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Probiotics: The guts of G.I. health

Probiotics: The guts of G.I. health

Human and animal studies have shown probiotics may have a beneficial role to play in the treatment of diarrheal disorders, irritable bowel syndrome, inflammatory bowel disease, colon cancer, lactose intolerance, vaginal infections, allergies, elevated cholesterol, liver disease, H. pylori infection and more.

Probiotics—often called "friendly bacteria"—are available in various foods or as dietary supplements. Americans spend millions of dollars each year to ingest these bugs, and for good reason: Probiotics have myriad positive effects on human health. An explosion of peer-reviewed clinical research over the last 20 years tends to support this statement. Human and animal studies have shown probiotics may have a beneficial role to play in the treatment of diarrheal disorders, irritable bowel syndrome, inflammatory bowel disease, colon cancer, lactose intolerance, vaginal infections, allergies, elevated cholesterol, liver disease, H. pylori infection and more.

While not quite a panacea for what ails you, probiotics do seem to have a wide variety of positive benefits. The main issues are determining which probiotics you should use for what condition, how much you should take and for how long.

What is a probiotic?

The concept of probiotics dates back to at least 1908, when famed Nobel Prize recipient Eli Metchnikoff suggested that the long life and health of Bulgarian peasants was in part the result of their consumption of fermented milk products. However, it was not until about 40 years ago that the actual term probiotic was first used. Since then, quite a bit of print has been spent defining the term. Recently, the United Nations Food and Agricultural Organization and the World Health Organization settled on this definition: Probiotics are "live microorganisms, which, when administered in adequate amounts, confer a health benefit on the host." Don't confuse probiotics with prebiotics, which are "non-digestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon that can improve host health."1 To complicate things just a little more, when probiotics and prebiotics are mixed together in a supplement or food, the product is called a synbiotic.

Some foods containing probiotics are yogurt, fermented and unfermented milk, miso, tempeh and some juices and soy beverages. In those foods, the probiotic bacteria may be naturally present or added during preparation.

Most often, probiotics come from two groups (genera) of bacteria, Lactobacillus and Bifidobacterium. However, other bugs, such as E. coli and Saccharomyces boulardii, have also been developed as probiotics. (S. boulardii is not a bacterium, but a yeast that fits the definition of a probiotic.) Within each genus are different species—for example, Lactobacillus acidophilus and Lactobacillus rhamnosus. Within species, there are different strains or varieties, such as Lactobacillus GG. (Lactobacillus GG is actually the common name for the bacterial strain Lactobacillus caseii subspecies rhamnosus; it is called Lactobacillus GG after the last names of the researchers who discovered it in 1985, Drs. Gorbach and Goldin.)

What do probiotics do?

In a healthy adult, the gastrointestinal tract contains 10 times as many bacteria as there are cells in the entire body itself. That works out to about 1014—or 100 trillion—bacteria of various species in the human gut. These organisms are extremely active and interact continuously with each other and with the cells lining the gut, as well as with the immune, endocrine and central nervous systems. Together, their metabolic activity matches that of the liver.2 This two-to-three pound mass of "microbiota" could really be considered as a separate organ itself.

In this mix of 400-odd different bacterial species are some good and bad actors. Probiotics act for the greater good in a number of ways: They competitively crowd out potential bad (pathogenic) bugs, stimulate the intestinal immune system and produce vitamins such as K, as well as other nutritive substances, such as short-chain fatty acids, amino acids, growth factors and antioxidants.3,4,5

Such characteristics mean probiotics can have far-reaching effects. For example, it has been shown that some probiotics increase the production of intestinal anti-inflammatory modulators (for example, cytokines like IL-10), while reducing the production of pro-inflammatory modulators.6,7 Probiotics can thus decrease inflammation in the gut and, possibly, systemically. Other studies have shown probiotics can improve a "leaky gut," a situation in which the cells lining the gut are damaged or porous, making it more likely that various toxins can cross the leaky barrier and cause internal havoc. Various probiotic bacteria have been shown to mend that barrier in test tube and animal studies.8,9,10,11 Human clinical trials have suggested but not proved this.

These and other activities of probiotics have excited researchers and spurred studies in patients with a number of different diseases. We will focus here on the three most promising and well-documented uses of probiotics to date: diarrhea, inflammatory bowel disease and irritable bowel syndrome.

Diarrheal disorders

Probiotics have been shown to be of benefit in three types of diarrheal disorders: antibiotic-associated, traveler's and infectious diarrhea.

