Effect of yogurt on symptoms and kinetics of hydrogen production in lactose-malabsorbing children

Yogurt, cultured fermented milk, and health: a systematic review

Consumption of yogurt and other fermented products is associated with improved health outcomes. Although dairy consumption is included in most dietary guidelines, there have been few specific recommendations for yogurt and cultured dairy products. A qualitative systematic review was conducted to determine the effect of consumption of fermented milk products on gastrointestinal and cardiovascular health, cancer risk, weight management, diabetes and metabolic health, and bone density using PRISMA guidelines. English language papers in PubMed were searched, with no date restrictions. In total, 1057 abstracts were screened, of which 602 were excluded owing to lack of appropriate controls, potential biases, and experimental design issues. The remaining 455 papers were independently reviewed by both authors and 108 studies were included in the final review. The authors met regularly to concur, through consensus, on relevance, methods, findings, quality, and conclusions. The included studies were published between 1979 and 2017. From the 108 included studies, 76 reported a favorable outcome of fermented milks on health and 67 of these were considered to be positive or neutral quality according to the Academy of Nutrition and Dietetics’ Quality Criteria Checklist. Of the 32 remaining studies, the study outcomes were either not significant (28) or unfavorable (4), and most studies (18) were of neutral quality. A causal relationship exists between lactose digestion and tolerance and yogurt consumption, and consistent associations exist between fermented milk consumption and reduced risk of breast and colorectal cancer and type 2 diabetes, improved weight maintenance, and improved cardiovascular, bone, and gastrointestinal health. Further, an association exists between prostate cancer occurrence and dairy product consumption in general, with no difference between fermented and unfermented products. This article argues that yogurt and other fermented milk products provide favorable health outcomes beyond the milk from which these products are made and that consumption of these products should be encouraged as part of national dietary guidelines.

Systematic review registration: PROSPERO registration no. CRD42017068953.

GI symptoms in infants are a potential target for fermented infant milk formulae: a review

Besides pre- and pro-biotic-containing infant formulae, fermented infant formulae are commonly used to relieve or prevent symptoms of gastrointestinal (GI) discomfort in young infants. During the fermentation process in cow's milk-based formulae, the beneficial bacteria modulate the product by forming several beneficial compounds, which contribute to the alleviation of the symptoms observed. This review summarizes the clinical evidence on the impact of fermented infant formulae on common pediatric GI-symptoms. The potential mechanisms involved are discussed: i.e., the lactose and protein (in-) digestibility, effects on gastric emptying and gut transit and modulation of the colonic microbiota. Although initial evidence indicates a beneficial effect of fermented formulae on GI discomfort in newborns, validation and confirmation of the clinical proof obtained so far is warranted, as well as further research to (more fully) understand the mode of action.

Guidance for substantiating the evidence for beneficial effects of probiotics: impact of probiotics on digestive system metabolism

Probiotic bacteria have been studied for their potential impact on the metabolism of dietary components in the small intestine lumen including lactose digestion, metabolism of lipids such as cholesterol, and oxalate metabolism. In the large intestine, they contribute to the metabolism of otherwise indigestible dietary carbohydrates (e.g., prebiotics) and have a favorable effect on colonic protein and ammonia metabolism, although their effect on the digestive fate of phytochemicals and xenobiotics is still uncertain. Probiotics also influence metabolism in the host tissues, in particular the gastrointestinal mucosa and the liver. Underlying mechanisms include supply of additional enzymatic activities in the gut lumen and alterations of the composition or metabolic pattern of the gut resident microbiota. For future studies, selection of probiotic strains should include assessment of their metabolic activities, and the outcome of the intervention studies should also take into account the composition of the probiotic matrix and the background diet of the target population. New technologies such as metabolomics hold great promise for assessment of probiotics functionality.

