Through National Health Service (NHS) clinical services in colorectal surgery and oncology, patients will be identified and recruited from surgical wards or surgical/oncology out-patient clinics. A sample of participants with and without a new or previous diagnosis of colorectal cancer will be included for comparison.~Participation will consist of two events in the majority of participants. Firstly a in the surgical ward or clinic lasting no longer than 20 minutes in which the research will be discussed and informed consent gained. A blood sample will be taken prior to the conclusion of recruitment and a rectal biopsy taken using a rigid sigmoidoscopy which may or may not be required as part of their routine clinical assessment. Participants will be asked to take pharmaceutical grade vitamin D tablets for 3 months. After 12 weeks of vitamin D supplementation, a final blood sample and rectal biopsy will be taken.~If patients would like to contribute but cannot or would prefer not to take vitamin D, or cannot return for future sampling, a single sampling will be offered. This participant would undergo blood sampling and rectal biopsy as above. After this no further events would occur.
AIMS To identify the underlying mechanism by which Vitamin D reduces colorectal cancer risk.~OBJECTIVES To demonstrate the effects of vitamin D supplementation on serum vitamin D levels.~To demonstrate dynamic changes in gene expression in response to vitamin D. To demonstrate the mechanism underlying the gene-environment interaction of vitamin D, susceptibility genetic variants (risk genes) and colorectal cancer.