Hypertension and oxidative stress: effects of antioxidants on blood pressure, endothelial function and oxidative stress

心血管疾病(CVD)是西方国家最常见的死亡原因之一。高血压(血压升高)是心血管疾病的主要危险因素，越来越多的证据表明，氧化应激导致血压升高。当人体的抗氧化剂防御系统无法阻止自由基(氧化剂)造成的损害时，就会发生氧化应激。自由基损伤可能导致血管功能受损，导致血压升高。因此，我们将检验这一假设，即高血压与氧化应激增加有关，并且在高血压患者中补充水溶性抗氧化剂将减少氧化应激，改善血管功能，降低高血压患者的血压，这些患者患心血管疾病的风险更高。到目前为止，几乎没有直接证据表明高血压本身与氧化应激增加有关。因此，我们将进行一项比较，在有和没有其他心血管疾病危险因素的高血压患者和正常健康受试者中评估和比较氧化应激状态。如果氧化应激导致高血压，那么饮食中的抗氧化剂有望降低高血压患者的血压。补充抗氧化剂也有望减少氧化应激，改善血管功能。人群和干预研究的结果表明，维生素C和其他水溶性抗氧化剂可以减少氧化应激，改善血管功能，降低血压。因此，我们将研究饮食中添加水溶性抗氧化剂，包括维生素C和多酚化合物(植物食品来源的抗氧化剂)对这三个主要终点的影响。我们还将调查提供抗氧化剂的形式，片剂和果汁饮料是否会影响观察到的效果。

Cardiovascular disease (CVD) is one of the most common causes of mortality in Western countries. Hypertension (raised blood pressure) is a major risk factor for CVD, and growing evidence suggests that oxidative stress contributes to raised blood pressure. Oxidative stress occurs when the body's antioxidant defences cannot prevent damage caused by free radicals (oxidants). Free radical damage may lead to impairment of blood vessel function resulting in raised blood pressure. Therefore, we will test the hypothesis that hypertension is associated with increased oxidative stress, and that dietary supplementation with water-soluble antioxidants will reduce oxidative stress, improve blood vessel function and lower blood pressure in hypertensives subjects with higher risk of CVD. To date, there is little direct evidence demonstrating that hypertension per se is associated with increased oxidative stress. Therefore, we will undertake a comparison where oxidative stress status will be assessed and compared in hypertensive subjects with and without other risk factors for cardiovascular disease and in normal healthy subjects. If oxidative stress were contributing to high blood pressure then dietary antioxidants would be expected to lower blood pressure in subjects with hypertension. Reduced oxidative stress and improved blood vessel function would also be expected with antioxidant supplementation. Results of population and intervention studies in humans suggest that vitamin C and other water-soluble antioxidants may reduce oxidative stress, improve blood vessel function and lower blood pressure. Therefore, we will study the effects of dietary supplementation with water-soluble antioxidants, including vitamin C and polyphenolic compounds (plant food-derived antioxidants) on these three main endpoints. We will also investigate whether the form in which the antioxidants are provided, tablets versus fruit juice drink, influences the effects observed.