Review articleProbiotic bacteria: safety, functional and technological properties
Introduction
Probiotics are live microbial food supplements which benefit the health of consumers by maintaining or improving their intestinal microbial balance (Fuller, 1989). Due to their perceived health benefits probiotic bacteria have been increasingly included in yoghurts and fermented milks during the past two decades. Most commonly they have been lactobacilli such as Lactobacillus acidophilus, and bifidobacteria often referred to as ‘bifidus’ (Daly and Davis, 1998). A major development in functional foods pertain to foods containing probiotics and prebiotics which enhance health promoting microbial flora in the intestine. There is growing scientific evidence to support the concept that the maintenance of healthy gut microflora may provide protection against gastrointestinal disorders including gastrointestinal infections, inflammatory bowel diseases, and even cancer (Haenel and Bendig, 1975, Mitsuoka, 1982, Salminen et al., 1998a). The use of probiotic bacterial cultures stimulates the growth of preferred micro-organisms, crowds out potentially harmful bacteria, and reinforces the body's natural defence mechanisms. Today, plenty of evidence exists on the positive effects of probiotics on human health. However, this has usually been demonstrated in diseased human populations only (Salminen et al., 1998a). Thus there is an urgent need for evidence for probiotic health benefits in average (generally healthy) populations.
Before a probiotic can benefit human health it must fulfil several criteria: It must have good technological properties so that it can be manufactured and incorporated into food products without loosing viability and functionality or creating unpleasant flavours or textures; it must survive passage through the upper gastrointestinal (GI) tract and arrive alive at its site of action; and it must be able to function in the gut environment. To study the probiotic strain in the GI-tract, molecular techniques must be established for distinguishing the ingested probiotic strain from the potentially thousands of other bacterial strains that make up the gastrointestinal ecosystem. Additionally, techniques are required to establish the effect of the probiotic strain on other members of the intestinal microbiota and importantly on the host. This includes not only positive health benefits, but also demonstration that probiotic strains do not have any deleterious effects. Armed with this knowledge, the probiotics can then enter human pilot studies that attempt to assess their health benefits to consumers (Mattila-Sandholm and Salminen, 1998, Mattila-Sandholm et al., 1999).
Section snippets
Selecting probiotic strains: important aspects
The theoretical basis for the selection of probiotic micro-organisms including safety, functional and technological aspects is illustrated in Fig. 1.
Current safety criteria for successful probiotics have been defined in several reviews (Lee and Salminen, 1995, Donohue and Salminen, 1996, Salminen et al., 1996b, Salminen et al., 1998b, Adams, 1999). The significance of human origin has been debated recently, but most current successful strains are indicated to be of human origin. It can also be
Safety aspects of probiotics
The safety of probiotic strains is of prime importance and guidelines for the safety assessment can be found in several articles (Lee and Salminen, 1995, Donohue and Salminen, 1996, Salminen et al., 1996b, Salminen et al., 1998b, Adams, 1999) (Fig. 2). Several approaches are possible in the assessment of the probiotic safety: (a) studies on the instrinsic properties of the probiotic strain; (b) studies on the pharmacokinetics of the probiotic strain; and (c) studies on interactions between the
Functional aspects of probiotics
Clinical effects of some probiotic strains in humans are shown in Table 1. These include, for example, immunomodulation, modulation of intestinal flora, prevention of diarrhoeas, and lowering of fecal enzyme activities. Some of the functional aspects of probiotics are discussed in more detail below.
Technological aspects of probiotics
Functional foods with probiotics are now well established on the European market. Starting about 20 years ago this product range has increased (Young, 1998) and is presently known to most consumers. To succeed in promoting the consumption of functional probiotic products the food industry has to satisfy the demands of the consumer. All probiotic foods should be safe and have good sensory properties. The probiotic foods should also include specific probiotic strains at a suitable level during
Future trends
Diet is a major focus of public health strategy aimed at maintaining optimum health throughout life, preventing early onset of chronic diseases such as gastrointestinal disorders, cardiovascular disease, cancer, osteoporosis, as well as promoting healthier ageing. Although the highly complex relationship of food and health is still poorly understood, recent research advances in different disciplines provide promising new approaches to improve our understanding. The growing demand for ‘healthy’
Acknowledgements
This work was supported by European Concerted Action PL98 4230.
References (165)
Safety of industrial lactic acid bacteria
J. Biotechnol.
(1999)- et al.
Antibiotic susceptibility of potentially probiotic Lactobacillus species
J. Food Prot.
(1998) - et al.
Viability of yoghurt and bacteria in yoghurts made from commercial starter cultures
Int. Dairy J.
(1997) - et al.
Ingredient supplementation effects on viability of probiotic bacteria in yougurt
J. Dairy Sci.
(1998) - et al.
Modulation of nonspecific mechanisms of defense by lactic acid bacteria: effective dose
J. Dairy Sci.
(1999) - et al.
Ability of dairy strains of lactic acid bacteria to bind a common food carcinogen, aflatoxin B1
Food Chem. Toxicol.
(1998) - et al.
Physicochemical alterations enhance the ability of dairy strains of lactic acid bacteria to remove aflatoxin from contaminated media
J. Food Prot.
(1998) - et al.
Anticarcinogenic and immunological properties of dietary lactobacilli
J. Food Prot.
(1990) - et al.
Therapeutic role of dietary lactobacilli and lactobacillic fermented dairy products
FEMS Microbiol. Rev.
(1987) - et al.
