RCT: Probiotics well tolerated and promote healthy gut flora in infants

By Olivia Brown

- Last updated on GMT


Related tags Probiotic Bacteria Lactobacillus Gut health infant microbiome

A new RCT observes an increased abundance of Bacteriodes and Lactobacillus genus following a four month intake period with L. salivarius (AP-32) and B. animalis (CP-9) probiotics respectively, in infants aged four days to two months old.

Both probiotic treatments were found to be well tolerated and safe for usage over this period, with no differences in digestive tolerance, occurrence of adverse events, or crying/fussing time when compared to the placebo group.

The Taiwanese researchers emphasised: “Our study findings indicate that the oral administration of both AP-32 and CP-9 strains has a positive impact on the maintenance of a healthy gut flora in infants.

“Long-term use of L. salivarius AP-32 or B. animalis CP-9 is safe for infants from 7 days to 6 months of age,” they concluded.

Probiotics for infants

The benefits of probiotics for health have been widely documented over recent years, with intakes being associated with improved gastrointestinal health to infectious disease prevention. Research​ has also suggested the importance of a healthy microbiome at early age in determining long-term health outcomes in later life.

Yet, determining the safety of different bacterial strains for consumption by infants is essential, due to the immature microbiome being vulnerable to gastrointestinal problems before six months of age.

Specific strains have been identified​ as safe for use within food and infant formula, such as essential breast milk-derived microbes including Lactobaccillus ​and Bifidobacterium ​which have been identified to make up 30% of all bacteria in the infant’s gut.

Whilst these strains have demonstrated​ multiple benefits to inflammatory responses, mitochondrial function, and microbiota composition in animal and adult human samples, their safe usage still needs to be determined in infants.

Thus, the present RCT was conducted to evaluate the long-term safety and effectiveness of probiotics within a healthy infant population to advance this area of research.

Study specifics

The randomised, double-blind study was a three-armed trial. The researchers utilised 88 infants aged between seven days and two months for the blinded treatment and were randomised to receive either L. salivarius AP-32, B. animalis CP-9, ​or a placebo over a four-month period. A further 76 unblinded infants were randomised into the same treatment groups.

Within the three groups, one capsule mixed in infant formula, breast milk, or water was given twice daily over the experimental period. The placebo tablets contained maltodextrin, whilst the probiotic tablets contained L. salivarius​ AP-32 (2.5 × 109 cfu) or B. animalis​ CP-9 (2.5 × 109 cfu).

It was reported that there was no significant difference in weight gain at four months across the different groups, as well as head circumference or recumbent length.

With regards to safety outcomes, it was reported that there were no differences in digestive tolerance, occurrence of adverse events, or crying/fussing time.

In addition, the CP-9 treated group showed a significant increase in the abundance of Bacteriodes ​genus, whilst the AP-32 group had a significant increase in the presence of Lactobacillus ​genus compared to the further two treatment groups.


The report emphasised: “The findings from this study suggest that the daily long-term oral administration of L. salivarius AP-32 or B. animalis CP-9 in infants aged 7 days to 6 months is safe, as no safety concerns were identified.”

Specifically, within the AP-9 group, the resultant higher Firmicute/Bacteroide ratio has been associated with an improved nutrient utilisation, suggesting the potential health benefits of supplementation within infants.

With regards to the increased Bacteroides ​genus identified in the CP-9 treated group, the researchers hypothesise that there was a symbiotic association with Bifidobacterium ​species.

The researchers urged further research to investigate the potential health benefits associated with probiotic consumption in the infants, following the increased abundance of positive bacterial species.




Source: Nutrients


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“A Three-Arm, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Safety of Lactobacillus salivarius AP-32 and Bifidobacterium animalis CP-9 Used Individually in Healthy Infants”

by Jui-Fen Chen, Mei-Chen Ou-Yang, Ko-Chiang Hsia, Ching-Min Li, Yao-Tsung Yeh, and Hsieh-Hsun Ho

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