European Journal of Clinical Nutrition (1999) 53, 339±350 ß 1999 Stockton Press. All rights reserved 0954±3007/99 $12.00 http://www.stockton-press.co.uk/ejcn
Review Lactic acid bacteria and the human gastrointestinal tract H Hove1*, H Nùrgaard1 and P Brùbech Mortensen1 1
Medical Department CA, Division of Gastroenterology, Rigshospitalet and Paediatric Department L, Gentofte University Hospital, Denmark.
Objective: This review summarises the effects of lactic acid bacteria on lactose malabsorption, bacterial=viral or antibiotic associated diarrhoea, and describes the impact of lactic acid bacteria on cancer and the fermentative products in the colon. Results: Eight studies (including 78 patients) demonstrated that lactase de®cient subjects absorbed lactose in yogurt better than lactose in milk, while two studies (25 patients) did not support this. Two studies (22 patients) showed that unfermented acidophilus milk was absorbed better than milk, while six studies (68 patients) found no signi®cant differences. Addition of lactose hydrolysing enzyme, lactase, to milk improved lactose malabsorption in seven studies (131 lactose malabsorbers), while one study (10 malabsorbers) demonstrated no improvement. Lactic acid bacteria alleviated travellers' diarrhoea in one study (94 individuals) while a study including 756 individuals was borderline statistically signi®cant. One study (50 individuals) did not ®nd an effect of lactic acid bacteria on travellers' diarrhoea. Six studies (404 infants) demonstrated a signi®cant effect of lactic acid bacteria on infant diarrhoea, while one study (40 infants) did not. Lactic acid bacteria moderated antibiotic associated diarrhoea in three studies (66 individuals), while two studies (117 individuals) were insigni®cant. Conclusions: Lactase de®cient subjects bene®t from a better lactose absorption after ingestion of yoghurt compared with milk and from milk added lactase, whereas ingestion of unfermented acidophilus milk does not seem to improve lactose absorption. The majority of studies support that lactic acid bacteria alleviate bacterial=viral induced diarrhoea, especially in infants, while the effect on antibiotic associated diarrhoea is less clear. Experimental studies indicate an effect of lactic bacteria on human cell cancer lines, but clinical evidence is lacking. A `stabilising' effect of lactic acid bacteria on the colonic ¯ora has not been documented. Descriptors: lactic acid bacteria; lactobacilli; bi®dobacteria; lactate; lactic acid; lactose malabsorption; antibiotic associated diarrhoea; diarrhoea; rotavirus; colonic cancer
Introduction Interest in the bene®cial effects of lactic acid bacteria dates to the Russian scientist, E. Metchnikoff (1845 ± 1919), who proposed that the extended longevity of the Balkan people could be attributable to their practice of ingesting fermented milk products (Metchnikoff, 1908). He believed that gastrointestinal disturbances occur by intestinal growth of putrefactive microbes, and that lactic acid bacteria could minimise or prevent the harmful effects of these microbes. The role of lactic acid bacteria within the gastrointestinal tract has been one of the most controversial subjects of the area of intestinal microbial ecology. No other group of bacteria has been proposed to be responsible for so many different bene®cial actions, but non-conclusive or insigni®cant results are often reported when attempts are made to con®rm that lactic acid bacteria improve the health of the host. Lactic acid bacteria consists of heterogeneous group of gram-positive bacteria, whose main fermentation product from carbohydrate is lactate. The group comprises cocci (streptococcus, pediococcus, leuconostoc) and rods (lactobacillus and bi®dobacterium), which are either exclusively *Correspondence: Hanne Hove, Ph.D., Hovmarksvej 77, 2920 Charlottenlund. Received 14 August 1998; revised 7 December 1998; accepted 20 December 1998
(homofermentative) or at least 50% (heterofer-mentative) lactate producers (Kandler, 1983, Table 1). Studies on the ¯ora of the gastrointestinal tract report that numbers of bi®dobacteria may exceed 1011 per gram of faeces (Finegold et al, 1983) accounting for 6 ± 25% of all cultivable bacteria in faeces (Kitsuoka, 1984; Scardovi, 1986) whereas lactobacilli only constitute 0 ± 1% of the bacteria in the faeces of healthy humans (Hill & Drasar, 1975; Gorbach, 1971; 1986, Brown, 1977). The exception of this condition is the dominant presence of bi®dobacteria in breast-fed infants (Stark & Lee, 1982). Lactic acid bacteria are described to be of nutritional and therapeutic bene®t to the host in several clinical conditions. The proposed effects of lactic acid bacteria on the intestinal tract are mentioned in Table 2. Discussion of these speci®c health targets follow. Lactic acid bacteria supposedly exert an impact on the small as well as the large intestine. First, bacterial derived lactase from ingested lactic acid bacteria might enhance the hydrolysis of lactose to glucose and galactose in the small intestine, which are rapidly absorbed or fermented. Secondly, lactic acid bacteria may have an impact on the colonic ¯ora in situations in which some sort of imbalance exists. The exact nature of this microbial imbalance and how it is corrected by the ingestion of lactic acid bacteria is not known.
Lactic acid bacteria H Hove et al
340
Table 1 The genera of lactic acid bacteria, their fermentation type and main products (Kandler, 1983) Genus
Fermentation type
Main product
Con®guration of lactate
Streptococcus Pediococcus Lactobacillus Leuconostoc Bi®dobacterium
homofermentative homofermentative homofermentative heterofermentative heterofermentative
lactate lactate lactate lactate : acetate lactate : acetate
L-lactate DL-lactate DL-lactate D-lactate L-lactate
Table 2 Studies evaluating the clinical effect of lactic acid bacteria
Yogurt improves lactose absorption compared with milk? (Table 3 a) Unfermented acidophilus milk improves lactose absorption compared with milk? (Table 3 b) Lactase relieves lactose malabsorption among lactose malabsorbers? (Table 5) Lactic acid bacteria reduce incidence of travellers diarrhoea? (Table 6 a) Lactic acid bacteria reduce incidence of diarrhoea among infants? (Table 6 b) Lactic acid bacteria alleviate antibiotic associated diarrhoea? (Table 7 a)
Over the past decade there has been increased interest in bacterial food supplements, called probiotics. The de®nition of a probiotic being: `A live microbial feed supplement which bene®cially affects the host animal by improving its intestinal microbial balance' (Fuller, 1989). There are several characteristics that are of importance for organisms used as probiotics (Kim, 1988). These include: the organism should maintain viability and activity in the carrier food before consumption, should survive the upper gastrointestinal tract, be capable of surviving and growing in the intestine, be a normal inhabitants of the intestinal tract, and eventually produce bene®cial effects when in the intestinal tract. Further, the organism must be non-pathogenic and non-toxic. Survival through the gastrointestinal tract The effect of lactic acid bacteria in the intestine requires that the bacteria or at least their enzymes survive the acid gastric content and are active after the passage of the stomach. Studies of orally administered lactic acid bacteria have demonstrated that the lactic acid bacterial counts in the small intestine increase signi®cantly after ingestion (Robins-Browne et al, 1981). The ability of Bi®dobacterium bi®dum to survive the passage through the upper gastrointestinal tract when ingested in fermented milk was investigated by Pochart et al (1992) using in vivo ileal perfusion, and he found that the average number of bi®dobacteria recovered from the terminal ileum constituted approximately 25% of the number ingested (ingested dose 1010 bacteria). This is in consistency with a study of ileotomic patients ingesting lactic acid bacteria, where bi®dobacteria were cultured from ileostomic contents in eight of nine ileostomists within six hours oral administration of 1010 bacteria, while not present in the ileostomy ef¯uents of patients during control sampling (Hove et al, 1994). Similarly, faecal levels of speci®c strains of lactic acid bacteria increase after ingestion. Goldin et al (1992) followed the excretion of Lactobacillus gg in faeces 3 and 7 d after subjects consumed 1011 of Lactobacillus gg as either concentrate or as a whey drink. Strain gg increased 4 ± 6 log cycles in almost all subjects, and remained present in faeces 7 d after feeding stopped. These results have also been obtained with bi®dobacteria (Bouhnik et al, 1992),
Positive studies
Negative studies
8 2 7 1 6 3
2 6 1 2 1 2
where intake of marked bi®dobacteria resulted in a rise in faecal levels to approximately 108 bi®dobacteria=g faeces followed by a gradual decrease after ingestion ceased. Thus, attempts to increase the number of lactic acid bacteria in the gastrointestinal tract by ingestion generally results in a temporary colonisation of the gut, which persists as long as the lactic acid bacteria are ingested (Goldin et al, 1992; Deneke et al, 1988; Saxelin et al, 1991). After consumption of a bacterium, recovery from the faeces is not evidence of implantation, even if recovery persists for a period after consumption has stopped. Continued faecal recovery of ingested lactic acid bacteria may be because of residence time in the large intestine that exceeds microbial generation time.
