Green tea is popular in Asia, including Japan, although it is rarely consumed by western people. It contains large amounts of catechins which are potent free radical scavengers and therefore has an antioxidant effect.¹ Oxidative stress participates in the pathogenesis of many cardiovascular diseases. Recently, black tea consumption has been shown to reverse endothelial dysfunction in patients with coronary artery disease through its antioxidant effects.² However, the number of catechins in non-fermented tea (green tea) is higher than that in fermented tea (black tea).¹ These findings raise the possibility that green tea acts as a potent antioxidant.

Smoking is a well recognised risk factor for cardiovascular diseases. Free radicals in cigarette smoke are responsible for endothelial dysfunction, leading to atherosclerosis.³ Earlier studies have shown that the flavonoid components of red wine and purple grape juice, which are powerful antioxidants, reverse endothelial dysfunction and reduce cardiovascular risk. However, any beneficial effect of green tea on vascular function in smokers remains unknown. Accordingly, the purpose of this study was to investigate whether green tea consumption reverses endothelial dysfunction in association with improvement of oxidative stress in healthy smokers.

METHODS

We studied 20 healthy male smokers (mean (SEM) age 33 (1) years, body mass index 22.9 (0.9) kg/m², smoking 15.5 (2.1) packs/year). They were randomised to consume green tea or hot water in a crossover design. All subjects gave written informed consent and the …