Lactose intolerance symptoms assessed by meta-analysis: a grain of truth that leads to exaggeration

A meta-analysis was conducted to compare the lactose intolerance symptoms of lactose maldigesters after consuming lactose (as milk, lactose dissolved in water, milk products, or commercial product) with responses after a placebo under masked conditions. An English language MEDLINE search was conducted using the medical subject heading of "lactose intolerance" from 1966 to January 2002. From an initial 1,553 citations, 2 independent reviewers selected 21 studies based on study design (randomized, crossover, blind) and use of an amount of lactose likely to be found in a meal (7-25 g) and a placebo among subjects free of gastrointestinal problems and >4 years old. Mean severity of symptom responses were analyzed as standardized differences, and the presence or absence of a symptom was estimated as pooled incidence differences (ID). For severity of flatulence, the standardized difference was 0.18 (95% confidence interval [CI] -0.16 to +0.52). The CIs for abdominal bloating and pain, degree of diarrhea, frequency of bowel movements per day, and frequency of diarrhea per day also included 0. For abdominal bloating, the ID was 5.9 more people per 100 with symptoms after lactose than placebo (CI -0.07 to +0.19). This same nonsignificant relationship was found for abdominal pain. The ID for diarrhea or loose stools was 0.15 (CI 0.03 to 0.28). Although the incidence of diarrhea was significantly higher, the size of the effect was very small. The results indicate that lactose is not a major cause of symptoms for lactose maldigesters following usual intakes of dairy foods, that is, 1 cup.

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.

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.

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.

Malnutrition and gastrointestinal disease

The recognition of several disease processes that cause or are associated with gastrointestinal malabsorption has led to extensive investigation into their pathogenesis, diagnosis, and treatment. This review of selected articles covers a range of subjects related to some of the more common malabsorptive disease. Selected topics including celiac disease, disaccharidase deficiencies, short bowel syndrome, and Crohn disease are discussed.

Human studies with probiotics and prebiotics: clinical implications

Probiotic agents have been shown to have significant clinical beneficial effects in the prevention and management of gastrointestinal and non-gastrointestinal conditions. These observations have led to work demonstrating that an important mechanism of these agents is their close interaction with the gut associated lymphoid tissue (GALT) and suggested immunomodulatory effects on systemic immune response. Studies on the possibility that prebiotic agents might directly or indirectly induce similar immunomodulation have only recently begun. The preliminary findings of several recent human clinical trials reviewed in this article indicate that prebiotics may indeed prove to be a clinically beneficial dietary supplement, in the context of novel nutritional strategies for the management of gastrointestinal and systemic conditions.

Malnutrition and gastrointestinal disease

The recognition of several disease processes that cause or are associated with gastrointestinal malabsorption has led to extensive investigation into their pathogenesis, diagnosis, and treatment. This review of selected articles covers a range of subjects related to some of the more common malabsorptive disease. Selected topics including celiac disease, disaccharidase deficiencies, short bowel syndrome, and Crohn disease are discussed.

Interrelationships between dairy product intake, microflora metabolism, faecal properties and plasmid dissemination in gnotobiotic mice

We previously described the effects of intake of dairy products on plasmid dissemination in the digestive tract of gnotobiotic mice associated with human faecal flora (HFF) and found that yoghurt, heat-treated yoghurt (HTY) and milk reduced population levels of transconjugants compared with findings in mice fed a standard mouse diet. In the case of lactose intake, transconjugants were not detected. The aim of the present study was to assess the possible interrelationships between these observations and other variables (bacterial ecology, pH, moisture, enzyme activities, short-chain fatty acid (SCFA) contents, lactic acid contents). Much of the interest of the present comparison lies in the fact that the animals were homogeneous in terms of age, gender, food and intestinal microflora, owing to the gnotobiotic mouse model maintained in sterile isolators. We observed no variation in SCFA and lactic acid contents or in the population levels of strictly anaerobic strains of Bacteroides and Bifidobacterium, and of the facultative anaerobic recipient Escherichia coli PG1 strain. The main modifications were the reduction of population levels of transconjugants in mice receiving yoghurt, HTY and milk, and concomitantly an increase of beta-galactosidase and a decrease of beta-glucosidase activities, compared with control mice fed a standard diet. Total inhibition of plasmid transfer was observed in HFF mice consuming lactose, and concomitantly the two enzyme activities (beta-glucosidase and beta-galactosidase) were increased, compared with the findings in control mice fed a standard diet. In axenic mice consuming lactose, plasmid transfer occurred, beta-galactosidase was not detected and beta-glucosidase was decreased. It is therefore proposed that these two enzyme activities influence plasmid transfer and persistence of transconjugants in the digestive tract of HFF associated mice. When both activities were increased there was a total inhibition of plasmid transfer (case of lactose intake). When beta-galactosidase increased and beta-glucosidase decreased (case of yoghurt, HTY and milk), plasmid transfer occurred at a lower efficiency than in the control group, resulting in lower population levels of transconjugants.

