Traber Maret G, Leonard Scott W, Bobe Gerd, Fu Xueyan, Saltzman Edward, Grusak Michael A, Booth Sarah L
From the Linus Pauling Institute, Oregon State University, Corvallis, OR (MGT, SWL, and GB); the USDA Human Nutrition Center on Aging, Tufts University, Boston, MA (XF, ES, and SLB); and the USDA/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX (MAG).
Am J Clin Nutr. 2015 Apr;101(4):752-9. doi: 10.3945/ajcn.114.100966. Epub 2015 Mar 4.
Little is known about α-tocopherol's bioavailability as a constituent of food or its dependence on a subject's age.
To evaluate the α-tocopherol bioavailability from food, we used collard greens grown in deuterated water ((2)H collard greens) as a source of deuterium-labeled ((2)H) α-tocopherol consumed by younger and older adults in a post hoc analysis of a vitamin K study.
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 (2)H collard greens (1.2 ± 0.1 mg (2)H-α-tocopherol). Plasma unlabeled α-tocopherol and (2)H-α-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.
Times (12.6 ± 2.5 h) of maximum plasma (2)H-α-tocopherol concentrations (0.82% ± 0.59% total α-tocopherol), fractional disappearance rates (0.63 ± 0.26 pools/d), half-lives (30 ± 11 h), and the minimum estimated (2)H-α-tocopherol absorbed (24% ± 16%) did not vary between age groups or sexes (n = 41). Unlabeled α-tocopherol concentrations were higher in older adults (26.4 ± 8.6 μmol/L) than in younger adults (19.3 ± 4.2 μmol/L; P = 0.0019) and correlated with serum lipids (r = 0.4938, P = 0.0012). In addition, (2)H-α-tocopherol half-lives were correlated with lipids (r = 0.4361, P = 0.0044).
Paradoxically, α-tocopherol remained in circulation longer in participants with higher serum lipids, but the (2)H-α-tocopherol absorbed was not dependent on the plasma lipid status. Neither variable was dependent on age. These data suggest that plasma α-tocopherol concentrations are more dependent on mechanisms that control circulating lipids rather than those related to its absorption and initial incorporation into plasma. This trial was registered at clinicaltrials.gov as NCT0036232.
关于α-生育酚作为食物成分的生物利用度及其对受试者年龄的依赖性，人们了解甚少。
为了评估食物中α-生育酚的生物利用度，我们在一项维生素K研究的事后分析中，使用在重水中种植的羽衣甘蓝（重水羽衣甘蓝）作为年轻和年长者摄入的氘标记（²H）α-生育酚的来源。
年轻成年人（平均±标准差年龄：32±7岁；12名女性和9名男性）和年长者（67±8岁；8名女性和12名男性）食用了一份测试早餐，其中包括120克重水羽衣甘蓝（1.2±0.1毫克²H-α-生育酚）。通过液相色谱-质谱法测定空腹（>12小时）早餐前（0小时）、24、48和72小时抽取的血样以及4、5、6、7、9、12和16小时采集的餐后血样中未标记的α-生育酚和²H-α-生育酚。
最大血浆²H-α-生育酚浓度出现的时间（12.6±2.5小时）（占总α-生育酚的0.82%±0.59%）、分数消失率（0.63±0.26池/天）、半衰期（30±11小时）以及估计的最小²H-α-生育酚吸收量（24%±16%）在年龄组或性别之间没有差异（n = 41）。年长者未标记的α-生育酚浓度（26.4±8.6μmol/L）高于年轻成年人（19.3±4.2μmol/L；P = 0.0019），且与血脂相关（r = 0.4938，P = 0.0012）。此外，²H-α-生育酚半衰期与血脂相关（r = 0.4361，P = 0.0044）。
矛盾的是，血清脂质较高的参与者中α-生育酚在循环中的停留时间更长，但吸收的²H-α-生育酚并不依赖于血浆脂质状态。这两个变量均不依赖于年龄。这些数据表明，血浆α-生育酚浓度更依赖于控制循环脂质的机制，而非与其吸收及最初进入血浆相关的机制。该试验在clinicaltrials.gov上注册，注册号为NCT0036232。
