Lactobacillus effects on cholesterol: in vitro and in vivo results

Verification of hypocholesterolemic effect of fermented milk on human subjects with different cholesterol levels

The possible hypocholesterolemic effect of acidophilus milk was evaluated on 27 human subjects having different levels of serum cholesterol, i.e. < 2.0 (group C1), 2.0-2.2 (C2), 2.2-2.5 (C3) and > 2.5 g/L (C4). The acidophilus milk was prepared by fermentation of low-fat milk with Lactobacillus acidophilus and was fed to each volunteer at the rate of 200 mL/d for 20 d. Blood samples from the volunteers were collected and analyzed for lipid profile twice prior to, during and after feeding, keeping a gap of 10 d between two collections. A significant decrease (p < 0.05) in average total cholesterol was found in the C2 and C3 groups, amounting to 21 and 12%, respectively. The average LDL cholesterol decreased in C2, C3 and C4 groups by 0.54, 0.26 and 0.46 g/L, respectively. In the C2 group, the LDL/HDL and total/HDL ratio was also reduced by 1.4 and 1.3, respectively. However, in the C1 group, the average total and LDL cholesterol level did not show any significant change but serum triacylglycerols and VLDL cholesterol showed a significant (p < 0.05) increase of 0.53 and 0.11 g/L, respectively. Regression analysis of the data revealed a square trend in most of the parameters over time period. Overall, the feeding had the best effect in the subjects with lipidemic status of borderline cholesterol level (2.0-2.2 g/L) group.

Three glycoproteins with antimutagenic activity identified in Lactobacillus plantarum KLAB21

Antimutagenic substances were purified from a culture supernatant of Lactobacillus plantarum KLAB21 cells isolated from kimchi, a Korean traditional fermented vegetable, and their characteristics were investigated. The antimutagenic substances were separated into two fractions by DEAE-cellulose ion-exchange column chromatography, which were designated the R1 and R2 fractions. The R1 fraction was then divided into two fractions again by Sephadex G200 gel filtration chromatography, and the fractions were designated R1-1 and R1-2. All three fractions were further purified using a Sepharose CL-6B gel filtration column. All the purified fractions were successfully stained with fuchsin as well as Coomassie brilliant blue, suggesting that they are glycoproteins. The purified fractions were confirmed to possess antimutagenic activity against N-methyl-N'-nitro-N-nitrosoguanidine on Salmonella enterica serovar Typhimurium TA100 cells. Their molecular masses were determined to be 16 (R1-1), 11 (R1-2), and 14 (R2) kDa on the Sepharose CL-6B column. Total sugar contents were 8.4% (R1-1), 7.3% (R1-2), and 9.4% (R2). The amino acid compositions of the fractions were different from each other; the major amino acids were glutamic acid (21.5%) and phenylalanine (17.1%) in the R1-1 fraction and glycine (41.3%) in the R1-2 fraction, but valine (31%) and phenylalanine (22.6%) were the major amino acids in the R2 fraction.

The use of probiotics in medical practice

Probiotics are defined as living organisms, beneficial to health when ingested. Different species of microorganisms such as lactic acid bacteria or yeasts have been proposed for human use. These microorganisms differ from each other and it is, therefore, unlikely that they will act in the same way. Probiotics could be used for several conditions such as diarrhoea, candidal vaginitis, urinary tract infections, immune disorders, lactose intolerance, hypercholesterolaemia and food allergy. The effects of probiotics in some of these conditions have been directly observed, in others it has been only suggested on the basis of in vitro studies and from experimental animal models. Controlled trials are needed to determine the scientific basis for their use, the correct formulation and ways of administration in different clinical situations.

Effect of administration of Lactobacillus gasseri on serum lipids and fecal steroids in hypercholesterolemic rats

The effects of milk and nonfermented milks produced from Lactobacillus gasseri on serum lipids and total bile acids and fecal steroids and microflora were estimated in rats fed cholesterol-enriched diets. Lactobacilli decreased and coliforms increased in feces of the control group; however, the concentrations of fecal lactobacilli remained unchanged when rats were fed nonfermented milks. Fecal coliforms in rats receiving milk and nonfermented milk produced from L. gasseri SBT0270 increased, while rats receiving nonfermented milk produced from L. gasseri SBT0274 had lower fecal coliform count than did the control group. Only NFM-A significantly reduced serum total cholesterol and low-density lipoprotein (LDL) cholesterol, and bile acids. High-density lipoprotein (HDL) cholesterol was significantly decreased when rats were given milk and nonfermented milks. Milk and NFM-A lowered serum triglycerides levels. Milk and nonfermented milks did not affect the total neutral steroids, but higher levels of acidic steroid were detected in the feces than the control group. The results showed that the hypocholesterolemic effect of L. gasseri SBT0270 was attributed to its ability to suppress the reabsorption of bile acids into the enterohepatic circulation and to enhance the excretion of acidic steroids in feces of hypercholesterolemic rats.

