Location: Food Components and Health Laboratory
Project Number: 8040-51000-059-015-I
Project Type: Interagency Reimbursable Agreement
Start Date: Jun 1, 2021
End Date: Aug 31, 2022
Individuals with diets high in beta-carotene appeared to have lower risk of lung cancer, which led the National Cancer Institute to run a study to determine if beta-carotene supplements would lower lung cancer incidence in smokers. Surprisingly, the smokers taking the beta-carotene supplements had higher incidence of lung cancer rather than lower incidence, and the reason has never been understood. One possible explanation is that a specific metabolite of beta-carotene (beta-apo-13-carotenone) might be affecting cell metabolism. The proposed research project will investigate whether smokers have higher conversion of beta-carotene to beta-apo-13-carotenone compared to nonsmokers. If smokers have higher conversion of beta-carotene to this metabolite, this conversion may explain the higher incidence of lung cancer in smokers taking beta-carotene supplements.
The blood of smokers and non-smokers will be analyzed for carotenoids, vitamin A, and beta-apo-13-carotenone, as well as cotinine as an index of smoking. The ratio of beta-carotene to beta-apo-13-carotenone will be compared between smokers and non-smokers to determine if smokers have increased metabolism of beta-carotene to beta-apo-13-carotenone. Such increased metabolism would likely increase risk for cancer due to the ability of beta-apo-13-carotenone to bind to nuclear receptors. The results may help explain the unexpected results of the National Cancer Institute’s Alpha-Tocopherol, Beta-Carotene Trial in which smokers taking beta-carotene supplements had an unexpectedly higher incidence of lung cancer.