Impact on the small intestine Relieving lactose intolerance in lactose malabsorbers Lactose is the predominate carbohydrate in milk, and it requires enzymatic hydrolysis to the monosaccharides glucose and galactose before intestinal absorption. Small intestinal epithelial cells (enterocytes) produce b-galactosidase in childhood, and some people continue to produce b-galactosidase throughout life, but globally most adults are lactose malabsorbers and are as non-milk consumers deprived of an important source of protein and calcium. Although lactose malabsorption is common worldwide, the symptomatic expression of lactose intolerance is less so. Lactose intolerance has a substantial psychological component: among individuals who believed they were lactose malabsorbers 64% were shown to be lactose digesters (Rosado et al, 1987); most lactase-de®cient people can consume one glass of milk per day asymptomatically (Savaiano & Kotz, 1988), and 85% of individuals with discomfort have only mild symptoms (Scrimshaw & Murray, 1988). Carbohydrate malabsorption increases the delivery of unabsorbed carbohydrates to the colon bacteria and results in increased intestinal production and respiratory excretion of hydrogen. Breath hydrogen excretion is therefore used as an indicator of malabsorption of simple carbohydrates as disaccharides (Welsh et al, 1981). A dose-response relationship between breath hydrogen excretion and the amount
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341
Figure 1 Prevalence of adult lactose malabsorption in Europe in percent (Gudmand-Hùyer & Skovbjerg, 1996). (Reprinted by permission of the author and Scandinavian University Press).
of malabsorbed disaccharide (non-absorbable lactulose) has been found by Rumessen et al (1990), while breath hydrogen excretion is of limited value in the evaluation of malabsorption of complex dietary carbohydrates (Nordgaard et al, 1995). The geographic incidence of lactose malabsorption is shown in Figure 1 (Gudmand-Hùyer & Skovbjerg, 1996). Yogurt is made from milk enriched with milk proteins (to improve consistency), which is incubated with two or three species of lactic acid bacteria (that is L. bulgaricus and S. thermophilus) at 42 C until the pH drops to approximately 4.5 (Martini et al, 1987). The resulting yogurt is cooled and stored until use. In contrast to yogurt, sweet acidophilus milk is unfermented, made by adding high concentrations of viable L. acidophilus cells to cold milk. In storage below 5 C L. acidophilus do not multiply and thus, sweet acidophilus milk has the bene®ts of lactase activity, without the acid taste of the corresponding fermented product (Martini et al, 1991). It seems evident that lactose intolerant individuals are able to substitute fermented milk (yogurt) for fresh milk, Table 3 (a). The rational for using fermented milk relates to the fact that lactose content is reduced between 25 and 50 percent
during the fermented process (McDonough et al, 1987; Gorbach, 1990). Reduced malabsorption may, however, not only be associated with the decreased lactose concentration, but also to high lactase activities in yogurt (Kolars et al, 1984, Savaiano et al, 1984). In considering how much of the improved digestion was due to reduction in lactose and how much was due to ingested lactase supplied by the cultures, the following investigations were performed (Table 4). When yogurt was heated in order to inactivate lactase, malabsorption measured by breath hydrogen test was still signi®cantly lower than after milk ingestion. Since both products had little or no lactase activity, it was assumed that the difference was due to reduced lactose in the heated yogurt (McDonough et al, 1987). Similarly, when lactose was added to yogurt so that lactose concentration was equal to that in milk, the mean breath hydrogen value was signi®cantly lower than the value for milk, thus indicating a response to lactase activity (McDonough et al, 1987). This was further substantiated by adding commercial lactase to heated yogurt, in an amount that produced an activity level comparable to that found in yogurt, resulting in signi®cantly lower breath hydrogen test than for heated yogurt. With similar lactose content and lactase activity in heated yogurt added lactase and in yogurt, the two products
Lactic acid bacteria H Hove et al
342
Table 3 The ability of fermented and non-fermented milk products in relieving lactose malabsorption. Comparison of yoghurt with regular milk is indicated by (a); while comparison of unfermented acidophilus milk with regular milk is indicated by (b). Comparison of lactose or lactulose with yogurt or heated yogurt with yogurt is indicated by (c) Reference
Number of lactose malabsorbers
Test
Genera and dose
Results (absorption measured by breath hydrogen test)
1981 Payne (b)
11
SAM vs milk lactose conc.?
L. acidophilus cfu=d?
NS between milk and SAM
1983 Kim (b)
12
SAM vs milk lactose conc.?
L. acidophilus 1011 cfu=d
SAM signi®cantly better absorbed than milk (P < 0.01)
1983 Newcomer (b)
18
SAM vs milk lactose conc.?
L. acidophilus 109 cfu=d
NS between milk and SAM
1984 Gilliland (c)
6
Y vs HY equal lactose conc.
L. bulgaricus S. thermophilus cfu=d?
Y signi®cantly better absorbed than HY (P < 0.05)
1984 Kolars (a)
10
Y vs milk 18 g lactose
L. bulgaricus S.thermophilus
Y signi®cantly better absorbed than milk (P < 0.01)
1984 Savaiano (a,b)
9
Y, HY and SAM vs milk 20 g lactose
genera? 109 ± 1011 cfu=d
1) Y sign®cantly better absorbed than milk, HY, and SAM (P < 0.05) 2) NS between milk and SAM
1987 McDonough (a,b)
14
Y, HY, Y lactose, HY lactase, SAM, SAM-S vs milk
L. bulgaricus S. thermophilus L. acidophilus 31011 cfu=d
1) Y signi®cantly better absorbed than milk, HY, and Y lactose (P < 0.05) 2) Y lactose and SAM-S signi®cantly better absorbed than milk (P < 0.05) 3) NS between SAM and milk and between Y and HY lactase. Two kinds of Y sign®cantly better absorbed than lactose (P < 0.05)
16 g lactose
1988 Wytock (c)
8
Lactose vs 3 kinds of Y 20 g lactose
L. bulgaricus S. thermophilus cfu=d?
1989 Onwulata (a,b)
10
Y, SAM vs milk 18 g lactose
L. bulgaricus S. thermophilus L. acidophilus cfu=d?
1) Y signi®cantly better absorbed than milk and SAM 2) NS between SAM and milk
1990 Marteau (a)
8
Y and HY vs milk 18 g lactose
genera? cfu=d?
1) Y and HY signi®cantly better absorbed than milk (P < 0.001) 2) NS between Y and HY
1991 Martini (a)
7
Y vs milk 18 g lactose
Y signi®cantly better absorved than milk (P < 0.025)
1991 Lin (a,b)
10
Y and SAM vs milk 20 g lactose
L. bulgaricus S. thermophilus 1011 cfu=d L. bulgaricus S. thermophilus L. acidophilus 41010cfu=d
1994 Arrigoni (a)
11*
Y vs milk 20 g lactose
genera? cfu=d?
NS between milk and Y
1994 Kotz (a)
10
High galactosidase Y vs milk 20 g lactose
L. bulgaricus S. thermophilus 2108 cfu=d
High galactosidase Y signi®cantly better absorbed than milk (P < 0.05)
1995 Dehkordi (b)
6
SAM vs milk 18 g lactose
L. acidophilus cfu=d?
NS between milk and SAM
1995 ShermaÈk (a)
14
Y and HY vs milk 12 g lactose
L. bulgaricus S. thermophilus cfu=d?
NS between milk, Y and HY
1996 Vesa (c)
14
lactulose vs 3 kinds of fermented milk products
L. bulgaricus S. thermophilus Bi®dobacteria
18 g lactose vs 10 g lactulose
L. acidophilus cfu=d?
1) Fermented milk signi®cantly better absorved than lactulose 2) NS between the 3 kinds of fermented milk
1) Y signi®cantly better absorbed than milk (P < 0.01) 2) SAM signi®cantly better absorbed than milk (P < 0.05)
Abbreviations: Lactose malabsorption was determined by breath hydrogen test; Y: yogurt; HY: heated yogurt; SAM: sweet acidophilus milk; SAM-S: sonicated sweet acidophilus milk (cell membranes disrupted); cfu=d: colony forming units lactic acid bacteria ingested per day; NS: not signi®cantly different * : patients with jejunocolic anastomsis.
