title: Bioavailability of beta-carotene is lower in raw than in processed carrots and spinach in women.
abstract: Populations at risk of vitamin A deficiency usually rely on dietary provitamin A carotenoids to meet vitamin A needs, yet bioavailability of these compounds is influenced by several factors as follows: location in the plant source, the presence of other influencing dietary components, and type and extent of processing. The purpose of this study was to examine the plasma beta-carotene response to raw vs. processed carrots and spinach. Subjects were eight healthy females aged 23-36 y who consumed approximately 9.3 mg beta-carotene daily from either raw or thermally processed and pureed vegetables in two 4-wk treatment periods in a crossover study. Plasma concentrations of total, all-trans-, and cis-beta-carotene and alpha-carotene were measured at base line and the end of each treatment period by using HPLC assays. Total and all-trans (but not cis) plasma beta-carotene concentrations were significantly greater than base-line concentrations in the processed feeding period (P < 0. 04) and tended to be greater in the raw feeding period (P = 0.08). Daily consumption of processed carrots and spinach over a 4-wk period produced an increase in plasma beta-carotene concentration that averaged three times that associated with consumption of the same amount of beta-carotene from these vegetables in the raw form (P = 0.09). Increased cis isomers provided in the processed vegetables did not result in significantly greater plasma cis-beta-carotene isomer concentrations. These results suggest that isomerization of beta-carotene by heat treatment does not negate the enhanced beta-carotene uptake associated with consuming commercially processed vegetables compared with raw vegetables.
authors.affiliation: Department of Family and Preventive Medicine, University of California, San Diego, La Jolla, CA 92093-0901, USA.
authors.forename: C L
authors.initials: CL
authors.lastname: Rock
authors.forename: J L
authors.initials: JL
authors.lastname: Lovalvo
authors.forename: C
authors.initials: C
authors.lastname: Emenhiser
authors.forename: M T
authors.initials: MT
authors.lastname: Ruffin
authors.forename: S W
authors.initials: SW
authors.lastname: Flatt
authors.forename: S J
authors.initials: SJ
authors.lastname: Schwartz
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000032:analysis*; D001682:Biological Availability; D015331:Cohort Studies; D018592:Cross-Over Studies; D018552:Daucus carota / Q000737:chemistry*; D005260:Female; D005511:Food Handling / Q000379:methods; D006358:Hot Temperature; D006801:Humans; D007536:Isomerism; D018724:Spinacia oleracea / Q000737:chemistry*; D019207:beta Carotene / Q000097:blood* / Q000737:chemistry
chemical_list: D000975:Antioxidants; D019207:beta Carotene