What Is It?
Health Benefits

Dosage Information
Guidelines for Use

General Interaction
Possible Side Effects



Evidence Based Rating Scale 

What Is It? 

Probiotic is the name microbiologists gave to the living "friendly" microorganisms found in the gastrointestinal (GI) tracts of healthy individuals in the late nineteenth century. The term probiotic means "for life" and there are many probiotics with therapeutic properties for animals and humans. Most probiotics are bacteria, but some yeasts and fungi may also fill this role. The two most popular groups of bacteria are Bifidobacterium and Lactobacillus, both of which contain multiple species. Bifidobacteria is helpful in treating infant diarrhea.  Lactobacillus bulgaricus makes milk products sour in order to extend their shelf life (think yogurt) while Lactobacillus acidophilus helps maintain intestinal health and is a natural antibiotic. Probiotics are essential to proper development of the immune system and to the digestion and absorption of food and nutrients. (1, 2) 

By 1994, the potential health benefits of these microorganisms were considered so significant that the World Health Organization declared that probiotics would be the next most important immune defense system as commonly prescribed antibiotics become increasingly useless due to antibiotic resistance. Advances in technology have allowed probiotics to be isolated and colonized in order to determine their specific therapeutic properties. (1) 

The human GI tract is a complex system where a surface epithelial layer lining the intestines acts as a barrier between the wall of the GI tract and the colonic bacteria when they become attached. Good bacteria and bad microorganisms act in a balancing act that can be upset by unfriendly disease-causing bacteria, fungi, parasites, and yeasts, or by antibiotics that inadvertently kill good bacteria while removing bad microorganisms. To qualify as beneficial microorganisms, bacteria must have:

  • acid and bile resistance

  • metabolic activity in the GI tract

  • the ability to adhere to the GI tract wall

  • antimicrobial activity toward pathogenic bacteria

  • the ability to reduce the pH (increase the acid level) of the colon contents

The types and amounts of bacteria normally increase along the length of the GI tract. The upper intestine has a colony count of less than 105 colony forming units (cfu) per milliliter (mL) while the mid ileum has 107cfu/mL. Bacterial colony counts in the colon are in the range of 1011-1012 cfu/mL. 

Favorable Lactobacillus species are L. plantarum, L. rhamnosus, L. reuteri, and L. agilis. However, these species are rarely found in the intestines of populations of industrialized nations. L. plantarum is found in nearly 100% of Asian and African populations but only about 25% of the United States population mainly because the Western diet is drastically low in Lactobacilli. Incidentally, before a baby is born, the GI tract is sterile until the baby ingests vaginal and fecal microorganisms during delivery and once feeding begins after delivery. Infants who are breast-fed soon have bacterial colonization in the large intestine that is 90% Bifidobacteria, which helps their immune response. However, infants who are bottle-fed infant formula do not immediately have bifidobacteria. (1, 2) 

Probiotics should not be confused with prebiotics, which are nondigestible food ingredients that stimulate the activity and/or growth of friendly microorganisms that already exist in the colon. When prebiotics meet probiotics, they form a supplement known as a synbiotic. (2) 

Health Benefits 

The beneficial effects of probiotics are most evident in diseases of the GI tract but other health benefits have been noted from numerous species of probiotics. (3) Lactobacillus acidophilus, or acidophilus for short, has been used to treat irritable bowel syndrome, vaginal yeast infections, and bad breath to name a few. (4-6) For a list of other disorders treated with acidophilus, please see the Whole Health MD entry on acidophilus.  