Lactic acid bacteria H Hove et al
would be expected to have comparable utilisation and indeed the breath hydrogen values were not signi®cantly different (McDonough et al, 1987). The majority of studies (Table 3a) support that yogurt enhances absorption of lactose when compared with equivalent amounts of lactose in milk. The improved tolerance of lactose when consumed as yogurt containing active live cultures is at least in part related to the inherent galactosidase activity of the yogurt bacteria, which hydrolyse a part of the ingested lactose (Kotz et al, 1994; SchermaÈk et al, 1995; Sanders, 1993). In spite of similar average values for the area under the breath hydrogen curve, yogurt and heated yogurt was associated with a delay in the time to breath hydrogen rise and the time to peak breath hydrogen when compared with milk (ShermaÈk et al, 1995), and studies have demonstrated a relationship between the rate of rise in Table 4 Lactose and lactase activity of milk and yogurt test products (McDonough et al, 1987) Product Control milk Yogurt Yogurt lactose Heated yogurt Heated yogurt lactase Sweet acidophilus milk Sweet acidophilus milk with sonicated cells
Lactose (g=250 ml)
Lactase (mg glucose=dl)
15.7 12.0 15.7 12.0 12.0 15.7 15.7
26 3724 3724 43 4138 1427 4263
Lactase activity was determined by measuring the amount of glucose released on hydrolysis during incubation at 37 C for 2 hours. Values are means of triplicate analysis.
breath hydrogen excretion and the severity of gastrointestinal symptoms (Dehkordi et al, 1995; ShermaÈk et al, 1995). In contrast to the above mentioned results, lactose intolerant individuals who ingest an unfermented milk product containing lactic acid bacteria (sweet acidophilus milk) with low concentration of bacterial lactase have no apparent bene®t from this as compared with milk, Table 3 (b), and Table 4. If, however, the bacterial cell-membranes are damaged by sonication, and intracellular lactase is released, breath hydrogen values were found in the same low level as for heated yogurt (McDonough et al, 1987). Thus, it seems that the bacterial lactase is not available or is insuf®cient to exert a measurable effect in sweet acidophilus milk during digestion, but can be made accessible after disruption of the cell membrane (Kolars et al, 1984; McDonough et al, 1987). In accordance, an increase in microbial galactosidase of yogurt, enhance lactose absorption compared with conventional yogurt (Kotz et al, 1994). These results are not supported by Kim & Gilliland 1983) and Lin et al (1991), but are in accordance with Hove et al (1994), who did not ®nd an improved lactose utilisation in lactase de®cient subjects after intake of large amounts of B. bi®dum (4.21010 cells). The ingestion of commerical lactase (often of yeast origin) either together with, immediately before or within 5 minutes after milk consumption (meal-time treated milk) is reported to improve lactose utilisation in most studies, while refuted in a single study (Onwulata et al, 1989), (Table 5). Milk treated with a commercial lactase preparation 20 ± 24 h prior to ingestion is approximately 90% hydrolysed (Payne et al, 1981). This milk has therefore a sweeter taste than regular milk. Aspects of lactic acid cultures effect on lactose digestion in lactose malabsorbers are discussed in detail in review articles (Gorbach, 1990;
Table 5 Ability of commercial lactase in relieving lactose malabsorption in lactose malabsorbers. The b-galactosidase preparations were ingested immediately before or after milk consumption ( 5 min) References
Lactose malabsorbers
Treatment
Doses
Results
1984, Rosado
13
LactAid, Lactase N vs milk
18 g lactose 1.5 g LactAid 0.4 g Lactase N
LactAcid and Lactase N signi®cantly improved lactose absorption
1985 Solomons
10
LactAid, Lactase N vs milk
18 g lactose 2 g LactAid 0.3 g Lactase N
1986 Rosado
21
1987 Barillas
9 infants
Lactase N vs milk LactAid, Takamine vs milk
18 g lactose 0.4 g Lactase N 12 g lactose 1.0 g LactAid 0.3 g Takamine
LactAid signi®cantly improved lactose absorption (P < 0.01). Lactrase N did not improve absorption. Lactase N signi®cantly improved lactose absorption LactAid and Takamine signi®cantly improved lactose absorption
1988 Lami
52
LactAid vs milk
25 g lactose LactAid?
LactAid signi®cantly improved lactose absorption (P < 0.0005)
1989 DiPalma
10
Lactrase vs milk
50 g lactose 0.5 g Lactrase
Lactrase signi®cantly improved lactose absorption (P < 0.05)
1989 Onwulata
10
LactAid vs milk
18 g lactose LactAid?
LactAid did not improve lactose absorption
1992 Corazza
16
A. niger b-galactosidase
Lactose? Galactosidase?
A. niger b-galactosidase signi®cantly improved lactose absorption (P < 0.01)
Abbreviations: Lactose malabsorption was determined by the use of breath hydrogen test after ingestion of lactose; A niger: Aspergillus niger derived bgalactosidase. LactAid is a b-galactosidase derived from the yeast Kluyveromyces lactis (pH and temperature optimum 6.8 and 37 C). Lactase N, Takamine and Lactrase are b-galactosidase preparations derived from the fungus Asperigillus (Lactase: Aspergillus niger: pH and temperature optimum 4.4 and 60 C; Takamine and Lactrase: Aspergillus oryzae).
343
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344
Sanders, 1993; Gurr, 1987, Fuller, 1989, Shahani & Ayebo, 1980; Bengmark, 1998). Prophylaxis against E. coli and antibiotic associated diarrhoea Although the intestinal ¯ora is a very steady ecosystem, the balance can be disturbed by a number of factors such as bacteria, viruses and antibiotics. Travellers from United States and Northern Europe often suffer diarrhoea when visiting less developed regions of the world. The clinical picture varies from a short and mild attack with watery diarrhoea to a severe incapacitating disease with a duration of more than a week. In 40 ± 70% of the cases the etiological agent is enterotoxigenic Escherichia coli (E. coli) (Merson et al, 1976; Gorbach et al,
1975). It is well established that travellers' diarrhoea to a great extent can be prevented by prophylactic intake of antibiotics, which have been reported to provide protection rates in the range of 60 ± 95% (DuPont et al, 1986; Sack, 1986). The use of these agents may cause adverse reactions and lead to emergence of resistant bacterial strains. Therefore, the effect of lactic acid bacteria and other probiotics in promoting gastrointestinal health by inhibiting or eliminating enteric pathogens have been investigated. Numerous publications based on uncontrolled clinical observations have suggested a role for lactic acid bacteria in the prevention of diarrhoea (Beck & Necheles, 1961; Winkelstein, 1955), and several preparations of lactic acid bacteria (Paraghurt1, Trevis1, Biotura1) are available without prescription as prophylaxis against diarrhoea.
Table 6 The effect of lactic acid bacteria on travellers' diarroea (a), diarrhoea in infants (b) and E. coli induced diarrhoea (c) References
No. individuals
Treatment
Doses 9
Results
1978 P.-Olano (a)
50* DB, R Travel to Mexico
Lactinex
610 =d
Results (no. indiv. with diarrhoea=no. indiv.) 7=17 lactic acid bact. 2=14 placebo (NS)
1981 Clements (c)
48 DB, R Challenge with 1081010E. coli
Lactinex
2109=d
Results (no. indiv. with diarrhoea=no. indiv.) 16=23 lactic acid bact. 17=25 placebo (NS)
1985 Black (a)
94* DB, R Travel to Egypt
L. acidophilus, B. bi®dum, L. bulgaricus, S. thermophilus
9109=d
Results (no. indiv. with diarrhoea=no. indiv.) 17=40 lactic acid bact. 29=41 placebo (P 0.019)
1990 Boudraa (b)
45 infants (3 ± 36 m) R. Persistent diarrhoea
Yogurt vs milk
?
Diarrhea > 5 days: 3=21 yogurt 8=24 milk (P < 0.05) Weight loss > 5%: 0=21 yoghurt 2=24 milk ((P < 0.05)
1990 Oksanen (a)
756 DB, R. Travel to Turkey
Lactobacillus GG
2109=d
Frequency of diarr. (%): 41.0% lactic acid bact. 46.5% placebo (P 0.065)
1991 Isolauri (b)
71 infants (4 ± 45 m), R
Lactobacillus gg 1) yogurt 2) freeze-dried powder
1010 ± 11)=d
Duration of diarr. (days): 1.4 0.8 yogurt 1.4 0.8 lactbact. powder 2.4 1.1 placebo (P < 0.001)
1010 ± 11=d
Results (no. indiv. with diarrhoea=no.indiv.) 2=29 lactic acid bact. 8=26 placebo (P 0.035) Rotavirus shedding: 3=29 lactic acid bact. 10=26 placebo (P 0.025)
Rotavirus diarrhoea 1994 Saavedra (b)
55 infants (5 ± 24 m) DB, R Rotavirus diarrhoea
B. bi®dum, S. termophilus philus
1995 Majama (b)
49 infants DB, R. Rotavirus diarrhoea
Three groups 1) Lactobacillus gg 2) Lactophilus 3) Yalacta
1997 Guarino (b)
61 infants (3 ± 36 m) R. Rotavirus diarrhoea
oral rehydration liophylised Lactobacillus gg
6109=d
Duration of diarr. (days): 2.9 1.2 lactic acid bact. 6.1 1.7 no lactic acid bact. (P < 0.01)
1997 Shornikova (b)
40 infants (6 ± 36 m) R. Acute diarrhoea
freeze-dried Lacto bacillus reuteri
1010 ± 11=d
Duration of diarr. (days): 1.7 1.6 lactic acid bact. 2.9 2.3 placebo (P 0.07)
1997 Shornikova (b)
123 infants (1 ± 36 m) DB, R. Acute diarrhoea
oral rehydration freeze-dried Lactobacillus gg
5109=d
Duration of diarr. (days): 2.7 2.2 lactic acid bact. 3.7 2.8 placebo (P 0.03)
Duration of diarr. (days): 1.8 0.8 Lactobacillus gg 2.8 1.2 Lactophilus 2.6 1.4 Yalacta (P 0.04)
* Number of patients in the study; results only given for a part of the group. Lactinex: a commercial preparation of lactobacilli, containing dried viable L. acidophilus and L. bulgaricus in equal proportions (5108 bacteria per g). Lactobacillus gg: aq lactobacillus strain isolated from healthy humans on the basis of its ability to resist acid and bile, and to adhere to the intestinal mucosa. Lactophilus: lactobacillus casei subsp. Rhamnosus. Yalacta: combination of S. thermophilus, L. delbruÈckii and L. casei. Abbreviations: No. indiv. with diarr.=no. indiv.: Number of individuals with diarrhoea=total number of individuals; DB.: double blind; R.: randomised; bact.: bacteria, m: months; y: years.
