The effect of Bifidobacterium lactis on the growth of infants: a pooled analysis of randomized controlled studies.

Background/aims: Breast milk is the best source of nutrition for the growth of the newborn infant. It is therefore essential that mothers who cannot breastfeed or choose not to are provided with alternatives that closely match the composition and functionality of breast milk. This study aimed to investigate the growth effects of probiotic-supplemented formulas on both healthy and vulnerable populations of infants.

Methods: A meta-analysis of data from 5 randomized controlled clinical trials that included infants fed formulas containing a probiotic Bifidobacterium lactis CNCM I-3446 was performed (n = 525). A sub-analysis was performed among infants of HIV-positive mothers (n = 120). Growth measurements (gain in weight and body mass index, BMI, from enrollment to 120 days) were compared between infants fed a formula containing B. lactis and those fed a control formula. Changes in length and Z-scores were also compared.

Results: Formula with B.lactis was demonstrated to be at least as good as formula without B. lactis in the meta-analysis of 5 studies. The lower boundary of the 95% confidence interval (CI) of the differences in mean weight gain (95% CI 0.09-2.93 g/day) was above the predefined non-inferiority margin of -3.0 g/day. Moreover, among infants with HIV-positive mothers, weight gain of those taking B. lactis was significantly higher than of those not taking B. lactis, by 3.1 g/day (95% CI 0.4-5.8 g/day, p = 0.0226) and the BMI gains were significantly higher, by 6.4 g/m(2)/day (95% CI 0.0.3-12.5 g/m(2)/day, p = 0.0400). The corresponding weight for age and BMI Z-scores were also significantly higher, by 0.37 (95% CI 0.03-0.71, p = 0.0308) and by 0.42 (95% CI 0.02-0.83, p = 0.0377), respectively, whereas differences in length gain or length-for-age Z-score were not significant. Among infants in the non-HIV mothers group, there were no significant differences between infants fed formulas with or without B. lactis, for any of the growth parameters.

Conclusions: The analysis suggests that B. lactis may have a positive effect on growth in vulnerable populations, specifically in infants born to mothers with HIV.