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摘要
Background: Little is known about a-tocopherol's bioavailability as a constituent of food or its dependence on a subject's age. Objective: To evaluate the a-tocopherol bioavailability from food, we used collard greens grown in deuterated water (2H collard greens) as a source of deuterium-labeled (2H) a-tocopherol consumed by younger and older adults in a post hoc analysis of a vitamin K study. Design: Younger (mean +/- SD age: 32 +/- 7 y; n = 12 women and 9 men) and older (aged 67 8 y; n = 8 women and 12 men) adults consumed a test breakfast that included 120 g 2H collard greens (1.2 +/- 0.1 mg H-2-alpha-tocopherol).. Plasma unlabeled a-tocophefol and 2H-a-tocopherol were measured by using liquid chromatography mass spectrometry from fasting (>12 h) blood samples drawn before breakfast (0 h) and at 24, 48, and 72 h and from postprandial samples collected at 4, 5, 6, 7, 9, 12, and 16 h. Results: Times (12.6 +/- 2.5 h) of maximum plasma H-2-alpha-tocopherol concentrations (0.82% +/- 0.59% total a-tocopherol), fractional disappearance rates (0.63 +/- 0.26 pools/d), half-lives (30 +/- 11 h), and the minimum estimated H-2-alpha-tocopherol absorbed (24% +/- 16%) did not vary between age groups or sexes (n = 41). Unlabeled a-tocopherol concentrations were higher in older adults (26.4 +/- 8.6 Amon) than in younger adults (19.3 +/- 4.2 mu mol/L; P = 0.0019) and correlated with serum lipids (r = 0.4938, P = 0.0012). In addition, H-2-alpha-tocopherol half-lives were correlated with lipids (r = 0.4361, P = 0.0044). Conclusions: Paradoxically, alpha-tocopherol remained in circulation longer in participants with higher serum lipids, but the H-2-alpha-tocopherol absorbed was not dependent on the plasma lipid status. Neither variable was dependent on age. These data suggest that plasma alpha-tocopherol concentrations are more dependent on mechanisms that control circulating lipids rather than those related to its absorption and initial incorporation into plasma.
- 出版日期2015-4
