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Gastrointestinal use of probiotics
Not all probiotics should be considered equally for clinical use.
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Probiotics, a term that is applied broadly by many, is defined in the medical literature as “live microorganisms administered in adequate amounts that confer a beneficial health effect on the host.”
Specific criteria must be met for a bacterial organism to be considered a probiotic: human origin, adhesion to target epithelial tissue, ability to persist in the gastrointestinal tract, ability to modulate the immune system, production of antimicrobial substances, ability to influence metabolite activities, viability in dosage forms, stability in acid and bile and nonpathogenic. Numerous bacterial organisms have been evaluated and used as probiotics. However, as will be discussed below, these bacteria do not behave equally as probiotics, and their efficacies as probiotics have varied in clinical studies. Thus, one should not consider all probiotics organisms equally for clinical use. Probiotics have been evaluated for a variety of uses in children and adults. Not all of these potential indications, however, are supported by evidence from well-done clinical trials in infants and children.
Acute infectious and antibiotic-associated diarrhea
The use of probiotics with the most evidence for effectiveness in children includes treatment of acute infectious diarrhea and antibiotic-associated diarrhea.
The benefit of probiotics in treating acute infectious diarrhea is well supported by published results of clinical studies of infants and children. Causes of diarrhea in these studies have largely been viral pathogens (eg, rotavirus) or unknown causes. Diarrhea from bacterial pathogens in children has not been well studied. Evidence for effectiveness is strongest for Lactobacillus, Bifidobacterium and the yeast organism Saccharomyces boulardii. A dose-response relationship is not well established, although some evidence indicates that doses of at least 100 billion colony-forming units (CFU) for Lactobacillus or Bifidobacterium per day are more likely to be effective. The mechanism of how probiotics exert their effectiveness has not been well characterized for every strain. Potential mechanisms of action include modification of colonic microflora and suppression of organisms, synthesis of antimicrobial substances or competition with pathogenic organisms for nutrients or intestinal binding sites. Researchers of many clinical trials have evaluated various probiotics strains for acute infectious diarrhea in young infants and older children, and most of these studies’ results have demonstrated beneficial effects.
Not all probiotic strains demonstrated equivalent effectiveness, however. Four meta-analyses evaluating many of these trials, have been published. Lactobacilli have been studied the most, and the strain Lactobacillus GG (L. GG) has demonstrated the strongest evidence for effectiveness in the treatment of acute infectious diarrhea, especially when the cause of diarrhea is rotavirus. Other Lactobacillus strains with demonstrated effectiveness include L. reuteri, L. acidophilus, L. bifidus and L. rhamnosus. The yeast S. boulardii may also be used. A benefit demonstrated in these studies was a reduction in the duration of diarrhea by 17 to 30 hours. Evidence from controlled trials also exists for demonstrating a positive effect upon reducing the need for and duration of hospitalization from diarrhea. A dose of 10 billion CFU/day for Lactobacillus species for two to five days may be used. Dosing for S. boulardii is 250 mg/day for two to five days.
Safety
Although the safety of probiotic therapy has not been systematically studied, probiotics’ use is generally believed to be associated with low risk in infants and children, including preterm infants.
As probiotics have been commonly used for many years, some epidemiologic evidence suggests that this use is safe in the general population. Many of the probiotic strains described above, including the Lactobacilli and Bifidobacteria, are commonly used in various foods given to infants and children, and this use has not demonstrated safety concerns. The most concerning potential risk associated with probiotic use is the development of bacteremia or sepsis. Several case reports of bacteremia, endocarditis, fungemia or sepsis from probiotic use in infants and children have been published. In some of these cases, molecular identification has demonstrated the same strain of organism used as the probiotic to be responsible for the resultant infection. All of the infants and children in these case reports have had a significant medical history, including short gut syndrome, recent surgery, immunosuppression or other debilitating conditions.
Probiotic products
Numerous probiotic products are available. As these products are not regulated by the FDA as are over-the-counter drug products, caregivers may be more likely to find probiotic products in health food stores. Larger health food stores may have many different products to choose from. Products may differ by the specific probiotic organisms, dosage form (eg, capsule, powder) and the number and amount of different specific organisms contained in the dosage form. Some products may contain 10 or more different species. The amount of organisms can vary as well, from 1 million to 10 billion CFU per dosage form.
As these products are not tightly regulated, the purity and content may vary considerably. Culturelle, a commonly used product, contains L. GG (10 billion CFU/capsule). Lactinex, another commonly used product, contains L. acidophilus/L. bulgaricus. Some yogurt products can be an additional source for probiotic organisms. Although yogurt products are produced from fermentation by L. bulgaricus and S. thermophilus (starter cultures), heat treatment kills all of these live cultures. Some products contain a “live active culture” seal, which indicates that refrigerated yogurt contains 100 million viable lactic acid bacteria/gram at the time of manufacture. However, this number does not differentiate between probiotic organisms from starter cultures and thus may not be indicative of an adequate amount of probiotic organisms for clinical use. A common yogurt brand, Dannon, has the “live and active cultures” seal, and the label states L. acidophilus is included. Other food sources of probiotic organisms usually contain Lactobacillus, Bifidobacterium or S. thermophilus.
Probiotics should not replace more traditional treatment strategies, such as oral rehydration therapy for diarrhea.
Caregivers who desire more “natural” treatments or caregivers who may be leery of more traditional medical treatments may be receptive to a recommendation for probiotic therapy. Children with frequent episodes of acute infectious diarrhea may also be candidates for treatment.
Additional studies evaluating probiotics for other uses have been conducted, but enough evidence is not yet available to define these roles. These uses include inflammatory bowel disease, necrotizing enterocolitis, allergic gut disorders and short gut syndrome.
Several specific probiotics have been evaluated and may be effective for acute infectious diarrhea and antibiotic-associated diarrhea. The most effective doses are not well defined. As L. GG has been frequently studied and has demonstrated efficacy, it may be reasonable to recommend this organism when a probiotic is to be used. At least one product containing L. GG is available (Culturelle), as a dose more likely to be effective. As probiotic products are not well regulated and purity and dose may vary, clinical failure of one product may not necessarily indicate that other products may not be effective.
Caregivers may ask about using probiotics long-term in otherwise healthy children to prevent gastrointestinal illness, such as diarrhea or other infections. Although researchers of several studies have evaluated the role of continuous probiotic therapy for the prevention of acute gastrointestinal or respiratory infection in otherwise healthy infants, evidence for a benefit for this use is not convincing.
For more information:
- Edward Bell, PharmD, is a Professor of Pharmacy Practice at Drake University College of Pharmacy, Blank Children’s Hospital in Des Moines, Iowa.
- Boyle RJ, Robins-Browne RM, Tang MLK. Probiotic use in clinical practice: What are the risks? Am J Clin Nutr. 2006;83:1256-1264.
- Goldin BR, Gorbach SL. Clinical indications for probiotics: an overview. Clin Infect Dis. 2008;46(Suppl 2):S96-S100.
- Lemberg DA, Ooi CY, Day AS. Probiotics in paediatric gastrointestinal diseases. J Paediatr Child Health 2007;43:331-336.
- Saavedra JM. Use of probiotics in pediatrics: rationale, mechanisms of action, and practical aspects. Nutr Clin Pract. 2007;22:351-365.
- Szajewska H, Setty M, Mrukowicz J, Guandalini S. Probiotics in gastrointestinal diseases in children: hard and not-so-hard evidence of efficacy. J Pediatr Gastroenterol Nutr. 2006;42:454-475.