Dai Jun, Jones Dean P, Goldberg Jack, Ziegler Thomas R, Bostick Roberd M, Wilson Peter W, Manatunga Amita K, Shallenberger Lucy, Jones Linda, Vaccarino Viola
Department of Medicine, Division of Cardiology, Emory Program in Cardiovascular Outcomes Research and Epidemiology, Emory University School of Medicine, Atlanta, GA 30306, USA.
Am J Clin Nutr. 2008 Nov;88(5):1364-70. doi: 10.3945/ajcn.2008.26528.
The cardioprotective property of the Mediterranean diet has been attributed to its antioxidant capacity, but direct investigation of this mechanism has been limited.
We examined the association between the Mediterranean diet and an established plasma marker of oxidative stress, the ratio of reduced to oxidized glutathione (GSH/GSSG), in a well-controlled study of twins.
We administered the Willett food-frequency questionnaire to 138 monozygotic and dizygotic twin pairs and to 21 unpaired twins and derived a score measuring adherence to the Mediterranean diet. Fasting plasma GSH and GSSG concentrations were measured to calculate the GSH/GSSG ratio. The higher the ratio, the lower the oxidative stress. Mixed-effect regression analysis was used to partition the association into between- and within-twin pair differences. When within-pair effects are examined, twins are matched for sociodemographic and familial factors.
A one-unit increment in the diet score was associated with a 7% higher GSH/GSSG ratio (P = 0.03) after adjustment for energy intake, other nutritional factors, cardiovascular disease risk factors, and medication use. The association persisted within twin pairs: a one-unit within-pair absolute difference in the diet score was associated with a 10% (95% CI: 2.7, 18.0) higher GSH/GSSG ratio in the twin with the higher score than in the co-twin with the lower score (P = 0.007). Results were similar in monozygotic and dizygotic twin pairs.
The association between the Mediterranean diet and plasma oxidative stress is robust and is not confounded by genetic or shared environmental factors. Decreased oxidative stress is a plausible mechanism linking the Mediterranean diet to reduced cardiovascular disease risk.
地中海饮食的心脏保护特性归因于其抗氧化能力，但对这一机制的直接研究有限。
在一项严格控制的双胞胎研究中，我们检验了地中海饮食与氧化应激的既定血浆标志物——还原型谷胱甘肽与氧化型谷胱甘肽的比值（GSH/GSSG）之间的关联。
我们对138对同卵和异卵双胞胎以及21对非配对双胞胎进行了威尔特食物频率问卷调查，并得出一个衡量对地中海饮食依从性的分数。测量空腹血浆GSH和GSSG浓度以计算GSH/GSSG比值。该比值越高，氧化应激越低。采用混合效应回归分析将这种关联分为双胞胎对之间和双胞胎对内部的差异。在检验双胞胎对内部的效应时，双胞胎在社会人口学和家族因素方面是匹配的。
在调整能量摄入、其他营养因素、心血管疾病危险因素和药物使用后，饮食分数每增加一个单位，GSH/GSSG比值就会升高7%（P = 0.03）。这种关联在双胞胎对内部持续存在：饮食分数在双胞胎对内部的绝对差异每增加一个单位，得分较高的双胞胎的GSH/GSSG比值比得分较低的双胞胎高10%（95%CI：2.7，18.0）（P = 0.007）。同卵和异卵双胞胎对的结果相似。
地中海饮食与血浆氧化应激之间的关联是稳健的，不受遗传或共同环境因素的混淆。氧化应激降低是将地中海饮食与降低心血管疾病风险联系起来的一个合理机制。
