Acidophilus

Acidophilus Clinical Report Summary

Acidophilus is a probiotic that belongs to the beneficial bacteria group known as Lactobacillus, and is found in the gastrointestinal tract of healthy mammals (1).  As a good microorganism in the body, it breaks down food in order to produce natural defensive byproducts like lactic acid, vitamin K and hydrogen peroxide.  As such, supplements of this probiotic are commonly used to treat bacterial vaginosis, allergy sufferers, diarrhea, gastrointestinal complaints, yeast infection, counteract lactose intolerance or boost the immune system, to name a few.   Evidence for use in bacterial vaginosis, diarrhea, and immune support demonstrate benefit, especially with regard to children's health, but immune function may differ depending on the health status of the patient. In people with immune system hypersensitivity, lactobacilli seem to down-regulate immune function and stimulate the immune system in healthy people without immune system hypersensitivity (2). Due to these immunomodulating effects, some researchers think lactobacillus like acidophilus and other probiotics might not only fight intestinal and urogenital pathogens, but might also be helpful for conditions such as inflammatory bowel disease, food allergy, and for use as an adjuvant to vaccination (1, 2).

Acidophilus Overview

Lactobacillus acidophilus, often referred to as simply acidophilus, is a lactic acid producing, gram-positive bacteria that is considered a "good" bacteria.  Acidophilus is normally present in the gastrointestinal flora, and helps maintain a healthy immune system by balancing out the body's response to pathogens.  Probiotics are often recommended during antibiotic treatment, because the theory is that taking lactobacillus probiotics during antibiotic treatment can prevent or minimize normal flora depletion and pathogenic bacteria colonization (3).  There are many different strains of acidophilus, some of which have greater adherence to the intestinal lining of the GI tract than others.  In foods, acidophilus is used to culture yogurt, and is naturally found in yogurt and acidophilus milk.  In supplemental form, it is available in liquid, capsule and tablet form and some supplements require refrigeration, while others are shelf stable. 

Safe Use of Acidophilus

Some products state potency at time of manufacture, but acidophilus can quickly die, resulting in a less effective product.  Higher quality probiotics generally state the guaranteed potency at the expiration date, ensuring maximum benefit.  Persons with an allergy or known hypersensitivity to any probiotic or probiotic-containing product should avoid Lactobacillus acidophilus.  Women who are pregnant or nursing should only use probiotic supplementation under the supervision of a medical professional. Probiotics should not be given to severely ill patients suffering from organ failure and on a feeding tube.  Increased mortality has been recognized in a small study of patients suffering from a severe form of acute pancreatitis.

Clinical Studies for Acidophilus

1. Acidophilus and Immune Support

A Lactobacillus acidophilus Strain of Human Gastrointestinal Microbiota Origin Elicits Killing of Enterovirulent Salmonella enterica Serovar Typhimurium by Triggering Lethal Bacterial Membrane Damage.  Coconnier-Polter M, Lievin-LeMoal V, Servin AL. (6)

The human gastrointestinal microbiota produces antagonistic activities against gastrointestinal bacterial pathogens. We undertook a study to investigate the mechanism(s) by which a Lactobacillus acidophilus strain of human microbiota origin antagonizes the gram-negative enteroinvasive pathogen Salmonella enterica serovar Typhimurium. We showed that the cell-free culture supernatant of L. acidophilus strain LB (LB-CFCS) induced the following effects in S. enterica SL1344: (i) a decrease in intracellular ATP that paralleled bacterial death, (ii) the release of lipopolysaccharide, (iii) permeabilization of the bacterial membrane, and (iv) an increase in the sensitivity of Salmonella to the lytic action of sodium dodecyl sulfate. Finally, we showed using two mutant strains of Salmonella, PhoP MS7953s and PmrA JKS1170, that the two-component regulatory systems PhoP-PhoQ and PmrA-PmrB that regulate the mechanisms of resistance to antibacterial agents in Salmonella did not influence the anti-Salmonella effect of LB-CFCS.

2. Acidophilus and the Prevention of Bacterial Vaginosis (BV)

In a review considering whether probiotics are effective for the treatment and/or prevention of bacterial vaginosis (BV), scientists noted that in clinical trials, intra-vaginal administration of Lactobacillus acidophilus for 6-12 days, or oral administration of L. acidophilus resulted in the cure of BV, and/or reduced the recurrences of BV, and/or caused restoration of a normal vaginal microbiota, significantly more frequently than did a placebo (4).   The abstract for this review can be found below:

Probiotics for the treatment of women with bacterial vaginosis.  Falagas, M.E., Betsi, G.I., Athanasious, S.

