Gamma-Tocopherol: An Important Dietary Factor for Protection Against Cardiovascular Disease

心脏病是西方国家最常见的死亡原因之一。氧化损伤被认为是许多慢性疾病（如心脏病）发展的主要原因。当身体的抗氧化防御不能阻止自由基或其他氧化剂造成的损伤时，氧化应激状态就会发生氧化损伤。抗氧化维生素有助于抵御氧化损伤，因此应该有助于预防心脏病（动脉粥样硬化）等疾病。人口研究支持膳食抗氧化剂如维生素E有助于预防心脏病的观点。然而，几项大型研究表明，给受试者补充维生素E（纯α -生育酚）对预防心脏病没有好处或保护作用。补充剂和维生素e的膳食摄入之间有一个关键的区别。补充剂只含有α -生育酚，而来自种子，坚果，谷物和油的膳食来源是不同形式的生育酚的混合物。最近的证据表明，其中一种形式（γ -生育酚）与α -生育酚具有不同的特性，并能以α -生育酚所不能的方式保护机体免受某些氧化剂的侵害。我们开发了一种专门的检测方法来检测人体血浆中与有毒氧化剂发生反应的γ -生育酚。通过这种检测，我们发现心脏病患者血液中这些产品的含量可能比没有心脏病的人高。该项目将调查γ和α生育酚膳食补充剂对心脏病危险因素的影响。它还将研究伽马生育酚如何防止心脏病的发生。这些研究可能对哪种类型的饮食或膳食补充剂最有利于预防心脏病有重要的意义。

Heart disease is one of the most common causes of death in Western Countries. Oxidative damage is thought to be a major contributor to the development of a number of chronic diseases such as heart disease. Oxidative damage can occur in states of oxidative stress when the body's antioxidant defences cannot prevent damage caused by free radicals or other oxidants. Antioxidant vitamins help defend against oxidative injury and therefore should help to protect against such diseases as heart disease (atherosclerosis). Population studies support the view that dietary antioxidants such as vitamin E help to protect against heart disease. However, several large studies giving subjects vitamin E supplements (pure alpha tocopherol) showed no benefits or protection against heart disease. There is a cruicial difference between supplements and dietary intake of vitamin E. Supplements contain only alpha tocopherol while dietary sources derived from seeds, nuts, grain and oils is a mixture of different forms of tocopherol. Recent evidence suggests that one of these forms (gamma-tocopherol) has different properties to alpha-tocopherol and can protect against certain oxidants in ways that alpha-tocopherol cannot. We have developed a specialised assay to detect forms of gamma-tocopherol in human plasma that have reacted with toxic oxidants. Using this assay we have shown that people with heart desease may have higher levels of these products in their blood than people without heart disease. This project will investigate the effects of gamma and alpha tocopherol dietary supplements on risk factors for heart disease. It will also investigate how gamma tocopherol may be working to protect against the development of heart disease. These studies could have important implications for what type of diet or dietary supplement is most beneficial to protect against heart disease.