Supplementation with Lactobacillus pentosus strain S-PT84 and Vitamin B Mixture Enhances Natural Killer Cell Activity in Healthy Humans

Abstract

Background: The maintenance of natural killer cell (NK) activity is critical for health, because NK cells target infected cells and cancer cells. In this study, we investigated the effect on human NK activity of supplementation with a combination of S-PT84 and vitamin B mixture (VBM: vitamin B1 (thiamin), vitamin B2 (riboflavin), and vitamin B6 (pyridoxine)). Methods: We designed randomized, placebo-controlled, double-blind, parallel-group comparative studies. In the first study, we recruited healthy middle-aged (30- to 69-year-old) subjects who had low NK activity (Study 1). Subjects received a combination of S-PT84 (1.5 × 109 cells) and VBM or placebo supplement (derived from dextrin) for 4 weeks, with a 4-week follow-up phase. In the second study, healthy middle-aged (40- to 69-year-old) subjects received a combination of S-PT84 and VBM or placebo supplement for 12 weeks (Study 2). In both studies, we measured NK activity in peripheral blood mononuclear cells using the 51Cr-release assay, and assessed safety by comprehensive analysis of blood hematology, serum biochemistry, urinalysis, and physical state. Results: In Study 1, supplementation with 1.5 × 109 cells of S-PT84 and VBM enhanced NK activity during the dosing interval; NK activity subsequently returned to baseline during the wash-out period. In Study 2, supplementation with S-PT84 and VBM enhanced NK activity during the 12 weeks of ingestion. The increase of NK activity in the placebo group (r=-0.193, p<0.01) and S-PT84-VBM group (r=-0.352, p<0.01) was inversely correlated with NK activity at baseline, respectively. Moreover, the regression coefficient of S-PT84-VBM’s regression line was smaller than that of placebo’s significantly (t=2.14, p=0.03). No adverse effects were observed in either study. Conclusions: These results suggest that daily supplementation with 1.5 × 109 cells of S-PT84 and VBM enhances NK activity in humans, even during long-term (12-week) administration. Therefore, our results indicate that S-PT84 and vitamin B supplementation may promote healthy state.