Long-term pharmacologic doses of vitamin E only moderately affect the erythrocytes of patients with type 1 diabetes mellitus.
In erythrocytes from diabetic patients, increased membrane lipid peroxidation might lead to abnormalities in composition and function. To study this relationship, we investigated the effects of a moderate pharmacologic dose of vitamin E for 1 y on erythrocyte membrane peroxidation in vitro and on its fatty acid composition, antioxidant capacity and rheological function. In a random and double-blind manner, type 1 diabetic patients (n = 44) were assigned to the following two groups: Group S received 250 IU (168 mg) d-alpha tocopherol 3 times daily for 1 y. Group P received placebo for 6 mo followed by d-alpha-tocopherol for an additional 6 mo. Variables were monitored every 3 mo. After 3 mo of supplementation, serum vitamin E doubled (P < 0.0005), thiobarbituric acid reactive substances in erythrocyte membranes incubated with tert-butyl hydroperoxide decreased by 25% (P = 0.006) and the lagtime of fluorescence increased from 28 +/- 16 to 41 +/- 28 min (P = 0.028). Patients who did not respond to supplementation (13 of 44) had lower serum lipids (P = 0.017) and body mass index (P = 0.024). We did not detect any significant effects of vitamin E supplementation on membrane lipid composition, antioxidant capacity or blood viscosity. Continuing supplementation for up to 1 y did not further affect serum vitamin E or membrane peroxidation. Stopping supplementation was followed by a return to inclusion values. These results show that the decrease in erythrocyte membrane peroxidation after vitamin E supplementation is moderate, saturable, reversible, restricted to some individuals and has no detectable effect on erythrocyte composition and function.
Manuel y Keenoy
B
B
Laboratory of Endocrinology, University of Antwerp, B-2610 Wilrijk-Antwerp, Belgium. begona@uia.ac.be
Shen
H
H
Engelen
W
W
Vertommen
J
J
Van Dessel
G
G
Lagrou
A
A
De Leeuw
I
I
D000328:Adult; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology*; D001809:Blood Viscosity; D008078:Cholesterol, LDL / Q000097:blood; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000378:metabolism*; D004311:Double-Blind Method; D004910:Erythrocyte Membrane / Q000737:chemistry / Q000187:drug effects*; D005227:Fatty Acids / Q000032:analysis; D005231:Fatty Acids, Unsaturated / Q000032:analysis; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D015227:Lipid Peroxidation; D008297:Male; D008875:Middle Aged; D010743:Phospholipids / Q000032:analysis; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis; D013997:Time Factors; D014810:Vitamin E / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D020122:tert-Butylhydroperoxide / Q000494:pharmacology
D000975:Antioxidants; D008078:Cholesterol, LDL; D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D010743:Phospholipids; D017392:Thiobarbituric Acid Reactive Substances; D014810:Vitamin E; D020122:tert-Butylhydroperoxide