EFFECTS OF 4 Y OF ORAL SUPPLEMENTATION WITH BETA-CAROTENE ON SERUM CONCENTRATIONS OF RETINOL, TOCOPHEROL, AND 5 CAROTENOIDS

beta-Carotene has been studied widely as a potential cancer-preventing agent. Recent studies found that subjects who took beta-carotene supp lements orally had increases in their serum concentrations of alpha-ca rotene and lycopene that were large (> 150% increase) and significantl y greater than such increases in subjects who received placebo and tha t similar supplementation was associated with a decrease of approximat e to 37% in plasma lutein concentrations. A biologic interaction betwe en beta-carotene and other carotenoids was suggested. We measured conc entrations of retinol, alpha-tocopherol, and five carotenoids in serum specimens from a random sample of subjects enrolled in a clinical tri al of the use of antioxidant vitamins in preventing colonic adenomas. We used serum specimens obtained at enrollment and after the subjects took placebo (n = 54) or 25 mg beta-carotene/d (n = 54) orally for 4 y . In a multivariate analysis, baseline serum concentrations of the ana lytes, sex, body mass index, diet, smoking status, and age were associ ated with variable changes in some analytes over the 4-y period but su pplementation with beta-carotene was related only to a mean increase i n serum beta-carotene itself of 151%. We excluded with 95% confidence an increase in lycopene > 4.9%, an increase in alpha-carotene > 17.6%, and a decrease in lutein > 14.7% in subjects given beta-carotene. The se results confirm previous findings that supplementation with beta-ca rotene given orally does not alter serum concentrations of retinol or alpha-tocopherol. The findings also indicate that beta-carotene supple mentation, which results in a moderate increase in serum beta-carotene concentration, does not significantly change serum concentrations of other carotenoids.