Archive for category General Reference
Berg R. The indigenous gastrointestinal microflora. Trends Microbiol 1996;4(11):430-435.
The indigenous gastrointestinal (GI) tract microflora has profound effects on the anatomical, physiological and immunological development of the host.
The indigenous microflora stimulates the host immune system to respond more quickly to pathogen challenge and, through bacterial antagonism, inhibits colonization of the GI tract by overt exogenous pathogens.
Indigenous GI bacteria are also opportunistic pathogens and can translocate across the mucosal barrier to cause systemic infection in debilitated hosts.
JADA ’08: Experts publish science and practice-based guidelines for food and nutrition professionals
Douglas L, Sanders E. Probiotics and Prebiotics in Dietetics Practice. J Am Diet Assn 2008;108(3):510-521.
Probiotics and prebiotics share a unique role in human nutrition, largely centering on manipulation of populations or activities of the bacteria that colonize our bodies.
Benefits of regular consumption of probiotics or prebiotics include enhanced immune function, improved colonic integrity, decreased incidence and duration of intestinal infections, down-regulated allergic response, and improved digestion and elimination.
Research has shown that probiotics and prebiotics may be useful in achieving these and other positive effects, provided that proper strain, product selection, and dosing guidelines of commercial products are followed. There is a need to consolidate the basic and applied research on probiotics and prebiotics into useful tools for food and nutrition professionals.
Information on probiotic species, applications for specific strains, dosages and forms, safety, and shelf life is not sufficiently summarized to allow practical and consistent recommendations to be made by most food and nutrition professionals. In addition, prebiotic fibers—although providing nutraceutical and nutritional value—are a group of diverse carbohydrate ingredients that are poorly understood in regard to their origin, fermentation profiles, and dosages required for health effects.
The science and practice-based guidelines presented here will enhance clinician and client understanding of probiotics and prebiotics, with the aim of improving appropriate recommendation and informed use of these emerging dietary ingredients and the products containing them.
FAO/WHO Expert Consultation. Health and Nutritional properties of probiotics in food including powder milk with live lactic acid bacteria. Cordoba, Argentina; 2001.
A joint Food and Agriculture Organization of the United Nations/World Health Organization (FAO/WHO) expert Consultation on Health and Nutritional properties of powder milk with live lactic acid bacteria was held in Amerian Córdoba Park Hotel, Córdoba, Argentina from 1 to 4 October, 2001.
The Consultation, which was the first meeting of this group, focused on the evaluation of the scientific evidence available on the properties, functionality, benefits, safety, and nutritional features of probiotic foods.
A total of 11 experts from 10 countries participated in the Consultation. The complete list of participants is given in Annex 1.
The Minister of Production of the Province of Córdoba, Mr. Juan Schiaretti opened the Consultation.
He acknowledged the need for sound scientific evidence to substantiate health benefits associated with probiotic foods. The Secretary of Agriculture of the Province of Córdoba Mr. Victor Faraudo; the President of the Córdoba Science Agency, Mr. Carlos Debandi and the Coordinator of the National Codex Committee Mr. Eduardo Echaniz also gave welcome addresses. Dr. Jorgen Schlundt and Dr. Maya Pineiro spoke on behalf of the World Health Organization and the Food and Agriculture Organization of the United Nations. In their statements, the importance of probiotics to the health of the human population was indicated, with particular reference to their potential in developing countries.
The beneficial effects of food with added live microbes (probiotics) on human health, and in particular of milk products on children and other high-risk populations, are being increasingly promoted by health professionals. It has been reported that these probiotics can play an important role in immunological, digestive and respiratory functions and could have a significant effect in alleviating infectious disease in children.
As there are no international consensus on the methodology to assess the efficacy and the safety of these products, at present, it was considered necessary to convene an Expert Consultation to evaluate and suggest general guidelines for such assessments.
The Consultation evaluated the latest information and scientific evidence available on the functional and safety aspects of probiotics, as well as the methodology to assess such aspects, by bringing together worldwide scientific experts in the field.