Lactic acid bacteria H Hove et al
Table 7
The effect of lactic acid bacteria on antibiotic associated diarrhoea (a) and Clostridium dif®cile induced diarrhoea (b).
References
No. individuals
Treatment
Doses 9
Results
1979 Gotz (a)
79 patients (19 ± 88y) DB, R. *) Ampicillin therapy
Lactinex
210 =d
No. indiv. with diarrhoea=no. indiv. 3=36 lactic acid bact. 9=43 placebo (NS)
1987 Colombel (a)
10 volunteers (22 ± 50y) DB, R. Erythromycin (2 g=d for 3 days)
Bi®dobact. longum
?
Stools per day: 1.2 0.1 lactic acid bact. 1.9 0.4 placebo (P < 0.025) Stool weight (g): 145 16 lactic acid bact. 208 29 placebo (P < 0.025)
1987 Gorbach (b)
5 patients (24 ± 93 y) C. dif®cile induced diarrhoea **)
Lactobacillus gg
1010=d
4 patients responded with decrease in stool frequency and became cytotoxin negative.
1990 Siitonen (a)
16 volunteers R. Erythromycin (1.2 g=d for 7 days) 38 infants (5 ± 72 m) DB, R. *) Amoxicillin
Lactobacillus gg
?
Lactinex
2109=d
Stools per day are reduced when receiving lactic acid bacteria (P < 0.05) No. indiv. with diarrhoea=no. indiv. 10=15 lactic acid bact. 16=23 placebo (NS)
1991 Contardi (a)
40 Infants (8 ± 36 m); R. Oral amoxicillin (50 mg=kg=d)
B. bi®dum L. acidophilus
?
Stools per day: 2.0 0.3 lactic acid bact. 2.7 0.5-lactic acid bact. P < 0.001
1995 Biller (b)
4 Infants (5 ± 70 m) C. dif®cile induced diarrhoea**)
Lactobacillus gg
1109=d
All patients responded within 5 ± 7 d: decrease in stool frequency and became cytotoxin negative
1990 Tankanow (a)
Lactinex is a commercial preparation of dried viable L. acidophilus and L. bulgaricus in equal proportions (5108 bacteria=1 g (Tankanow et al, 1990)). Abbreviations: No. indiv. with diarr.=no. indiv.: Number of individuals with diarrhoea=total number of individuals; DB.: double blind; R.: randomised; bact.:bacteria; *): both oral and=or injectable ampicillin against infectious disease other than diarrhoea; **) positive test for C dif®cile cytotoxin in the stool; m: months.
In controlled clinical trials lactic acid bacteria have had varying degrees of success in preventing diarrhoea: in a double-blinded randomised study, 48 volunteers received either Lactinex (L. acidophilus and L. bulgaricus) in total of 2108 bacteria=d or placebo and were challenged with enterotoxin producing E. coli (108 Ð 1010). No signi®cant differences were noted with respect to attack rate, incubation period, duration of diarrhoea, volume or number of liquid stools (Clements et al, 1981), (Table 6 (c)). On the contrary, a prospective double blind investigation of travellers' diarrhoea in 94 tourists travelling to Egypt found that daily intake of 1010 lactic acid bacteria (L. acidophilus, B. bi®dum, L. bulgaricus, S. thermophilus) signi®cantly reduced the incidence of diarrhoea compared to the placebo treated group (17 cases of diarrhoea in the lactic acid bacteria treated group in comparison with 29 in the placebo treated group, P 0.02) (Black et al, 1989), Table 6 (a). Rotavirus is a common cause of non-bloody diarrhoea in children accounting for 50 ± 75 percent of episodes of acute diarrhoea in children below 3 y referred to the hospital (Guarino et al, 1997; Shornikova et al, 1997). No speci®c therapy is available for rotavirus, and treatment is limited to rehydration. Probiotics has been suggested as a mode of preventing or moderating the infection. The group of Isolauri et al (1991) has reported a positive effect of a human lactic acid bacterial species, Lactobacilli casei strain gg, on the recovery from acute rotavirus induced diarrhoea in children. The children were randomised to either a lactic acid bacteria fermented milk product
containing 1010 ± 11 Lactobacillus casei, a Lactobacillus casei freeze-dried powder (1010 ± 11), or placebo (pasteurised yogurt with only trace amounts of live lactic acid bacteria). The mean duration of diarrhoea after commencing the therapy was signi®cantly shorter in the two groups receiving live lactic acid bacteria in comparison with the placebo group, P < 0.001. Analysis of speci®c antibody-secreting cells among circulating lymphocytes revealed that lactic acid bacterial therapy resulted in an augmentation of the local immune defence re¯ected in an IgA speci®c antibody-secreting cell response to rotavirus (Kaila et al, 1992). The use of lactic acid bacteria as prophylaxis against E. coli diarrhoea is supported by both in vitro and in vivo animal studies. Investigations using rabbit ileal loops have shown that lactic acid bacteria signi®cantly reduce the ¯uid retention caused by enterotoxigenic E. coli (Foster et al, 1980; Johnson & Calia, 1979). The reduced ¯uid accumulation depended on the administration of a large dose of lactic acid bacteria (108=bacteria), whereas the individual ingredients in the lactic acid bacterial preparation did not demonstrate any anti¯uid response. In vivo studies of 28 piglets placed in pens, contaminated with enterotoxigenic E. coli demonstrated that prophylactic feeding with lactic acid bacteria (109=d) signi®cantly reduced the mortaility of E. coli enteropathy (1=14 in treatment group in comparison to 7=14 in the control group) (Nielsen et al, 1988). Further, the average daily weight gain (0 ± 14 d post weaning) was signi®cantly
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higher in the treatment group (231 g) compared to the surviving control group (101 g). Similar convincing results has been reported by Underdahl et al (1982). When Streptococcus faecium were fed to gnotobiotics (animals which are obtained by hysterotomy and kept under sterile conditions and therefore have no intestinal ¯ora) to prevent E. coli induced diarrhoea. Pigs fed S. faecium and challenge exposed with E. coli developed mild diarrhoea, but none of the pigs died, and they continued to eat well and gained weight. Pigs given E. coli only, developed severe diarrhoea and lost weight, and 5 of 8 infected pigs died. How lactic acid bacteria diminish diarrhoeal disease is not known. One proposed mechanism is competitive colonisation. Competitive colonisation occurs when one intestinal microbe interferes with the colonisation of another. But documentation of this phenomenon by observing lactic cultures displacing pathogens or preventing pathogen adherence has been dif®cult experimentally. Other studies have demonstrated that lactic acid bacteria stimulate macrophage phagocytosis of viable Salmonella (Hatcher & Lambrecht, 1993), enhance IgA production in intestinal secretions (Perdigon et al, 1990), produce an antimicrobial substance (Shahani & Ayebo, 1980; Silvia et al, 1987), inhibit cell attachment and cell invasion by enterovirulent bacteria (Bernet et al, 1994), and decrease intestinal permeability for macromolecules during rotavirus induced diarrhoea (Isolauri et al, 1993). In conclusion, Table 6 shows that seven of nine studies since 1985, show an effect of lactic acid bacteria on a 5% signi®cance level while two studies show an effect on a 7% sign®cance level. Two early studies are insigni®cant. The overall impression left by the mentioned human studies is that lactic acid bacterial therapy can limit the course of diarrhoeal diseases, especially rotavirus diarrhoea (Table 6). A possible explanation for the often found inconsistency of results may be the use of different species and subspecies of lactic acid bacteria with different af®nity towards the human intestine. Host speci®city in colonisation by individual species has been demonstrated: L. acidophilus, L. fermentum, and L. plantarum are commonly found in the faeces of humans, whereas L. bulgaricus, the organism used in combination with S. thermophilus to make yogurt, is unable to colonise the bowel. The speci®city is possibly related to the individual lactic acid bacteria ability to colonise mucosal surface by binding to epithelial cells. Variations in lactic acid bacterial preparations and storage of fermented products may also in¯uence results (Gorbach, 1990). The best results seem to have been obtained by using Lactobacillus gg (Isolauri et al, 1991, Siitonen et al, 1990), which is a lactobacillus strain initially isolated from healthy humans. The strain was originally selected for its tolerance to acid and bile and the ability to adhere to human small intestinal cells. The results of lactic acid bacteria treatment against antibiotic associated diarrhoea are shown in Table 7 (a). Siitonen et al (1990) studied 16 subjects, who ingested 400 mg erythromycin three times daily for seven days together with either 125 ml Lactobacillus gg fermented yogurt or 125 ml pasteurised regular yoghurt. The subjects receiving Lactobacillus gg yogurt were colonised with these bacteria even during antibiotic treatment and had fewer daily defecations than the group ingesting pas-
teurised yoghurt, Table 7. Further, usual side effects as abdominal distress, pain and ¯atulence tended to be reduced in the lactic acid bacterial treated group, while the difference in faecal volumes was not signi®cantly different. In ®ve studies of antibiotic associated diarrhoea including 183 subjects, an alleviating effect of lactic acid bacteria ingestion was found in 3 studies including 66 individuals. Therefore, no convincing effect of lactic acid bacteria on antibiotic associated diarrhoea was demonstrated. The studies of C. dif®cile induced diarrhoea included only ®ve and four patients, allowing no conclusions to be drawn. Recent controlled studies have demonstrated that another probiotic, the yeast Saccharomyces bouradii, reduce the risk of recurrent Clostridium dif®cile associated disease (including patients with Clostridium dif®cile diarrhoea, colitis and pseudomembranous colitis (McFarland et al, 1994)) and antibiotic associated diarrhoea (McFarland et al, 1995; Surawicz et al, 1989).
