivocal evidence that administration of probiotics could be effective in the treatment of acute infectious diarrhoea in children and the prevention of antibiotic associated diarrhoea and nosocomial/community acquired diarrhoea. Encouraging evidence is also emerging for the effectiveness of probiotics in the prevention and management of pouchitis and paediatric atopic diseases, and the prevention of postoperative infections. There is also strong evidence that certain probiotic strains are able to enhance immune function, especially in subjects with less than adequate immune function such as the elderly. Efficacy of probiotics in the prevention of traveller's diarrhoea, sepsis associated with severe acute pancreatitis, and cancers, the management of ulcerative colitis, and lowering of blood cholesterol remains unproven. In addition to firm evidence of efficacy (for a range of conditions), major gaps exist in our knowledge regarding the mechanisms by which probiotics modulate various physiological functions and the optimum dose, frequency, and duration of treatment for different probiotic strains.

Yogurt and gut function

In recent years, numerous studies have been published on the health effects of yogurt and the bacterial cultures used in the production of yogurt. In the United States, these lactic acid-producing bacteria (LAB) include Lactobacillus and Streptococcus species. The benefits of yogurt and LAB on gastrointestinal health have been investigated in animal models and, occasionally, in human subjects. Some studies using yogurt, individual LAB species, or both showed promising health benefits for certain gastrointestinal conditions, including lactose intolerance, constipation, diarrheal diseases, colon cancer, inflammatory bowel disease, Helicobacter pylori infection, and allergies. Patients with any of these conditions could possibly benefit from the consumption of yogurt. The benefits of yogurt consumption to gastrointestinal function are most likely due to effects mediated through the gut microflora, bowel transit, and enhancement of gastrointestinal innate and adaptive immune responses. Although substantial evidence currently exists to support a beneficial effect of yogurt consumption on gastrointestinal health, there is inconsistency in reported results, which may be due to differences in the strains of LAB used, in routes of administration, or in investigational procedures or to the lack of objective definition of "gut health." Further well-designed, controlled human studies of adequate duration are needed to confirm or extend these findings.

Long-term consumption of infant formulas containing live probiotic bacteria: tolerance and safety

BACKGROUND

Nonpathogenic live bacteria are consumed as food by many children, particularly in the form of yogurt. The tolerance and safety of long-term consumption of specific types and strains of probiotic bacteria are not well documented.

OBJECTIVE

The goal was to evaluate tolerance to formulas containing 2 levels of probiotic supplementation and effects on growth, general clinical status, and intestinal health in free-living healthy infants.

DESIGN

This was a prospective, double-blind, randomized, placebo-controlled study of healthy infants aged 3-24 mo. Infants were assigned to receive a standard milk-based formula containing 1 x 10(7) colony-forming units (CFU)/g each of Bifidobacterium lactis and Streptococcus thermophilus, formula containing 1 x 10(6) CFU/g each of B. lactis and S. thermophilus, or unsupplemented formula. Clinical outcomes included formula intake, gastrointestinal tolerance, anthropometric measures, daycare attendance, and history of illness.

RESULTS

One hundred eighteen infants aged ( +/- SD) 7.0 +/- 2.9 mo at enrollment consumed formula for 210 +/- 127 d. There were no significant differences in age, sex, formula consumption, or length of study between groups. The supplemented formulas were well accepted and were associated with a lower frequency of reported colic or irritability (P < 0.001) and a lower frequency of antibiotic use (P < 0.001) than was the unsupplemented formula. There were no significant differences between groups in growth, health care attention seeking, daycare absenteeism, or other health variables.

CONCLUSION

Long-term consumption of formulas supplemented with B. lactis and S. thermophilus was well tolerated and safe and resulted in adequate growth, reduced reporting of colic or irritability, and a lower frequency of antibiotic use.

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.

Gut flora in health and disease

The human gut is the natural habitat for a large and dynamic bacterial community, but a substantial part of these bacterial populations are still to be described. However, the relevance and effect of resident bacteria on a host's physiology and pathology has been well documented. Major functions of the gut microflora include metabolic activities that result in salvage of energy and absorbable nutrients, important trophic effects on intestinal epithelia and on immune structure and function, and protection of the colonised host against invasion by alien microbes. Gut flora might also be an essential factor in certain pathological disorders, including multisystem organ failure, colon cancer, and inflammatory bowel diseases. Nevertheless, bacteria are also useful in promotion of human health. Probiotics and prebiotics are known to have a role in prevention or treatment of some diseases.