- The experts agreed that adequate scientific evidence exists to indicate that there is potential for the derivation of health benefits from consuming food containing probiotics. However, it was felt that additional research data are needed to confirm a number of these health benefits in humans, applying a systematic approach and following the guidelines for the assessment of probiotics suggested in this report.
- There is good evidence that specific strains of probiotics are safe for human use and able to confer some health benefits on the host, but such benefits cannot be extrapolated to other strains without experimentation.
- The health benefits for which probiotics can be applied include conditions such as gastrointestinal infections, certain bowel disorders, allergy, and urogenital infections, which afflict a large portion of the world’s population. The application of probiotics to prevent and treat these disorders should be more widely considered by the medical community.
- In addition, there is emerging evidence to indicate that probiotics can be taken by otherwise healthy people as a means to prevent certain diseases and modulate host immunity.
- The regulatory status of probiotics as a component in food is currently not established on an international basis. In only a few countries, regulatory procedures are in place or sufficiently developed to enable probiotic products to be allowed to describe specific health benefits.
Lee J, O’Sullivan D. Genomic Insights into Bifidobacteria. Microbiol Mol Biol Rev 2010;74(3): 378–416.
Since the discovery in 1899 of bifidobacteria as numerically dominant microbes in the feces of breast-fed infants, there have been numerous studies addressing their role in modulating gut microflora as well as their other potential health benefits. Because of this, they are frequently incorporated into foods as probiotic cultures.
An understanding of their full interactions with intestinal microbes and the host is needed to scientifically validate any health benefits they may afford.
Recently, the genome sequences of nine strains representing four species of Bifidobacterium became available. A comparative genome analysis of these genomes reveals a likely efficient capacity to adapt to their habitats, with B. longum subsp. infantis exhibiting more genomic potential to utilize human milk oligosaccharides, consistent with its habitat in the infant gut. Conversely, B. longum subsp. longum exhibits a higher genomic potential for utilization of plant-derived complex carbohydrates and polyols, consistent with its habitat in an adult gut.
An intriguing observation is the loss of much of this genome potential when strains are adapted to pure culture environments, as highlighted by the genomes of B. animalis subsp. lactis strains, which exhibit the least potential for a gut habitat and are believed to have evolved from the B. animalis species during adaptation to dairy fermentation environments.
Salminen S, Bouley C, Boutron-Rualt M, et al. Functional food science and gastrointestinal physiology and function. Br J Nutr 1998;80(1):S147-S171.
The gut is an obvious target for the development of functional foods, acting as it does as the interface between diet and the metabolic events which sustain life.
The key processes in digestive physiology which can be regulated by modifying diet are satiety, the rate and extent of macronutrient breakdown and absorption from the small bowel, sterol metabolism, the colonic microflora, fermentation, mucosal function and bowel habit, and the gut immune system. The intestinal microflora is the main focus of many current functional foods.
Probiotics are foods which contain live bacteria which are beneficial to health whilst prebiotics, such as certain non-digestible oligosaccharides which selectively stimulate the growth of bifidobacteria in the colon, are already on the market. Their claimed benefits are to alleviate lactose maldigestion, increase resistance to invasion by pathogenic species of bacteria in the gut, stimulate the immune system and possibly protect against cancer. There are very few reports of well-designed human intervention studies with prebiotics as yet. Certain probiotic species have been shown to shorten the duration of rotavirus diarrhoea in children but much more work is needed on the mechanism of immunomodulation and of competitive exclusion and microflora modification.
The development of functional foods for the gut is in its infancy and will be successful only if more fundamental research is done on digestive physiology, the gut microflora, immune system and mucosal function.
Elias J, Bozzo P, Einarson A. Are probiotics safe for use during pregnancy and lactation? Canadian Family Physician 2011;57(3):299-301.
There has been a great deal of discussion in both the medical and lay literature about the use of probiotics to improve general health. Subsequently, pregnant women have been asking me if probiotics used for treating conditions such as bacterial vaginosis and diarrhea are safe to use during pregnancy and lactation.
