The Relevance of Supplemental Vitamin D in Malignancies

Background: Vitamin D has a widely acknowledged role in regulating the metabolism of calcium and phosphate, both essential to bone remodeling. However, numerous studies in recent decades have emphasized the association between low sun exposure and vitamin D deficiency, and an increased risk of extra-skeletal disorders such as cancer. Objective: This mini-review of literature aims to present an objective overview of several recent studies and meta- analyses evaluating the role of vitamin D in cancer prevention, its potential to improve cancer treatment outcomes, as well as the negative effects of vitamin D deficiencies. Methods: The antitumor effects of calcitriol and analogs in the treatment of cancer, either as single agent or in combination with other anticancer agents, are based on several mechanisms: inhibition of cancer cell proliferation and invasiveness, induction of differentiation and apoptosis, and promotion of angiogenesis, all recorded in numerous preclinical studies of various cancer types. Results: The importance of VDR polymorphisms for individual malignancies remains a topic of debate. Contradictory effects have been recorded in recent studies, the results of which include positive associations of VDR when cumulated with other risk factors, both an increase and a decrease in cancer risks, as well as no correlation between VDR polymorphisms and individual malignancies. Conclusion: The scientific evidence reviewed in this paper suggests that health care providers and individuals should consider increasing concentrations of 25 (OH) D through sensitive sun exposure and / or by supplementing with vitamin D to reduce cancer risk and, in combination with standard care, to treat cancer.