How host-microbial interactions shape the nutrient environment of the mammalian intestine

Humans and other mammals are colonized by a vast, complex, and dynamic consortium of microorganisms. One evolutionary driving force for maintaining this metabolically active microbial society is to salvage energy from nutrients, particularly carbohydrates, that are otherwise nondigestible by the host. Much of our understanding of the molecular mechanisms by which members of the intestinal microbiota degrade complex polysaccharides comes from studies of Bacteroides thetaiotaomicron, a prominent and genetically manipulatable component of the normal human and mouse gut. Colonization of germ-free mice with B. thetaiotaomicron has shown how this anaerobe modifies many aspects of intestinal cellular differentiation/gene expression to benefit both host and microbe. These and other studies underscore the importance of understanding precisely how nutrient metabolism serves to establish and sustain symbiotic relationships between mammals and their bacterial partners.

Lactase deficiency: not more common in pediatric patients with inflammatory bowel disease than in patients with chronic abdominal pain

OBJECTIVE

Lactase deficiency is commonly found in adults with inflammatory bowel disease (IBD). Our aim was to determine its prevalence in children with IBD.

METHODS

We conducted a retrospective and descriptive analysis of patients with symptomatic IBD whose mucosal lactase activity was measured on duodenal biopsies obtained during gastrointestinal endoscopic evaluations. Age- and gender-matched controls were chosen randomly from a group with chronic abdominal pain.

RESULTS

One hundred twelve patients with IBD were identified from January 1994 to December 2000. Seventy-nine (71%) had Crohn disease, and 33 (29%) had ulcerative colitis. Forty-five (40%) of all IBD patients (29 with Crohn disease and 16 with ulcerative colitis) had low lactase activity levels (< 15 microM/min/gm). The prevalence of lactase deficiency in patients with IBD was 37% (38 of 103) in white patients and 78% (7 of 9) in blacks. Thirty-four of 112 controls (30%) had lactase deficiency. IBD patients were more likely to be lactase deficient than the controls, but the difference was not statistically significant ( = 0.162). Normal duodenal histology was found in 67% of lactase-deficient IBD patients compared with 82% in lactase-sufficient IBD patients. The frequency of duodenal inflammation did not differ significantly between lactase-deficient and -sufficient patients with IBD ( = 0.068).

CONCLUSIONS

More than one third of pediatric patients with IBD have lactase deficiency, which is not significantly different from non-IBD patients with chronic abdominal pain. The majority of lactase-deficient patients with IBD have normal duodenal biopsy results. Lactase activity from small bowel biopsy specimens can be measured at the time of initial endoscopy. Reevaluation, either by small bowel biopsy or the breath hydrogen test, may then be considered during follow-up of symptomatic patients.

Effect of feeding yogurt versus milk in children with acute diarrhea and carbohydrate malabsorption

BACKGROUND

The aim of this study was to compare the effect of infant formula and the same formula subjected to microbial fermentation (yogurt) on the duration of diarrhea in young children with acute watery diarrhea, with or without reducing substances in stools.

METHODS

One hundred twelve well-nourished children, aged 3 to 24 months, who were admitted to the hospital with acute watery diarrhea were included in a randomized trial. After appropriate rehydration, they were fed either an infant formula (group M, n = 56) or the same formula fermented with Lactobacillus bulgaricus and Streptococcus thermophilus (group Y, n = 56). The two feedings were comparable in lactose concentration (40 to 42 g/L), pH 4.5, flavor, and texture. The groups were subdivided into those with or without reducing sugars in stools at presentation. The presence of reducing sugars in stool was used as a marker of carbohydrate malabsorption.

