Folic acid (FA) and its derivatives (folate) which play a role in nucleotide synthesis and methylation reactions as well as calcium and vitamin D are assumed to be effective in the prevention of colorectal polyps and Colorectal cancer (CRC). The aim of this study is to investigate the roles of FA as well as calcium and vitamin D in the prevention of CRC.

Colorectal cancer (CRC) affects approximately one million people each year with a five-year survival rate of 62% . Considerable interest has recently been focused on the relationship between the chemoprevention of colorectal polyps/CRA and CRC. Therefore, the use of nutritional compounds which are usually less afflicted with the risk of severe side effects for colorectal adenoma (CRA) prevention and health maintenance is an emerging field.

Inclusion Criteria:

• individuals aged 50-80 years
• Patients had undergone complete colonoscopy with no adenoma found
• Those who voluntarily sign the consent form after being fully informed and understanding the purpose and procedures of the study, characters of the disease, effect of medications, methods of related examinations, and potential risk/benefits of the study

Exclusion Criteria:

• Patients who are hypersensitive or intolerant to the drugs
• Patients who are intolerant to another colonoscopy examination
• Pregnant women, woman during breast-feeding period, or women with expect pregnancy
• Patients with diabetes mellitus, severe heart or renal disease，or cancer history
• Patients with malignant neoplasm, or suspicious colorectal cancer
• Patients who are not able to cooperate
• Individuals who are involved in designing, planning or performing this experiment
• Patients with medical conditions who are not appropriate to participate the study
• Patients who are take aspirin or cyclooxygenase 2 inhibitor （COX2）.