Immunomodulatory effects of supercritical CO₂ extracted oils from Portulaca oleracea and Perilla frutescens (PPCE) in healthy individuals: a randomized double-blind clinical trial

The human immune system plays a crucial role in defending the body against various infections, viruses, and external substances, contributing to overall well-being. However, an imbalance in the immune system can lead to increased susceptibility to infections, impacting overall health. Preclinical investigations suggest the potential application of Portulaca oleracea L. and Perilla frutescens var. japonica Hara seed complex extract (PPCE) as a potent biological response modifier in terms of immunity. However, the safety and efficacy of PPCE in boosting immune function have not been investigated clinically. The present study aims to evaluate the safety and efficacy of PPCE on the immune system in healthy adults. An 8-week randomized, double-blinded, placebo-controlled cross-over clinical trial was adopted for the study. Study participants were administered either 1080 mg day⁻¹ of a PPCE supplement or a placebo. The study assessed the Natural Killer (NK) cell activity as the primary outcome measure. Serum concentrations of cytokines (IL-6, IL-12, IFN-γ, TNF-α) and a questionnaire-based assessment of upper airway infection were the secondary outcomes. At the end of the 8 weeks, NK cell activity significantly improved in the PPCE group compared to the placebo group (p < 0.05). Similarly, the concentrations of IFN-γ and IL-12 significantly increased (p < 0.05). However, there were no significant differences between the two groups in the cytokines IL-6 and TNF-α. Additionally, no adverse effects were observed during the trial. These findings suggest that PPCE supplementation is safe and potentially benefits immune stimulation by enhancing NK cell activity and inducing the production of Th-1 type cell-stimulating cytokines like IL-12 in healthy individuals.