Effect of mixed tocopherols on ecNOS, SOD and PKC in leukocytes in human subjects

Epidemiological studies have shown that intake of vitamin E derived from food decreases the risk of cardiovascular disease. However, recent clinical studies revealed no beneficial effect of α-tocopherol alone on cardiac death. Absence of other tocopherols in these latter studies may explain the conflicting results. This study was designed to compare the effects of mixed tocopherols with α-tocopherol alone on endothelial constitutive nitric oxide synthase (ecNOS), superoxide dismutase (SOD) and protein kinase C (PKC) in human leukocytes, which are known to be involved in cardiovascular disease. Sixty-four subjects were randomized into three groups: α-tocopherol, mixed tocopherols, and controls. After 8 weeks of tocopherol supplementation, SOD activity in plasma, ecNOS activation and SOD protein expression in leukocytes were increased, and PKC activation in leukocytes was decreased. Mixed tocopherols had a more potent effect than α-tocopherol alone on ecNOS activation, which may be of importance for the beneficial effects of mixed tocopherols on leukocyte function and cardiovascular disease.