Human vitamin E requirements assessed with the use of apples fortified with deuterium-labeled [alpha]-tocopheryl acetate
2006
Bruno, Richard S | Leonard, Scott W | Park, Su-il | Zhao, Yanyun | Traber, Maret G.
BACKGROUND: Little is known about factors that modulate dietary [alpha]-tocopherol bioavailability. OBJECTIVES: The study aimed to assess the efficacy of vitamin E-fortified apples as a low-fat vitamin E delivery system, the influence of fat on vitamin E absorption, and human vitamin E requirements by using plasma [alpha]-tocopherol kinetics at a dosage of [alpha]-tocopherol found in food. DESIGN: Apples fortified with deuterium-labeled [alpha]-tocopheryl acetate were consumed by 5 participants at a breakfast containing 0%, 6%, or 21% kcal from fat in 3 sequential trials. The trials were separated by a 2-wk washout period. Blood samples were obtained up to 72 h, and plasma was analyzed for labeled and unlabeled [alpha]-tocopherol. RESULTS: Compared with observations in the 0% fat trial, the maximum observed plasma d₆-[alpha]-tocopherol concentrations (C[subscript max]) and the areas under the curve increased 2- and 3-fold during the 6% and 21% fat trials, respectively. The mean (±SD) estimated percentage d₆-[alpha]-tocopherol absorbed increased from 10 ± 4% during the 0% fat trial to 20 ± 3% and 33 ± 5% during the 6% and 21% fat trials, respectively. The mean time to C[subscript max] (9 ± 2 h), fractional disappearance rates (0.022 ± 0.003 pools/d), and half-lives (32 ± 4 h) did not differ significantly between the trials. With the use of fractional disappearance rates and baseline plasma [alpha]-tocopherol concentrations, the estimated daily plasma [alpha]-tocopherol efflux was 13-14 mg. The estimated rate of [alpha]-tocopherol delivery to tissues was 5 mg/d. CONCLUSIONS: Given an estimated 33% absorption, the amount of dietary vitamin E needed daily to replace irreversible losses is </=15 mg. These estimates support the current human vitamin E requirements despite the claims that the median amount of vitamin E that Americans consume is 7 mg/d.
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