Sen Chandan K, Khanna Savita, Rink Cameron, Roy Sashwati
Laboratory of Molecular Medicine, Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University Medical Center, Columbus, Ohio 43210, USA.
Vitam Horm. 2007;76:203-61. doi: 10.1016/S0083-6729(07)76008-9.
Natural vitamin E includes eight chemically distinct molecules: alpha-, beta-, gamma-, and delta-tocopherols and alpha-, beta-, gamma-, and delta-tocotrienols. More than 95% of all studies on vitamin E are directed toward the specific study of alpha-tocopherol. The other forms of natural vitamin E remain poorly understood. The abundance of alpha-tocopherol in the human body and the comparable efficiency of all vitamin E molecules as antioxidants led biologists to neglect the non-tocopherol vitamin E molecules as topics for basic and clinical research. Recent developments warrant a serious reconsideration of this conventional wisdom. The tocotrienol subfamily of natural vitamin E possesses powerful neuroprotective, anticancer, and cholesterol-lowering properties that are often not exhibited by tocopherols. Current developments in vitamin E research clearly indicate that members of the vitamin E family are not redundant with respect to their biological functions. alpha-Tocotrienol, gamma-tocopherol, and delta-tocotrienol have emerged as vitamin E molecules with functions in health and disease that are clearly distinct from that of alpha-tocopherol. At nanomolar concentration, alpha-tocotrienol, not alpha-tocopherol, prevents neurodegeneration. On a concentration basis, this finding represents the most potent of all biological functions exhibited by any natural vitamin E molecule. Recently, it has been suggested that the safe dose of various tocotrienols for human consumption is 200-1000/day. A rapidly expanding body of evidence supports that members of the vitamin E family are functionally unique. In recognition of this fact, title claims in publications should be limited to the specific form of vitamin E studied. For example, evidence for toxicity of a specific form of tocopherol in excess may not be used to conclude that high-dosage "vitamin E" supplementation may increase all-cause mortality. Such conclusion incorrectly implies that tocotrienols are toxic as well under conditions where tocotrienols were not even considered. The current state of knowledge warrants strategic investment into the lesser known forms of vitamin E. This will enable prudent selection of the appropriate vitamin E molecule for studies addressing a specific health need.
天然维生素E包含八种化学结构不同的分子：α-、β-、γ-和δ-生育酚以及α-、β-、γ-和δ-生育三烯酚。所有关于维生素E的研究中，超过95%都针对α-生育酚的具体研究。天然维生素E的其他形式仍未得到充分了解。人体内α-生育酚的含量丰富，且所有维生素E分子作为抗氧化剂的效率相当，这使得生物学家忽视了非生育酚类维生素E分子作为基础和临床研究的课题。最近的进展值得对这种传统观念进行认真反思。天然维生素E的生育三烯酚亚家族具有强大的神经保护、抗癌和降胆固醇特性，而生育酚通常不具备这些特性。维生素E研究的当前进展清楚地表明，维生素E家族成员在生物学功能方面并非多余。α-生育三烯酚、γ-生育酚和δ-生育三烯酚已成为在健康和疾病中具有与α-生育酚明显不同功能的维生素E分子。在纳摩尔浓度下，是α-生育三烯酚而非α-生育酚可预防神经退行性变。基于浓度而言，这一发现代表了任何天然维生素E分子所展现的所有生物学功能中最有效的一种。最近有人提出，人类食用各种生育三烯酚的安全剂量为每天200 - 1000。越来越多的证据支持维生素E家族成员在功能上是独特的。认识到这一事实，出版物中的标题声明应限于所研究的维生素E的特定形式。例如，某种特定形式的生育酚过量时的毒性证据，不能用于得出高剂量“维生素E”补充剂可能增加全因死亡率的结论。这样的结论错误地暗示在甚至未考虑生育三烯酚的情况下，生育三烯酚也是有毒的。当前的知识状况需要对鲜为人知的维生素E形式进行战略投资。这将有助于为满足特定健康需求的研究审慎选择合适的维生素E分子。
