Calcium Intake and Cancer Risk: Current Evidence and Future Research Directions

Purpose of Review: Previous epidemiological studies reported equivocal associations between calcium intake and cancer risk by organ site. Here, we summarized the latest evidence on associations between calcium intake and risk of major cancers (lung, breast, prostate, and colorectal cancers) from epidemiological studies and the potential molecular mechanisms supporting such associations. Recent Findings: In observational studies, calcium intake from food and/or supplements was inversely associated with risk of colorectal and breast cancers and suggestively inversely associated with lung cancer risk, whereas it was positively associated with prostate cancer risk. In trials of calcium-containing supplements, a protective effect was suggested for prostate cancer and no consistent effects for colorectal, breast, and lung cancers. Potential molecular mechanisms by cancer site are discussed. Summary: More studies are needed to evaluate associations between cancer and sources of calcium intake, and to further elucidate potential molecular mechanisms and how these may differ by cancer site.