Adams P W, Wynn V, Folkard J, Seed M
Lancet. 1976 Apr 10;1(7963):759-64. doi: 10.1016/s0140-6736(76)91607-x.
Carbohydrate metabolism and vitamin-B6 status were assessed before and after pyridoxine administration in 46 women taking combined oestrogen-progestagen oral contraceptives (O.C.). 18 women had evidence of tissue depletion of vitamin B6, although all the women had abnormal tryptophan metabolism, including increased urinary xanthurenic acid (X.A.) excretion. In the women with vitamin B6 deficiency, administration of this vitamin caused elevation of fasting blood-pyruvate levels, and reduction in plasma glucose, insulin, and blood-pyruvate responses after an oral glucose load. These changes in carbohydrate metabolism were not found in the 28 non-vitamin-B6-deficient women. These results indicate that carbohydrate intolerance in women on O.C. is unlikely to be mediated by the formation of a complex of X.A. with insulin, as has formerly been proposed. Since the synthesis of the tryptophan metabolite quinolinic acid, an inhibitor of the heptaic enzyme phosphoenolpyruvate carboxykinase, may be enhanced by the administration of pyridoxine, it is suggested that this metabolite might be the important factor in the improvement of glucose tolerance in the vitamin-B6-deficient women. This conclusion is supported by the improvement in glucose tolerance observed in 6 women on O.C. and in 4 patients with glucocorticoid excess who were not vitamin-B6 deficient, when they were given tryptophan to augment the synthesis of quinolinic acid.
对46名服用复方雌激素 - 孕激素口服避孕药（O.C.）的女性在服用吡哆醇前后的碳水化合物代谢和维生素B6状态进行了评估。18名女性有维生素B6组织耗竭的证据，尽管所有女性都有异常的色氨酸代谢，包括尿中黄尿酸（X.A.）排泄增加。在维生素B6缺乏的女性中，给予这种维生素会导致空腹血丙酮酸水平升高，口服葡萄糖负荷后血浆葡萄糖、胰岛素和血丙酮酸反应降低。在28名非维生素B6缺乏的女性中未发现碳水化合物代谢的这些变化。这些结果表明，服用O.C.的女性中的碳水化合物不耐受不太可能如先前所提出的那样由X.A.与胰岛素形成复合物介导。由于给予吡哆醇可能会增强色氨酸代谢产物喹啉酸（一种肝脏酶磷酸烯醇丙酮酸羧激酶的抑制剂）的合成，因此有人认为这种代谢产物可能是维生素B6缺乏女性葡萄糖耐量改善的重要因素。在6名服用O.C.的女性和4名非维生素B6缺乏的糖皮质激素过多患者中，当给予色氨酸以增加喹啉酸的合成时观察到葡萄糖耐量改善，这一结论得到了支持。
