title: Effects of 4 y of oral supplementation with beta-carotene on serum concentrations of retinol, tocopherol, and five carotenoids.
abstract: beta-Carotene has been studied widely as a potential cancer-preventing agent. Recent studies found that subjects who took beta-carotene supplements orally had increases in their serum concentrations of alpha-carotene and lycopene that were large (> 150% increase) and significantly greater than such increases in subjects who received placebo and that similar supplementation was associated with a decrease of approximately 37% in plasma lutein concentrations. A biologic interaction between beta-carotene and other carotenoids was suggested. We measured concentrations of retinol, alpha-tocopherol, and five carotenoids in serum specimens from a random sample of subjects enrolled in a clinical trial 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 analytes, sex, body mass index, diet, smoking status, and age were associated with variable changes in some analytes over the 4-y period but supplementation with beta-carotene was related only to a mean increase in 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. These results confirm previous findings that supplementation with beta-carotene given orally does not alter serum concentrations of retinol or alpha-tocopherol. The findings also indicate that beta-carotene supplementation, which results in a moderate increase in serum beta-carotene concentration, does not significantly change serum concentrations of other carotenoids.
authors.affiliation: Department of Medicine, Dartmouth Medical School, Hanover, NH. david.nierenberg@dartmouth.edu
authors.forename: D W
authors.initials: DW
authors.lastname: Nierenberg
authors.forename: B J
authors.initials: BJ
authors.lastname: Dain
authors.forename: L A
authors.initials: LA
authors.lastname: Mott
authors.forename: J A
authors.initials: JA
authors.lastname: Baron
authors.forename: E R
authors.initials: ER
authors.lastname: Greenberg
mesh_terms: D000328:Adult; D000368:Aged; D002338:Carotenoids / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010919:Placebos; D014801:Vitamin A / Q000097:blood*; D014810:Vitamin E / Q000097:blood*; D019207:beta Carotene / Q000008:administration & dosage*
chemical_list: D010919:Placebos; D019207:beta Carotene; D014801:Vitamin A; D014810:Vitamin E; D002338:Carotenoids