RESULTS

Group M and group Y had comparable clinical characteristics at admission, including the number of patients with reducing sugars in stools (n = 31 in group M and 27 in group Y). The success rate (cessation of diarrhea and appropriate weight gain 7 days after enrollment into the study) was similar in both groups (82% in group M vs. 84% group Y). Clinical failure was 3.6% in both groups. The percentage of patients withdrawn from the study for medical reasons (5.4% in group M vs. 7.1% in group Y) or withdrawn at the parents' request (8.9% in group M vs. 5.4% in group Y) was similar. Duration of diarrhea and number of stools were significantly less in group Y compared with group M. Forty-eight hours after inclusion, diarrhea was still present in 62% of group M versus in 35% of group Y (P < 0.002). In children with reducing sugars in stools, the rate of success (82%) was similar in groups M and Y, but the duration of diarrhea and number of stools per day were significantly decreased in group Y. Forty-height hours after inclusion, diarrhea was still present in 75% of group M patients and in 20% of group Y patients who had reducing substances in the stool.

CONCLUSION

Young children with acute watery diarrhea, without malnutrition or associated disease, can be equally well treated with feeding of either infant formula or yogurt. Yogurt feeding is associated with a clinically relevant decrease in stool frequency and duration of diarrhea in children who have reducing sugars in stools.

Hydrogen excretion upon ingestion of dairy products in lactose-intolerant male subjects: importance of the live flora

OBJECTIVE

To assess the effects of the ingestion of milk, yoghurt (10(8) bacteria/ml), heat-treated yoghurt (<15 bacteria/ml) and two products obtained by dilution of yoghurt with heat-treated product (10(6) and 10(5) bacteria/ml) on hydrogen production and symptoms of lactose intolerance in lactose malabsorbers.

DESIGN

Double-blind, randomised cross-over design.

SETTING

The study was performed in the phase 1 clinical unit of OPTIMED, Nancy, France.

SUBJECTS

Twenty-four male lactose malabsorbers were selected for the study.

INTERVENTIONS

Hydrogen production and adverse events were followed during 8 h after ingestion of the products.

RESULTS

The results clearly demonstrate that ingestion of yoghurt with 10(8) bacteria/ml leads to lower H(2) excretion and complaints than the other products. Results observed with the products containing a reduced population of live flora remain better than those observed with milk.

CONCLUSIONS

The importance of a high population of the live flora is underlined.

Clinical applications of probiotic agents

In the past century the beneficial roles of nonpathogenic bacteria in the intestinal lumen were described. In the past decade there has been a dramatic increase in scientific work supporting the concept that there are clinical benefits to ingesting specific nonpathogenic organisms (probiotics). The potential benefits of modifying the intestinal flora composition of certain high-risk groups, eg, premature infants, travelers, and children receiving antibiotics, are emerging in the literature. Studies documenting prophylactic and therapeutic benefits in acute viral gastroenteritis and in atopic disease point not only to the potential applications, but also to the fact that the mechanisms of action of these agents may be due to their interaction with the gut as an immunologic organ. The benefits documented thus far are of varying degree and are most likely dependent on the number of agents, the dose, the dosing patterns, and the characteristics of the host and its underlying luminal microbial environment. Consequently, the safety and specification of a particular probiotic agent and methods of delivery to a particular population for a particular purpose should be carefully documented before making broad recommendations. The cost-benefit assessment of adding probiotics to our diet for prophylactic or therapeutic purposes, as well as better regulation of these agents as commercial products, is also needed.

Natural exopolysaccharides enhance survival of lactic acid bacteria in frozen dairy desserts

Viable lactic acid-producing bacteria in frozen dairy desserts can be a source of beta-galactosidase for persons who absorb lactose insufficiently. However, freezing kills many of the cells, causing loss of enzymatic activity. Cultures selected for high beta-galactosidase activities and high survival rates in the presence of bile were examined for survivability during freezing in reduced-fat ice cream. Encapsulated S. thermophilus strains survived better than their nonencapsulated mutants in reduced-fat ice cream after freezing and frozen storage at -29 degrees C for 16 d (28 vs. 19%). However, a small nonencapsulated strain of Lactobacillus delbrueckii sp. bulgaricus survived better than the large encapsulated strain in reduced-fat ice cream. Factors that improved survival of encapsulated S. thermophilus 1068 in ice cream were 1) harvest of cells in the late-log phase of growth at 37 degrees C rather than at 40, 42.5, or 45 degrees C; 2) overrun at 50% rather than 100%; and 3) storage at -17 degrees C rather than -23 or -29 degrees C. Survival of strain ST1068 was unaffected by 1) neutralization of acid during growth or 2) substitution of nitrogen for air in building overrun.

