Within recent times, influenza has become a major respiratory infection worldwide. The preventative vaccination reduces the severity of infection but ageing reduced its efficacy and it is only effective in 17-53% in elderly individuals. Thus, nutritionists and medical researchers are looking for opportunities to improve the immune response to influenza vaccine. Functional foods, such as probiotics, prebiotics and synbiotics, apart from other health benefits, may contribute towards immune protection.~Probiotics are beneficial bacteria, which are regarded as safe and serve health benefits to the host, while prebiotics are carbohydrates which by escaping digestion in the upper gastrointestinal tract may reach the colon and there serve as food for beneficial bacteria in the colon. When prebiotic used in combination with probiotic bacteria, it is called synbiotic, and it may improve survival and implantation of probiotic in the gut.~The human study will examine the immune response to vaccination and changes in faecal microbiota during administration of probiotic, prebiotic and synbiotic supplements. The study will be conducted between vaccinations seasons in 2010-2011 and recruit 100 healthy subjects aged 40-65years old. Participant will be given one of four different treatments over a 7 week period following 3 weeks of wash-out period. Treatments given include: a probiotic, a prebiotic, a synbiotic and a placebo. In the 3rd week of product consumption the participant will be given a flu jab. Specific antibody titre against the 3 viral strains composing the vaccine and total immunoglobulin concentration in the serum will be monitored during 2 and 4 weeks after vaccination. Faecal samples and saliva will be collected and analysed for changes in faecal microbial populations.
The aim of the study is to investigate the effect of dietary supplements such as probiotic, prebiotic and synbiotic on the immune response to influenza vaccination and faecal microbiota in adult healthy volunteers.