Lactococcus lactis JCM 5805

Lactococcus lactis JCM 5805 (also referred to as "LC-Plasma" due to its capacity to activate plasmacytoid dendritic cells, a specialized immune cell type) has been examined in a substantial human RCT evidence base. Multiple double-blind, placebo-controlled trials in adults and athletes have examined both heat-killed and live preparations, looking at mucosal and systemic immune parameters and incidence of influenza-like illness. A 2025 multicenter RCT examined its use in mild COVID-19 cases, and observational data from schoolchildren examined respiratory infection-related absences. The strain's proposed mechanism — activation of plasmacytoid dendritic cells, a cell type involved in antiviral immune responses — has been examined in vitro and in animal models, and continues to be studied across diverse populations. These are research topics, not findings; the papers do not establish that this strain treats or prevents any condition.