Probiotic supplementation to enhance natural immunity in the elderly: effects of a newly characterized immunostimulatory strain Lactobacillus rhamnosus HN001 (DR20 (TM)) on leucocyte phagocytosis

Consumption of some species and strains of lactic acid bacteria (LAB) has b een shown to enhance immunity in humans. In this study, the effect of dieta ry supplementation with Lactobacillus rhamnosus HN001 (DR20(TM)), a newly c haracterized LAB strain, on immune cell function in healthy elderly subject s was investigated. The study comprised three stages, each lasting 3 weeks. In stages 1 (run-in) and 3 (washout), subjects (n = 13) received low fat m ilk (LFM, 200 mt twice daily) as a base diet. In Stage 2 (supplement interv ention), subjects received LFM supplemented with L. rhamnosus HN001 (1.25 X 10(8) CFU/mL). Assessment of immune function was made at the beginning, an d the end of each stage. Consumption of milk supplemented with L, rhamnosus HN001 for three weeks resulted in a significant increase in the phagocytic activity of peripheral blood polymorphonuclear cells and monocytes. These responses returned to baseline following 3 weeks washout with un-supplement ed milk. This suggests that L. rhamnosus HN001 is able to enhance aspects o f natural immunity in humans, and could be used as a dietary adjunct for op timizing immune responsiveness in the elderly. (C) 2001 Elsevier Science In c. All rights reserved.