Should long-term prophylactic use of probiotics for infants and young children give cause for concern?

Abstract

In the past decade, several probiotic strains have been investigated for health benefit effects and Lactobacillus rhamnosus GG (LGG) has been one of the most studied probiotic strains. Short-term beneficial effects on viral infectious diarrhoea have been reported in a number of studies, but a prophylactic effect on diarrhoea has not been documented. Furthermore, while some studies have reported a prophylactic, or even a curative, effect of LGG on atopic eczema in young children, more recent studies have not confirmed these findings. Quite the contrary, an increased incidence of allergic sensitization has been reported among children receiving LGG-supplemented infant formula feed at an early age. To date, there is thus no certain documented prophylactic effect of LGG on any medical condition in children. When used as a supplement in infant formula and baby foods, LGG is intended for long-term daily use in children as opposed to a short-term, specific, treatment. Furthermore, the targeted consumer group includes children below the age of 12 months. These two aspects demand particular consideration with regard to the lack of knowledge of the effects of long-term treatment with large doses of live bacteria both on the ecology of the microbiota of the gastrointestinal tract and on its immunomodulating properties. Neither of these systems is fully matured in infants and small children, and may therefore be particularly vulnerable. Probiotics may also alter intestinal metabolism due to their enzymatic activities, transfer genes coding for resistance to antimicrobials and have other adjuvant effects of which we yet know very little. In conclusion, we consider that there is insufficient scientific knowledge to support manipulation of the immune system in a predictable manner by administration of probiotics to young children. Manipulation at an early age is of particular concern, as the effects may be non-reversible. Key words: probiotics, diarrhoea, infant formula, baby foods, Lactobacillus rhamnosus GG, microbiota, atopic eczema, allergic sensitization