Effects of probiotic bacteria on diarrhea, lipid metabolism, and carcinogenesis: a review of papers published between 1988 and 1998

We reviewed the evidence from human intervention studies for the health effects of probiotic bacteria, ie, live bacteria that survive passage through the gastrointestinal tract and have beneficial effects on the host. Of the 49 studies reviewed, 26 dealt with the prevention or treatment of diarrheal disease, 9 with the prevention of cancer or of the formation of carcinogens, 7 with the lowering of serum cholesterol, and 7 with the stimulation of the immune system. The most widely studied probiotic bacteria were Lactobacillus GG (22 studies), Lactobacillus acidophilus (16 studies), Bifidobacterium bifidum (6 studies), and Enterococcus faecium (7 studies). Intake of Lactobacillus GG consistently shortened the diarrheal phase of rotavirus infection by 1 d. However, evidence for the prevention by Lactobacillus GG and other probiotics of diarrhea due to viral or bacterial infections was less strong. Effects of probiotics on the immune system are inconclusive because of the variety of outcome variables reported. Cholesterol lowering by L. acidophilus was shown in some but not all studies; cholesterol lowering by E. faecium seems to be transient. Two studies of one research group showed a smaller recurrence of bladder tumors in patients after treatment with Lactobacillus casei; these results await confirmation. The production of mutagens after a meal might be reduced by the concomitant intake of probiotics, but the relevance of this finding is unclear. In conclusion, consumption of foods containing Lactobacillus GG may shorten the course of rotavirus infection. Other health effects of probiotic bacteria have not been well established. Well-designed placebo-controlled studies with validated outcome variables are needed to determine the health effects of probiotics.

Dietary modulation of the human gut microflora using the prebiotics oligofructose and inulin

Although largely unproven in humans, better resistance to pathogens, reduction in blood lipids, antitumor properties, hormonal regulation and immune stimulation may all be possible through gut microflora manipulation. One approach advocates the oral intake of live microorganisms (probiotics). Although the probiotic approach has been extensively used and advocated, survivability/viability after ingestion is difficult to guarantee and almost impossible to prove. The prebiotic concept dictates that non viable dietary components fortify certain components of the intestinal flora (e.g., bifidobacteria, lactobacilli). This concept has the advantage that survival of the ingested ingredient through the upper gastrointestinal tract is not a prerequisite because it is indigenous bacterial genera that are targeted. The feeding of oligofructose and inulin to human volunteers alters the gut flora composition in favor of bifidobacteria, a purportedly beneficial genus. Future human studies that exploit the use of modern molecular-based detection methods for bacteria will determine the efficacy of prebiotics. It may be possible to address prophylactically certain gastrointestinal complaints through the selective targeting of gut bacteria.

Evidence for hypocholesterolemic effect of Lactobacillus reuteri in hypercholesterolemic mice

Swiss Albino mice were fed a diet enriched with fat to produce hypercholesterolemia. The further administration of Lactobacillus reuteri CRL 1098 (10(4) cells/d) to hypercholesterolemic mice for 7 d decreased total cholesterol by 38%, producing serum cholesterol concentrations similar to that of the control group (67.4 mg/ml). This low dose of L. reuteri caused a 40% reduction in triglycerides and a 20% increase in the ratio of high density lipoprotein to low density lipoprotein without bacterial translocation of the native microflora into the spleen and liver. These data suggest that L. reuteri CRL 1098 is an effective hypocholesterolemic adjuvant at a low cell concentration for mice.