Screening of intestinal microflora for effective probiotic bacteria

Increasing consumer awareness of health-promoting intestinal bacteria has fueled the addition of viable probiotic bacteria as functional ingredients in certain foods. However, to effectively market the enhanced attributes of these foods, the added probiotic bacteria need to have scientific credibility. The scientific rationale for using many of the strains of probiotic bacteria currently on the market is weak. Furthering the current understanding of what features a bacterium needs to have for effective probiotic functionality will enable the selection of strains with a more credible scientific rationale. To screen for effective strains, one must understand the microbial diversity in the intestines of healthy individuals. The advent of molecular tools has greatly enhanced our ability to accomplish this. These tools comprise genetic fingerprinting, specific probes, molecular speciation, and techniques for the in situ analysis of specific microbial groups in the intestine. This review will detail these scientific approaches and how their impact will improve criteria for selection of probiotic bacteria.

Lactose Maldigestion, Calcium Intake and Osteoporosis in African-, Asian-, and Hispanic-Americans

Dietary calcium is critical for the development of the human skeleton and likely plays an important role in the prevention of osteoporosis. Dairy products provide approximately three-fourths of calcium consumed in the diet and are the most concentrated sources of this essential nutrient. One obstacle that likely interferes with calcium consumption among many ethnic groups is lactose maldigestion. The real or perceived occurrence of intolerance symptoms after dairy food consumption may cause maldigesters to avoid dairy products. Several investigators have observed a relationship between lactose maldigestion, dietary calcium and osteoporosis in Caucasian populations. Research on ethnically diverse populations is necessary to better understand how lactose maldigestion influences the risk for osteoporosis. Low calcium intakes, a greater than previously thought potential for low bone density and extensive lactose maldigestion among Hispanic-American and Asian-American populations may create an elevated risk for osteoporosis. Dietary management strategies for lactose maldigesters to increase calcium consumption include consuming (1) dairy foods with meals, (2) yogurts, (3) calcium-fortified foods, (4) using lactose digestive aids and (5) including dairy foods daily in the diet to enhance colonic metabolism of lactose.

Microbiological and biochemical properties of canestrato pugliese hard cheese supplemented with bifidobacteria

Canestrato Pugliese cheeses from ewe milk were produced according to a traditional protocol and by adding 7.0 log10 cfu of fresh cells per gram of Bifidobacterium bifidum Bb02, Bifidobacterium longum Bb46, or both species. The traditional technology was modified slightly to favor the survival of probiotic microorganisms. After 56 d of ripening, the survival of B. bifidum Bb02 and B. longum Bb46 was 6.0 and 5.0 log10 cfu/g, respectively. After 19 d cheeses contained ca. 7.0 log10 cfu/g of bifidobacteria. Compared to traditional cheese, the addition of bifidobacteria seemed to support the growth and survival of mesophilic lactobacilli and Streptococcus thermophilus, used as starter, during ripening. No significant differences were observed in the main chemical composition, and only a slightly higher concentration of acetic acid was found in cheeses with bifidobacteria added. On the contrary, alpha- and beta-galactosidase activities were markedly more pronounced in the presence of bifidobacteria, especially with B. bifidum Bb02. In contrast with traditional cheese, the lactose was completely hydrolyzed in cheeses made with bifidobacteria. Urea-PAGE electrophoresis of the pH 4.6-soluble and pH 4.6-insoluble N fractions did not show appreciable variations. Only the reversed-phase-HPLC analysis of the pH 4.6-soluble N showed a slightly more complex profile in the presence of bifidobacteria. This finding was in agreement with the higher value of the pH 4.6-soluble N/total N ratio and with the more pronounced amino-, imino-, and dipeptidase activities found in all the cheeses with the bifidobacteria added, especially B. bifidum Bb02. No differences were found in the free amino acid and free fatty acid contents. The amino acids glutamic acid, valine, proline, leucine, and lysine and the fatty acids butyric, caproic, capric, and oleic acids were found at the highest concentrations. The sensory evaluation did not show significant differences, and Canestrato Pugliese cheeses were characterized by small and uniformly distributed eyes, were pale yellow, had an elastic consistency and a Pecorino-like smell, were very salty, and tended to be moderately piquant.

