Many times during a routine visit I am asked a "by the way" question. Recently I was asked what I thought about probiotics as the parents were thinking of using a probiotic as a supplement for their child. My initial answer was I didn't have enough information to make a definitive decision. After looking further, that opinion is unchanged.
Probiotics are discussed as everything from a miracle microbe to a natural remedy for ailments as variable as diarrhea to acne. There are multiple probiotic supplement types and forms. They are available in artificial powder and pill formations, and as ingredients in common foods. The differences are in the type and quantity of probiotics included in these products. The difficulty is that there is significant variability in the discussion of the recommended dose for any one probiotic, on the scale of millions to billions of units. This is a big difference! Most researchers agree that the safest forms of probiotics are obtained in fermented foods such as yogurt. But the doses available in a typical serving may not be significant for any immunologic effect.
Probiotics are touted to balance our natural sources of bacteria and to direct immune function. Multiple mechanisms of action have been proposed in an attempt to understand how this might occur. But there is not a single agreed upon explanation. In general, most agree that in a healthy individual child or adult, probiotics should not cause harm. While in an immune compromised person there can be significant danger. This is related to the fact that probiotics are bacteria or yeasts and, therefore, may contribute to infection in an already stressed body. For similar reasons, probiotics as enhanced supplements are not suggested for pregnant or breast feeding women.
Gastrointestinal disorders have been the primary focus of many of the studies involving probiotics. However, data has not been uniform enough to routinely suggest a dose or particular type of probiotic to treat a specific disorder. Also, there is not uniform standardization in the production of the supply of powder and pill form probiotics. This makes it difficult to assure exactly what an individual is getting when purchasing these category of supplements. While there is research suggesting that probiotics may have a role in both preventive and treatment based therapies, there is currently conflicting data on these supplements efficacy, dosage, and administration. This makes it tough to have an evidence based medical opinion that does not come with reservations.