Streptococcus thermophilus is able to produce a beta-galactosidase active during its transit in the digestive tract of germ-free mice

This work presents data on the application of a bacterial luciferase used to monitor gene expression of Streptococcus thermophilus in the digestive tract. The main result is that the bacterium was able to produce an active beta-galactosidase in the digestive tract, although it did not multiply during its transit. This production was enhanced when lactose (the inducer) was added to the diet.

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.

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

BACKGROUND

The relationship of symptoms with objective measurements, as well as some of the mechanisms involved in lactose tolerance after yoghurt consumption, remain unclear.

METHODS

The trial had a double-blind design in which 22 lactose malabsorbers received 25 g daily lactose in fresh (living bacteria > 108 cfu/g) yoghurt or heated (< 102 cfu/g) yoghurt for 15 days, followed by a cross-over (15 days) after a wash-out period (14 days). The lactose digestion was determined by the breath H2 test, the gastric emptying (GE) with a 13C-acetate breath test and the revealed transit time (OCTT) by 15N-lactose-ureide test. Subjects reported their gastrointestinal symptoms (GIS) in a validated questionnaire.

RESULTS

Breath H2 test indicated more effective lactose digestion after fresh yoghurt intake. The OCTT was shorter after heated yoghurt ingestion as compared with the fresh. There was lower severity of GIS (P < 0.05) after fresh yoghurt intake, and this showed an inverse correlation with OCTT (P < 0.05).

CONCLUSIONS

Delayed orocoecal transit time was associated with fewer gastrointestinal symptoms. The improved lactose digestion and tolerance of fresh yoghurt should be mainly attributed to the presence of living bacteria.

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.

Chronic consumption of fresh but not heated yogurt improves breath-hydrogen status and short-chain fatty acid profiles: a controlled study in healthy men with or without lactose maldigestion

BACKGROUND

Ingestion of fermented dairy products induces changes in the equilibrium and metabolism of the intestinal microflora and may thus have beneficial effects on the host.

OBJECTIVE

We compared the effects of chronic consumption of yogurt with (fresh) or without (heated) live bacterial cultures (Lactobacillus bulgaricus and Streptococcus thermophilus) on plasma glucose, insulin, triacylglycerols, cholesterol, fatty acids, and short-chain fatty acids.

DESIGN

Two groups of 12 healthy men with or without lactose malabsorption were selected with use of a breath-hydrogen test after a 30-g lactose load. Subjects were randomly assigned in a crossover design to 500 g/d of either fresh or heated yogurt for 2 periods of 15 d each, separated by a 15-d washout interval.

RESULTS

Chronic consumption of fresh or heated yogurt had no detrimental effects on plasma glucose, insulin, or fatty acid areas under the curve in response to acute ingestion of 500 g yogurt in healthy men with or without lactose malabsorption. There were also no detectable changes in fasting plasma glucose, insulin, fatty acid, triacylglycerol, or cholesterol concentrations. In contrast, plasma butyrate was higher (P: < 0.03) and plasma propionate tended to be higher (P: = 0.059) in subjects without lactose malabsorption after fresh yogurt consumption than after heated yogurt consumption. There were no significant changes in plasma acetate. In subjects with lactose malabsorption, 15 d of fresh yogurt consumption also increased propionate production compared with values at baseline (P: < 0.04). In the same group, the production of breath hydrogen was lower after fresh yogurt consumption than after heated yogurt consumption (P: < 0.01).

CONCLUSIONS

In men with lactose malabsorption, chronic consumption of yogurt containing live bacterial cultures ameliorated the malabsorption, as evidenced by lower breath-hydrogen excretion, but increased propionate concentrations. In subjects without lactose malabsorption, such yogurt tended to increase propionate and increased butyrate.

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.

