Department of Nutrition, University of California, Davis, CA 95616, USA.
J Nutr. 2010 Sep;140(9):1588-94. doi: 10.3945/jn.110.125500. Epub 2010 Jul 21.
A survey indicated that high-dose vitamin A (HD-VA) supplements had no apparent effect on vitamin A (VA) status, assessed by serum retinol concentrations, of Zambian children lt 5 y of age. To explore possible reasons for the lack of response, we quantified absorption, retention, and urinary elimination of either a single HD-VA supplement (209.8 micromol; 60 mg) or a smaller dose of stable isotope (SI)-labeled VA (17.5 micromol; 5 mg), which was used to estimate VA pool size, in 3- to 4-y-old Zambian boys (n = 4 for each VA dose). A tracer dose of [(14)C(2)]-labeled VA (0.925 kBq; 25 nCi) was coadministered with the HD-VA supplement or SI-labeled VA, and 24-h stool and urine samples were collected for 3 and 7 consecutive days, respectively, and 24-h urine samples at 4 later time points. Accelerator MS was used to quantify (14)C in stool and urine. Estimates of absorption, retention, and the urinary elimination rate (UER) were 83.8 +/- 7.1%, 76.3 +/- 6.7%, and 1.9 +/- 0.6%/d, respectively, for the HD-VA supplement and 76.5 +/- 9.5%, 71.1 +/- 9.4%, and 1.8 +/- 1.2%/d, respectively, for the SI-labeled VA. Mean estimates of absorption, retention, and the UER did not differ by size of the VA dose administered. Estimated absorption and retention were negatively associated with reported fever (r = minus 0.83; P = 0.011). The HD-VA supplement and SI-labeled VA were adequately absorbed, retained, and utilized in apparently healthy Zambian preschool-age boys; absorption and retention may be affected by recent fever.
一项调查表明，大剂量维生素 A（HD-VA）补充剂对赞比亚 5 岁以下儿童的血清视黄醇浓度评估的维生素 A（VA）状况没有明显影响。为了探究缺乏反应的可能原因，我们分别对 3 至 4 岁的赞比亚男孩（每个 VA 剂量组各 4 名）单次给予 HD-VA 补充剂（209.8 微摩尔；60 毫克）或较小剂量的稳定同位素（SI）标记 VA（17.5 微摩尔；5 毫克），并定量检测了吸收、保留和尿排泄情况，SI 标记 VA 用于估计 VA 池大小。同时给予示踪剂量的[(14)C(2)]标记 VA（0.925 kBq；25 nCi），分别连续 3 天和 7 天收集 24 小时粪便和尿液样本，之后在 4 个后续时间点收集 24 小时尿液样本。使用加速器质谱法对粪便和尿液中的（14)C 进行定量。HD-VA 补充剂和 SI 标记 VA 的吸收、保留和尿排泄率（UER）估计值分别为 83.8 +/- 7.1%、76.3 +/- 6.7%和 1.9 +/- 0.6%/d，SI 标记 VA 分别为 76.5 +/- 9.5%、71.1 +/- 9.4%和 1.8 +/- 1.2%/d。给予的 VA 剂量大小对吸收、保留和 UER 的平均估计值没有影响。吸收和保留与报告的发热呈负相关（r = -0.83；P = 0.011）。HD-VA 补充剂和 SI 标记 VA 在健康状况良好的赞比亚学龄前男孩中被充分吸收、保留和利用；吸收和保留可能受到近期发热的影响。
