Strep Thermophilus in Baby Formula: Is It Safe?

Key Findings

The study found that infant formulas (IF) containing postbiotics, including Streptococcus thermophilus (ST) and Bifidobacterium breve C50 (BB), were safe and well tolerated by infants who cannot be breastfed. However, no consistent clinical benefits were observed across trials, and the addition of other modifications (e.g., prebiotics, modified milk fat) did not demonstrate reproducible advantages. Limited data on Lactobacillus paracasei CBA L74-fermented formulas were also noted, but conclusions could not be drawn due to insufficient evidence.

Study Design

This systematic review analyzed 11 randomized controlled trials (RCTs) up to December 2021, using the Cochrane Risk of Bias Tool 2 to assess methodological quality. Trials evaluated IF fermented with BB/ST alone or combined with prebiotics, modified milk fat, or antiregurgitation agents. The review focused on safety (primary outcome) and health effects (e.g., gastrointestinal tolerance, immune markers). Sample sizes and infant demographics (e.g., age, health status) were not detailed in the provided summary, but the target population was infants unable to receive breast milk.

Dosage & Administration

The postbiotic formulas tested included inanimate microorganisms (B. breve C50 and S. thermophilus) derived from fermented milk. Specific dosages of ST were not reported in the summary, but administration occurred via standard infant feeding protocols (oral consumption). Some formulas combined BB/ST with prebiotics (e.g., galacto-oligosaccharides) or other modifications, though dosing regimens for these additives were also unspecified.

Results & Efficacy

Safety was the primary outcome: BB/ST-fermented IF showed no adverse effects in included trials. For secondary outcomes (e.g., stool consistency, infection rates, growth parameters), no significant or consistently replicated benefits were observed. For example, partly fermented BB/ST formulas with prebiotics did not demonstrate statistically significant improvements in gastrointestinal health or immune function compared to standard IF. The review noted heterogeneity in study designs, limiting pooled efficacy analysis. No p-values, confidence intervals, or effect sizes were reported in the provided summary.

Limitations

1. Risk of Bias: Five trials had high overall bias risk, and six had "some concerns" based on Cochrane criteria.
2. Heterogeneity: Formulas varied in postbiotic strains, fermentation processes, and additional modifications (e.g., prebiotics), complicating comparisons.
3. Limited Data: Only one trial evaluated L. paracasei CBA L74-fermented IF, and few studies reported long-term health outcomes.
4. Industry Funding: Some trials were sponsored by formula manufacturers, potentially influencing results.
5. Lack of Quantitative Data: The summary did not provide specific effect sizes or statistical metrics for efficacy outcomes.

Clinical Relevance

Infant formulas with BB/ST postbiotics appear safe for healthy infants unable to breastfeed, but current evidence does not support definitive clinical advantages over standard IF. Parents and healthcare providers should weigh potential costs of specialized formulas against uncertain benefits. The authors recommend discussing individual needs with medical professionals to determine whether postbiotic-modified formulas are justified. Future research should prioritize standardized dosing, long-term efficacy endpoints, and independent funding to validate findings.