Optimizing vitamin D status to reduce colorectal cancer risk: an evidentiary review.

Vitamin D deficiency is common in the general public and in patients with cancer. Optimizing vitamin D intake is increasingly recognized in cancer risk reduction, particularly in decreasing colorectal cancer risk. Therefore, summarizing the current evidence to promote best practices related to vitamin D intake and colorectal cancer risk reduction is important. The objectives of this article are to examine the current evidence regarding the impact of vitamin D on colorectal cancer risk reduction and provide practice recommendations for clinicians. Relevant research articles from 2002-2008 were retrieved from multiple electronic databases. Reference lists of relevant articles also were searched manually. Twenty-five research reports were selected for this article: 4 randomized, controlled trials; 11 cohort or case-control studies measuring serum 25-OH-D levels; and 10 cohort studies reporting vitamin D intake. This review generated three themes: raising 25-OH-D levels to a vitamin D sufficient state (32-100 ng/ml) achieved colorectal cancer risk reduction, increasing the intake of vitamin D reduced colorectal cancer risk, and increasing vitamin D intake to 1,000 IU daily is safe and likely sufficient to raise serum 25-OH-D levels above 32 ng/ml to achieve colorectal cancer risk reduction. Several practice recommendations are suggested.