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Scientific Name(s): Lactobacillus acidophilus

Clinical Overview

Uses of Acidophilus

L. acidophilus has been used to restore normal oral, GI, and vaginal flora in those affected by antibiotics or by Candida and bacterial infections. Its value in treating these infections, lower urinary tract infections, and lactose intolerance remains unclear. In vitro, it suppresses growth of C. pylori , implicated in acid-peptic disease. In vivo, it suppresses growth of H. pylori , also implicated in upper GI diseases.

Acidophilus Dosing

Similar to yogurt, used as a food.


Complete avoidance of L. acidophilus in children with short-bowel syndrome may help prevent episodes of D-lactic acidosis.


Information regarding safety and efficacy in pregnancy and lactation is lacking.

Acidophilus Interactions

None well documented.

Acidophilus Adverse Reactions

L. acidophilus is generally considered safe, as it is normally found in the human alimentary tract. However, in patients with abnormal heart valves who have recently experienced dental manipulation, endocarditis caused by Lactobacillus species has been reported.


No data.


For several decades, health and nutritional benefits have been claimed for products containing Lactobacillus cultures. The topical or intravaginal application of yogurt products has been reported to control yeast and bacterial infections, and the ingestion of these preparations has been recommended to reduce the symptoms of antibiotic-induced diarrhea or sore mouth caused by Candida infections. 1 Other reports have indicated that the ingestion of acidophilus-containing products can reduce serum cholesterol levels, improve lactose intolerance, and slow the growth of experimental tumors. 2 L. acidophilus has been referred to as a probiotic, defined as microorganisms that have a beneficial effect on the host by improving the properties of the indigenous microflora. 3

Acidophilus Uses and Pharmacology

Replenishment of normal bacterial flora

Products containing live cultures have been investigated for their ability to compete with pathogens in the microenvironment, thereby permitting the reestablishment of normal bacterial flora.

Lactobacilli have been shown to inhibit the growth of other vaginal microorganisms including Escherichia coli , Candida albicans , and Gardnerella vaginalis . 4 Several factors may contribute to the possible activity of Lactobacillus , including the ability to generate lactic acid, hydrogen peroxide, and exogenous antibacterial compounds, to influence the production of interferon by target cells, 5 and to alter the adherence of bacteria. Lactacin F, an antibacterial compound produced by L. acidophilus , has been isolated and partially characterized as a heat-stable protein with at least 56 amino acid residues. 6 , 7

Lactobacillus has long been considered to be a component of the protective flora in the vagina. Recently, Lactobacillus species that produce hydrogen peroxide have been found in normal vaginal flora. Consequently, the therapeutic benefits of Lactobacillus products have been investigated in women with vaginal and urinary tract infections.

Animal data

Research reveals no animal data regarding the use of acidophilus for the replenishment of normal bacterial flora.

Clinical data

Women who used acetic acid jelly, an estrogen cream, a fermented lactobacillus-containing milk product, or metronidazole (eg, Flagyl ) were evaluated to determine the effects of intravaginal therapy on bacterial vaginosis. Clinical cures were obtained for 13 of 14 women receiving metronidazole but for only 1 of 14 using the fermented milk product. This latter intervention did not influence the predominance of lactobacilli in the vagina. 8 An evaluation of 16 commercially available products containing Lactobacillus in the form of capsules, powders, and tablets (in addition to yogurt and milk) found that all 16 products contained lactobacilli, of which 10 strains produced hydrogen peroxide. At least one contaminant was detected in 11 of the products, including Enterococcus faecium , Clostridium sporogenes , and Pseudomonas species. Only 4 of the products contained L. acidophilus and, therefore, the authors concluded that most commercially available products may not be appropriate for recolonization of the vagina. 4 The American Medical Association proposed guidelines for manufacturers to state on yogurt containers the number of viable L. acidophilus organisms contained therein. 9 Vaginal tablets containing L. acidophilus and estriol were shown to cure bacterial vaginosis. 10 A study showed decreased candidal vaginitis after ingestion of yogurt containing L. acidophilus . 11 However, ingestion of yogurt containing L. acidophilus increased colonization of the vagina and showed a reduction in the episodes of bacterial vaginosis but not in episodes of candidal vaginitis when compared to pasteurized yogurt. 12 Lactobacillus species that are strong producers of hydrogen peroxide and are highly adherent to vaginal epithelial cells effectively treat bacterial vaginosis. 13 , 14 Specific isolates of Lactobacillus with these characteristics are potential probiotics for vaginal recolonization. 14 The weekly instillation of Lactobacillus has been shown to reduce the recurrence rate of uncomplicated lower urinary tract infections in women, and the use of a strain that is resistant to nonoxynol-9, a spermicide that kills protective vaginal flora, may have potential for use in women with recurrent cystitis using this contraceptive agent. 15

