Epidemiologic evidence of a protective effect of vitamin C for non-hormone-dependent cancers is strong.

Of the 46 such studies in which a dietary vitamin C index was calculated, 33 found statistically significant protection, with high intake conferring approximately a twofold protective effect compared with low intake.

Of 29 additional studies that assessed fruit intake, 21 found significant protection.

For cancers of the esophagus, larynx, oral cavity, and pancreas, evidence for a protective effect of vitamin C or some component in fruit is strong and consistent.

For cancers of the stomach, rectum, breast, and cervix there is also strong evidence.