Impact on colon Prevention of colonic cancer There is considerable interest in the metabolic activities of the intestinal micro¯ora, especially in relation to the aetiology of colon cancer. Epidemiological studies have suggested a correlation between intake of a `Western diet' abundant in beef, fat, and protein but low in ®bre, fruit, and vegetables, and the occurrence of colon cancer. Indeed, a positive correlation has been found in several countries between dietary factors such as meat and animal fat consumption and the incidence of large bowel cancer (Howel, 1975). Finland is an exception, being a nation with a high per capita fat consumption and a relatively low incidence of colon cancer (Armstrong & Doll, 1975). Dairy products, especially yogurt, are a common compound of the Finnish diet, and possibly as a result, the intestinal micro¯ora of the Finns harbours high numbers of lactic acid bacteria (International Agency for Research on Cancer, 1997). In an attempt to explain these epidemiological ®ndings, alterations in the metabolic activity of the intestinal ¯ora have been studied. The studies have involved measurements of key enzymes: b-glucuronidase, azoreductase, and nitroreductase, which catalyse the conversion of indirect acting carcinogens to proximal carcinogens in the large bowel (Goldin & Gorbach, 1984). Oral supplementation of the diet with viable bile-resistant L. acidophilus of human origin caused a signi®cant decline in these three key-enzymes (Goldin & Gorbach, 1984; Gordin et al, 1980). These results were only partly con®rmed by Marteau et al (1990) in a study where 9 subjects ingested lactic acid bacteria (L. acidophilus, B. bi®dum) for 3 weeks. He reported of unchanged levels of faecal azo-reductase and b-glucuronidase, while only nitroreductase decreased during the observation period. The studies were extended in an animal model of colon cancer induced by the chemical carcinogen, 1,2-dimethylhydrazine dihydrochloride (DMH). The activation of DMH to a potent carcinogen occurs in the large intestine, and the bacterial enzyme-b-glucuronidase is involved in this process. Suppression of this enzyme might reduce DMH activation and subsequent tumour formation. In experiments DMH-treated animals with given L. acidophilus in powdered form and compared with controls (Goldin & Gorbach, 1980). At 20 weeks, 40% of the L. acidophilus
Lactic acid bacteria H Hove et al
treated animals had colon tumours versus 77% of the controls, P 0.02. At 36 weeks, however, 73% of the L. acidophilus treated animals and 83% of the controls had colon tumours. These studies show that the addition of lactic acid bacteria to the diet may delay colon tumour formation by prolonging the induction, indicating that lactobacilli may slow tumor development in experimental animals. Lactic acid bacteria have shown antineoplastic properties in a variety of cancer cell lines of both human and animal origin. The literature substantiating this in vitro effect has increased tremendously over the last decade. In brief, lactic acid bacteria reduce tumour cell viability (McGroatry et al, 1988; Sekine et al, 1985; Reddy et al, 1973; Reddy et al, 1983; Kato et al, 1981), suppress induced carcinogenesis in the liver and colon (Reddy & Riverson, 1993), inhibit mutagenic activity (Hosono et al., 1986; Renner & MuÈntzner, 1991), and bind potent mutagenic metabolic compounds (Morotomi & Mutai, 1986) and food mutagen (Zhang et al, 1990). However, in spite of a wealth of indirect evidence, no direct data have yet proven cancer suppression in humans, as a result of consumption of lactic cultures in fermented or unfermented dairy products. High concentrations of faecal bile acids have also been associated with the development of colon cancer, and the lithocholic acid=deoxycholic acid ratio has been reported to be increased in patients with colon cancer compared to controls (Owen et al, 1987). Ingestion of L. acidophilus for 6 weeks have been demonstrated to lower concentrations of total bile acid and deoxycholic acid (Lidbeck et al, 1991), although the changes were not signi®cant. Correcting of a colonic `imbalance' Lactic acid bacteria may have an impact on the colonic ¯ora in situations where some sort of imbalance exists. The exact nature of this microbial imbalance and how it is corrected by the ingestion of lactic acid bacteria has not been substantiated. A prerequisite for an effect on the colonic ¯ora is that a substantial number of ingested lactic acid bacteria reach the large bowel. The work of others (Robins-Browne et al, 1981; Hove et al, 1984; Goldin et al, 1992; Saxelin et al, 1991; Lidbeck et al, 1991) indicate that ingested lactic acid bacteria do reach the caecum. It is, however, questionable whether an ingested dose of lactic acid bacteria in the range of 1010 ± 11 bacteria is able to in¯uence the colonic ¯ora, which number approximately 1013 bacteria (1011 g), a number of 100 ± 1000 times higher than the ingested amount of lactic acid bacteria. This question is even more pertinent in light of the widely held belief that a dietary culture, even one possessing in vitro adhering capabilities, is highly unlikely to displace any bacterial strain that colonises a healthy human intestinal tract (Savage, 1977). Human gastrointestinal microbiology is notably a dif®cult ®eld to study because of limits on direct experimentation and the dif®cult physiological requirements of the intestinal microbes. As indicated by Tannock (1984): `All investigators approaching the study of the normal ¯ora of the gastrointestinal tract must sooner or later be horri®ed by the complexity of an ecosystem that contains about 500 species of bacteria most of which are technically dif®cult to work with under laboratory conditions'. The ability of lactic acid bacteria to in¯uence the fermentation processes, that is changes in organic acid production was examined by investigation of the fermentative products of human ileostomic ef¯uent after ingestion
of large quantities of B. bi®dum (Hove et al, 1994). When in isolated culture, B. bi®dum had a speci®c fermentative pattern, but this pattern could not be reencountered in the ileostomic outputs of nine ileostomists after oral ingestion of large quantities of B. bi®dum. As B. bi®dum, L. acidophilus had a speci®c fermentation pattern when in isolated culture, but after incubation in mixed lactic acid bacteria=faecal incubations the speci®c pattern disappeared although L. acidophilus was added in unphysiological large amounts constituting 50 ± 90% of the total ¯ora. The fermentation products in mixed L. acidophilus=faecal incubations were related to the type of added substrate rather than to the addition or not of acid bacteria (Hove et al, 1994). This does not imply that lactic acid bacteria do not contribute to the organic acid formation in the mixed homogenates, but rather that the capability for saccharide fermentation represented by the added bacteria already exists in the faecal ¯ora. New perspectives of modulating the colonic ¯ora has recently been introduced by Gibson et al. (1995), who showed that oral ingestion of a diet rich in the indigestible carbohydrates oligofrutose and inulin signi®cantly increases the number of bi®dobacteria. Therefore, the prospect of lactic acid bacteria therapy may be a change in diet which subsequently alters colonic ¯ora rather than ingestion of cultures of lactic acid bacteria themselves. Lactic acid bacteria as pathogenic organisms Although infections with these organisms are rare, it has been reported that lactic acid bacteria may play a role in a variety of serious infections. These include endocarditis (Axelrod et al, 1973), bacteraemia (Bayer et al, 1978), gastrointestinal infections (Bourne et al, 1978), and splenic abscess (Sherman et al, 1987). A risk factor is immunosuppressive therapy (Sherman et al, 1987) and poor oral hygiene where dental procedures can cause endocarditis. Treatment of lactic acid bacterial infections can be dif®cult since eradication is complicated by the often deep-seated location, the antimicrobial resistance to antibiotics, and the problem in identifying the organisms and thereby to initiate apppropriate treatment (Sherman et al, 1987). In a single case L. acidophilus ingestion has been associated with the development of D-lactic acidosis (Mason, 1986). Conclusion Lactic acid bacteria appear to alleviate lactose malabsorption in lactose malabsorbers when administered in fermented dietary milk products (yogurt, Table 3 (a)), but not in infermented milk products (set acidophilus milk, Table 3(b)). Lactic acid bacteria seem to shorten the course of infectious diarrhoea especially in infants with rotavirus diarrhoea (Table 6 (b)) and reduce the risk of travellers' diarrhoea (Table 6 (a)). The ability of lactic acid bacteria to prevent antibiotic associated diarrhoea is less convincing, and results from studies of Clostridium dif®cile are preliminary and yet inconclusive. Experimental studies indicate an effect of lactic acid bacteria on human cell cancer lines, but clinical evidence is lacking. References Armstrong B, Doll R (1975): Environmental factors and cancer incidence and mortality in different countries with special reference to dietary practices. Int. J. Cancer. 15: 617±631.