Current data suggest that probiotic supplementation is rarely systemically absorbed when used by healthy individuals. One meta-analysis and several randomized controlled trials conducted with women during the third trimester of pregnancy did not report an increase in adverse fetal outcomes. There have been no published studies addressing Saccharomyces species use in pregnancy. Probiotics are unlikely to be transferred into breast milk.
J Am Coll Nutr ’10: Significant improvements in immune health shown in stressed but healthy shift workers with supplementation of L. casei
Guillemard E, Tanguy J, Flavigny, et al. Effects of Consumption of a Fermented Dairy Product Containing the Probiotic Lactobacillus casei DN-114 001 on Common Respiratory and Gastrointestinal Infections in Shift Workers in a Randomized Controlled Trial. J Am Coll Nutr 2010;29(3):455-468.
Objective: The risk of infection may be increased in people under stress such as shift workers. This study examined the effect of a fermented dairy product containing the probiotic Lactobacillus casei DN-114 001 (verum) on the incidence of respiratory and gastrointestinal common infectious diseases (CIDs) and on immune functions in healthy shift workers.
Methods: The study was single-center, randomized, double-blind, and controlled. Volunteers received 200 g/day of verum (n = 500) or control product (n = 500) for 3 months; 1-month follow-up was carried out.
Results: The cumulated number of CIDs (primary outcome) was not significantly different between groups. Because the Poisson distribution of the primary parameter did not fully fit the observed data, a post hoc categorical analysis was applied and showed a significantly lower cumulated number of CIDs in the verum group during the product consumption phase (odds ratio [OR] = 0.75, 95% confidence interval [CI] 0.59–0.95, p = 0.017). Verum also reduced the proportion of volunteers experiencing at least 1 CID (43% vs. 51%, p = 0.005), increased the time to the first occurrence of CID (p = 0.017) in the whole population, and reduced the cumulated number of CIDs in the subgroup of smokers (p = 0.033). In the course of CID, cumulated duration of fever was lower in the verum group (in the whole study phase) (p = 0.022), and an increase in leukocyte, neutrophil, and natural killer (NK) cell counts and activity (p = 0.047 to p < 0.001) was observed compared with control group. Verum was safe and well tolerated.
Conclusion: The results indicate that daily consumption of a fermented dairy product containing Lactobacillus casei DN-114 001 could reduce the risk of common infections in stressed individuals such as shift workers.
J Nutr Healthy Aging ’07: All doses used in B. lactis dose-response trial in the elderly show benefit on intestinal flora
Ahmed M, Prasad J, Gill H, et al. Impact of consumption of different levels of Bifidobacterium lactis HN019 on the intestinal microflora of elderly human subjects. J Nutr Health Aging 2007;11:26-31.
Age-related changes in the physiology and intestinal function of the elderly render them more susceptible to gut-related illnesses. Probiotic dietary supplementation has been shown to enhance the health indices in the elderly.
To determine the effect of three different doses [5 x 109 CFU/day (high), 1.0 x 109 CFU/day (medium) and 6.5 x 107 CFU/day (low)] of Bifidobacterium lactis HN019 (DR10TM) on the intestinal flora of elderly human subjects and the dose response effect.
Randomised, double-blind and placebo-controlled human dietary intervention study consisting of four groups of 20 elderly (over 60 years old) volunteers. Each volunteer consumed 250 mL per day of reconstituted skim milk (RSM) which either did not contain any probiotic supplement (placebo group) or contained B. lactis HN019 at different levels (low, medium and high dose groups). The study comprised three stages: a 2-week pre-intervention (without any supplement), followed by 4 weeks of test feeding (dietary intervention) and then a 2-week washout period.
