Background: Chemopreventive agents developed to be used in a moderate-risk
but otherwise healthy population need to be both efficacious and to have mi
nimal adverse effects.
Objective: The objective of this study was to evaluate the adverse effects
of long-term retinol intake in a skin cancer chemoprevention trial in a lar
ge population at moderate risk for skin cancer.
Design: Participants (n = 2297) were randomly assigned to receive retinol [
7576 retinol equivalents (RE). or 25 000 IU] or a placebo daily. The advers
e effects of retinol intake were studied by monitoring 14 clinical symptoms
and laboratory indexes. The median follow-up time was 3.8 y.
Results: No adverse effects concerning the 14 symptoms were observed. Signi
ficant differences in alkaline phosphatase (P < 0.0001), triacylglycerol (P
< 0.0001), cholesterol (P = 0.04), and HDL (P = 0.01) were observed over t
ime between the 2 soups. After 49 mo of follow-up, alkaline phosphatase was
7% higher, triacylglycerol was 11% higher, cholesterol was 3% higher, and
HDL was 1% lower in the retinol group than in the placebo group.
Conclusions: Because a 1% increase in cholesterol concentrations has been r
eported to be associated with a 2% increase in coronary artery disease risk
, long-term ingestion of 7576 RE vitamin A/d should be considered with caut
ion. However, further studies are needed to confirm this finding.