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Arrigoni E, Marteau P, Briet F, Pochart P, Rambaud JC & Messing B (1994): Tolerance and absorption of lactose from milk and yogurt during short-bowel syndrome in humans. Am. J. Clin. Nutr. 60: 926 ± 929. Axelrod J, Keusch GT, Buttone E, Cohen SM, Hirschman SZ (1973): Endocarditis caused by Lactobacillus plantarum. Ann. Intern. Med. 78: 33±37. Barillas C, Solomons NW (1987): Effective reduction of lactose maldigestion in preschool children by direct addition of beta-galactosidases to milk at mealtime. Pediatrics 79: 766±772. Bayer AS, chow AW, Betts D, Guze LB (1978): Lactobacillemia Ð report of nine cases: Important clinical and therapeutic considerations. Am. J. Med. 64: 808±813. Beck C, Necheles H (1961): Bene®cial effects of administration of Lactobacillus acidophilus in diarrhea in other intestinal disorders. Am. J. Gastroenterol. 35: 522±530. Bengmark S (1998): Leading article: Ecological control of the gastrointestinal tract. The role of probiotic ¯ora. Gut 42: 2 ± 7. Bernet MF, Brassart D, Neeser JR, Servin AL (1994): Lactobacillus acidophillus LA 1 binds to cultured human intestinal cell lins an inhibits cell attachment and cell invasion by enterovirulent bacteria. Gut. 35: 483±489. Biller JA, Katz AJ, Flores AF, Buie TM, Gorbach SL (1995): Treatment of recurrent Clostridium dif®cile colitis with Lactobacillus gg. J. Ped. Gastroenterol. Nutr. 21: 224±226. Black FT, Anderson PL, érskov J, érskov F, Gaarslev K, Laulund S (1989): Prophylactic ef®cacy of lactobacilli on traveler's diarrhea. Travel Medicine 333±335. Boudraa G, Touhami M, Pochart P, Soltana R, Mary JY, Desjeux JF (1990): Effect of feeding yoghurt versus milk in children with persistent diarrhea. J. Ped. Gastr. Nutr. 11: 509±512. Bouhnik Y, Pochart P, Marteau P, Arlet G, Goderel I & Rambaudj JC (1992): Faecal recovery in humans of viable Bi®dobacterium sp. ingested in fermented milk. Gastroenterol. 102: 875 ± 878. Bourne KA, Beebe JL, Lue YA, Ellner PD (1978): Bacteremia due to Bi®dobacterium, Eubacterium or Lactobacillus, twenty-one cases and review of the literature. Yale J Biol Med. 51: 505±512. Brown JP (1977): Role of gut bacterial ¯ora in nutrition and health: A review of recent advances in bacteriological techniques, metabolism, and factors affecting ¯ora composition. CRC Crit. Rev. Food Sci. Nutr. 8: 229 ± 336. Clements ML, Levine MM, Black RE, Robins-Browne RM, Cisneros LA, Drusano GL, Lanata CF, Saah AJ (1981): Lactobacillus prophylaxis for diarrhea due to enerotoxigenic Escherichia coli. Antimicrob Agents Chemother. 20: 104±108. Colombel JF, Cortot A, Neut C, Romond C (1987): Yogurt with Bi®dobacterium longum reduces erytromycin induced gastrointestinal effects. Lancet. 2: 43. Contardi I (1991): Batteriterapia orale quale prevenzione della diarrea da antibiotici in eta pediatria. La Clinical Terapeutica. 136: 409±413. Corazza GT, Benati G, Sorge M, Strocchi A, Calza G, Gasbarrini G (1992): Beta-galactosidase from Aspergillus niger in adult lactose malabsorption: a double-blind crossover study. Aliment Pharmacol Therap. 6: 61±66. Dehkordi N, Rao DR, Warren AP & Chasan CB (1995): Lactose malabsorption as in¯uenced by chocolate milk, skim milk, sucrose, whole milk, and lactic cultures. J. Am. Dietetic Ass. 95: 484 ± 486. Deneke C, Goldin B, Gorbach S & Barakat S (1988): Correlation between human intestinal cell colonization and human cell binding by Lactobacillus strain GG. Am. Soc. Miorobiol D149,96. DiPalma JA, Collins MS (1989): Enzyme replacement for lactose malabsorption using a beta-D-galactosidase. J. Clin. Gastroenterol. 11: 290±293. DuPont HL, Ericsson Cd, Johnsson Pc, Cabada FJ (1986): Antimicrobial agents in the prevention of travelers' diarhea. Rev. Infect. Dis. 8 (Suppl 2): S167±S171. Finegold SM, Sutter VL & Mathisen GE (1983): Normal indigenous intestinal ¯ora. In: Hentges DJ, (ed.) Human intestinal micro¯ora in health and disease, London, Academic Press, pp 3 ± 31. Foster TL, Winans L, Carski T (1980): Evaluation of lactobacillus preparation on enterotoxigenic E. coli-induced rabbit ileal loop reations. Am. J. Gastroenterology 73: 238±243. Fuller R (1989): Probiotics in man and animals. A review. J. Appl. Bact. 66: 365 ± 378. Gibson GR, Beatty ER, Wang X, Cummings JH (1995): Selective stimulation of bi®dobacteria in the human colon by oligofructose and inulin. Gastroenerology 108: 975±982. Gilliland SE & Kim HS (1984): Effect of viable starter culture bacteria in yoghurt on lactose utilization in humans. J. Dairy Sci. 67: 1 ± 6.
