Probiotic may improve immunity in the elderly

February 14, 2014

A study published in the Journal of Nutritional Science shows that the probiotic Bifidobacterium lactis may help improve the immune function in healthy elderly subjects.

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/day), prebiotic galacto-oligosaccharides (GOS) (8 g/day), probiotic (Bifidobacterium lactis Bi-07; 109 colony-forming units/day), and synbiotic GOS + Bi-07 (8 g GOS/day and 109 colony-forming units Bi-07/day). 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. 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.

The researchers found that subjects in the B. lactis Bi-07 group had higher phagocytic activity of monocytes and granulocytes than subjects in the placebo group. Changes in other markers of immune function or microbiota composition were not detected in any supplementation groups. They concluded that Bifidobacterium lactis Bi-07 improves the function of specialized innate immune cells, the phagocytes, in elderly subjects. This could be beneficial to elderly who suffer from decreased phagocytic activity and higher susceptibility to infections.