After dietary intervention, statistically significant increases in bifidobacteria, lactobacilli and enterococci were observed. At the end of the 4-week feeding period the mean number of bifidobacteria recorded in the placebo group were 9.31 +/- 0.01 log CFU/g of faeces. In the high, medium and low dose groups the bifidobacteria levels were significantly (p < 0.006) higher (9.88 +/- 0.1, 9.75 +/- 0.14 and 9.74 +/- 0.11 log CFU/g of faeces, respectively), when compared to the respective pre-intervention levels. There were no significant differences (p superior 0.05) between the responses of the different dose groups, indicating that even the lowest dose tested augmented the changes in bifidobacteria. Similar trends were observed for lactobacilli and enterococci. In contrast, the counts of enterobacteria were reduced in all the probiotic dose groups.
The present study showed that dietary supplementation with B. lactis HN019 significantly increased the number of resident bifidobacteria and reduced the enterobacteria counts. In addition, enterococci and lactobacilli were also increased. Based on this study and already published clinical evidence (4, 5, 8, 9) we conclude that, B. lactis HN019 is a suitable probiotic for elderly human subjects and even the lowest dose (6.5 x 107 CFU/day) tested is able to confer desired changes in the intestinal microflora.
Goldin B, Gorbach S, Saxelin M, et al. Survival of Lactobacillus species (strain GG) in human gastrointestinal tract. Digestive Dis Sci 1992;37(1):121-128.
A newly isolated strain of a species of Lactobacillus of human origin, designated GG (Lactobacillus GG), has been studied to determine its ability to survive in the human gastrointestinal tract.
When fed to 76 volunteers as a frozen concentrate or as a fermented preparation in milk or whey, Lactobacillus GG was recovered in the feces of all subjects receiving the fermented milk or whey and in 86% receiving the frozen concentrate when a single fecal specimen was cultured. The organism was also present in the feces of subjects concurrently receiving ampicillin.
After terminating feeding of the organism, Lactobacillus GG persisted in the feces of 87% of volunteers four days later and in 33% of subjects seven days later. Lactobacillus GG lowered fecal bacterial -glucuronidase activity by approximately 80% in volunteers given the organism for four weeks.
These studies demonstrate that Lactobacillus GG can survive and temporarily colonize the human gastrointestinal tract and can affect the metabolic activity of the resident microflora.
Gopal, P, Prasad J, Gill H. Effects of the consumption of Bifidobacterium lactis HN019 (DR10TM) and galacto-oligosaccharides on the microflora of the gastrointestinal tract in human subjects. Nutrition Research 2003;23(10):1313-1328.
The effects of dietary consumption of milk derived oligosaccharides and a probiotic bacterium Bifidobacterium lactis HN019 (also known as DR10TM) on the microbial composition of the gastrointestinal tract of human subjects was examined using a randomized, double blind, placebo-controlled study design.
Thirty subjects (age range 20–60 years) were divided randomly into three groups. After two weeks of a pre-intervention period, volunteers in group one consumed a reconstituted milk containing 2.4 g of galacto-oligosaccharides per day, volunteers in group two consumed reconstituted milk containing 3 × 1010 CFU of B. lactis HN019 per day, and group three volunteers consumed reconstituted milk without galacto-oligosaccharides or probiotic bacteria. The feeding period continued for four weeks followed by a wash out period of two weeks. Faecal samples were collected at weekly intervals and analysed for eight major groups of microbes associated with human gastrointestinal tract.
Subjects receiving reconstituted milk containing either galacto-oligosaccharides or probiotic bacteria (B. lactis HN019) exhibited a significant increase in the faecal counts of both lactobacilli (p < 0.004) and bifidobacteria (p < 0.0002). In comparison, little or no changes were observed in lactobacilli and bifidobacteria counts in subjects who consumed reconstituted milk without supplementation with either galacto-oligosaccharides or probiotic B. lactis HN019 (placebo control group).
Furthermore, B. lactis HN019 survived the digestion through human gastrointestinal tract and colonised transiently. It is believed that desirable bacteria including members of the genera bifidobacterium and lactobacillus, have a positive impact on human health.
The results presented in this study demonstrate that dietary supplementation with B. lactis HN019 or galacto-oligosaccharides increases the proportion of bifidobacterium and lactobacillus in the human gastrointestinal tract and hence may improve human health.