Influence of dyslipidemia and smoking on redox markers in humans--a critical study.

Unlabelled: Experimental research indicates that oxidative processes play a role in susceptibility to a large number of diseases. A better understanding of the parameters affecting redox balance could delay and even prevent such processes.

Objective: The present study aims to investigate blood parameters associated with antioxidant systems in a Portuguese population for the first time, taking into consideration gender, age range, lipid profile and smoking habits as influencing factors.

Design And Participants: One hundred and eighty-three healthy Portuguese subjects of both genders were recruited from the metropolitan area of Lisbon. The group consisted of individuals aged from 20 to 70 years, who gave their informed consent before participating in the study. All subjects were screened to determine eligibility, which was based on a clinical report. Subjects were considered eligible if they had no acute or chronic illness and were not taking any drugs or dietary supplements that could compromise the values of the studied parameters. The subjects were then divided into different subgroups according to gender, age range, lipid profile and smoking habits.

Methods: Whole blood glutathione peroxidase activity and serum albumin, transferrin and uric acid were determined using commercially available kits. Superoxide dismutase activity in erythrocytes and thiobarbituric acid reactive substances in serum were measured using methods published elsewhere.

Results: Glutathione peroxidase activity was not affected by any of the studied variables, but superoxide dismutase activity decreased with smoking. Albumin levels remained unchanged under all conditions. Hyperlipidemia was associated with higher lipid peroxidation as well as higher uric acid levels. Gender was the strongest predictor for transferrin, total iron binding capacity and uric acid variations. Finally, a multivariate statistical model clearly separated genders and lipid profile and genders and smoking.

Conclusions: The present study suggests that hyperlipidemia and smoking should be considered important selection criteria in epidemiological studies focusing on oxidative stress and on the atherosclerotic process.