Probiotics: Functionality and commercial status

Probiotics in the form of fermented milk products have been consumed for centuries. In this century various health benefits have been purported to result from consumption of foods containing live microorganisms, particularly lactic acid bacteria (LAB). Probiotics can provide relief for lactose intolerant individuals and reduce bouts of diarrhea. Evidence for other claims such as lowering serum cholesterol, suppressing cancer and stimulating the immune system remains to be clearly established by conducting well-controlled, statistically-valid clinical trials. Although the benefits to healthy individuals are uncertain, many consumers especially in Japan and Europe, perceive probiotic products to be healthful, and sales are robust.

Characterisation and selection of probiotic lactobacilli for a preliminary minipig feeding trial and their effect on serum cholesterol levels, faeces pH and faeces moisture content

Three out of 297 Lactobacillus strains isolated from pig faeces were selected for a feeding trial on account of their high bile-salt hydrolase (BSH) activity, bile-salt resistance, low pH tolerance and the production of antimicrobial substances. Two strains were identified as Lactobacillus johnsonii and one as Lactobacillus reuteri by DNA-DNA hybridisation. L. johnsoniii BFE 1061 produced a bacteriocin active against a range of lactic acid bacteria (LAB) and nonrelated bacteria including Clostridium perfringens. Six minipigs were maintained on a high-fat, high-cholesterol ('Western Style') diet for 17 weeks after which the diet was supplemented with the 'probiotic mixture' containing the above mentioned three Lactobacillus strains at 2 x 10(12) CFU per pig per day for five weeks. The mixture was given as a resuspended lyophilisate. During a two week follow-up period the minipigs received only the 'Western-style' diet without probiotic supplementation. A lowering effect on serum cholesterol levels was indicated after three weeks probiotic feeding, concomitant with an increase in the moisture content of the faeces and Lactobacillus cell numbers. Triglycerides, pH and number of lactic acid bacteria in faeces were not significantly influenced by probiotic supplementation.

Hypocholesterolemic action of Lactobacillus acidophilus ATCC 43121 and calcium in swine with hypercholesterolemia induced by diet

Thirty-three Yorkshire barrows (92 kg), fed a high cholesterol diet for 14 d had mean concentrations of serum cholesterol of 294.6 +/- 7.8 mg/dl. Starting on d 15 and for an additional 15 d, crystalline cholesterol was removed from the diet and pigs were assigned to one of four treatments: including two levels of calcium (0.7% and 1.4%) with and without added viable Lactobacillus acidophilus ATCC 43121 (2.5 x 10(11) cells per feeding). Serum cholesterol levels decreased, as expected, for all groups. However, the declines were initiated sooner for the groups receiving L. acidophilus. and those receiving the high level of calcium than for the respective control groups. When averaged over days, pigs fed L. acidophilus had 11.8% lower total cholesterol than pigs fed a diet without L. acidophilus. Similarly, pigs fed 1.4% calcium had a significantly lower total cholesterol than pigs fed 0.7% calcium. The effects were greater on low density lipoprotein cholesterol than on high density lipoprotein cholesterol. In addition, during the overall 15-d experimental period, serum bile acids were reduced 23.9% by dietary L. acidophilus and by 21.4% by 1.4% dietary calcium compared with those of their controls. Total bile acid concentration was positively correlated with total cholesterol concentration for pigs fed L. acidophilus or 1.4% calcium. These data suggest that both L. acidophilus and calcium can enhance the reduction of serum cholesterol in pigs that had been fed a high cholesterol diet, probably through alteration in the enterohepatic circulation of bile acids.

Modulation of proliferation, second messenger levels, and morphotype expression of the rat intestinal epithelial cell line IEC-6 by fermented milk

Trophic effects of milk fermented with Lactobacillus helveticus, Lactobacillus paracasei ssp. paracasei, Bifidobacterium sp., or the combination of Lactobacillus bulgaricus and Streptococcus thermophilus (yogurt) were studied on the IEC-6 intestinal epithelial cell line. Incorporation of [methyl-3H]thymidine, mitochondrial dehydrogenase activities, cyclic AMP production, and differentiation of levels of the IEC-6 strain were evaluated between the 15th and 30th passage in culture. All fermented and unfermented milks enhanced trophic responses of IEC-6 cells in a dose-dependent manner. Compared with the corresponding milks, supernatant fractions were more effective in stimulating mitochondrial dehydrogenase response. Fermented milk supernatants were also more effective than the corresponding unfermented fractions. Increases in DNA synthesis and cyclic AMP confirmed the activation observed with mitochondrial dehydrogenase. Yogurt induced the more trophic response with an increased number of the more differentiated cell morphotype. Fermentation with L. casei also demonstrated an important trophic adaptation of IEC-6 cells. Milk processing by lactic acid bacteria enhanced trophic and proliferation responses of intestinal epithelial cell line IEC-6. These results suggested that IEC-6 cells could represent an accurate and easy in vitro model for testing the trophic quality of various nutrients and for an optimization of physiological digestive functions.