Specifically, probiotics may help: 

Strengthen immunity. The aging process leads to a decline in cellular immunity. A 2001 study in the American Journal of Clinical Nutrition found that elderly volunteers who were given milk containing Bifidus experienced an increase in white blood cells, which help fight off infection and increase immunity. (7)  

Probiotics seem to have a beneficial effect on people with HIV/AIDS whose deteriorating immune systems can be seriously impacted by gastrointestinal infections. In one study of Tanzanian women living with HIV/AIDS, consumption of yogurt supplemented with Lactobacillus was associated with an increase in immune function. (8) 

Protect against colon cancer. Probiotics create an acidic environment in the intestine and neutralize the enzymes that convert precarcinogens into carcinogens. Studies are promising concerning their protective effect on colon, liver, and bladder cancer. Recent in vitro (laboratory) and in vivo animal studies indicate probiotic bacteria may reduce the risk, incidence, and number of tumors in colon cancer. However, more studies are needed in humans before probiotics can be recommended for prevention of colon cancer. (9, 10) 

Alleviate symptoms of lactose intolerance. Bifidus is a "lactic acid" bacterium. For people who are lactose-intolerant or cannot digest the natural sugars in milk, Bifidus and other probiotics, such as acidophilus, can help. Studies show that foods containing bifidus such as yogurt alleviate the bloating and gassiness associated with lactose intolerance. However, supplements may be a better choice since these foods usually don't contain high levels of "live" probiotic organisms. (11) 

Reduce inflammation from rheumatoid arthritis. Probiotics demonstrated anti-inflammatory effects in early animal and human studies. In a small pilot study of 45 men and women with symptoms of rheumatoid arthritis (RA), the patients were given probiotics or placebo for 60 days in conjunction with their anti-arthritic medication. The probiotic group had less pain and demonstrated greater mobility. Larger studies are needed to confirm these results. (12) 

Suppress response to food allergies and asthma. Animal studies indicate treatment with bifidobacteria suppressed the immune response and improved the function of the epithelial barrier in allergic mice. (13) For asthma, studies in mice indicate oral supplementation with Lactobacillus alleviates the allergic airway response seen in asthma. (14) Studies are needed in humans to confirm these results for both allergic responses. 

Treat eczema in children. In one study of eighty-eight children, forty-five were supplemented with Lactobacillus daily for twelve weeks. At the end of that time, the probiotic group showed improvement in symptoms and a decrease in the activity of the eczema. 15 

Benefit liver disease. Early studies indicated probiotics benefited early-stage liver disease. However, a recent study suggested supplementation with probiotics did not significantly benefit advanced liver cirrhosis. Larger studies are needed to clarify the potential role for probiotics in liver disease. (16) 

Reduce cholesterol levels. Several species of probiotics have been shown to "mop up" cholesterol in the absence of oxygen and the presence of bile—similar to conditions in the GI tract. Animal and human studies have given mixed results; beneficial effects appear to be dependent upon the species of probiotics. (1, 17) 

Alleviate symptoms of Irritable Bowel Syndrome (IBS). Several short-term studies have given mixed results for the potential efficacy of probiotics in IBS. Studies indicating efficacy show a modest improvement and suggest that probiotics may be significant for IBS patients whose main symptom is diarrhea. More studies of a longer duration are needed to confirm the role of probiotics for IBS. (18-19) 

Treat diarrhea. Numerous small studies have evaluated probiotics for the prevention and treatment of diarrhea. A recent meta-analysis concluded Lactobacillus was effective in preventing antibiotic-associated diarrhea in adults but not children. (20) Another review of studies concluded probiotics may prevent and treat antibiotic-associated diarrhea by producing antimicrobial compounds and chemicals. (21) For infectious diarrhea, a minimum dose of 10 billion cfu of Lactobacillus was effective in relieving symptoms when taken within 48 hours of onset. (22) 

Relieve constipation. Results from studies of probiotics and constipation are mixed. In one study, otherwise healthy patients complaining of constipation were given a daily serving of 100g of yogurt made from plant-derived Lactobacillus. At the end of six weeks, patients showed a significant improvement in symptoms. (23) However, a recent review of five studies concluded the use of probiotics for constipation should be considered investigational until more studies have been completed. (24)  