Effect of a probiotic formula on intestinal immunoglobulin A production in healthy children
Int. J. Food Microbiol.
(1998)
The development of functional foods: lessons from the gut
TIBTECH
Growth enhancement of Bifidobacterium lactis Bo and Lactobacillus acidophilus Ki by milk hydrolyzates
J. Dairy Sci.
Suppressing effect of Lactobacillus casei administration on the urinary mutagenicity arising from ingestion of fried ground beef in human
Cancer Lett.
Potential of lactic acid bacteria and novel antimicrobials against gram-negative bacteria
Trends Food Sci. Technol.
Biological preservation of foods with reference to protective cultures, bacteriocins and food-grade enzymes
Int. J. Food Microbiol.
Antimutagenic properties of lactic acid cultured milk on chemical and fecal mutagens
J. Dairy Sci.
Survival of Lactobacillus plantarum DSM 9843 (299v), and effect on the short-chain fatty acid content of faeces after ingestion of a rose-hip drink with fermented oats
Int. J. Food Microbiol.
The ability of probiotic bacteria to bind human intestinal mucus
FEMS Microbiol. Lett.
Lactobacillus rhamnosus GG (ATCC 53013) and platelet aggregation in vitro
Int. J. Food Microbiol.
The coming of age of probiotics
Trends Food Sci. Technol.
Antimicrobial susceptibility of bifidobacteria
J. Dairy Sci.
Lactobacillus strain GG supplementation decreases colonic hydrolytic and reductive enzyme activities in healthy female adults
J. Nutr.
Modulation of a specific humoral immune response and changes in intestinal flora mediated through fermented milk intake
FEMS Immunol. Med. Microbiol.
Lactobacillus endocarditis caused by a probiotic organism
Clin. Microbiol. Infect.
Probiotics: a novel approach in the management of food allergy
J. Allergy Clin. Immunol.
Effect of chronic ingestion of a fermented dairy product containing Lactobacillus acidophilus and Bifidobacterium bifidum on metabolic activities of the colonic flora in humans
Am. J. Clin. Nutr.
Antimicrobial susceptibility of Bifidobacterium
Ann. Microbiol. (Paris)
Lactic acid bacteria with health claims — interference and interactions with gastrointestinal flora
Int. Dairy J.
Recovery of Lactobacillus rhamnosus GG from human colonic biopsies
Lett. Appl. Microbiol.
Persistence of colonization of human colonic mucosa by a probiotic strain, Lactobacillus rhamnosus GG, after oral consumption
Appl. Environ. Microbiol.
Pre- and probiotics — sausage science
Functional Foods
Prophylactic Lactobacillus GG reduces antibiotic-associated diarrhea in children with respiratory infections: a randomized study
Pediatrics
Prophylactic effect of a Lactobacillus casei preparation on the recurrence of superficial bladder cancer
Urol. Int.
Preventive effect of a Lactobacillus casei preparation on the recurrence of superficial bladder cancer in a double-blind trial
Eur. Urol.
The relationship between the volume of antimicrobial consumption in human communities and the frequency of resistance
PNAS
Treatment of relapsing Clostridium difficile diarrhea with Lactobacillus GG
Nutr. Today
Adhesion of human bifidobacterial strains to cultured human intestinal epithelial cells and inhibition of enteropathogen–cell interactions
Appl. Environ. Microbiol.
Lactobacillus acidophilus LA 1 binds to cultured human intestinal cell lines and inhibits cell attachment and cell invasion by enterovirulent bacteria
Gut
The human Lactobacillus acidophilus strain LA1 secretes a nonbacteriocin antibacterial substance(s) active in vitro and in vivo
Appl. Environ. Microbiol.
Modification of peptidoglucan precursors is a common feature of the low-level vancomycin-resistant VANB-type Enterococcus D366 and of the naturally glycopeptide-resistant species Lactobacillus casei, Pediococcus pentosaceus, Leuconostoc mesenteroides, and Enterococcus gallinarum
J. Bacteriol.
Effect of lactic acid producing bacteria on the human intestinal microflora during ampicillin treatment
Scand. J. Infect. Dis.
Saccharomyces boulardii prevents diarrhea in critically ill tube-fed patients. A multicenter, randomized, double-blind placebo-controlled trial
Intensive Care Med.
Saccharomyces boulardii for Clostridium difficile-associated enteropathies in infants
J. Pediatr. Gastroenterol. Nutr.
Antibiotic susceptibility of potentially probiotic Bifidobacterium isolates from the human gastrointestinal tract
Lett. Appl. Microbiol.
Adhesion of human Lactobacillus acidophilus strain LB to human enterocyte-like Caco-2 cells
J. Gen. Microbiol.
Adhering heat-killed human Lactobacillus acidophilus, strain LB, inhibits the process of pathogenicity of diarrhoeagenic bacteria in cultured human intestinal cells
J. Diarrh. Dis.
Inhibition of adhesion of enteroinvasive pathogens to human intestinal Caco-2 cells by Lactobacillus acidophilus strain LB decreases bacterial invasion
FEMS Microbiol. Lett.
Cited by (886)
Exploring marine Lactobacillus and its protein for probiotic-based oral cancer therapy
2024, International Journal of Biological MacromoleculesThe regulation of key flavor of traditional fermented food by microbial metabolism: A review
2023, Food Chemistry: XSelected fermented indigenous vegetables and fruits from Malaysia as potential sources of natural probiotics for improving gut health
2023, Food Science and Human Wellness