A collaborative study by ­­­­­DuPont Nutrition & Health and the University of Reading (UK) on the effect of probiotic Bifidobacterium lactis Bi-07™ on immune function in healthy elderly subjects has been published in the Journal of Nutritional Science. The results of this study found that consumption of the probiotic Bifidobacterium lactis Bi-07 improves the function of specialized innate immune cells, the phagocytes, in elderly subjects. The elderly commonly have reduced immune function and this physiological effect may thus contribute to a better maintenance of their health.

“Immunity continues to be one of the main fields of research for DuPont Nutrition & Health. Alterations in the gut microbiota and immune functions of elderly adults are associated with higher susceptibility to infections and metabolic disorders,” said Dr. Markus Lehtinen, senior scientist, DuPont Nutrition & Health. “Phagocytosis, by which immune cells ‘eat’ bacteria or infected cells, is one of the mechanisms that help to resist infections. Results of this study show that the probiotic Bi-07 may provide health benefits to elderly individuals by increasing the activity of phagocytic cells.”

Study design
Upon completion of a screening process, 40 healthy elderly volunteers were found to be eligible for the study and were randomly divided into four groups. A double-blinded, placebo-controlled, randomized cross-over study was designed in which volunteers received maltodextrin as a placebo (8 g/d), prebiotic galacto-oligosaccharides (GOS) (8 g/d), probiotic (Bi-07; 109 colony-forming units/d) and synbiotic GOS + Bi-07 (8 g GOS/d and 109 colony-forming units Bi-07™/d). Daily portions were based on dose-response clinical studies showing that an 8 g portion of GOS increases the number of bifidobacteria in the intestine, and that 109 colony-forming units of B. lactis induce changes in elderly microflora. Volunteers were randomized to four groups that consumed the study products in random order in four periods. Supplements were provided for 21 days, with a 28-day wash-out period that has been effective in previous studies with B. lactis and GOS.

Study data
Blood, saliva and fecal samples were taken from the study subjects to analyze markers of immune function and microbiota composition. The phagocytic activity was analyzed using fluorescent bacteria that were incubated in blood samples containing phagocytes. The number of bacteria in the phagocytes was detected by using flow cytometry.

Primary statistical analysis revealed carry-over effects, which had the potential to bias results, and thus the statistical analysis was conducted for parallel groups using results from samples obtained on day 0 (before the first supplementation) and on day 21 (after the first supplementation period). It was found that subjects in the Bi-07 group had higher phagocytic activity of monocytes (p<0.001) and granulocytes (p=0.02) than subjects in the placebo group.