The objectives of this study are to use a nutritional change in the diet to improve gut health in older people. Ageing can result in major changes in the composition and activities of the bacteria in your gut, leading to a higher incidence of gastrointestinal infections, decreased intestinal motility and impaired bowel function as people get older. This can result in constipation or diarrhoea, increased levels of inflammation and reduced immune response to infection. Therefore, individuals aged 65 or over could benefit from safe and effective interventions that maintain a healthy balance of gut bacteria as well as restoring the immune response. Bacteria in the gut are known to promote health. Eating foods containing beneficial bacteria for example (probiotics) or food which contain substrates for the bacteria to grow on (prebiotics) can improve the balance of gut bacteria. The investigators will use a synbiotic with known anti-inflammatory properties, comprising a probiotic Bifidobacterium longum strain and inulin (Synergy 1), The synbiotic has been previously shown to be beneficial in reducing inflammation and to increase levels of beneficial bacteria in the gut in two studies in patients with inflammatory bowel disease. The investigators would now for these reasons, like to determine the effects of our Synbiotic on the gut bacteria and immune function of older individuals in a double-blinded, crossover, placebo controlled, randomised investigation involving 40 volunteers for three months. The trial is designed so that participants will be assigned to receive the Synbiotic preparation or the placebo for the first four weeks, this will be followed by four weeks without treatment, and then they will switch to the opposite preparation for another four weeks.

Inclusion Criteria:

• 65-90 years
• BMI 18.5-30.0 kg m2.

Exclusion Criteria:

• asplenia and other acquired or congenital immunodeficiencies
• any autoimmune disease
• connective tissue diseases
• self-reported symptoms of acute or recent infection (including use of antibiotics within the previous 3 months)
• taking probiotics or prebiotics, including lactulose for constipation
• chronic gastrointestinal problems (e.g. Inflammatory bowel disease, irritable bowel syndrome, cancer)
• use of immunosuppressive or anti-inflammatory drugs.