Probiotics: hype or helpful?

December 1, 2008

This review will present an objective summary of what is known about probiotics, and outline safety considerations and recommendations for use.

"Doctor, will probiotics help my son's eczema?" Insert any other medical condition, and you have a question that many pediatricians and family practitioners have been facing in recent years, due to the skyrocketing interest in probiotics.

Truth be told, most physicians feel less than comfortable giving straight answers to questions on probiotics, because we simply don't know enough about them. Therefore, in this review we will: 1) define what probiotics are, 2) present an objective summary of available evidence and what is "known" about probiotics in different disease states that pertain to pediatrics, 3) discuss the safety of probiotics, and 4) outline recommendations for use based on our own practice patterns.

Readers should keep in mind that these recommendations are not formal recommendations. They are rather guidelines for practitioners faced with parents who are interested in giving probiotics and seeking advice.

Probiotics are defined as "live microorganisms which when administered in adequate amounts confer a health benefit on the host."1 In the early 20th century, Russian scientist and Nobel laureate Eli Metchnikoff, PhD, first introduced the concept of replacing harmful microbes in the body by ingesting certain bacteria. While he and several other scientists supported the consumption of sour milk containing the bacteria, the use of probiotics did not become popular in the US until the last five to 10 years.

A simple search of online medical databases reflects this trend. In 1996, the total number of articles indexed in Medline containing the word probiotic(s) was 30: three of these were randomized clinical trials. In 2005, the total number of articles jumped to 565, with 66 randomized controlled trials.2 In our personal searches this year for probiotic-related articles, we have typically found around 30 new papers per week on PubMed.

Areas of clinical benefit

In the following section, we will present disease states seen in general pediatrics where probiotics have been studied, and where they have the strongest evidence of benefit. The majority of these recommendations come from the clinical practice guideline from the North American and European Pediatric Gastroenterology, Hepatology, and Nutrition Medical Position reports and the Cochrane Collaboration.3-5 These sources have included very strict criteria for evaluation and inclusion of published studies into their analyses. While their recommendations are stringently evidence-based, the field is full of other studies of different organisms and doses that may not have been included, because they were not optimally designed or were statistically underpowered. These studies may also be helpful in formulating future studies that are better designed, with more solid recommendations.

Antibiotic-associated diarrhea

Antibiotic-associated diarrhea (AAD) is a common side effect of antibiotic administration. AAD occurs when antibiotics disturb the balance of the normal microflora of the gastrointestinal tract, resulting in frequent, watery bowel movements. In some cases, inflammation of the colon during this type of reaction can lead to colitis. In Clostridium difficile (C difficile) infection, pseudomembranous colitis with bloody diarrhea can occur.