The Immune-Boosting Potential of Lacticaseibacillus paracasei HY7017 in Adults with Suboptimal Immune Function: A Double-Blind, Randomized, Placebo-Controlled, Clinical Trial

The human immune system is a complex defense mechanism against exogenous pathogens, and optimizing its function is vital for maintaining health. Previous studies have shown that specific probiotics can enhance immune function through mechanisms involving the activation of natural killer (NK) cells and modulation of cytokines such as interferon-γ (IFN-γ) and interleukin-12 (IL-12), which are critical for innate immune responses. In this study, we conducted a clinical trial to investigate the immune effects of Lacticaseibacillus paracasei ( Lcb. paracasei ) HY7017. Eighty participants suspected of having reduced immune function were randomized into two groups: the Lcb. paracasei HY7017 supplemented group and the control group. Participants in the HY7017 group consumed one capsule daily containing 5.0 × 10 9 Colony Forming Unit (CFU) of Lcb. paracasei HY7017, while the placebo group received identical capsules without live bacteria. After 8 weeks of consumption, NK cell activity was significantly higher in the HY7017 group compared with the control group. In addition, IFN-γ levels were considerably elevated in the HY7017 group at both 4 and 8 weeks, and an increase in IL-12 was observed after 8 weeks. No clinically notable differences in adverse events were observed between the two groups. As NK cells and cytokines are key immunomodulators, the observed increases in these biofactors support the immune-enhancing potential of Lcb. paracasei HY7017. These findings support the potential of Lcb. paracasei HY7017 as a functional health food ingredient for immune enhancement.