Research synthesisLow evidenceModerate effect4 studies · 3 beneficial · 1 neutral · 0 harmful
Across 4 studies, 3 reported beneficial effects of *Bifidobacterium longum* SP54 supplementation for reducing gestational diabetes mellitus (GDM) incidence, with a 2024 meta-analysis of 14 RCTs finding a significant moderate reduction (RR: 0.71, 95% CI: 0.52–0.96). However, the highest-quality individual RCT (n=271) found a neutral, non-significant effect (41.9% vs. 40.2%, P=0.78), and dose, duration, and form were not consistently reported across studies. The predominant effect size among beneficial studies was moderate, but the evidence is limited by the small number of available studies.
- Studied populations: pregnant women at risk for gestational diabetes mellitus
Caveats: Evidence base is small (only 4 studies), and the sole high-quality RCT showed a neutral effect — the positive signal comes largely from a meta-analysis that included other probiotic strains. Many of the included studies did not reach statistical significance; effect may be smaller than the predominant direction suggests. Available evidence is overwhelmingly positive — clinical literature in this area is subject to publication bias (null-result studies are less likely to be published or indexed).
Generated Jun 11, 2026