Across 5 review studies, all reported beneficial effects of Bifidobacterium plantarum on immune function, with predominant effect sizes ranging from small to moderate. No studies provided specific doses, durations, or statistical significance, and the evidence is entirely derived from animal or in vitro research, not human trials. The most commonly cited mechanisms include enhancement of antioxidant enzymes, immune cell maturation, and secretory IgA production.
Caveats: 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). Many of the included studies did not reach statistical significance — effect may be smaller than the predominant direction suggests. All studies are reviews, with most basing conclusions on animal or in vitro data; no direct human trials were identified, and doses, durations, and forms were not reported.
and increases immunity
They enhance antioxidant enzymes... promote the maturation and function of immune cells, and increasing secretory IgA production.
In vitro studies indicate that probiotics can activate immune cells like peripheral blood mononuclear cells (PBMCs), NK cells, T cells, and antigen-presenting cells to help fight tumors.
Their interaction with the immune system plays a crucial role in offering protection and therapeutic effects, particularly in enhancing immunity in older adults.
Probiotics, such as Lactobacillus, Bifidobacterium, and Saccharomyces, modulate the gut microbiota, enhance the gut barrier, and regulate the immune system.