Probiotics--compensation for lactase insufficiency

Yogurt and other conventional starter cultures and probiotic bacteria in fermented and unfermented milk products improve lactose digestion and eliminate symptoms of intolerance in lactose maldigesters. These beneficial effects are due to microbial beta-galactosidase in the (fermented) milk product, delayed gastrointestinal transit, positive effects on intestinal functions and colonic microflora, and reduced sensitivity to symptoms. Intact bacterial cell walls, which act as a mechanical protection of lactase during gastric transit, and the release of the enzyme into the small intestine are determinants of efficiency. There is a poor correlation between lactose maldigestion and intolerance; in some studies, low hydrogen exhalation without significant improvement of clinical symptoms was observed. Probiotic bacteria, which by definition target the colon, normally promote lactose digestion in the small intestine less efficiently than do yogurt cultures. They may, however, alleviate clinical symptoms brought about by undigested lactose or other reasons.

Prophylactic and therapeutic uses of probiotics: a review

Probiotics, live microbial food supplements that beneficially affect the host by improving its intestinal microbial balance, are quickly gaining interest as functional foods in the current era of self-care and complementary medicine. Microbes have been used for years in food and alcoholic fermentations and relatively recently have undergone scientific scrutiny to examine their purported health benefits. Some of the claims for which research supports a beneficial effect of probiotic consumption include: improving intestinal tract health, enhancing the immune system, synthesizing and enhancing the bioavailability of nutrients, reducing symptoms of lactose intolerance, decreasing the prevalence of allergy in susceptible individuals, and reducing risk of certain cancers. The mechanisms by which probiotics exert their effects are largely unknown, but may involve modifying gut pH, antagonizing pathogens through production of antimicrobial and antibacterial compounds, competing for pathogen binding and receptor sites as well as for available nutrients and growth factors, stimulating immunomodulatory cells, and producing lactase. Selection criteria, efficacy, food and supplement sources and safety issues around probiotics are reviewed. Nutrition professionals can provide a tremendous service by helping clients overcome negative perceptions of all bacteria and, when appropriate, by developing individualized dietary plans to take advantage of the benefits probiotics may confer.

Lactase haplotype diversity in the Old World

Lactase persistence, the genetic trait in which intestinal lactase activity persists at childhood levels into adulthood, varies in frequency in different human populations, being most frequent in northern Europeans and certain African and Arabian nomadic tribes, who have a history of drinking fresh milk. Selection is likely to have played an important role in establishing these different frequencies since the development of agricultural pastoralism approximately 9,000 years ago. We have previously shown that the element responsible for the lactase persistence/nonpersistence polymorphism in humans is cis-acting to the lactase gene and that lactase persistence is associated, in Europeans, with the most common 70-kb lactase haplotype, A. We report here a study of the 11-site haplotype in 1,338 chromosomes from 11 populations that differ in lactase persistence frequency. Our data show that haplotype diversity was generated both by point mutations and recombinations. The four globally common haplotypes (A, B, C, and U) are not closely related and have different distributions; the A haplotype is at high frequencies only in northern Europeans, where lactase persistence is common; and the U haplotype is virtually absent from Indo-European populations. Much more diversity is seen in sub-Saharan Africans than in non-Africans, consistent with an "Out of Africa" model for peopling of the Old World. Analysis of recent recombinant haplotypes by allele-specific PCR, along with deduction of the root haplotype from chimpanzee sequence, allowed construction of a haplotype network that assisted in evaluation of the relative roles of drift and selection in establishing the haplotype frequencies in the different populations. We suggest that genetic drift was important in shaping the general pattern of non-African haplotype diversity, with recent directional selection in northern Europeans for the haplotype associated with lactase persistence.

