Background: Both statins and vitamin E, by reducing the rate of lipid peroxidation, may interfere with oxidative stress, but the impact of their combination is unknown.
Methods and results: We randomized 43 hypercholesterolemic patients (21 men, 22 women, age 63+/-11 years) to either simvastatin, to achieve >20% reduction of total cholesterol, or simvastatin plus 600 mg/d vitamin E for 2 months. Patients were then crossed over to the alternative treatment. Lipid parameters documented patients' compliance to simvastatin, whereas plasma levels of vitamin E documented compliance and absorption of vitamin E. We assessed urinary excretion of the isoprostane 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)) as an in vivo index of oxidative stress at baseline and after each month of therapy. 8-Iso-PGF(2alpha) was significantly reduced by simvastatin, from 361+/-148 pg/mg creatinine (mean+/-SD) at baseline to 239+/-124 pg/mg creatinine after 1 month. The addition of vitamin E did not reduce such levels any further (256+/-125 after 1 month). Linear regression analysis showed a weak inverse relationship of 8-iso-PGF(2alpha) with vitamin E levels but a much stronger relationship with LDL cholesterol (R(2)=0.162; P<0.001).
Conclusions: In hypercholesterolemic patients, LDL cholesterol is a major correlate of oxidative stress. Concomitant with LDL cholesterol reduction, simvastatin causes a drastic reduction of oxidative stress to a level that is not further reduced by the addition of vitamin E. Results of clinical trials with vitamin E may have been hampered by inadequate knowledge of the background level of lipid peroxidation, which is a major determinant of vitamin E bioactivity.