Gastrointestinal uses

L. acidophilus is normally found in the human alimentary tract. Because of its acid-resistance, it persists in the stomach much longer than other bacteria do. Consequently, the oral administration of products containing L. acidophilus may be useful in the management of a variety of conditions associated with altered GI flora.

Their beneficial effects may be related to the ability to suppress the growth of pathogens.

Animal data

Research reveals no animal data regarding acidophilus for gastrointestinal uses.

Clinical data

In vitro, L. acidophilus has been shown to suppress the growth of Campylobacter pylori , a pathogen implicated as a causative factor in acid-peptic disease, although the therapeutic implications of these findings are not clear. 16 , 17 In vivo, inactivated L. acidophilus added to the triple regimen of an acid-suppressor plus two antibiotics increased eradication rates of Helicobacter pylori , another pathogen implicated in myriad upper GI diseases. Larger clinical trials are necessary to validate this finding. 18

Antibiotic-induced diarrhea

No consensus has been reached regarding the effectiveness of Lactobacillus -containing products in ameliorating antibiotic-induced diarrhea.

Animal data

Research reveals no animal data regarding the use of acidophilus for antibiotic-induced diarrhea.

Clinical data

When Lactinex granules, a combination of L. acidophilus and L. bulgaricus , were given 4 times daily for 10 days to children concomitantly with amoxicillin (eg, Amoxil ) therapy under double-blind conditions, 70% of the patients receiving placebo and 66% of those taking Lactinex experienced diarrhea. Closer analysis suggested that the incidence of diarrhea diminished during the last 4 days of therapy for the Lactinex patients, while it remained constant for those given placebo. 19 However, in a study of 40 children who received amoxicillin concomitantly with fermented Lactobacillus milk products, the treated group showed a lower frequency of stool passages and more fully formed feces compared with no treatment. 20 In a study of 27 patients randomized to amoxicillin/clavulanate (eg, Augmentin ) with or without Lactinex , there were fewer episodes of diarrhea reported in the Augmentin -only group, although the addition of Lactinex resulted in reduction of nausea, cramping, flatulence, and yeast superinfection. 21

Addition of lyophilized, heat-killed L. acidophilus LB to oral rehydration therapy decreased duration of diarrhea in a randomized clinical trial of children not on antibiotic therapy. 22 However, L. acidophilus did not prevent traveler's diarrhea. 23

Effect on cholesterol levels

It has been suggested that appropriately selected strains of Lactobacillus may be useful adjuncts for the control of hypercholesterolemia in humans, by virtue of the bacteria's ability to assimilate cholesterol and to grow well in the presence of bile. 24

Animal data

Research reveals no animal data regarding the use of acidophilus for the treatment of hypercholesterolemia.

Clinical data

The results of one study, in which 354 subjects took Lactinex tablets or placebo 4 times a day for 3 weeks in a crossover fashion, found no clinically significant changes in lipoprotein concentrations for either group. 25 Serum LDL-cholesterol was lowered in a study of healthy male patients consuming low-fat milk fermented with 2 strains of Lactobacillus and fructo-oligosaccharides (which could have contributed to the results). 26 Yogurt enriched with L. acidophilus did not lower serum cholesterol in another study of men and women. 27 Conflicting results remain concerning Lactobacillus species' effect on serum cholesterol levels.

Effect on lactose intolerance

Acidophilus milk containing L. acidophilus has been used in hospitals to treat patients with lactose intolerance, although controversy remains regarding effectiveness on lactose digestion. 28

Animal data

Research reveals no animal data regarding the use of acidophilus for its effects on lactose intolerance.