This review considers whether probiotics are effective agents for the treatment and/or prevention of bacterial vaginosis (BV). There seems to be an association between the absence of, or low concentrations of, vaginal lactobacilli and the development of BV. Many studies have suggested that the presence of H₂O₂-producing vaginal lactobacilli may protect against BV, although some studies do not support this hypothesis. In-vitro studies have suggested that certain specific strains of lactobacilli are able to inhibit the adherence of Gardnerella vaginalis to the vaginal epithelium and/or produce H₂O₂, lactic acid and/or bacteriocins, which inhibit the growth of bacteria causing BV. Clinical trials showed that intra-vaginal administration of Lactobacillus acidophilus for 6-12 days, or oral administration of L. acidophilus or Lactobacillus rhamnosus GR-1 and Lactobacillus fermentum RC-14 for 2 months, resulted in the cure of BV (defined as a 0-1 positive score according to Amsel's criteria), and/or reduced the recurrences of BV, and/or caused an increase in vaginal lactobacilli and restoration of a normal vaginal microbiota, significantly more frequently than did a placebo, acetic acid or no treatment. However, several trials have found no significant difference in the cure rate of BV and in the number of vaginal lactobacilli after intra-vaginal instillation of lactobacilli when compared with the effect of a placebo or oestrogen. Thus, although the available results concerning the effectiveness of the administration of lactobacilli for the treatment of BV are mostly positive, it cannot yet be concluded definitively that probiotics are useful for this purpose.

3. Lactobacillus and the Treatment of Infant Diarrhea

In a meta-analysis of probiotic use and diarrhea in the pediatric population, the combination of Lactobacillus rhamnosus and Lactobacillus reuteri reduced the duration of diarrhea in babies and children ages 9 to 44 months attending day-care centers. Early intervention reduced recovery time by about 43% (5). Overall, Lactobacillus seems to reduce the duration of diarrhea by 0.7 days and diarrheal stools by 1.6 stools on day 2 of treatment (5). Effectiveness appears to be dose dependent; at least 10 billion colony-forming units during the first 48 hours should be used.  The abstract for this meta-analysis can be found below:

Lactobacillus therapy for acute infectious diarrhea in children: a meta-analysis. Van Niel C.W., Feudtner C., Garrison M.M., Christakis D.A.

OBJECTIVE: Childhood diarrhea accounts for substantial morbidity and mortality worldwide. Multiple studies in children have shown that Lactobacillus, administered orally, may have antidiarrheal properties. We conducted a meta-analysis of randomized, controlled studies to assess whether treatment with Lactobacillus improves clinical outcomes in children with acute infectious diarrhea. METHODS: Studies were sought in bibliographic databases of traditional biomedical as well as complementary and alternative medicine literature published from 1966 to 2000. Search terms were "competitive inhibition," "diarrhea," "gastroenteritis," "Lactobacillus," "probiotic," "rotavirus," and "yog(h)urt." We included studies that were adequately randomized, blinded, controlled trials in which the treatment group received Lactobacillus and the control group received an adequate placebo and that reported clinical outcome measures of diarrhea intensity. These inclusion criteria were applied by blind review and consensus. The original search yielded 26 studies, 9 of which met the criteria. Multiple observers independently extracted study characteristics and clinical outcomes. Data sufficient to perform meta-analysis of the effect of Lactobacillus on diarrhea duration and diarrhea frequency on day 2 were contained in 7 and 3 of the included studies, respectively. RESULTS: Summary point estimates indicate a reduction in diarrhea duration of 0.7 days (95% confidence interval: 0.3-1.2 days) and a reduction in diarrhea frequency of 1.6 stools on day 2 of treatment (95% confidence interval: 0.7-2.6 fewer stools) in the participants who received Lactobacillus compared with those who received placebo. Details of treatment protocols varied among the studies. A preplanned subanalysis suggests a dose-effect relationship. CONCLUSION: The results of this meta-analysis suggest that Lactobacillus is safe and effective as a treatment for children with acute infectious diarrhea.

Acidophilus References

1. Goldin B.R. Health Benefits of probiotics. Br J Nutr 1998;80:S203-7.
2. Pelto L., Ioslauri E., Lilius E.M., et al. Probiotic bacteria down-regulate the milk-induced inflammatory response in milk-hypersensitive subjects but have an immunostimulatory effect in healthy subjects. Clin Exp Allergy 1998;28:1474-9.
3. Schultz M, Sartor RB. Probiotics and inflammatory bowel diseases. Am J Gastroenterol 2000;95:S19-21.
4. Falagas, M.E., Betsi, G.I., Athanasious, S. Probiotics for the treatment of women with bacterial vaginosis. Clin Microbiol Infect. 2007 Jul;13(7):657-64.  
5. Van Niel C.W., Feudtner C., Garrison M.M., Christakis D.A. Lactobacillus therapy for acute infectious diarrhea in children: a meta-analysis. Pediatrics 2002;109:678-84.
6. Coconnier-Polter M, Lievin-LeMoal V, Servin AL. A Lactobacillus acidophilus Strain of Human Gastrointestinal Microbiota Origin Elicits Killing of Enterovirulent Salmonella enterica Serovar Typhimurium by Triggering Lethal Bacterial Membrane Damage.  App & Environ Microbiology. Oct 2005; 71 (10): 6115-6120.