Effect of supplemental β-carotene on plasma concentrations of carotenoids, retinol, and α-tocopherol in humans

High doses of β-carotene, a lipid-soluble nutrient, may affect the plasma concentrations of other lipid-soluble nutrients. The purpose of this study was to assess the effects of long-term daily supplementation with β- carotene (50 mg/d) on circulating concentrations of other carotenoids, retinol, and α-tocopherol over time. Data were available from 259 men and women participating in the Carotene Prevention Trial, a 2-center chemoprevention trial designed to determine whether supplemental β-carotene can prevent second malignant tumors in patients cured of an early stage cancer of the oral cavity, pharynx, or larynx. Up to 2 blood samples were obtained before the intervention (before and after a 1-mo placebo run-in), with postrandomization samples obtained at 3, 12, 24, 36, 48, and 60 mo. Supplementation with β-carotene produced a persistent 9- to 10-fold increase in median plasma β-carotene concentrations (225 nmol/L at baseline to 2255 nmol/L at 3 mo) and a persistent 2-fold increase in median plasma α-carotene concentrations (45 nmol/L at baseline to 95 nmol/L at 3 mo). Concentrations of retinol, α-tocopherol, lycopene, and lutein/zeaxanthin were not affected by supplemental β-carotene. Up to 5 y of daily supplementation with β- carotene increased circulating concentrations of α- and β-carotene, but did not alter concentrations of lycopene, lutein/zeaxanthin, retinol, or α- tocopherol.