Bifidobacterium lactis supplementation in preterm infants across four trials
What it found
In 324 preterm infants, Bifidobacterium lactis raised levels of helpful gut bacteria and changed stool chemistry.
It did not clearly change the risk of serious gut disease or blood infections.
What they found
Studies in people
Gut bacteria counts
Babies given the probiotic had higher counts of bifidobacteria in their stools after 7 days. They also had lower counts of Enterobacteriaceae and Clostridium species compared with babies who did not get it.
Stool chemistry changes
The probiotic group had lower stool pH and lower levels of calprotectin, a marker of gut inflammation. Their stools also contained more immunoglobulin A and more short-chain fatty acids, including 42% more acetate.
Gut barrier function
After 30 days, babies receiving the probiotic had a lower ratio on a test that measures how easily molecules pass through the gut wall. This suggests the gut lining was less leaky than in the control group.
Serious gut disease
Three trials involving 293 infants looked at necrotizing enterocolitis, a severe gut condition. The authors say these studies were too small to show whether the probiotic lowered the risk.
Growth and head size
Weight gain and length gain were similar between groups. However, one trial found that head circumference grew faster in babies who received the probiotic.
Reported adverse events
None of the four trials reported any adverse events linked to the probiotic. In one trial, no blood cultures grew the probiotic strain.
What the authors conclude
- They describe the evidence for using this probiotic in preterm infants as encouraging but not yet fully convincing.
- They call for larger trials designed specifically to see if it lowers the risk of severe gut disease.
- They advise that future studies should define the best dose and how long babies should take it.
How it was done
Preterm babies often develop different gut bacteria than full-term babies, which might raise their risk of gut disease and infections. The authors wanted to see if one specific strain, Bifidobacterium animalis subsp lactis CNCM I-3446, could help.
They combined results from four randomised trials involving 324 preterm infants born before 37 weeks or weighing under 2500 g. The babies received the probiotic added to formula or human milk for 3 to 6 weeks at doses ranging from 2×10^7 to 6×10^9 colony-forming units per day.
What it can’t tell you
- These trials were very small, so they cannot prove whether the probiotic prevents serious gut disease or blood infections.
- The studies only looked at preterm infants in hospital settings, so the results may not apply to healthy full-term babies or older children.
Who paid
- Funding
- Funded by NIDDK NIH HHS (from the PubMed record).
- Authors work at
- Medical University of Warsaw, Poland
The paper
- Title
- Effect of Bifidobacterium animalis subsp lactis supplementation in preterm infants: a systematic review of randomized controlled trials
- Type
- Systematic review and meta-analysisThe authors follow a set, published method to find every relevant study, then combine the numbers from them into one result.
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Szajewska H, Guandalini S, Morelli L, Van Goudoever JB, Walker A (2010). Effect of Bifidobacterium animalis subsp lactis supplementation in preterm infants: a systematic review of randomized controlled trials. Journal of pediatric gastroenterology and nutrition. doi:10.1097/MPG.0b013e3181dc0d93Free full textPubMed 20543719DOI
Summary written 1 Oct 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error