Abstract
Elderly people have increased susceptibility to infections and cancer that are associated with decline in cellular immune function. The objective of this work was to determine the efficacy of Bifidobacterium (B.) animalis ssp. lactis HN019 (HN019) supplementation on cellular immune activity in healthy elderly subjects. We conducted a systematic review of Medline and Embase for controlled trials that reported polymorphonuclear (PMN) cell phagocytic capacity or natural killer (NK) cell tumoricidal activity following B. lactis HN019 consumption in the elderly. A random effects meta-analysis was performed with standardized mean difference (SMD) and 95% confidence interval between probiotic and control groups for each outcome. A total of four clinical trials were included in this analysis. B. lactis HN019 supplementation was highly efficacious in increasing PMN phagocytic capacity with an SMD of 0.74 (95% confidence interval: 0.38 to 1.11, p < 0.001) and moderately efficacious in increasing NK cell tumoricidal activity with an SMD of 0.43 (95% confidence interval: 0.08 to 0.78, p = 0.02). The main limitations of this research were the small number of included studies, short-term follow-up, and assessment of a single probiotic strain. In conclusion, daily consumption of B. lactis HN019 enhances NK cell and PMN function in healthy elderly adults.
Highlights
Elderly people represent the fastest growing population
Age-related alterations have been reported for innate immune system and for function of neutrophils and natural killer (NK) cells
It has been suggested that probiotic supplementation could offer means to reverse some age-related changes in intestinal microflora composition and to help maintain the aging immune system that are associated with age-related morbidities [30]
Summary
Older individuals have typically weaker immune responses to vaccination and elevated risk for infections, certain autoimmune diseases, and cancer [1]. Many of these health risks are a consequence of declining immune function associated with the aging process, i.e., immunosenescence [2]. Age-related alterations have been reported for innate immune system and for function of neutrophils and natural killer (NK) cells. Neutrophils, which are important for early immune response for infections, show decreased chemotaxis, phagocytic activity, and declined superoxide generation in the elderly [5,6]
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