Vitamin D and Calcium as Key Potential Factors Related to Colorectal Cancer Prevention and Treatment: A Systematic Review

Colorectal cancer (CRC) is currently considered one of the most common and lethal types of tumors. Nutrition is of notorious relevance, given its influence in CRC prevention and treatment. This systematic review aimed to revise and update the state of knowledge regarding the potential role of vitamin D and calcium as key factors involved in the prevention and treatment of CRC. A literature search was performed in PubMed and Web of Science. A total of eight studies were finally included in the present review. Vitamin D showed a protective role by promoting transcriptomic changes associated with antitumor effects. However, no significant effects of vitamin D were noted in the relapse-free survival of patients at 5 years. On the other hand, previous scientific evidence demonstrated that calcium regulates the expression of colonic proteins that decrease cell proliferation and increase cell differentiation. Nevertheless, an increased risk of associated serrated adenomas was found in response to calcium and calcium + vitamin D supplementation. Moreover, supplementation with both nutrients showed positive changes on relevant CRC biomarkers including TGFα, TGFβ1, APC, β-catenin and E-cadherin. In conclusion, vitamin D supplementation seems to have a protective effect in the prevention and treatment of CRC, while calcium intake showed contradictory effects as a prevention or treatment tool; therefore, further studies are necessary to well understand its relevance in patients with CRC.