Vitamin A and cancer incidence in a retirement community.

The use of vitamin A supplements and the risk of cancer was examined in a cohort of 11,888 residents of a retirement community near Los Angeles, California. After 2 1/2 years of follow-up, 445 incident cancers occurred in 435 of the study participants. Overall, the relative risk of cancer for supplement users versus nonusers was 1.0. In a subset of 32 randomly selected individuals, the 14 supplement users had a significantly higher mean serum retinol level (86 micrograms/dl) than did the 18 nonusers (74 micrograms/dl).