Clinical data

In a randomized trial of 18 patients, symptoms were not significantly improved after ingestion of L. acidophilus . 29

Other uses

The ingestion of these products has been associated with decreases in the concentration of several fecal enzymes that have the capacity to convert procarcinogens to carcinogens in the colon. This suggests that consumption of Lactobacillus -containing products may have beneficial health effects, although no further data are available to support this hypothesis. 30 The combination of L. acidophilus and lactulose appears beneficial in the therapy of radiotherapy-related intestinal side effects. 31

Consumption of yogurt containing L. acidophilus in 15 asthmatic patients showed trends in decreased eosinophilia and increased interferon gamma, however, without improving clinical parameters. 32 Viability might be a prerequisite for effects on the immune system. 33 Further studies are necessary to ascertain if L. acidophilus has an effect on immunity.


Similar to yogurt, used as a food.


Information regarding safety and efficacy in pregnancy and lactation is lacking.


None well documented.

Adverse Reactions

Endocarditis caused by Lactobacillus species, including L. acidophilus has been reported. 34 This is a rare infection seen in patients with abnormal heart valves who have recently experienced dental manipulation. 34 Neurological sequelae from D-lactic acidosis, caused by consumption of acidophilus tablets and yogurt containing L. acidophilus , was observed in a child with short-bowel syndrome. 35 Complete avoidance of L. acidophilus in children with short-bowel syndrome may help prevent episodes of D-lactic acidosis. 35


Research reveals little or no information regarding toxicology with the use of this product.