Kinetic modeling of lactose hydrolysis with an immobilized beta-galactosidase from Kluyveromyces fragilis

The kinetic model of the hydrolysis of lactose with a beta-galactosidase from Kluyveromyces fragilis immobilized on a commercial silica-alumina (KA-3, from Südchemie) has been determined. A wide experimental range of the main variables has been employed: temperature, concentrations of substrate, and products and concentration of enzyme. The runs were performed in a complex buffer with the salt composition of milk. The effect of pH and temperature on the stability and the activity of the enzyme have been studied. The optimum pH for the enzyme activity was, approximately, seven. The immobilized enzyme was more stable than the free one at acidic pH, but more instable at basic pH. The maximum temperature used for the hydrolysis runs performed to select the kinetic model was 40 degrees C, so inactivation of the enzyme during the kinetic runs has been avoided. Agitation, concentration of enzyme in the solid and particle size were selected to ensure that the overall rate was that of the chemical reaction. Eleven kinetic models were proposed to fit experimental data, from first order to more complex ones, such as those taking into account inhibition by one of the compounds involved in the hydrolysis reaction. Applying statistical and physical criteria, a Michaelis-Menten model with a competitive inhibition by galactose has been selected. The model is able to fit the experimental data correctly in the wide experimental range studied. Finally, the model obtained is compared to the one selected in a previous work for the hydrolysis of lactose with the free enzyme.

Fermentation of fructooligosaccharides by lactic acid bacteria and bifidobacteria

Lactic acid bacteria and bifidobacteria were screened of their ability to ferment fructooligosaccharides (FOS) on MRS agar. Of 28 strains of lactic acid bacteria and bifidobacteria examined, 12 of 16 Lactobacillus strains and 7 of 8 Bifidobacterium strains fermented FOS. Only strains that gave a positive reaction by the agar method reached high cell densities in broth containing FOS.

Effect of lactic acid bacteria on diarrheal diseases

Microbial balance is an important factor in the maintenance of intestinal homeostasis, and yogurt or fermented milk supplementation has been proposed to control diarrheal diseases. A number of studies using animal models and clinical studies in humans have confirmed the beneficial effect of such fermented products in case of lactose intolerance, viral diarrhea or antibiotics-associated diarrhea. The mechanisms by which lactic acid bacteria exert their effects are multiple. Bacterial lactase improves the absorption of lactose, but fermented products slow down the intestinal transit facilitating the action of residual intestinal lactase. The transient passage of lactic acid bacteria in the digestive tract may represent a microbial barrier against the development of pathogenic bacteria, probably due to the release of compounds contributing to the maintenance of colonization resistance to pathogens. The beneficial effects are mainly described in the presence of live bacteria, but inactivated bacteria may also present preventive or curative capacities in diarrheal diseases. Moreover, lactic acid bacteria has been described as reinforcing the non-specific immune defence but also specific immunity, particularly the secretory immune system mediated by secretory IgA or IgM in response to particulate infectious antigens and perhaps to soluble food antigens. Other possible mechanisms include the trophic effect on the intestinal layer, and a down-regulatory activity in cow's milk allergy as well as anti-inflammatory effects have also been suggested.

Immunologic effects of yogurt

Many investigators have studied the therapeutic and preventive effects of yogurt and lactic acid bacteria, which are commonly used in yogurt production, on diseases such as cancer, infection, gastrointestinal disorders, and asthma. Because the immune system is an important contributor to all of these diseases, an immunostimulatory effect of yogurt has been proposed and investigated by using mainly animal models and, occasionally, human subjects. Although the results of these studies, in general, support the notion that yogurt has immunostimulatory effects, problems with study design, lack of appropriate controls, inappropriate route of administration, sole use of in vitro indicators of the immune response, and short duration of most of the studies limit the interpretation of the results and the conclusions drawn from them. Nevertheless, these studies in toto provide a strong rationale for the hypothesis that increased yogurt consumption, particularly in immunocompromised populations such as the elderly, may enhance the immune response, which would in turn increase resistance to immune-related diseases. This hypothesis, however, needs to be substantiated by well-designed randomized, double-blind, placebo-controlled human studies of an adequate duration in which several in vivo and in vitro indexes of peripheral and gut-associated immune response are tested.

Lactose intolerance

Lactose maldigestion has been under intensive research since its discovery in the 1960's. We know the prevalence of lactose maldigestion in a great number of countries and ethnic groups. However, there is often no provision made for the secondary type of maldigestion, and the study populations have sometimes been selected rather than picked at random. New methods for the measurement of lactose digestion have been developed, and its genetic mechanisms have received a great deal of attention during the last few years. However, in many studies the measurement and/or reporting of symptoms has quite often been overlooked. In this review, various topics related to lactose intolerance are discussed with a special emphasis on its symptoms.