Compared to those fed with regular infant formula, those who were fed with synbiotics had a higher level of Bifidobacterium in their gut, fewer pathogens such as C. difficile, as well as a lower fecal pH – signs which resemble the gut environment of healthy breastfed infants.
Writing in Scientific Reports, the researchers said the results showed that the synbiotic infant formula could “create a homeostatic beneficial microbial community and thus improves gut microbiota resilience.”
The RCT, which took place in Thailand, was an eight-week study consisting of a six-week intervention period followed by a two-week washout period.
A total of 239 healthy infants aged six to 19 weeks completed the study.
During the study, they were randomised into three groups.
One took a control infant formula while the other two groups took an infant formula containing prebiotic short-chain Galacto-oligosaccharides/ long-chain Fructo-oligosaccharides (scGOS/lcFOS) and probiotic Bifidobacterium breve M-16V at a ratio of 1:9.
The difference between the two groups taking the synbiotic formula lies in the CFU count of the probiotic. One group took Bifidobacterium breve M-16V at 1 x 104 cfu/ml, while the other took a higher count of Bifidobacterium breve M-16V at 1 x 104 cfu/ml.
Their stool samples were collected at before the intervention, after the intervention is over, and after the wash-out period is over.
The researchers then compared their gut microbiome with that of another 42 infants who were exclusively breastfed.
Both groups which took the synbiotic formula saw significantly increased Bifidobacterium as compared to the control group.
“This unique synbiotic increased the prevalence of B. breve and B. breve M-16V in the infants’ gut. It is interesting to note that these effects sustained after 2 weeks wash-out period,” said the researchers.
The researchers added that the formula had helped infants acquire infant-type Bifidobacterium species and enrich bifidobacteria abundance.
The findings resemble that of a previous study published in 2017, where the use of the same symbiotic combination led to an increased prevalence of B. breve, B. bifidum and B. longum, but had no effect on B. catenulatum.
Intake of the synbiotics formula also decreased the prevalence and abundance of C. difficile – a pathogen that can cause severe diarrhoea and colon inflammation.
Notably, this is the first study to demonstrate that this particular synbiotics could reduce C. difficile levels, the researchers pointed out.
They added that not all probiotics from the Bifidobacterium species could lead to pathogen reduction.
Citing a study published in 2016, the researchers said that an in-vitro study showed that B. breve or B. longum combined with scFOS had reduced C. difficile growth and toxicity.
However, an opposite effect was observed for B. animalis subsp. lactis Bb12.
The reduction in pathogen is an important finding, as reducing potential pathogens could be a key step towards reducing infections in early life, said the researchers.
“Reduction of C. diffficile abundance as well as the reduction trend of C. perfringens, EPEC and EAEC, suggests that this specific synbiotic mixture may be able to protect infants against C. difficile infections and other gastrointestinal infectious diseases during early life.”
Fecal pH decreased
The fecal pH in the groups which took synbiotic formula had dropped from baseline, resembling that of exclusively breastfed infants.
The fecal pH of exclusively breastfed infants were consistently low, while that of the control group was higher and remained at about the same levels throughout the study.
As for the two groups which took the synbiotic formula, their fecal pH dropped by week six but rebound after the two-week washout period was over.
This is because the synbiotic formula promoted an acidic environment by increasing the production of acetate and lactate, which is similar to the gut environment of healthy breastfed infants, the researchers explained.
There was no difference in stool frequency between the three groups, but infants fed with the synbiotic formula had softer stools by the end of the intervention.
Existing studies show that constipation or hard stools are more common among formula-fed infants than breast-fed infants.
“The facts that this specific synbiotic mixture reduced potential pathogens and increased bifidobacteria proportions as well as the prevalence of B. breve implies that this synbiotic mixture creates a homeostatic beneficial microbial community and thus improves gut microbiota resilience.
“The resilience of a healthy microbiota further protects infants from dysbiosis-related diseases such as allergy and infections,” the researchers concluded.
Source: Scientific Reports
Impact of synbiotics on gut microbiota during early life: a randomized, double-blind study
Authors: Phavichitr, Nopaorn et al