Antibiotic-associated diarrhea occurs with surprising frequency; some reports suggest up to 20 percent of patients taking antibiotics experience this side effect. A number of clinical trials have assessed whether taking probiotics when an antibiotic is prescribed decreases the rate of diarrhea. Four controlled studies showed reduced rates of occurrence of AAD using Saccharomyces boulardii.12,13,14,15 Another probiotic that has shown promise in this area is Lactobacillus rhamnosus GG. A review of Lacto GG in AAD looked at six placebo-controlled trials. Four reported a significant reduction in the risk of AAD with co-administration of Lacto GG, one concluded that co-administration of Lacto GG reduced the number of days of antibiotic-induced diarrhea, and the final trial found no benefit.16 Other probiotic strains have been used in AAD, but the studies are sparse and the results mixed.

Traveler's diarrhea can be caused by a variety of microorganisms; the most common are enteroaggregative E. coli and Shigella spp. Administration of Lacto GG has been reported to decrease occurrence of TD, but has shown inconsistent results for this condition. The most significant study involved 245 New Yorkers traveling to a developing nation; those who took Lacto GG had a nearly 50 percent lower risk for TD than the placebo-treated group.17 However, a more recent study demonstrated no difference in incidence of diarrhea between two groups traveling abroad, one of which was given Lacto GG and the other placebo.18S. boulardii showed some positive results in TD in an older trial. In this placebo-controlled, double-blind study, various dosages (250 mg and 1,000 mg of S. boulardii) were administered prophylactically to 3,000 Austrians embarking on foreign travel. Results showed a significant reduction in diarrhea in those taking S. boulardii.19

The third cause of diarrhea for which probiotics seem to have some salutary effect is infectious diarrhea. Infectious diarrhea is caused by a variety of organisms, but in children, the most common infectious agent by far is rotavirus. A combination of two Lactobacillus strains—L. rhamnosus 19070-2 and L. reuteri DSM12246—was more effective than placebo in decreasing acute diarrhea caused by rotavirus infection in hospitalized and nonhospitalized children.20,21Lacto GG has also been shown to be effective in some (but not all) studies in reducing the duration of rotavirus infection in kids.22,23 The effects of probiotics in infectious diarrhea may be cause-specific; in one trial Lacto GG shortened the duration of rotavirus-induced diarrhea, but showed no effect with other pathogens.22

Inflammatory bowel disease

IBD encompasses intestinal inflammatory diseases such as Crohn's disease and ulcerative colitis. These diseases have unknown origins, but intestinal flora disturbances and breakdown of the mucosal barrier have been hypothesized as contributing factors. The most promising work here with probiotics has used a combination product called VSL#3. VSL#3 consists of a defined ratio of Bifido?bacterium breve, B. longum, B. infantis, Lactobacillus acidophilus, L. plantarum, L. casei, L. bulgaricus and Streptococcus delivered at very high levels. Data from nonplacebo-controlled trials suggest that VSL#3 has potential as maintenance therapy for patients with ulcerative colitis in remission.24 Additionally, it may be effective with active UC. In a recent, nonplacebo-controlled trial, patients with active UC not responding to conventional therapy received VSL#3 for six weeks. Treatment resulted in a combined remission/response rate of 77 percent with no adverse events.25Saccharomyces boulardii has also been shown to significantly reduce disease activity and the frequency of bowel movements in people with Crohn's disease and UC in non-placebo-controlled trials.26,27

VSL#3 also seems helpful for a condition called chronic pouchitis, a complication of surgery for ulcerative colitis. Two recent double-blind, placebo-controlled studies showed positive outcomes with VSL#3 versus placebo.28,29 By contrast, a double-blind, placebo-controlled trial with Lacto GG versus placebo showed no significant differences in chronic pouchitis.30

Irritable bowel syndrome

IBS is characterized by a group of symptoms in which abdominal pain or discomfort, such as flatulence and bloating, are associated with a change in bowel pattern, such as loose or more frequent bowel movements, diarrhea and/ or constipation. Results of treatment with probiotics have been quite mixed and confusing, in part because different types of IBS exist and there is a very high placebo-response rate. One double-blind, controlled trial using L. plantarum 299V noted a significant improvement in symptoms, with a 95 percent overall improvement (abdominal pain and normalization of stool frequency) seen in the group treated with L. plantarum.31 In another study using L. plantarum, there was an improvement in flatulence, but no difference in bloating or pain.32

VSL#3 has also shown some efficacy in IBS. In randomized, controlled trials, VSL#3 caused a significant reduction in abdominal bloating.33,34 However, other placebo-controlled studies using different Lactobacillus strains have been less positive.35,36,37 A novel Bifidobacterium strain (B. infantis 35624) has shown good promise in IBS. In one study, symptoms such as abdominal pain and discomfort, bloating and distention, and bowel movement difficulty were significantly lower with B. infantis 35624 treatment than with placebo. In a dosing study, it appeared that B. infantis 35624 at a dose of 1 x 10(8) colony-forming units was significantly superior to placebo and all other Bifidobacterium doses.38,39


The bottom line seems to be that different probiotics may be useful for different disorders, and at different concentrations (see below). Effects associated with one species or strain do not necessarily hold true for others. Additionally, most studies seem to indicate that benefits wane sometime soon after discontinuation of the probiotics.40 This indicates that the probiotic bacteria may colonize the intestines only transiently.

