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

Consumption of some species and strains of lactic acid bacteria (LAB) has been shown to enhance immunity in humans. In this study, the effect of dietary supplementation with Lactobacillus rhamnosus HN001 (DR20™), a newly characterized LAB strain, on immune cell function in healthy elderly subjects 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 milk (LFM, 200 mL twice daily) as a base diet. In Stage 2 (supplement intervention), subjects received LFM supplemented with L. rhamnosus HN001 (1.25 × 108 CFU/mL). Assessment of immune function was made at the beginning, and 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-supplemented milk. This suggests that L. rhamnosus HN001 is able to enhance aspects of natural immunity in humans, and could be used as a dietary adjunct for optimizing immune responsiveness in the elderly.