Goldin BR, Gorbach SL, Saxelin M, Barakat S, Gualtieri L. & Salminen S (1992): Survival of lactobacillis species (strain gg) in human gastrointestinal tract. Dig. Dis. Sci. 37: 121 ± 128. Goldin BR, Gorbach SL (1980): Effect of Lactobacillus acidophilus dietary supplementation on 1,2-dimethylhydrazine dihydrochlorideinduced intestinal cancer in rats. J. Natl. Cancer Inst. 64: 263±265. Goldin BR, Gorbach SL (1984): The effect of milk and lactobacillus feeding on human intestinal bacterial enzyme activity. Am. J. Clin. Nur. 39: 756±761. Goldin BR, Swenson L, Dwyer J, Sexton M, Gorbach SL (1980): Effect of diet and Lactobacillus acidophilus supplements on human fecal bacterial enzymes. JNCI. 64: 255±261. Gorbach SL, Chang TW, Goldin B (1987): Successful treatment of relapsing Clostridium dif®cile colities with lactobacilli gg. Lancet. 2: 1519. Gorbach SL, Kean BH, Evans DG, Evans DJ, Bessudo D (1975): Travelers' diarrhea and toxigenic Escherichia coli. N. Engl. J. Med. 292: 933±936. Gorbach SL (1971): Progress in gastroenterology. Intestinal micro¯ora. Gastroenterol 60: 1110 ± 1129. Gorbach SL (1986): Function of the normal human micro¯ora. Scand. J. Infect. Dis. Suppl. 49: 17 ± 30. Gorbach SL (1990): Lactic acid bacteria and human health. Ann. Med. 22: 37 ± 41. Gotz V, Romankiewicz JA, Moss J, Murray HW(1979): Prophylaxis against ampicillin-associated diarrhea with a lactobacillus preparation. Am. J. Hosp. Pharm. 36: 754±757. Guarino A, Canai RB, Spagnuolo MI, Albano F, Boccia MC, Polito G, Stabile A (1997): Oral bacterial therapy reduces the duration of symptoms and of viral excretion in children with mild diarrhea. J. Pedr. Gastroenterol Nutr. 25: 516±519. Gudmand-Hùyer E & Skovbjerg H (1996): Disaccharide digestion and maldigestion. Scand. J. Gastroenterol. 31: (Suppl) S111 ± S121. Gurr MI (1987): Nutritional aspects of fermented milk products. FEMS Microbiology Reviews 46: 337 ± 342. Hatcher GE, Lambrecht RS (1993): Augmentation of macrophage phagocytic activity by cell-free extracts of selected lactic acid-producing bacteria. J. Dairy. Sci. 76: 2485±2492. Hill MJ & Drasar BS (1975): The normal colonic bacterial ¯ora. Gut 16: 318 ± 323. Hosono A, Kashina T, Kada T (1986): Antimutagenic properties of lactic acid-cultured milk on chemical and fecal mutagens. J. Dairy Sci. 69: 2237±2242. Hove H, Nordgaard-Andersen I & Mortensen PB (1994): Effect of lactic acid bacteria on the intestinal production of lactate and short-chain fatty acids, and the absorption of lactose. Am. J. Clin. Nutr. 59: 74 ± 79. Howell MA (1975): Diet as an etiological factor in the development of cancer of the colon and rectum. J. Chronic Dis. 28: 67±80. International Agency for Research on Cancer (1977): Dietary, ®bre, transit-time, fecal bacteria, steroids and colon cancer in two Scandianvian populations. Lancet 2: 207±211. Isolauri E, Juntunen M, Rautanen T, Sillanaukee P, Koivula T (1991): A human lactobacillus strain (Lactobacillus casei sp strain GG) promotes recovery from acute diarrhea in children. Pediatrics 88: 90±97. Isolauri E, Kaila M, Arvola T, Majamaa H, Rantala I, Virtanen E, Arvilommi H (1993): Diet during rotavirus enteritis affects jejunal permeability to macromolecules in suckling rats. Ped. Res. 33: 548±553. Johnson DE, Calia FM (1979): The effect of latinex on rabbit ileal loop reactions induced by enterotoxigenic Escherichia coli. Curr. Microbiol. 2: 207±210. Kaila M, Isolauri E, Soppi E, Virtanen E, Laine S, Arvilommi H (1994): Enhancement of the circulating antibody secreting cell response in human diarrhea by a human lactobacillus strain. Pediatr Res. 32: 141±144. Kandler O (1983): Carbohydrate metabolism in lactic acid bacteria. Antonie van Leeuwenhoek 49: 209 ± 224. Kato I, Kobayashi S, Yokokura T, Mutai M (1981): Antitumor activity of Lactobacillua casei in mice. Gann. 72: 517±723. Kim HS, Gilliland SE (1983): Lactobacillus acidophilus as a dietary adjuct for milk to aid lactose digestion in humans. J. Dairy Sci. 66: 959 ± 966. Kim HS (1988): Characterization of lactobacilli and bi®dobacteria as applied to dietary adjucts. Cult. Dairy Prod. J. 23: 6 ± 9. Kitsuoka T (1984): Taxonomy and ecology of bi®dobacteria. Bi®dobacteria Micro¯ora 3: 11 ± 28. Kolars JC, Levitt MD, Aouji M & Savaiano DA (1984): Yoghurt Ð an autodigesting source of lactose. N. Engl. J. Med. 310: 1 ± 3. Kotz CM, Furne JK, Savaiano DA & Levitt MD (1994): Factors affecting the ability of a high beta-galactosidase yogurt to enhance lactose absorption. J. Dairy Sci. 77: 3358 ± 3544.
Lactic acid bacteria H Hove et al
Lami F, Callegari C, Tatali M, Graziano L, Guidetti C, Miglioli M, Barbara L (1998): Ef®ciency of addition of exogenous lactase to milk in adult lactate de®ciency. Am. J. Gastroenterol. 83: 1145±1149. Lidbeck A, Allinger UG, Orrhage KM, Ottova L, Brismar B, Gustafsson J, Rafter JJ, Nord CE (1991): Impact of lactobacillus acidophilus supplemenmts on the faecal micro¯ora and soluble faecal bile acids in colon cancer patients. Microbial Eco Health Dis. 4: 81±88. Lin M, Savaiano D & Harlander S (1991): In¯uence of nonfermented dairy products containing bacterial starter cultures on lactose maldigestion in humans. J. Dairy Sci. 74: 87 ± 95. Majamaa H, Isolauri E, Saxelin M, Vesikari (1995): Lactic acid bacteria in the treatment of acute rotavirus gastroenteritis. J. Ped.Gas. Nutr. 20: 333±338. Marteau P, Flourie B, Pochart P, Chastang C, Desjeux J & Rambaud J (1990): Effect of the microbial lactase (EC 3.2.1.23) activity in yoghurt on the intestinal absorption of lactose: an in vivo study in lactase-de®cient humans. Br. J. Nutr. 64: 71 ± 79. Marteau P, Pochart P, Flouri, B, Pellier P, Santos L, Desjeux J, Rambaud J (1990): Effect of chronic ingestion of a fermented dairy product containing Lactobacillus acidophilus and Bi®dobacterium bi®dum on metabolic activities of the colonic ¯ora in humans. Am. J. Clin. Nutr. 52: 685±688. Martini MC, Bollweg GL, Levitt MD & Savaiano DA (1987): Lactose digestion by yogurt beta galactosidase: in¯uence of pH and microbial cell integrity. Am. J. Clin. Nutr. 45: 432 ± 436. Martini MC, Lerebours EC, Lin WJ, Harlander SK, Berrada NM, Antoine JM & Savaiano DA (1991): Strains and species of lactic acid bacteria in fermented milks (yoghurts): effect on in vivo lactose digestion. Am. J. Clin. Nutr. 54: 1041 ± 1046. Mason PD (1986): Metabolic acidosis due to D-lactate. BMJ. 292: 1105± 1106. McDonough FE, Hitchins AD, Wong NP, Wells P & Bodwell CE (1987): Modi®cation of sweet acidophilus milk to improve utilization by lactose-intolerant persons. Am. J. Clin. Nutr. 45: 570 ± 574. McFarland LV, Surawicz CM, Greenberg RN, Elmer GW, Moyer KA et al. (1995): Prevention of beta-lactam-associated diarrhoea by saccharomyces boulardii compared with placebo. Am. J. Gasterol. 90: 439±448. McFarland LV, Surawicz CM, Greenberg RN, Fekety R, Elmer GW et al. (1994): A randomized placebo-controlled trial of Saccharomyces boulardii in combination with standard antibiotics for Clostridium dif®cile disease. JAMA. 271: 1913±1918. McGroatry JA, Hawthorn AA, Reid G (1988): Anti-tumor activity of lactobacilli in vitro. Microbios. Lett. 39: 105±112. Merson MH, Morris GK, Sack DA, Well JG, Feeley JC, Sack RB, Creech WB, Kapikian AZ, Gangarosa EJ (1976): Travellers' diarrhea in Mexico. N Engl J Med. 1976: 1299±1305. Metchnikoff E (1908): The prolongation of life. New York: GP Putnam and Sons. Morotomi M, Mutai M (1986): In vitro binding of potent mutagenic pyrolyzates to intestinal bacterial. J. Natl. Cancer Inst. 77: 195±201. Newcomer AD, Park HS, O'Brian PC & McGrill DB (1983): Response of patients with irritable bowel syndrome and lactase de®ciency using unfermented acidophilus milk. Am. J. Clin. Nutr. 38: 257 ± 263. Nielson NC, Suhr-Jessen T, Jensen MM (1988): Inhibitive effect of 5 probiotic porcine lactobacillus strains on the incidence and severisty of experimentally induced post weaning E. coli syndrome in pigs. International pig veterinary society 10th congress Rio de Janeiro, Brazil. Nordgaard I, Stenbaek Hansen B & Mortensen PB (1995): Colonic fermentation of complex dietary carbohydrates in short-bowel patients. No association with hydrogen excretion and fecal and plasma shortchain fatty acids. Scand. J. Gastroenterol 30: 897 ± 904. Oksanen PJ, Salminen S, Saxelin M HaÈmaÈlaÈinen P et al. (1990): Prevention of travellers diarrhoea by lactobacillus gg. Ann Med. 22: 53±56. Onwulata CI, Rao DR & Vankineni P (1989): Relative ef®ciency of yogurt, sweet acidophilus milk, hydrolyzed-lactose milk, and a commercial lactase tablet in alleviating lactose maldigestion. Am. J. Clin. Nutr. 49: 1233 ± 1237. Owen RW, Dodo M, Thompson MH, Hill MJ (1987): Fecal steroids and colorectal cancer. Nutrition and Cancer. 9: 73±80. Payne DL, Welsch JD, Manion CV, Tsegaye A & Herd LD (1981): Effectiveness of milk products in dietary management of lactose malabsorption. Am. J. Clin. Nutr. 34: 2711 ± 2715. Perdigon G, Alvarez S, Nader de Macias ME, Roux ME, Pesce A, Holgado R (1990): The oral administration of lactic acid bacteria increase the mucosal intestinal immunity in response to enteropathogens. J. Food. Proct. 53: 404±410.
