The response to vaccination in the elderly has been found to be considerably weaker than in younger adults, due to deterioration in the function of the immune system, known as immunosenescence.
A number of polysaccharide compounds from plants, bacteria, fungi, and synthetic sources have emerged as promising vaccine adjuvant candidates. Among these, the non-digestible polysaccharides (NPS) β-glucans, arabinoxylans and exopolysaccharides have attained promising results in vitro as well as in vivo.
Despite the emerging evidence suggesting that NPS may enhance the immune response to vaccination, the effectiveness of these as oral vaccine adjuvants has not been confirmed yet in humans. Therefore, the aim of this pilot trial was to investigate the effects of a five-week consumption period of different dietary NPS on the antibody response to influenza vaccination Vaxigrip, respiratory tract infections and cellular immunity of healthy volunteers aged 50–79 years. Furthermore, the effects on faecal microbiota and its metabolites as well as on gastrointestinal wellbeing were investigated.
The study
This was a randomised, controlled, double-blind, parallel-group study in which 240 participants (231 completed the study) were randomly assigned to one of six intervention groups.
They were asked to consume a powder stirred in 200 mL milk or apple juice once daily for five weeks. The powder contained either: Maltodextrin (CTRL), a β-glucan preparation from yeast (Wellmune, 500 mg, YBG), a β-glucan preparation from shiitake (Wageningen, 500 mg, SBG), a β-glucan preparation from oat (Oatwell, 10.0 g, OBG), an arabinoxylan preparation from wheat endosperm (Naxus, BioActor, 10.0 g, AX) or an exopolysaccharide preparation from Limosilactobacillus mucosae (DPC 6426 by Teagasc, 2.3 g, EPS).