Relieve Inflammatory Bowel Disease (IBD). Inflammatory Bowel Disease includes Crohn's disease and ulcerative colitis. A review of studies of probiotics in the treatment of IBD indicated that the majority of studies suggest that probiotics may benefit IBD, particularly when combined with standard treatment. However, more large-scale studies are needed to determine the extent of effectiveness and to recommend the use of probiotics for IBD. (25)


  • Capsules
  • Liquids
  • Powders
  • Suppositories
  • Tablets 

Dosage Information 

  • For irritable bowel syndrome: On a maintenance basis, 2 tablets a day of acidophilus with at least 1 billion live organisms per tablet; take with meals.

  • For diarrhea: Take 2 acidophilus tablets 3 times a day with meals or enough to total 10 billion cfu Lactobacillus acidophilus.

  • For eczema. For children, take 5x109 cfu each day of Lactobacillus sakei. (15)

  • For rheumatoid arthritis. Take a multi-strain probiotic supplement containing 1.8 x 109 cfu/day. (26) 

Special Tips: 

  • Look for probiotic supplements in the refrigerator section of your health foods store. Read the label to confirm that the product contains "live" or "active" cultures.

  • Check the expiration date. As there are numerous brands of probiotics, with a wide variety of strengths, forms, and concentrations, dosing should be guided by the instructions on the package or the advice of your health-care practitioner.

  • Read labels carefully to confirm that the product contains live or "active" cultures. Check the expiration date, too.

  • Different strains work better in different parts of the body. Look for a supplement that has a variety of strains. Some manufacturers are even creating specialty blends emphasizing strains that contribute to intestinal health or urinary tract health.

  • Typically, for an acute situation, probiotics are taken three times a day, whereas for a more chronic problem, or for prevention, reduce the dose to once or twice a day. As a general rule, probiotics are taken with food to reduce the number of organisms destroyed by stomach acid, or before bed so they have longer to sit in the intestine and do their good work. 

Guidelines for Use 

If attempting to treat chronic diarrhea, recent study findings suggest that heat-killed Lactobacillus acidophilus is more effective than living Lactobacillus cultures. (27) Also, different strains may exhibit different metabolic activity. Some researchers believe probiotic preparations containing several species may be more beneficial than a single species. (28, 29) Ask your doctor which kind of probiotic is right for your condition. 

General Interaction 

Antibiotics may kill some probiotics and decrease their effectiveness. Allow at least 2 hours between administrations of each. 

Possible Side Effects 

Side effects of probiotics tend to be mild and digestive such as bloating and flatulence. Potentially, probiotics could cause overstimulation of the immune system, unhealthy metabolic activities, or insertion of genetic material into a cell (gene transfer). In people with underlying health conditions, probiotics could theoretically cause infections that need to be treated with antibiotics. 


The safety of probiotics has not been studied, particularly for use by the elderly, young children, and those with compromised immune systems. Anyone considering probiotics as a complementary alternative medicine (CAM) should consult their physician first. Probiotics should not be used in place of conventional medicine.  


