Variability in conversion of beta-carotene to vitamin A in men as measured by using a double-tracer study design.
Variability in conversion of beta-carotene to vitamin A in men as measured by using a double-tracer study design.
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DOI：
10.1093/ajcn/71.6.1545
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发表时间：
2000-06
期刊：
影响因子：
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通讯作者：
S. Hickenbottom;J. Follett;Yumei Lin;S. Dueker;B. Burri;T. Neidlinger;A. Clifford
中科院分区：
文献类型：
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作者：
S. Hickenbottom;J. Follett;Yumei Lin;S. Dueker;B. Burri;T. Neidlinger;A. Clifford
背景：β-胡萝卜素的维生素A活性在女性中是可变的，并且出人意料地低。造成这种情况的原因还不是很清楚。男性体内β-胡萝卜素的维生素A活性仍不确定。与个体特征相比，饮食因素的贡献在很大程度上是未知的。目的我们的目标是测量生活在受控环境中的健康、饮食充足的男性中β-胡萝卜素的维生素A活性的内在变异性。设计：采用双示踪重测设计。给11名健康男性口服全反式-19，19，19，20，20，20-[2H6]维甲酸乙酯30微克分子，1wk后口服37微克D6β-胡萝卜素(19，19，19，19‘，19’，19‘-[2H6]-β-胡萝卜素)。剂量与含16克脂肪的早餐一起服用。我们测量了血浆中D6视黄醇、D6β-胡萝卜素和三氢(D3)视黄醇(源自D6β-胡萝卜素)的浓度。测定D6视黄醇、D6β-胡萝卜素和D3视黄醇的血药浓度x给药曲线下面积(AUC)。结果所有受试者血浆中均可检测到D6视黄醇浓度。所有受试者对D6β-胡萝卜素的平均(+/-SE)吸收为2.235+/-0.925%，平均转化率为0.0296+/-0.0108摩尔视黄醇至1摩尔β-胡萝卜素。我们可以测量的11名男性中只有6名有足够的血浆D6β-胡萝卜素和D3视黄醇浓度。6名受试者对D6β-胡萝卜素的平均吸收率为4.097+/-1.208%，平均转化率为0.0540+/-0.0128摩尔视黄醇至1摩尔-胡萝卜素。结论：即使在受控条件下测定，β-胡萝卜素的维生素A活性也可能低得令人惊讶，而且变化很大。
BACKGROUND The vitamin A activity of beta-carotene is variable and surprisingly low in women. The reasons for this are not well understood. The vitamin A activity of beta-carotene in men is still uncertain. Contributions of dietary factors compared with individual traits are largely unknown. OBJECTIVE Our objective was to measure the intrinsic variability in the vitamin A activity of beta-carotene among healthy, well-fed men living in a controlled environment. DESIGN We used a double-tracer test-retest design. We dosed 11 healthy men orally with 30 micromol hexadeuterated (D6) retinyl acetate (all-trans-19,19,19,20,20,20-[2H6]retinyl acetate) and then with 37 micromol D6 beta-carotene (19,19,19,19',19',19'-[2H6]beta-carotene) 1 wk later. Doses were taken with breakfasts containing 16 g fat. We measured D6 retinol, D6 beta-carotene, and trideuterated (D3) retinol (derived from D6 beta-carotene) concentrations in plasma. Areas under the plasma concentration x time since dosing curves (AUCs) were determined for D6 retinol, D6 beta-carotene, and D3 retinol. RESULTS All men had detectable D6 retinol concentrations in plasma. The mean (+/-SE) absorption of D6 beta-carotene in all subjects was 2.235 +/- 0.925%, and the mean conversion ratio was 0.0296 +/- 0.0108 mol retinol to 1 mol beta-carotene. Only 6 of 11 men had sufficient plasma concentrations of D6 beta-carotene and D3 retinol that we could measure. The mean absorption of D6 beta-carotene in these 6 subjects was 4.097 +/- 1.208%, and the mean conversion ratio was 0.0540 +/- 0.0128 mol retinol to 1 mol beta-carotene. CONCLUSION The vitamin A activity of beta-carotene, even when measured under controlled conditions, can be surprisingly low and variable.