The 12-week randomised, placebo-controlled study of 101 infants aged 6–24 months found the beneficial effects were most obvious in the youngest group of infants.
Previous research suggests the colonization and dominance of Bifidobacteria and Lactobacillus in the intestine of infants delivered by C-section occurs late. This late colonisation is closely related to metabolism, immunity, intestinal diseases, allergies, neuropsychiatric growth disorders, obesity, diabetes, and other chronic diseases in adulthood.
Dysbacteriosis of the early intestinal flora in C-section babies is an important public health problem and the first two years of life are seen as a window of opportunity to compensate for early microbial imbalance, making this the opportune time for probiotic intervention.
Lactobacillus is one of the most studied probiotics with research confirming that it has multiple health benefits, such as regulating the intestinal microecology and promoting the development of the intestinal immune system.
The authors of the current study note most of the research into Lactobacillus paracasei N1115 (Lp N1115) has been conducted on animals or in adults, with fewer trials conducted on infants.
This study aimed to investigate the efficacy of Lp N1115 as a probiotic on immunomodulatory and gut microbial composition in Chinese infants and toddlers born by C-section.
This single-centre, randomised, triple-blind placebo-controlled trial and was conducted at Xuchang Maternal and Child Health Hospital, Henan Province, China, from January 2020 to April 2021. Healthy infants born by C-section were recruited at the age of 6–24 months and divided into two age groups: 6–12 months and 13–24 months.
Infants and toddlers were randomly assigned to either the experimental group (Lp N1115 group) or the placebo-control group, and a total of four main visits were conducted with an intervention duration of 12 weeks.
The collection of saliva samples was completed by doctors or nurses in the hospital on the day the subjects were recruited or followed up. Samples were analysed for cortisol, an indicator or stress.
Faecal samples were collected from infants at home by their parents or guardians during the 24 hours before the baseline and at week 4, 8, and 12. Samples were analysed for secretory IgA, which can reflect an activated immune response to chronic infections, and stool pH which can indicate digestive problems such as lactose intolerance, an infection or overgrowth of acid-producing bacteria.
Samples were also analysed for protein markers faecal calprotectin (FC) and α1-antitrypsin (AAT), which can indicate intestinal maturity in infants.
The researchers found that the stool pH of the control group increased significantly (a negative health indicator) after the intervention. Although the faecal pH of the intervention group also increased, the change was not significant.
After the intervention, the salivary cortisol of infants in the probiotic group was significantly lower than at baseline, suggesting their stress level was reduced, while the change in the control group was not significant. This decreasing trend was most obvious in infants aged 6–12 months.
The researchers found that the stool sIgA of the intervention group improved while that of the control group showed a downward trend, but statistically significant differences were only detected in the 6–12-month-old group, which may be due to factors such as weaning at 6–12 months and supplementary food, which accelerated the development of infant humoral immunity and made them more susceptible to probiotics.
In order to understand the relevant mechanisms linking changes in the bacterial flora composition and the health effects of probiotic intervention, the study attempts to analyse the relationship between the intestinal flora and biochemical indicators and diseases.
The researchers report Lp N1115 had no significant effect on calprotectin or AAT in infant faeces. However they note that Mohan et al. carried out a randomized double-blind controlled trial of Bifidobacterium lactis Bb12 in premature infants and found that after 3 weeks of intervention, the calprotectin in the probiotic group was lower, and the difference was statistically significant, suggesting that the influence of probiotics on gastrointestinal development-related indicators may be more sensitive in newborns, premature infants, or other conditions causing a high level of inflammation in the body.
The team conclude: "Lp N1115 was able to enhance the content of Lactobacillus and maintain fecal pH levels. Lp N1115 could increase fecal sIgA levels and, to some extent, reduce cortisol levels in infants and children, and its beneficial effects were more obvious in 6–12-month-old infants."
The authors note that limitations of the study include the number of uncontrolled confounding factors, including the varied diets of participants. In addition, to avoid invasive tests such as blood collection, only saliva and stool samples were collected in this study, and the biochemical indicators measured were of limited representativeness.
The report states: "This study is a preliminary exploration of the application of Lp N1115 in infants and young children, and a control group of infants delivered naturally and young children was not included in the design. The extrapolation of the results is limited, and the long-term impact of the Lp N1115 intervention cannot be obtained."
Additionally, the report notes that two of the study team were employed by Shijiazhuang Junlebao Dairy Co., Ltd. and cooperated in designing the project.
https://doi.org/10.3390/nu15081970 (registering DOI)
"Effect of Lacticaseibacillus paracasei N1115 on Immunomodulatory and Gut Microbial Composition in Young Children: A Randomized, Placebo-Controlled Study"
Li, P.; Ren, Z.; Zhou, J.; Zhao, A.; Wang, S.; Xun, Y.; Jiang, H.; Wang, P.; Yuan, Q.; Zhang, Y.