The investigators will recruit DoD beneficiaries 18 years or older, that have been referred for a screening colonoscopy or polyp surveillance (or had one in the last 2 weeks), and have no previous diagnosis of colorectal cancer. They will have a 25 OH Vitamin D level drawn to determine if there is an association between the level obtained and findings on colonoscopy, or previous findings (if repeating).

DoD beneficiaries age 18 or older will be recruited from the clinics at the Mike O'Callaghan Federal Medical Center (MOFMC). Subjects meeting the inclusion/exclusion criteria will be offered an opportunity to participate:

Screening Visit:

• Obtain signed Informed Consent Document and HIPAA Authorization (research-driven).
• Record: Date of birth, age, gender, race, ethnicity, current email address, height (in inches), weight (in pounds), waist circumference (in inches) measurement, blood pressure, and whether subject is taking or has taken any vitamin D supplement or derivative, and if so, note the dosage, frequency, and duration of therapy.
• Subjects will be told to fast for at least 10 hours prior to Visit 1

Visit 1 (within two weeks of their screening colonoscopy):

-Subjects will have the following research-driven blood test drawn which include: Serum 25-OH vitamin D via 1 venipuncture (5-10 mls, approximately 1-2 teaspoons of blood will be drawn)

THIS STUDY IS BEING CONDUCTED AT A MILITARY INSTALLATION. YOU MUST HAVE MILITARY INSURANCE IN ORDER TO PARTICIPATE IN THIS STUDY.

Inclusion:

• DoD beneficiaries 18 years or older
• Referred for a screening colonoscopy or polyp surveillance or had one in the last 2 weeks

Exclusion:

• Previous diagnosis of colorectal cancer, adenomatous polyps, and/or cancer
• Military trainees
• Pregnant women

DoD beneficiaries age 18 or older will be recruited from the clinics at the Mike O'Callaghan Federal Medical Center (MOFMC). Subjects meeting the inclusion/exclusion criteria will be offered an opportunity to participate.

2 weeks