Hypocholesterolemic and immunostimulatory effects of orally applied Enterococcus faecium M-74 in man

Lyophilized Enterococcus faecium M-74 was administered to 12 adult subjects in a daily oral dose of 5 x 10(9) bacteria for six weeks. The bacterium temporarily colonized the host intestine and its excretion with stool persisted for five weeks after the last does. The mean levels of serum cholesterol and LDL showed a a biphasic effect--an elevation followed by a sharp decrease (on day 64 of investigation). The decrease corresponded in time with a significant increase in the ability to reduce iodonitrotetrazolium and superoxide production by peripheral neutrophils incubated with zymosan or phorbol myristate acetate, and also with an elevated production of IgG by peripheral blood mononuclear cells. Hence, intake of E. faecium may have a hypocholesterolemic and immunostimulatory effect. It was also demonstrated that E. faecium significantly reduced the average activity of beta-D-glucuronidase in stools.

Comparisons of freshly isolated strains of Lactobacillus acidophilus of human intestinal origin for ability to assimilate cholesterol during growth

Fecal isolates of Lactobacillus acidophilus were obtained from human volunteers and tested for bile tolerance, the ability to deconjugate bile salts, and the ability to assimilate (take up) cholesterol during growth. One hundred and twenty-three of the 304 isolates of lactobacilli obtained were identified as L. acidophilus. In most cases, isolates of L. acidophilus from the same volunteer varied significantly in the amount of cholesterol assimilated, bile salt deconjugated, and bile tolerance. The two cultures from each of nine volunteers that assimilated the most cholesterol were compared as a group to select the most active cultures. Lactobacillus acidophilus ATCC 43121 (an isolate from the intestines of a pig, which in an earlier study aided significantly in controlling serum cholesterol in pigs) was included in this comparison. Significant variation in the ability to assimilate cholesterol was observed among these isolates from different volunteers. Eight of 17 isolates assimilated numerically but not significantly more cholesterol than L. acidophilus ATCC 43121, and 4 isolates assimilated significantly less. Bile tolerance and bile salt deconjugation also varied significantly among the selected isolates. Six of the selected isolates were quantitatively but not significantly better able to deconjugate bile salts than L. acidophilus ATCC 43121, but none was significantly more bile tolerant. Based on characteristics tested, isolates B7, D3, L1, 016, and 017 have the most potential of those included in this study for use as dietary adjuncts to lower human serum cholesterol.

Potential of using lactic acid bacteria for therapy and immunomodulation in man

There is in 1993 no proven medical indication of lactic acid bacteria (LAB) for therapy or immunomodulation in man. However, within the bulk of publications, rigorous trials have now opened rational fields of research on beneficial effects of LAB. These include lactose digestion, cholesterol metabolism, diarrheal disorders, prophylaxis of intestinal or urogenital infections, immunomodulation or even oral vaccination. We try here to analyse these studies, considering LAB as pharmacological agents, and conclude that pursuit of research could be promising for ecological therapy of mucosal diseases, and for development of original and flexible vectors for targeting in the gastrointestinal tract.

Health and nutritional benefits from lactic acid bacteria

There are several potential health or nutritional benefits possible from some species of lactic acid bacteria. Among these are: improved nutritional value of food, control of intestinal infections, improved digestion of lactose, control of some types of cancer, and control of serum cholesterol levels. Some potential benefits may result from growth and action of the bacteria during the manufacture of cultured foods. Some may result from growth and action of certain species of the lactic acid bacteria in the intestinal tract following ingestion of foods containing them. In selecting a culture to produce a specific benefit it is necessary to consider not only the wide variation among species of the lactic acid bacteria but also that among strains within a given species. With the possible exception of improving lactose utilization by persons who are lactose maldigestors, no specific health or nutritional claims can yet be made for the lactic acid bacteria.