Plasma Ascorbic Acid In Hypercholestrlaemic Subjects

Abstract

Plasma Ascorbic acid, total cholesterol, High density lipoprotein cholesterol levels and Total cholesterol/High density lipoprotein cholesterol ratio were determined in 52 newly diagnosed hypercholesterolaemic subjects and 48 normocholesterolaemic subjects. Hypercholesterolaemic subjects were defined as those with plasma total cholesterol ≥200mg/dl. The results showed that the mean plasma ascorbic acid levels were significantly lower in hypercholesterolaemic subjects when compared to normocholesterolaemics (P< 0.005) while total cholesterol , high density lipoprotein cholesterol and total cholesterol/high density lipoprotein cholesterol ratio were higher in hypercholesterolaemics than control (P<0.005). The low ascorbic acid levels observed in hypercholesterolaemics may be due to increased lipid peroxidation and hence low ascorbic acid levels may play a role in the aetiology of hypercholesterolaemia and therefore vitamin C supplements maybe useful in the management of Hypercholesterolaemia. INTRODUCTION Plasma lipids have many physiological functions and they have been incriminated as aetiological factors in atherosclerosis and coronary heart disease 1 . Hypercholesterolaemia is due to an increase in both free and esterified cholesterol. It could be genetic, acquired or may be secondary to other disorders or to dietary factors 2 . The beneficial effect of lowering serum cholesterol have been demonstrated in several experiments and results show that reducing serum cholesterol on average by just 1 mmol/l (34.6 mg/dl) with diet or drugs resulted in significant decreases in the incidence of coronary heart disease and rate of progression of coronary lesions 3 . Ascorbic acid has antioxidant properties protecting cellular membranes 4 and could therefore protect against atherosclerosis 5 ; of which hypercholesterolaemia is a risk factor. This study is aimed at determining the level of ascorbic acid in hypercholesterolaemics. MATERIALS AND METHODS SUBJECTS AND SAMPLES Patients attending the medical outpatient of the University of Benin Teaching Hospital, Benin City, Nigeria, had their plasma total and high density lipoprotein cholesterol estimated and those with total cholesterol levels ≥ 200 mg/dl were selected for the study as hypercholesterolaemic subjects. 52 newly diagnosed subjects were selected for this study and 48 apparently healthy normocholesterolaemic subjects were used as control. Prior to the study, the subjects were not on Ascorbic acid supplement and were also not on treatment as they had no knowledge of their cholesterol levels. 10 ml of venous blood sample were collected in appropriately labeled potassium EDTA anticoagulated containers. These were centrifuged and plasma separated into appropriately labeled containers. The cholesterol was assayed immediately while the plasma was stored frozen and the Ascorbic acid assayed within 48 hours. ESTIMATION OF PLASMA ASCORBIC ACID REAGENTS Trichloroacetic acid (TCA) 5 %( w/v)