01/04/2026
According to a review published in Molecular Cancer (2019), the active form of vitamin D, calcitriol (1,25(OH)₂D₃), has been shown in experimental studies to directly influence cancer cell behavior. It binds to the vitamin D receptor (VDR) and regulates genes involved in cell cycle control, leading to reduced cancer cell proliferation and activation of apoptosis (programmed cancer cell death). These effects have been observed across multiple cancer types, including colorectal, breast, and prostate cancer, primarily in cell and animal models rather than human trials.
The same publication describes how calcitriol also suppresses angiogenesis (formation of new blood vessels that feed tumors) and limits metastasis (spread of cancer to other parts of the body) by altering tumor signaling pathways and the surrounding microenvironment. It further highlights calcitriol’s role in modulating immune responses and inflammatory pathways within tumors, showing that its effects are multi-layered—impacting not just tumor cells, but also the environment that allows tumors to grow and spread.
PMCID: PMC6437556 PMID: 30972274