Effects of yoghurt intake on plasmid transfer and colonisation with transconjugants in the digestive tract of mice associated with human faecal flora

This study deals with the effects of yoghurt intake on wild-type and recombinant plasmid transfer from an exogenous Escherichia coli K12-derivative donor strain to an endogenous recipient strain in the digestive tract of mice associated with human faecal flora. We showed that the self-transmissible plasmid R388 was efficiently transferred to recipient strain PG1 in mice associated with human faecal flora (HFF-PG1) and that the resulting transconjugants (PG1-R388) became established at a high and maximal population level without any selective pressure. Using HFF-PG1 mice made it possible to determine whether yoghurt consumption decreases R388 transfer efficiency and the ability of transconjugant PG1-R388 to successfully colonise the digestive tract. Results indicated that yoghurt consumption had two effects: it reduced the efficacy of plasmid transfer 10-fold and decreased the transconjugant PG1-R388 population density 100-fold, compared to the control group. We also describe another HFF mouse model in which recipient PG1 was replaced by EM0 with which no plasmid transfer was observed. This model made it possible to demonstrate the potential promoting effect of yoghurt intake on transconjugant formation and establishment. Our results indicated no yoghurt effect; no transconjugants appeared in the digestive tract of HFF-EM0 mice fed on yoghurt or on standard food. In both mouse models, HFF-PG1 and HFF-EM0, yoghurt intake did not promote the mobilisation of either the non-self-transmissible plasmid pUB2380 or the recombinant plasmid pCE325.

Bacteria and yeasts in the treatment of acute and chronic infectious diarrhea. Part I. Bacteria

Treatment of acute infectious gastroenteritis consists mainly of rehydration and rapid realimentation. However, the natural intestinal microflora is disrupted in both acute and chronic infectious diarrhea, resulting in complex interactions possibly aggravating this frequently self-limiting condition. Therefore, additional therapeutic intervention with biotherapeutic agents is worth considering. The results of most randomized prospective double-blind clinical trials with bacterial biotherapeutic agents are disappointing, showing a lack of efficacy, except for Lactobacillus casei strain GG, for which both positive and negative results have been published.

Use of probiotics in childhood gastrointestinal disorders

Probiotics appear to be useful in the prevention or treatment of several gastrointestinal disorders, including infectious diarrhea, antibiotic diarrhea, and traveler's diarrhea. Results of preliminary human and animal studies suggest that patients with inflammatory diseases, and even irritable bowel syndrome, may benefit from probiotic therapy. Probiotics represent an exciting therapeutic advance, although much investigation must be undertaken before their role in gastroenterology is clearly delineated. Questions related to probiotic origin, survivability, and adherence are all important considerations for further study. More important, each probiotic proposed must be studied individually and extensively to determine its efficacy and safety in each disorder for which its use may be considered.

Immunonutrition: the pediatric experience

The health benefits of specific nutrients in the diet are reviewed as they pertain to the pediatric population and its unique needs. Secretory immunoglobulins, lysozyme, interferon, and growth factors, among others, are known to confer immunological advantages to breast milk. Inhibition of bacterial pathogens, as well as permissive growth of a protective colonic ecoflora occur as a result of various cellular and biochemical mechanisms at play. The immunomodulatory properties of minerals such as iron, zinc, and selenium, are presented and the newly recognized protective role of vitamin A and its importance in developing countries and in conditions of compromised nutrition are discussed. The review also covers the role of arginine, glutamine, and nucleotides in adaptive responses of the developing gut and in pathologic states such as necrotizing enterocolitis, short bowel syndrome, and inflammatory bowel disease. Probiotics (specific microbial feeds with potential benefits to the host), and prebiotics (dietary components such as complex carbohydrates able to change the colonic microenvironment fostering colonization with non-enteropathogens) are areas of current interest because they offer alternatives for the management of the growing problem of multiple antibiotic resistance and overwhelming infections in the hospitalized patient.

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.

Prevalence of lactose malabsorption in Galicia

BACKGROUND

The aim of the current study was to evaluate the prevalence of lactose malabsorption (LM) in Galicia (NW Spain) in order to design nutritional intervention and/or public education strategies for high risk groups.

METHODS

We conducted a study of LM by breath-hydrogen carbohydrate absorption test (BH2 test) in 850 healthy subjects. All subjects underwent BH2 tests following ingestion of a aqueous solution of 2 g lactose/kg body weight up to a maximum of 50 g. Subjects with LM were retested after ingesting 250 ml of milk and/or 250 ml of yogurt.