VSL#3, Lacto GG, Saccharomyces boulardii, L. rhamnosus 19070/L. reuteri DSM 12246, B. infantis 35624 and L. plantarum 299V all have significant research backing their use. That doesn't mean that other strains aren't effective, but focusing on strains supported by substantial research may be the best way to proceed.

Dan Lukaczer, N.D., has a private practice in Tacoma, Wash., and is associate director of medical education at the Institute for Functional Medicine in Gig Harbor, Wash.

Types of probiotics, conditions and dosages



Amount Daily

Lactobacillus rhamnosus GG

Infectious diarrhea
Antibiotic-associated diarrhea
Traveler's diarrhea

10?20 billion CFU*
10?20 billion CFU
10?20 billion CFU

VSL#3 (Bifidobacterium breve, B. longum, B. infantis, L. acidophilus, L. plantarum, L. casei, L. bulgaricus and Streptococcus)

Inflammatory bowel disease
Irritable bowel syndrome

450 billion? 1.3 trillion CFU
450 billion? 3 trillion CFU
450 billion CFU


Saccharomyces boulardii

Antibiotic-associated diarrhea
Inflammatory bowel disease

1?2 g
1?2 g

L. plantarum 299V B. infantis 35624

Irritable bowel syndrome
Irritable bowel syndrome

20 billion CFU
100 million CFU

L. rhamnosus 19070-2 and L. reuteri DSM 12246

Infectious diarrhea

20 billion CFU each

CFU= colony-forming units


1. Gibson GR, Roberfroid MB. Dietary modulation of the human colonic microbiota: introducing the concept of prebiotics. J Nutr,1995;125(6):1401-12.
2. Hart AL, et al. The role of the gut flora in health and disease, and its modification as therapy. Aliment Pharmacol Ther 2002;16(8): 1383-93.
3. Batt RM, et al. Enteric bacteria: friend or foe? J Small Anim Pract,1996; 37(6):261-7.
4. Bengmark S. Colonic food: pre- and probiotics. Am J Gastroenterol 2000; 95(Suppl 1):S5-7.
5. 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(2): 405-11.
6. Maassen CB, et al. Strain-dependent induction of cytokine profiles in the gut by orally administered Lactobacillus strains. Vaccine 2000;18(23): 2613-23.
7. Morita H, et al. Adhesion of lactic acid bacteria to caco-2 cells and their effect on cytokine secretion. Microbiol Immunol 2002;46(4):293-7.
8. Mack DR, et al. Probiotics inhibit enteropathogenic E. coli adherence in vitro by inducing intestinal mucin gene expression. Am J Physiol 1999;276(4):G941-50.
9. Madsen K, et al. Probiotic bacteria enhance murine and human intestinal epithelial barrier function. Gastroenterology 2001;121(3): 580-91.
10. Resta-Lenert S, Barrett KE. Live probiotics protect intestinal epithelial cells from the effects of infection with enteroinvasive Escherichia coli (EIEC). Gut 2003;52(7):988-97.
11. Yan F, Polk DB. Probiotic bacterium prevents cytokine-induced apoptosis in intestinal epithelial cells. J Biol Chem 2002; 277(52):50959-65.
12. Can M, et al. Prophylactic Saccharomyces boulardii in the prevention of antibiotic-associated diarrhea: a prospective study. Med Sci Monit 2006;12(4):19-22.
13. Kotowska MP, et al. Saccharomyces boulardii in the prevention of antibiotic-associated diarrhoea in children: a randomized double-blind placebo-controlled trial. Aliment Pharmacol Ther 2005;21(5):583-90.
14. McFarland LV, et al. Prevention of beta-lactam-associated diarrhea by Saccharomyces boulardii compared with placebo. Am J Gastroenterol 1995;90(3):439-48.
15. Surawicz CM, et al. Prevention of antibiotic-associated diarrhea by Saccharomyces boulardii: a prospective study. Gastroenterology 1989;96(4):981-8.
16. Hawrelak JA, et al. Is Lactobacillus rhamnosus GG effective in preventing the onset of antibiotic-associated diarrhoea: a systematic review. Digestion 2005;72(1):51-6.
17. Hilton E, et al. Efficacy of Lactobacillus GG as a Diarrheal Preventive in Travelers. J Travel Med 1997;4(1):41-3.
