Human vitamin E requirements assessed with the use of apples fortified with deuterium-labeled alpha-tocopheryl acetate.
BACKGROUND
Little is known about factors that modulate dietary alpha-tocopherol bioavailability.


OBJECTIVE
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.


METHODS
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 (Cmax) 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 Cmax (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.
Bruno
Richard S
RS
Department of Food Science and Technology, Oregon State University, Corvallis, OR 97331, USA.
Leonard
Scott W
SW
Park
Su-Il
SI
Zhao
Yanyun
Y
Traber
Maret G
MG
D000293:Adolescent; D000328:Adult; D000975:Antioxidants / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001682:Biological Availability; D018592:Cross-Over Studies; D003903:Deuterium; D004041:Dietary Fats / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005527:Food, Fortified; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects; D008297:Male; D027845:Malus; D009751:Nutritional Requirements; D024505:Tocopherols; D014810:Vitamin E / Q000097:blood / Q000493:pharmacokinetics*; D024502:alpha-Tocopherol / Q000031:analogs & derivatives / Q000493:pharmacokinetics
D000975:Antioxidants; D004041:Dietary Fats; D014810:Vitamin E; D003903:Deuterium; D024502:alpha-Tocopherol; D024505:Tocopherols