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Laboratory of Endocrinology and * Laboratory of Human and Pathological Biochemistry, University of Antwerp, B-2610 Wilrijk-Antwerp, Belgium
2To whom correspondence should be addressed. E-mail: begona{at}uia.ua.ac.be.
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-
tocopherol 3 times daily
for 1 y. Group P received placebo for 6 mo followed by
d-
-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.
KEY WORDS: vitamin E type 1 diabetes mellitus erythrocytes lipid peroxidation membranes viscosity humans