Effect of long-term beta-carotene and vitamin A on serum cholesterol and triglyceride levels among participants in the Carotene and Retinol Efficacy Trial (CARET)

Objective: The Carotene and Retinol Efficacy Lung Cancer Chemoprevention Tr ial (CARET) ended prematurely due to the unexpected findings that the activ e treatment group on the combination of 30 mg beta-carotene and 25 000 IU r etinyl palmitate had a 46% increased lung cancer mortality and a 26% increa sed cardiovascular mortality compared with placebo. This study was designed when the CARET intervention was halted to evaluate the effects of long-ter m supplementation with beta-carotene and retinol on serum triglyceride and cholesterol levels, in an attempt to explore possible explanations for the CARET result. Methods: Serum triglyceride levels, and total, high-density l ipoprotein (HDL), and low-density lipoprotein (LDL) cholesterol levels were determined in a subgroup of 52 CARET participants. Baseline and mid-trial levels were available on 23 participants on placebo and 29 on active treatm ent who were then serially followed for 10 months after trial termination. Results: Triglyceride, and total, HDL and LDL cholesterol levels were simil ar in the two groups at baseline. After a mean of 5 years on the interventi on there was a small nonsignificant increase in serum triglyceride levels i n the active group, but no difference in total, HDL, or LDL cholesterol lev els. After stopping the intervention there was a decrease in triglyceride l evels in the active intervention group, and no change in the other paramete rs. Conclusion: Based on a small convenience sample, CARET participants in the active treatment arm had a small nonsignificant increase in serum trigl yceride levels while on the intervention, and a decrease in serum triglycer ide levels after the intervention was discontinued. No significant changes in total or HDL cholesterol were noted. These results argue against a major contribution of treatment-induced changes in serum lipid and lipoprotein l evels to the increased cardiovascular mortality in the active treatment gro up. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.