Probiotics for Infants: Safety, doses and strains

Safety is paramount when practitioners consider infant and child health - always front of mind is to “first do no harm”. As gut and immune health are often at the core of infant care, it’s not surprising that probiotics have been in the firing line as a questionable intervention for little ones. Practitioners are left with a myriad of myths, particularly when prescribing and dosing probiotic strains.

The infant gastrointestinal system is primarily colonised by bifidobacteria, leading to a belief that other strains are potentially harmful. It is often advised that probiotics should be kept to very low doses in infants. However, a surprising new study debunks long-held beliefs regarding probiotic dosage in infants, giving peace of mind to practitioners whilst paving the way for greater application of strains at higher strength doses in children up to two years of age.

This new research is featured in the journal Beneficial Microbes 2014. Researchers reviewed 57 trials, using 53 probiotic strains in various dosages as a health intervention in newborns to two year olds. Collectively this research involved more than 10,000 infants and included high dose trials. What is even more unique about this review is that adverse events (AE) were the main focus, rather than just the clinical outcomes and efficacy of probiotic strains. AE’s highlight any potential contraindications or precautions for practitioners when prescribing.

The infants trialled were grouped into healthy, preterm, those suffering from gastrointestinal disorders such as diarrhoea and constipation; and those suffering from inflammatory conditions such as dermatitis, eczema and cow’s milk allergy. Of the 53 probiotic strains administered almost 50% of the strains used were from the Lactobacillus genus in addition to beneficial probiotic strains including L. rhamnosus GG, B. breve M-16V, B. lactis HN019, L. rhamnosus HN001, B. infantis M-63 and B. longum BB536.

The review found the highest daily dosage given to infants with diarrhoea was between 20 million and 2 trillion CFU with the lowest daily dosage of 7 million CFU given to preterm babies. All formula-fed infants received 10 billion CFU every day.

Contrary to popular belief, despite the high dosed strengths very few AEs were reported in the studies on infants with diarrhoea. Some of these infants received a strain of L. rhamnosus at a dose of 2 trillion CFU daily with no AEs, showing that even at a very high dose L. rhamnosus is safe. The authors concluded that administration of all of the strains trialled is safe for all groups with most AEs that did occur were considered unrelated to the probiotic.

Reflective of the long-term use of probiotics, the review included follow-up studies, and they showed there are no long-term AEs for any of the strains regardless of dose. In fact, there were some positive long-term effects reported. Infants receiving B. breve M-16V had fewer asthma-like symptoms than placebo, while other strains provided increased resistance to respiratory infections.

While not the aim of the review, it did emphasise the efficacy of probiotics in increasing stool frequency, softening stools and reducing diarrhoea. In contrast, the control group experienced 86 more infections and infestations. This is consistent with reports in other studies indicating that probiotics reduce the incidence of infection.

Reference:
Van den Nieuboer, M, Classen, E, Morelli, L, Guarner, F & Brummer, RJ, 2014, ‘Probiotic and symbiotic safety in infants under two years of age’, Beneficial Microbes, vol. 5, no. 3, pp.45-60.

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