Ekvall S, Chen I W, Bozian R
Am J Clin Nutr. 1981 Jul;34(7):1356-61. doi: 10.1093/ajcn/34.7.1356.
Serum levels of ascorbic acid and vitamin B12 were analyzed in 40 myelomeningocele children to study the effect of supplemental ascorbic acid on serum vitamin B12 levels. The experimental group was composed of 20 children receiving ascorbic acid for urinary acidification: 10 received an average of 1.8 g daily, 10 received an average of 1.5 g daily (the amount depending on the requirement needs for urinary acidification) half of each group received ascorbic acid for less than 3 yr (an average of 2.1 yr) and half received ascorbic acid for more than 3 yr (an average of 4.3 yr). The control group consisted of 20 myelomeningocele children not receiving supplemental ascorbic acid. Both groups were matched for age, sex, race, and physical activity. Dietary levels of ascorbic acid and B12 were calculated to rule out their influence on serum levels. Results showed that the experimental group with supplemental ascorbic acid produced significantly higher ascorbic acid values than the control group. The serum B12 levels of the experimental group were not significantly different than those of the control groups and these children showed neither a deficient serum levels of B12, anemia, nor elevated mean corpuscular volume. Hemoglobin levels were slightly higher for the experimental group. Dietary calculations of B12 and ascorbic acid were not significantly greater than the Recommended Daily Allowance ruling out any influence of diet on serum levels. No evidence of vitamin B12 deficiency developed in 20 myelomeningocele children receiving daily mean doses of 1.65 g of supplemental ascorbic acid. In view of our findings, it is highly improbable that megadoses of supplemental ascorbic acid would induce vitamin B12 deficiency in man.
对40名脊髓脊膜膨出患儿的血清抗坏血酸和维生素B12水平进行了分析，以研究补充抗坏血酸对血清维生素B12水平的影响。实验组由20名接受抗坏血酸以酸化尿液的儿童组成：10名儿童平均每天接受1.8克，10名儿童平均每天接受1.5克（剂量根据尿液酸化的需求而定），每组一半儿童接受抗坏血酸的时间少于3年（平均2.1年），另一半儿童接受抗坏血酸的时间超过3年（平均4.3年）。对照组由20名未接受抗坏血酸补充剂的脊髓脊膜膨出患儿组成。两组在年龄、性别、种族和身体活动方面进行了匹配。计算了抗坏血酸和B12的饮食摄入量，以排除它们对血清水平的影响。结果显示，补充抗坏血酸的实验组的抗坏血酸值明显高于对照组。实验组的血清B12水平与对照组无显著差异，这些儿童既没有血清B12水平不足、贫血，也没有平均红细胞体积升高的情况。实验组的血红蛋白水平略高。B12和抗坏血酸的饮食计算值并不显著高于推荐每日摄入量，排除了饮食对血清水平的任何影响。在20名每天平均接受1.65克补充抗坏血酸的脊髓脊膜膨出患儿中，没有出现维生素B12缺乏的证据。鉴于我们的研究结果，大剂量补充抗坏血酸极不可能导致人类维生素B12缺乏。
