In 2003, the United States Food and Drug Administration (FDA) received a health claim petition for calcium supplements and reduced risk of colorectal, breast, and prostate cancers. Health claims characterize the relationship between a substance (food or food component) and disease (e.g., cancer or cardiovascular disease) or health-related condition (e.g., hypertension) and require premarket approval for the labeling of conventional foods and dietary supplements by the FDA. This review describes how the FDA used the evidence-based review system to evaluate the scientific evidence for these proposed health claims. FDA found no credible evidence to support health claims for calcium and a reduced risk of breast and prostate cancers. The agency did find limited evidence for the relationship between calcium intake and colorectal cancer risk.