1. Lewis WH. Medical Botany . New York, NY: J. Wiley and Sons; 1977.
2. Gorbach SL. Lactic acid bacteria and human health. Ann Med . 1990;22:37-41.
3. Holzapfel WH, Haberer P, Geisen R, Bjorkroth J, Schillinger U. Taxonomy and important features of probiotic microorganisms in food and nutrition. Am J Clin Nutr 2001;73(2 Suppl):365S-373S.
4. Hughes VL, Hillier SL. Microbiologic characteristics of Lactobacillus products used for colonization of the vagina. Obstet Gynecol . 1990;75:244-248.
5. Mihal V, Lackovic V, Plockova M, Brezina P. Immunobiologic properties of lactobacilli. Cesk Pediatr . 1990;45:587-590.
6. Muriana PM, Klaenhammer TR. Purification and partial characterization of Lactacin F, a bacteriocin produced by Lactobacillus acidophilus 11088. Appl Environ Microbiol . 1991;57:114-121.
7. Muriana PM, Klaenhammer TR. Cloning, phenotypic expression and DNA sequence of the gene for Lactacin F, an antimicrobial peptide produced by Lactobacillus spp. J Bacteriol . 1991;173:1779-1788.
8. Fredricsson B, Englund K, Weintraub L, Olund A, Nord CE. Bacterial vaginosis is not a simple ecological disorder. Gynecol Obstet Invest . 1989;28:156-160.
9. Podolsky S, Tauber AI. Yogurt for candidal vaginitis [editorial]. Ann Intern Med . 1992;117:345-346.
10. Parent D, Bossens M, Bayot D, et al. Therapy of bacterial vaginosis using exogenously-applied Lactobacilli acidophili and a low dose of estriol: a placebo-controlled multicentric clinical trial. Arzneimittel-Forschung . 1996;46:68-73.
11. Hilton E, Isenberg HD, Alperstein P, France K, Borenstein MT. Ingestion of yogurt containing Lactobacillus acidophilus as prophylaxis for candidal vaginitis. Ann Intern Med . 1992;116:353-357.
12. Shalev E, Battino S, Weiner E, Colodner R, Keness Y. Ingestion of yogurt containing Lactobacillus acidophilus compared with pasteurized yogurt as prophylaxis for recurrent candidal vaginitis and bacterial vaginosis. Arch Fam Med . 1996;5:593-596.
13. Hallen A, Jarstrand C, Pahlson C. Treatment of bacterial vaginosis with lactobacilli. Sexually Transmitted Diseases . 1992;19:146-148.
14. McLean NW, Rosenstein I. Characterisation and selection of a Lactobacillus species to re-colonise the vagina of women with recurrent bacterial vaginosis. J Med Microbiol . 2000;49:543-552.
15. Reid G, Bruce AW, McGroarty JA, Cheng KJ, Costerton JW. Is there a role for lactobacilli in prevention of urogenital and intestinal infections? Clin Microbiol Rev . 1990;3:335-344.
16. Bhatia SJ, Kochar N, Abraham P, Nair NG, Mehta AP. Lactobacillus acidophilus inhibits growth of Campylobacter pylori in vitro. J Clin Microbiol . 1989;27:2328-2330.
17. Gismondo MR, Lo Bue AM, Chisari G, Pecorella G, Malandrino G, Petralito E. Competitive activity of a bacterial preparation of colonization and pathogenicity of C. pylori . A clinical study [in Italian]. Clin Ter . 1990;134:41-46.
18. Canducci F, Armuzzi A, Cremonini F, et al. A lyophilized and inactivated culture of Lactobacillus acidophilus increases Helicobacter pylori eradication rates. Aliment Pharmacol Ther 2000;14:1625-1629.
19. Tankanow RM, et al. A double-blind, placebo-controlled study of the efficacy of Lactinex in the prophylaxis of amoxicillin-induced diarrhea. DICP Ann Pharmacother . 1990;24:382.
20. Contardi I. Oral bacteria therapy in prevention of antibiotic-induced diarrhea in childhood. Clin Ter . 1991;136:409.
21. Witsell DL, Garrett CG, Yarbrough WG, Dorrestein SP, Drake AF, Weissler MC. Effect of Lactobacillus acidophilus on antibiotic-associated gastrointestinal morbidity: a prospective randomized trial. J Otolaryngol . 1995;24:230-233.
22. Simakachorn N, Pichaipat V, Rithipornpaisarn P, Kongkaew C, Tongpradit P, Varavithya W. Clinical evaluation of the addition of lyophilized, heat-killed Lactobacillus acidophilus LB to oral rehydration therapy in the treatment of acute diarrhea in children. J Pediatr Gastroenterol Nutr . 2000;30:68-72.
23. Katelaris PH, Salam I, Farthing MJG. Lactobacilli to prevent traveler's diarrhea? N Engl J Med . 1995;333:1360-1361.
24. Gilliland SE, Walker DK. Factors to consider when selecting a culture of Lactobacillus acidophilus as a dietary adjunct to produce a hypocholesterolemic effect in humans. J Dairy Sci . 1990;73:905.
25. Lin SY, Ayres JW, Winkler W Jr, Sandine WE. Lactobacillus effects on cholesterol: In vitro and in vivo results. J Dairy Sci . 1989;72:2885-2899.
26. Schaafsma G, Meuling WJ, van Dokkum W, Bouley C. Effects of a milk product, fermented by Lactobacillus acidophilus and with fructo-oligosaccharides added, on blood lipids in male volunteers. Eur J Clin Nutr 1998;52:436-440.
27. de Roos NM, Schouten G, Katan MB. Yoghurt enriched with Lactobacillus acidophilus does not lower blood lipids in healthy men and women with normal to borderline high serum cholesterol levels. Eur J Clin Nutr . 1999; 53:277-280.
28. Lin MY, Yen CL, Chen SH. Management of lactose maldigestion by consuming milk containing lactobacilli. Dig Dis Sci . 1998;43:133-137.
29. Saltzman JR, Russell RM, Golner B, Barakat S, Dallal GE, Goldin BR. A randomized trial of Lactobacillus acidophilus BG2FO4 to treat lactose intolerance. Am J Clin Nutr . 1999;69:140-146.
30. Marteau P, Pochart P, Flourie B, et al. Effect of chronic ingestion of a fermented dairy product containing Lactobacillus acidophilus and Bifidobacterium bifidum on metabolic activities of the colonic flora in humans. Am J Clin Nutr . 1990;52:685-688.
31. Salminen S, Salminen E. Lactulose, lactic acid bacteria, intestinal microecology and mucosal protection. Scand J Gastroenterol . 1997;222:45-48.
32. Wheeler JG, Shema SJ, Bogle ML, et al. Immune and clinical impact of Lactobacillus acidophilus on asthma. Ann Allergy Asthma Immunol . 1997;79:229-233.
33. de Roos NM, Katan MB. Effects of probiotic bacteria on diarrhea, lipid metabolism, and carcinogenesis: a review of papers published between 1988 and 1998. Am J Clin Nutr . 2000;71:405-411.
34. Griffiths JK, Daly JS, Dodge RA. Two cases of endocarditis due to Lactobacillus species: antimicrobial susceptibility, review, and discussion of therapy. Clin Infect Dis . 1992;15:250-255.
35. Day AS, Abbott GD. D-lactic acidosis in short bowel syndrome. N Z Med J . 1999;112:277-278.

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