The effect of probiotics, parabiotics, synbiotics, fermented foods and other microbial forms on immunoglobulin production: a systematic review and meta-analysis of clinical trials

Study answer

What this study found

Pooled microbial supplementation produced a small increase in salivary IgA secretion rate, but most other immunoglobulin outcomes were not significantly changed. Salivary IgA secretion rate improved in 8 studies (N=452; SMD 0.21, 95% CI 0.02 to 0.39; p=0.03), but the effect was no longer significant after excluding inactivated probiotic studies (SMD 0.16, 95% CI -0.11 to 0.44). No significant effects were seen for salivary IgA concentration (N=1651; SMD 0.11, 95% CI -0.02 to 0.24), IgE, Japanese cedar pollen-specific IgE, IgG, or IgM; serum IgA was significant only when healthy and ill…

Study & population

Systematic review and meta-analysis of adult clinical trials in participants older than 18 years.

Intervention

Clinical trials of oral microbial-form interventions, including probiotics, parabiotics, synbiotics, fermented foods, and other microbial forms, were pooled across studies.

Key limitation

Findings were driven by heterogeneous interventions, populations, and outcome definitions, with several analyses showing substantial heterogeneity.

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Original abstract