Pochart P, Marteau P, Bouhnik Y, Goderel I, Bourlioux P & Rambaud J (1992): Surival of bi®dobacteria ingested via fermented milk during their passage through the human small intestine: an in vivo study using intestinal perfusion. Am. J. Clin. Nutr. 55: 78 Ð 80. Pozo-Olano JDD, Warram JH, GoÂmez RG, Cavazos MG (1978): Effect of a lactobacilli preparation on traveler's diarrhea. Gastroenterology. 74: 829±830. Reddy BS, Riverson A. (1993): Inhibitory effect of Bi®dobacterium longum on colon, mammary, and liver carcinogenesis induced by 2amino-3-methylimidazo (4,5-f)quinoline, a food mutagen. Cancer Res. 53: 3914±3918. Reddy GV, Friend BA, Shahani Km, Farmer RE (1983): Antitumor activity of yogurt components. J. Food Prot. 46: 8±11. Reddy GV, Shahani KM, Benerjee MR (1973): Inhibitory effect of yogurt on Ehrlich ascites tumor cell proliferation. J. Natl. Cancer Inst. 50: 815±817. Renner HW, MuÈntzner R (1991): The possible role of probiotics as dietary antimutagens. Mut. Res. 262: 239 ± 245. Robins-Browne RM, Path FF & Levine MM (1981): The fate of ingested lactobacilli in the proximal small intestine. Am. J. Clin. Nutr. 34: 514 ± 519. Rosado JL, Solomons NW, Lisker R & Bourges H (1984): Enzyme replacement therapy for primary adult lactate de®ciency. Gastroenterol 87: 1071 ± 1082. Rosado JL, Deodhar AD, Bourges H, Solomons NW (1986): The effect of the digestion products of lactose (glucose and galactose) on its intraintestinal, in vivo hydrolysis by exogenous microbial beta-Dgalactosidase. J. Am. College Nutrition 5: 281±290. Rosado JD, Lindsay HA & Solomons NW (1987): Milk consumption, sympton response, and lactose digestion in milk intolerance. Am. J. Clin. Nutr. 45: 1457 ± 1460. Rumensen JJ, Hamberg O & Gudman-Hùyer E (1990): Interval sampling of end-expiratory hydrogen concentration to quantify carbohydrate malabsorption by means of lactulose standards. Gut 31: 37 ± 42. Sack RB (1986): Antimicrobial prophylaxis of travelers' diarrhea: a selected summary. Rev. Infect Dis. Suppl. 8: 160±166. Sanders ME (1993): Effect of consumption of lactic cultures on human health. Adv. Food Nutr. Res. 37: 67 ± 130. Savage DC (1977): Microbial ecology of the gastrointestinal tract. Ann Rev Microbiol. 3: 107±133. Savaiano DA, AbouElAnouar A, Smith DE & Levitt MD (1984): Lactose malabsorption from yoghurt, pasteurized yogurt, sweet acidophilus milk, and cultured milk in lactate-de®cient individuals. Am. J. Clin. Nutr. 40: 1219 ± 1223. Savaiano DA & Kotz C (1988): Recent advances in the management of lactose intolerance. Contemp. Nutr. 13: 10. Saxelin M, Elo S, Salminen S & Vapaatalo H (1991): Dose response colonisation of faeces after oral administration of lactobacillus casei strain gg. Micro. Ecol. Health Dis 4: 209 ± 214. Scardovi V (1986): Genus Bi®dobacterium. In: Mair NS, (ed.) Bergey's manual of systematic bacteriology, New York: Williams and Wilkins, pp 1418 ± 1434. Scrimshaw NS & Murray EB (1988): The acceptability of milk and milk products in populations with a high prevalence of lactose intolerance. Am. J. Clin. Nutr. 48: (Suppl) S1083 ± S1159. Sekine K, Toida T, Saito M, Kuboyama M, Kawashima T, Hashimoto Y (1985): A new morphologically characerized cell wall properation (whole peptidoglycan) from Bi®dobacterium infantis with a higher ef®cacy on the regression of an established tumor in mice. Cancer Res. 45: 1300±1307. Shahani KM & Ayebo AD (1980): Role of dietary lactobacilli in gastrointestinal microecology. Am. J. Clin. Nutr. 33: 2448 ± 2457. Sherman ME, Albrecht M, DeGirolami PC, Kirkley SA, Wolf B, Eliopoulos GM, Rohre RJ, Monaco AP (1987): An unusual case of splenic abscess and sepsis in an immunocompromised host. Am. J. Clin. Pathol. 88: 659±662. ShermaÈk MA, Saavedra JM, Jackson TL, Huang SS, Bayless TM & Perman JA (1995): Effect of yogurt on symtoms and kinetics of hydrogen production in lactose-malabsorbing children. Am. J. Clin. Nutr. 62: 1003 ± 1006. Shornikova AV, Casas IA, Isolauri E, Mykkanen, Vesikari T (1997): Lactobacillus reuteri as a therapeutic agent in acute diarrhea in young children. J. Pedr. Gastroenterol Nutr. 24: 399±404. Shornikova AV, Isolauri E, Burkanova L, Lukovnikova S, Vesikari T (1997): A trial in the Karelian Republic of oral rehydration and Lactobacillus gg for treatment of acute diarrhoea. Acta. Paediatr. 86: 460±465. Siitonen S, Vapaatalo H, Salminen S, Gordin A, Saxelin M, Wikberg R, Kirkkola A (1990): Effect of lactobacillus gg yoghurt in prevention of antibiotic associated diarrhoea. Ann. Med. 22: 57±59.
349
Lactic acid bacteria H Hove et al
350
Silvia M, Jacobus NV, Deneke C, Gorbach SL (1987): Antimicrobiol substance from a human lactobacillus strain. Antimicr. Agen. Chemother. 31: 1231±1233. Solomons NW, Guerrero A, Torun B (1985): Effective in vivo hydrolysis of milk lactose by beta-galactosidases in the presence of solid foods. Am. J. Clin. Nutr. 41: 222±227. Stark PL & Lee A (1982): The microbial ecology of the large bowel of breast-fed and formula-fed infants during the ®rst year of life. J. Med. Microbiol. 15: 189 ± 203. Surawicz CM, Elmer GW, Speelman P, McFarland LV, Chinn J, Van Belle G (1989): Prevention of antibiotic-associated diarrhea by Saccharomyces boulardii: a prospective study. Gastroenterology 96: 981± 988. Saavedra JM, Bauman NA, Oung I, Perman JA, Yolken RH (1994): Feeding of Bi®dobacterium bi®dum and Streptococcus thermophilus to infants in hospital for prevention of diarrhoea and shedding of rotavirus. Lancet 344: 1046±1049. Tankanow RM, Ross MB, Ertel IJ, Dickinson DG, McCormick L, Gar®nkel JF (1990): A double blind, placebo-controlled study of the ef®cacy of lactinex in the prophylaxis of amoxicillin-induced diarrhea. DICP, Ann. Pharmacotherapy. 24: 382±384.
Tannock GW (1984): Control of gastrointestinal pathogens by normal ¯ora. In: Current Perspectives in Microbial Ecology, Klug MJ, Reddy CA, (eds). American Society of Microbiologists, Washington DC. Underdahl Nr, Torres-Medina A, Doster AR (1982): Effect of Streptococcus faecium C-68 in control of Escheriachia coliinduced diarrhea in gnotobiotic pigs. Am. J. Vet. Res. 43: 2227±2232. Vesa TH, Marteau PH, Zidi S, Briet F, Pochart PH & Rambaud JC (1996): Digestion and tolerance of lactose from yoghurt and different semi-solid fermented dairy products containing Lactobacillus acidophilus and bi®dobacteria in lactose maldigesters Ð is bacterial lactase important? Eur. J. Clin. Nutr. 50: 730 ± 733. Welsh JD, la Verne Payne D, Manion C, Morrison RD & Nichols MA (1981): Interval sampling of breath hydrogen as an index of lactose malabsorption in lactase-de®cient subjects. Dig. Dis. Sci. 26: 681 ± 685. Winkelstein A (1955): Lactobacillus acidophilus tablets in the therapy of various intestinal disorders: a preliminary report. Am. Pract. Dig. Treat. 6: 1022±1025. Wytock DH & DiPalma JA (1988): All yoghurts are not created equal. Am. J. Clin. Nutr. 47: 454 ± 457. Zhang XB, Ohta Y, Hosono A (1990): Antimutagenic and binding of lactic acid bacteria from a chinese cheese to mutagenic pyrolyzates. J. Dairy Sci. 73: 2702±2710.
