Enhancement of natural immune function by dietary consumption of Bifidobacterium lactis (HN019).

To determine the effects of dietary consumption of Bifidobacterium lactis (strain HN019, DR10TM) on natural immunity. A randomized, double blind, placebo-controlled clinical trial. Janeway Medical Centre, Memorial University, St Johns, Newfoundland. Twenty-five healthy elderly volunteers (median age 69 y; range 60-83 y). Twelve control subjects consumed 180 ml low-fat/low-lactose milk twice daily for a period of 6 weeks; 13 test subjects consumed milk supplemented with 1.5x1011 colony-forming units of B. lactis twice daily. Indices of natural immunity, including interferon production, phagocytic capacity and phagocyte-mediated bactericidal activity, were determined via peripheral blood at 0, 3, 6 and 12 weeks post-trial commencement. Subjects who consumed milk containing B. lactis for 6 weeks produced significantly enhanced levels of interferon-alpha, upon stimulation of their peripheral blood mononuclear cells in culture, in comparison to the placebo control group who received milk alone. There were also significant increases in polymorphonuclear cell phagocytic capacity among test group subjects, following consumption of milk supplemented with B. lactis, while individuals who consumed B. lactis-supplemented milk or milk alone showed enhanced phagocyte-mediated bactericidal activity. The results demonstrate that dietary consumption of B. lactis HN019 can enhance natural immunity in healthy elderly subjects, and that a relatively short-term dietary regime (6 weeks) is sufficient to impart measurable improvements in immunity that may offer significant health benefits to consumers. Financial support for this project was provided by the New Zealand Dairy Board.