1. Drisko JA, Giles CK, Bischoff BJ. Probiotics in health maintenance and disease prevention. Altern Med Rev. 2003 May;8(2):143-55.
2. National Center for Complementary and Alternative Medicine. Available at Accessed June 19, 2010.
3. Macdonald TT, Bell I. Probiotics and the immune response to vaccines. Proc Nutr Soc. 2010 Jun 14:1-5. [Epub ahead of print]
4. Nobaek S, Johansson M-L, Molin G, et al. Alteration of intestinal microflora is associated with reduction in abdominal bloating and pain in patients with irritable bowel syndrome. Am J Gastroenterol. 2000;95:1231–1238.
5. Elmer GW, Surawicz CM, McFarland LV. Biotherapeutic agents. A neglected modality for the treatment and prevention of selected intestinal and vaginal infections. JAMA. 1996 Mar 20;275(11):870-6.
6. Flichy-Fernández AJ, Peñarrocha-Diago M. Probiotic treatment in the oral cavity: an update. Med Oral Patol Oral Cir Bucal. 2010 Feb 21.
7. Gill HS, Rutherfurd KJ, Cross ML, Gopal PK. Enhancement of immunity in the elderly by dietary supplementation with the probiotic Bifidobacterium lactis HN019. Am J Clin Nutr. 2001 Dec;74(6):833-9.
8. Irvine SL, Hummelen R, Hekmat S, W N Looman C, Habbema JD, Reid G. Probiotic Yogurt Consumption is Associated With an Increase of CD4 Count Among People Living With HIV/AIDS. J Clin Gastroenterol. 2010 May 11.
9. Kumar M, Kumar A, Nagpal R, Mohania D, Behare P, Verma V, Kumar P, Poddar D, Aggarwal PK, Henry CJ, Jain S, Yadav H. Cancer-preventing attributes of probiotics: an update. Int J Food Sci Nutr. 2010 Feb 26.
10. de Moreno de Leblanc A, Perdigón G. The application of probiotic fermented milks in cancer and intestinal inflammation. Proc Nutr Soc. 2010 Jun 16:1-8. [Epub ahead of print]
11. He T, Priebe MG, Zhong Y, Huang C, Harmsen HJ, Raangs GC, Antoine JM, Welling GW, Vonk RJ. Effects of yogurt and bifidobacteria supplementation on the colonic microbiota in lactose-intolerant subjects. J Appl Microbiol. 2008 Feb;104(2):595-604.
12. Mandel DR, Eichas K, Holmes J. Bacillus coagulans: a viable adjunct therapy for relieving symptoms of rheumatoid arthritis according to a randomized, controlled trial. BMC Complement Altern Med. 2010 Jan 12;10:1.
13. Zhang LL, Chen X, Zheng PY, Luo Y, Lu GF, Liu ZQ, Huang H, Yang PC. Oral Bifidobacterium modulates intestinal immune inflammation in mice with food allergy. J Gastroenterol Hepatol. 2010 May;25(5):928-34.
14. Li CY, Lin HC, Hsueh KC, Wu SF, Fang SH. Oral administration of Lactobacillus salivarius inhibits the allergic airway response in mice. Can J Microbiol. 2010 May;56(5):373-9.
15. Woo SI, Kim JY, Lee YJ, Kim NS, Hahn YS. Effect of Lactobacillus sakei supplementation in children with atopic eczema-dermatitis syndrome. Ann Allergy Asthma Immunol. 2010 Apr;104(4):343-8.
16. Pereg D, Kotliroff A, Gadoth N, Hadary R, Lishner M, Kitay-Cohen Y. Probiotics for patients with compensated liver cirrhosis: A double-blind placebo-controlled study. Nutrition. 2010 May 6. [Epub ahead of print]
17. Huang Y, Zheng Y. The probiotic Lactobacillus acidophilus reduces cholesterol absorption through the down-regulation of Niemann-Pick C1-like 1 in Caco-2 cells. Br J Nutr. 2010 Feb;103(4):473-8.
18. O'Sullivan, MA, O'Morain, CA. Bacterial supplementation in the irritable bowel syndrome. A randomised double-blind placebo-controlled crossover study. Dig Liver Dis 2000; 32:294.
19. Brenner, DM, Moeller, MJ, Chey, WD, Schoenfeld, PS. The utility of probiotics in the treatment of irritable bowel syndrome: a systematic review. Am J Gastroenterol 2009; 104:1033.
