Vitamin C function and status in chronic disease.
Vitamin C function and status in chronic disease.
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DOI：
10.1046/j.1523-5408.2002.00005.x
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发表时间：
2002-03-01
期刊：
影响因子：
--
通讯作者：
Sotoudeh, Gity
中科院分区：
文献类型：
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作者：
Jacob, Robert A;Sotoudeh, Gity
维生素C是一种必需的膳食营养素，作为许多酶的辅助因子，人类是少数缺乏从葡萄糖合成该化合物的能力的动物之一。还原形式的维生素，抗坏血酸，是一种特别有效的抗氧化剂，由于其高电子供给能力和容易转换回活性还原形式。维生素在身体组织和体液中的浓度通过肠道吸收、细胞运输和排泄的相互作用来调节。预防坏血病所需的维生素C量非常小，几乎在所有西方饮食中都很容易获得。人们对维生素C的临床作用非常感兴趣，因为有证据表明氧化损伤是许多疾病的根本原因，或至少与许多疾病有关。人口研究表明，维生素C摄入量高的人患一些慢性疾病的风险较低，包括心脏病，癌症，眼疾和神经退行性疾病。然而，这些结果可能只是反映了维生素C摄入量高的人更健康的饮食或生活方式。目前，来自对照临床试验的数据还没有确定单独增加维生素C的摄入量将有助于预防慢性退行性疾病。然而，有证据表明抗坏血酸在许多身体组织中充当重要的抗氧化剂，这是令人信服的。新的更高的维生素C推荐膳食允许量（RDA）为女性75毫克和男性90毫克，这是第一次基于维生素作为抗氧化剂的作用以及对缺乏的保护。在健康人群中，大于RDA的量似乎没有帮助。维生素C营养可能对患有某些疾病或病症的人更重要。维生素的高摄入量通常耐受良好;最近根据胃肠道不适（有时伴随过量摄入）将可耐受上限设定为2 g。
Vitamin C is an essential dietary nutrient required as a co-factor for many enzymes, and humans are among the few animals that lack the ability to synthesize the compound from glucose. The reduced form of the vitamin, ascorbic acid, is an especially effective antioxidant owing to its high electron-donating power and ready conversion back to the active reduced form. Concentrations of the vitamin in body tissues and fluids are regulated through interactions of intestinal absorption, cellular transport, and excretion. The amount of vitamin C needed to prevent scurvy is very small and easily obtained in nearly all Western diets. There is great interest in the clinical roles of vitamin C because of evidence that oxidative damage is a root cause of, or at least associated with, many diseases. Population studies show that individuals with high intakes of vitamin C have lower risk of a number of chronic diseases, including heart disease, cancer, eye diseases, and neurodegenerative conditions. However, these results may simply reflect a more healthful diet or lifestyle for individuals with a high vitamin C intake. At present, data from controlled clinical trials have not established that higher intakes of vitamin C alone will help prevent chronic degenerative diseases. However, the evidence that ascorbic acid acts as an important antioxidant in many body tissues is convincing. The new higher Recommended Dietary Allowance (RDA) for vitamin C of 75 mg for women and 90 mg for men is, for the first time, based on the vitamin's role as an antioxidant as well as protection from deficiency. In healthy people, amounts greater than the RDA do not appear to be helpful. Vitamin C nutriture may be more important for people with certain diseases or conditions. High intakes of the vitamin are generally well tolerated; a Tolerable Upper Level was recently set at 2 g based on gastrointestinal upset that sometimes accompanies excessive intakes.