The digestive tract (large intestine) contains microorganisms that digest complex carbohydrates in food to produce chemical substances which are beneficial to human health. The population of these microorganisms in faeces (stool samples) could be used to diagnose the health status of a person and this can be changed with the use of antibiotics, diet, radiotherapy or infection. Dietary fibre supplements can help provide nutrients for the beneficial bacteria from the large intestine to produce useful chemicals that may delay growth or even shrink prostate cancer in patients. The investigators will feed mice diets containing several dietary fibres (including inulin, pectin and hemp hull) and also faeces from healthy male human volunteers over 60 years old to see what effect this has on the makeup of the bacteria in their gut and the resulting beneficial metabolites (chemicals). For this work, the research team need to obtain four to six fresh faecal samples on the same day, so that these can be mixed fresh and stored for use as faecal microbiota transplant (FMT) in the mice. The researchers will then test how altering the gut microorganisms with faeces and dietary fibre supplements can influence the growth of prostate cancer cell tumours in mice. The investigators expect to see an effect of the fibres in promoting beneficial bacteria and in shrinking the tumours. This work will allow the investigators to identify dietary fibres that could be used in nutritional therapies for management of prostate cancer patients in future.