32 Agro FOOD Industry Hi Tech - vol. 29(6) November/December 2018 PROBIOTICS LEHTORANTA LIISA*, LEHTINEN MARKUS *Corresponding author DuPont Nutrition and Health, Kantvik, Finland One of the most investigated strains for immune stimulation in the elderly is Bifidobacterium ( B. ) lactis HN019. The objective of this short review is to give an overview of the effects of the probiotic B. lactis HN019 supplementation on microbiota composition and immune function in the elderly. Further, we discuss in a broader way about the effect of probiotics on cellular immunity and their potential effect on the resistance to the common cold and on the improvement of vaccine response in the elderly. THE EFFECT OF BIFIDOBACTERIUM LACTIS HN019 ON THE MICROBIOTA OF THE ELDERLY With aging, the microbiota of the gut undergoes changes in its composition that may compromise health (2). As key examples of changes in the microbiota of the elderly, clinical studies have shown a decline in the number of bifidobacteria and an increase in proteolytic bacteria (5, 6). The effect of B. lactis HN019 on the elderly gut microbiota has been investigated in a double-blind placebo controlled trial (7). Eighty elderly volunteers were randomized and administered either placebo or B. lactis HN019: in low (6.5 × 10 7 Colony Forming Units (CFU)), medium (1 × 10 9 CFU), or high dose (5 × 10 9 CFU) in milk. The study results showed that B. lactis HN019 increased the levels of bifidobacteria, streptococci, and lactobacilli in faecal samples during the 4-week intervention period. The higher daily dose also reduced the levels of enterobacteria in the faeces indicating a lower presence of potentially opportunistic pathogenic bacteria. In summary, the results indicate that HN019 supplementation could be beneficial by inducing a shift in the microbiota of the elderly, thus favoring the growth of more beneficial bacteria. Although research findings in the area of microbiota modulation by probiotics are still scarce (8), similar observations were found in a study where the levels of bifidobacteria were increased in the elderly after the consumption fermented oat drink containing B. longum 46 and B. longum 2C (9). However, further research on the effect of probiotic consumption on the microbiota and its correlation to the health of the elderly is needed. ELDERLY IMMUNE FUNCTION AND ITS MODULATION BY BIFIDOBACTERIUM LACTIS HN019 The recognition of the microbiota by the immune system and its correct response is a key for maintaining INTRODUCTION Health care has improved globally in recent decades and it is now expected that most people reach the age of 60 and beyond in low and middle-income countries. In the high-income countries life expectancy has been increasing (1) and thus healthy aging is becoming a key public health target. Furthermore, health consciousness of senior consumers has increased and they are looking for nutritional aids to improve their quality of life. Aging and age-related loss of health are associated with altered gut microbiota (“dysbiosis”) (2) and immunological aging (“immunosenescence”) (3). Current scientific literature clearly points to an intimate interplay between gut microbiota and immune function, and associates dysbiosis and immunosenescence with an increased susceptibility to infections, infectious diarrhea, decreased vaccine responses, and frailty. Nutritional supplementations, such as probiotics, that target both the microbiota and immune function, are being investigated as a means to counteract dysbiosis and immunosenescence. As preclinical and clinical studies have shown, there is variation between probiotic strains in their efficacy on immune health outcomes. Strain specific research is warranted in addition to a more general discussion on the benefits of probiotics for elderly. It has been suggested in a consensus opinion article that the mechanisms by which probiotics influence the immune function are most likely strain specific (4). Probiotics and Bifidobacterium lactis HN019 in gastrointestinal and immune health of the elderly Probiotics are being investigated to counteract age-associated microbiota dysbiosis and decline of immune function. Thus far, probiotic effects on the elderly microbiota have not been well characterized. In contrast, several clinical studies have investigated the role of specific probiotics in maintaining elderly cellular immune function, focusing on Natural Killer cell activity and polymorphonuclear cell phagocytic capacity. Meta-analysis has shown that Bifidobacterium lactis HN019 may improve both outcomes in the elderly. In general, probiotics are considered potential supplements for reducing the risk of infectious diseases and improving vaccine responses in the elderly. However, the link between the modification of the microbiota, the stimulation of the immune system by Bifidobacterium lactis HN019 and other probiotics and the improvement of health in the elderly remains to be established. This review aims to discuss the effect of Bifidobacterium lactis HN019 on the elderly microbiota and immune function in the broader context of probiotics. ABSTRACT KEYWORDS: Probiotics, immune, gastrointestinal, elderly.