18. Briand V, et al. Absence of efficacy of nonviable Lactobacillus acidophilus for the prevention of traveler's diarrhea: a randomized, double-blind, controlled study. Clin Infect Dis 2006;43(9):1170-5.
19. Kollaritsch H, et al. Prevention of traveler's diarrhea with Saccharomyces boulardii. Results of a placebo controlled double-blind study. [In German with English abstract.] Fortschr Med 1993;111(9):52-6.
20. Rosenfeldt V, et al. Effect of probiotic Lactobacillus strains in young children hospitalized with acute diarrhea. Pediatr Infect Dis J 2002;21(5):411-6.
21. Rosenfeldt V, et al. Effect of probiotic Lactobacillus strains on acute diarrhea in a cohort of nonhospitalized children attending day-care centers. Pediatr Infect Dis J 2002;21(5):417-9.
22. Guandalini S, et al. Lactobacillus GG administered in oral rehydration solution to children with acute diarrhea: a multicenter European trial. J Pediatr Gastroenterol Nutr 2000;30(1):54-60.
23. Salazar-Lindo E, et al. Lactobacillus casei strain GG in the treatment of infants with acute watery diarrhea: a randomized, double-blind, placebo controlled clinical trial [ISRCTN67363048]. BMC Pediatr 2004;4:18.
24. Chapman TM, et al. Spotlight on VSL#3 probiotic mixture in chronic inflammatory bowel diseases. BioDrugs 2007;21(1):61-3.
25. Bibiloni R, et al. VSL#3 probiotic-mixture induces remission in patients with active ulcerative colitis. Am J Gastroenterol 2005;100(7):1539-46.
26. Guslandi M. et al. A pilot trial of Saccharomyces boulardii in ulcerative colitis. Eur J Gastroenterol Hepatol 2003;15(6): 697-8.
27. Guslandi M. et al. Saccharomyces boulardii in maintenance treatment of Crohn's disease. Dig Dis Sci 2000;45(7):1462-4.
28. Gionchetti P, et al. Prophylaxis of pouchitis onset with probiotic therapy: a double-blind, placebo-controlled trial. Gastroenterology 2003;124(5):1202-9.
29. Gionchetti P, et al., Oral bacteriotherapy as maintenance treatment in patients with chronic pouchitis: a double-blind, placebo-controlled trial. Gastroenterology 2000;119(2):305-9.
30. Kuisma J, et al. Effect of Lactobacillus rhamnosus GG on ileal pouch inflammation and microbial flora. Aliment Pharmacol Ther 2003;17(4):509-15.
31. Niedzielin K, et al. A controlled, double-blind, randomized study on the efficacy of Lactobacillus plantarum 299V in patients with irritable bowel syndrome. Eur J Gastroenterol Hepatol 2001;13(10): 1143-7.
32. Nobaek S, 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(5):1231-8.
33. Kim HJ, et al. A randomized controlled trial of a probiotic, VSL#3, on gut transit and symptoms in diarrhoea-predominant irritable bowel syndrome. Aliment Pharmacol Ther 2003;17(7):895-904.
34. Kim HJ, et al. A randomized controlled trial of a probiotic combination VSL# 3 and placebo in irritable bowel syndrome with bloating. Neurogastroenterol Motil 2005;17(5): 687-96.
35. Newcomer AD. et al. Response of patients with irritable bowel syndrome and lactase deficiency using unfermented acidophilus milk. Am J Clin Nutr 1983;38(2): 257-63.
36. 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(4):294-301.
37. Sen S, et al. Effect of Lactobacillus plantarum 299v on colonic fermentation and symptoms of irritable bowel syndrome. Dig Dis Sci 2002;47(11):2615-20.
38. O'Mahony L. et al. Lactobacillus and bifidobacterium in irritable bowel syndrome: symptom responses and relationship to cytokine profiles. Gastroenterology 2005; 128(3):541-51.
39. Whorwell PJ, et al. Efficacy of an encapsulated probiotic Bifidobacterium infantis 35624 in women with irritable bowel syndrome. Am J Gastroenterol 2006;101(7):1581-90.
40. Quigley EM. Probiotics for the irritable bowel syndrome (IBS): A randomized, double-blind placebo controlled comparison of Lactobacillus and Bifidobacterium strains. Gastroenterology 2002;122:A59.

Natural Foods Merchandiser volume XXVIII/number 5/p.40-42

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