20. Kale-Pradhan PB, Jassal HK, Wilhelm SM. Role of Lactobacillus in the prevention of antibiotic-associated diarrhea: a meta-analysis. Pharmacotherapy. 2010 Feb;30(2):119-26.
21. Rohde CL, Bartolini V, Jones N. The use of probiotics in the prevention and treatment of antibiotic-associated diarrhea with special interest in Clostridium difficile-associated diarrhea. Nutr Clin Pract. 2009 Feb-Mar;24(1):33-40.
22. Van Niel, CW, Feudtner, C, Garrison, MM, Christakis, DA. Lactobacillus therapy for acute infectious diarrhea in children: a meta-analysis. Pediatrics 2002; 109:678.
23. Higashikawa F, Noda M, Awaya T, Nomura K, Oku H, Sugiyama M. Improvement of constipation and liver function by plant-derived lactic acid bacteria: a double-blind, randomized trial. Nutrition. 2010 Apr;26(4):367-74. Epub 2009 Jul 22.
24. Chmielewska A, Szajewska H. Systematic review of randomised controlled trials: probiotics for functional constipation. World J Gastroenterol. 2010 Jan 7;16(1):69-75.
25. Cary VA, Boullata J. What is the evidence for the use of probiotics in the treatment of inflammatory bowel disease? J Clin Nurs. 2010 Apr;19(7-8):904-16.
26. Lee HJ, Waller RD, Stebbings S, Highton J, Orlovich DA, Schmierer D, Fawcett JP. The effects of an orally administered probiotic on sulfasalazine metabolism in individuals with rheumatoid arthritis: a preliminary study. Int J Rheum Dis. 2010 Feb 1;13(1):48-54.
27. Xiao SD, Zhang de Z, Lu H, Jiang SH, Liu HY, Wang GS, Xu GM, Zhang ZB, Lin GJ, Wang GL. Multicenter, randomized, controlled trial of heat-killed Lactobacillus acidophilus LB in patients with chronic diarrhea. Adv Ther. 2003 Sep-Oct;20(5):253-60.
28. Gionchetti P, Rizzello F, Venturi A, et al. Oral bacteriotherapy as maintenance treatment in patients with chronic pouchitis: a double-blind, placebo-controlled trial. Gastroenterology 2000;119:305-9.
29. Bruce AW, Reid G. Intravaginal instillation of Lactobacilli for prevention of recurrent urinary tract infections. Can J Microbiol 1988;34:339-43.
30. Halpern GM, Prindiville T, Blankenberg M, et al. Treatment of irritable bowel syndrome with Lacteol Fort: a randomized, double-blind, cross-over trial. Am J Gastroenterol. 1996;91:1579–1585.
31. Sen S, Mullan MM, Parker TJ, et al. Effect of Lactobacillus plantarum 299v on colonic fermentation and symptoms of irritable bowel syndrome. Dig Dis Sci. 2002;47:2615–2620.
32. Saggioro A. Probiotics in the treatment of irritable bowel syndrome. J Clin Gastroenterol. 2004 Jul;38(6 Suppl):S104-6.
33. Tsuchiya J, Barreto R, Okura R, Kawakita S, Fesce E, Marotta F. Single-blind follow-up study on the effectiveness of a symbiotic preparation in irritable bowel syndrome. Chin J Dig Dis. 2004;5(4):169-74.
34. Jeavons HS. Prevention and treatment of vulvovaginal candidiasis using exogenous Lactobacillus. J Obstet Gynecol Neonatal Nurs. 2003 May-Jun;32(3):287-96.
35. Levri KM, Ketvertis K, Deramo M, Merenstein JH, D'Amico F. Do probiotics reduce adult lactose intolerance? A systematic review. J Fam Pract. 2005 Jul;54(7):613-20.

Evidence Based Rating Scale

The Evidence Based Rating Scale is a tool that helps consumers translate the findings of medical research studies and what our clinical advisors have found to be efficacious in their personal practice into a visual and easy to interpret format. This tool is meant to simplify the information on supplements and therapies that demonstrate promise in the treatment of certain conditions.






Allergies (food)


Animal studies indicate Bifidobacteria suppressed immune response and improved function of the epithelial barri
Date Published: 06/27/2010

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