Effects of prebiotics on the immune response to vaccination in the elderly

Prebiotics stimulate the growth of bifidogenic bacteria in the gut. The aim of this work was to assess the effects of a prebiotic mixture on the immune response in healthy elderly people.

Healthy free-living elderly people (age, > or = 70 years), receiving a nutritional supplement that provided 1.6 MJ, 15 g of protein, and 50% of vitamin daily reference values per day, were randomly assigned to receive a prebiotic mixture (6 g/d of a 70% raftilose and 30% raftiline mixture) or placebo (6 g of maltodextrin powder) for 28 weeks. At week 2 of the study, all subjects were vaccinated with influenza and pneumococcal vaccines. At weeks 0, 2, and 8 of the study, serum total proteins, albumin, immunoglobulins, saliva secretory immunoglobulin A (IgA), and serum titers of influenza A and B and pneumococcal antibodies were measured. At week 8, cultured peripheral monocyte cell secretion of interleukin-4, interferon-gamma, and lymphocyte proliferation, stimulated with phytohemagglutinin and influenza antigen, were measured.

Sixty-six subjects were considered eligible for the study, and 43 (20 receiving prebiotics and 23 receiving placebo) were considered for final analyses on a per protocol basis. No changes in serum proteins, albumin, immunoglobulins, and secretory IgA were observed. Antibodies against influenza B and pneumococcus increased significantly from weeks 0 to 8, with no significant differences between groups. Antibodies against influenza A did not increase. No effects of prebiotics on interleukin-4 and interferon-gamma secretion by cultured monocytes were observed.

No immunological effects of prebiotics were observed in this study.