Clinical Report: Probiotics and Prebiotics in Pediatrics

Editor's Note:

The American Academy of Pediatrics (AAP) recently issued an extensive Clinical Report: Probiotics and Prebiotics in Pediatrics authored by Dan W. Thomas, MD, Frank R. Greer, MD, and the Committee on Nutrition and the Section on Gastroenterology, Hepatology, and Nutrition. Medscape asked Dr. Thomas, a pediatric gastroenterologist with Children's Hospital Los Angeles, to discuss the implications of this information for primary care pediatric providers. Dr. Thomas has served as a pediatric gastroenterologist at Children's Hospital for more than 30 years treating patients and also participating in clinical research. Dr. Thomas is board certified in Pediatric Gastroenterology and Pediatric Transplant Hepatology, and is a member of the American Gastroenterological Association; North American Society for Pediatric Gastroenterology, Hepatology and Nutrition; and the Society for Pediatric Research, American Academy of Pediatrics (AAP).

The Evidence for Use of Probiotics in Children

Medscape: Dr. Thomas, can you share with us some background about this report?

Dan W. Thomas, MD: The decision to examine the issue of the medical uses of probiotics and prebiotics was the result of recognition of a growing number of products, as well as increased use of these agents by a broad segment of the population. The report attempted to summarize the evidence about the health benefits of these products and dietary supplements added to food products marketed to children, including infant formula. Additionally, we examined the role of these agents in the potential treatment of gastrointestinal (GI) and non-GI disease. Review of the report and comments were solicited from the committees and sections of the AAP. Additionally, representatives from the Centers for Disease Control and Prevention (CDC), National Institutes of Health (NIH), US Food and Drug Administration (FDA), US Department of Agriculture, and the Canadian Paediatric Society participated in the report's development. A complete list of participants is included in the report.

Medscape: The clinical report includes definitions of a number of terms. However, it appears that the most relevant of these agents are probiotics and prebiotics. Can you discuss some of the data regarding use of these agents by children?

Dr. Thomas: Prebiotics are supplements or foods that contain viable microorganisms that cause alterations in the microflora of the host and stimulate favorable growth of probiotic bacteria. Human milk contains substantial quantities of prebiotics, and prebiotics and probiotics have also recently been added to infant formulas. Human milk and formula therefore are examples of functional foods -- a modified food that provides a health benefit that cannot be attributed to the nutrients in that food (see the Table for terms). The most studied probiotic bacteria to date include Lactobacillus rhamnosus GG (LGG), Bifidobacterium lactis, and Streptococcus thermophilus. Live yogurt, which contains probiotics, is the most common example of a functional food. The list of products containing probiotics is rapidly expanding and clinicians can access the most up-to-date information at www.usprobiotics.org. It should be noted that this is an industry-maintained Website.

Table. Definitions of Agents

Probiotic	A supplement or food containing a sufficient number of viable microorganisms to alter microflora and has the potential for health benefit
Prebiotic	A nondigestible food ingredient that selectively stimulates favorable growth and/or activity of 1 or more indigenous probiotic bacteria
Synbiotic	A product containing both probiotics and prebiotics. Synergy of a specific probiotic for a probiotic in the product is not essential. May be separate supplements or added to food
Postbiotic	A metabolic byproduct generated by a probiotic microorganism that influences biologic functions
Functional food	Any modified food that provides a health benefit beyond that ascribed to any specific nutrients it contains

Medscape: What is the mechanism of action of these agents?

Dr. Thomas: At birth, infants have a sterile GI tract, but bacterial colonization occurs rapidly with different organisms predominating in formula-fed and breast-fed infants. In resource-rich countries such as the United States, those differences are not as pronounced. In healthy persons, the composition of intestinal microflora does not usually change significantly after infancy. The acquisition of these microflora contributes to the intestinal mucosal defense system, which is an integral part of the body's sophisticated immunoregulatory network. The immunoresponsiveness of the GI defense system is affected by an infant's diet, bacterial colonization, and early exposure to infectious pathogens and antibiotics. The development of a number of allergic conditions, such as eczema, and autoimmune conditions, like diabetes or inflammatory bowel disease, may be affected by dysregulation or interference with the early development of the intestinal mucosal defense system. The infant's early diet and intestinal microbes are likely to play a pivotal role in overall health. Probiotics and dietary prebiotics likely exert positive effects on the development of the mucosal immune system.

Medscape: Can you summarize the report's conclusions regarding the overall safety of these agents?

Dr. Thomas: While there have been anecdotal reports of serious infection, including sepsis, with use of these products, most of those cases occurred in ill, pre-term infants and older immunocompromised children or those with indwelling medical devices. Studies in healthy infants and children have found the agents to be both safe and well tolerated. In the United States, products marketed as dietary supplements, such as probiotics, do not require approval by the FDA. Infant formulas, however, must be made in compliance with manufacturing practices regulated by the Infant Formula Act of 1980 and are under the auspices of the FDA. All ingredients in infant formula must be in accordance with FDA food-additive regulations that require that they be generally regarded as safe (GRAS). Prebiotics and probiotics added to infant formulas in the US are classified as GRAS. Other organizations, including the Committee on Nutrition of the European Society of Pediatric Gastroenterology, Hepatology and Nutrition and the Food and Agriculture Organization of the United Nations World Health Organization, while acknowledging the safety of probiotics in general, have recommended centralized product oversight and monitoring. It should be emphasized that while these products are generally recognized as safe, evidence of their overall efficacy has yet to be established and human milk remains the best food for young infants. There is no evidence that would support a recommendation of infant formula supplemented with probiotics in place of human milk.

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