RESULTS

The frequency of LM in the subjects who ingested 2 g lactose/kg body weight was 32.5%. This percentage decreased significantly with a decrease in the quantity of administered lactose and the vehicle was milk or yogurt-only 13.7% was LM after 250 ml of milk and 3.8% after 250 ml of yogurt. Gastrointestinal symptoms also depend on dosage of lactose and vehicle, decreasing from 54.3% after 2 g lactose/kg to 18.5% after milk and to 0% after yogurt. The frequency and number of gastrointestinal symptoms were significantly higher (p < 0.001) in LM than in lactose absorption (LA).

CONCLUSIONS

Lactose malabsorption is prevalent in the population of Galicia. An important number of subjects identified as LM with usual clinical testing become LA when the ingestion of dairy products is limited so that the amount of lactose consumed is similar to that contained in a usual serving. Our results suggest the importance of BH2 testing following ingestion of usual consumed amounts of lactose per serving.

Carbohydrate absorption from one serving of fruit juice in young children: age and carbohydrate composition effects

OBJECTIVES

To test the hypotheses that: the efficiency of carbohydrate absorption in childhood increases with age, and decreased carbohydrate absorption occurs more frequently with juices containing more fructose than glucose and/or sorbitol than with juices which contain equal amounts of fructose and glucose and are sorbitol-free.

METHODS

One hundred and four healthy children were recruited from the Ambulatory Center at Maimonides Children's Center. They were assigned to one of three age groups: approximately 1, 3 and 5 years of age. Each child received one age-specific dose (by randomization) of one of four juices: a) pear juice which contains fructose in excess to glucose and a large amount of sorbitol; b) apple juice which is similar to pear juice in its fructose to glucose ratio but contains four times less sorbitol than pear juice; c) white grape juice or d) purple grape juice both of which contain equal amounts of fructose and glucose and are sorbitol-free. Breath hydrogen excretion (BH2) was utilized as the index of carbohydrate absorption. It was measured in fasting children and at 30-minute intervals for 3 hours after drinking the single serving of juice. Multiple breath hydrogen related parameters were quantified and results were expressed as: BH2 peak, area under the curve, and degree of carbohydrate malabsorption. After the test, parents completed a questionnaire and recorded signs and symptoms of intestinal malabsorption for 24 hours.

RESULTS

Pear juice related BH2 levels were significantly higher among children 1 and 3 years of age as compared to the levels achieved after the other juices. Apple juice related BH2 levels were significantly higher only among the youngest age group of children. There was no significant difference in carbohydrate absorption among the 5 year old children regardless of the juice consumed. Incomplete carbohydrate absorption (BH2 peak above 20 ppm) occurred more frequently after pear juice consumption (84%) than after apple juice (41%) or grape juice (white 20%, purple 24%) [p < 0.05]. Further outcome measures of BH2 excretion did not elicit differences beyond those detected by the above-mentioned parameters. Parents reported diarrhea in six children after pear juice, two after apple juice and two after purple grape juice and these children had the highest BH2 levels in their respective groups. No other symptoms were reported.

CONCLUSIONS

The data show that the efficiency of carbohydrate absorption of one age-specific serving of juice increases with advancing age of children. Decreased carbohydrate absorption occurs more often after ingestion of juices that contain more sorbitol, a nonabsorbable sugar and higher concentrations of fructose over glucose than after ingestion of juices which lack sorbitol and contain equal amounts of fructose and glucose.

Digestion and absorption of fruit juice carbohydrates

As consumption of dietary fructose and sorbitol increases, the association between consumption of these sugars and gastrointestinal symptoms has been recognized. As a result, studies of fructose and sorbitol absorption and malabsorption have emerged with investigations relying largely on the use of breath hydrogen (H2) measurements. Since these sugars are prevalent in fruit juices, a major dietary staple in the first 5 years of life, an understanding of fructose and sorbitol absorption is particularly important to pediatric health care providers. This review examines fructose and sorbitol absorption in humans, reviewing as well the breath H2 method upon which studies of fructose and sorbitol absorption largely depend.