Cancer patients receiving pelvic radiotherapy suffer side effects to the intestine, including diarrhoea and occasionally rectal bleeding, often worsened by chemoradiation. Many pelvic radiotherapy patients receive a form of dietary fibre, psyllium husk, to manage their diarrhoeal symptoms. There is evidence in mice that dietary fibre supplementation can improve tumour response and reduce normal tissue side effects caused by radiation. If this were to be confirmed in humans, it would be a major advance in patient treatment. The investigators will conduct a study in healthy subjects to assess mechanisms and response to dietary fibre. The investigators will conduct a within-subject diet intervention study on healthy older adults (\>60 years old) to determine if a subset of the population are responders to dietary fibre manipulation, using inulin with or without psyllium. This will allow assessment of the physiological impact of dietary fibre. Participants will receive placebo, inulin, or psyllium plus inulin in random order (6 possible combinations) for two weeks each with two-week washout periods. Baseline faecal microbial activity, short chain fatty acid (SCFA) concentrations, and habitual fibre intake, determined by dietary questionnaires/food diaries will be used to identify individuals in whom dietary fibre manipulation might have a positive impact. Individuals who respond to dietary fibre supplementation may be found to have elevated levels of some SCFAs and significantly increased relative abundance of certain microbiota. Dietary parameters, bacterial relative abundance and SCFA levels will be correlated with plasma cytokine levels.
Age range
60 Years
Sex
ALL
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Microbial composition using 16S sequencing
Timeframe: 11 weeks per participant
Short Chain Fatty Acid (SCFA) levels
Timeframe: 11 weeks per participant