Diabetes Care, Vol 22, Issue 10 1626-1631, Copyright © 1999 by American Diabetes Association
Vitamin E supplementation and oxidative damage to DNA and plasma LDL in type 1 diabetes
S Astley, A Langrish-Smith, S Southon and M Sampson
Institute of Food Research, Norwich, U.K.
OBJECTIVE: To determine the effect of 400 IU/day of the antioxidant vitamin
E on the susceptibility of plasma LDL and lymphocyte DNA to oxidative
damage in type 1 diabetes. RESEARCH DESIGN AND METHODS: We studied 42
patients with type 1 diabetes and 31 age- and sex-matched control subjects
in a randomized prospective double-blind placebo-controlled trial by using
400 IU/day of oral vitamin E for 8 weeks. Measurements were made of
single-strand breaks in lymphocyte DNA at baseline and after hydrogen
peroxide-induced stress (comet assay) and of copper-induced LDL oxidization
and plasma antioxidant profiles. RESULTS: Plasma LDL and lymphocyte DNA
were more resistant to induced oxidative change in the type 1 diabetes
group than in control subjects. Vitamin E supplementation reduced LDL
oxidizability in the control subjects but not in the type 1 diabetes group
and had no effect on oxidative DNA damage in either group. The type 1
diabetes group had a significantly poorer plasma antioxidant profile with
lower mean serum concentrations of alpha-tocopherol and most carotenoids
than control subjects. CONCLUSIONS: Plasma LDL and lymphocyte DNA appear to
be more resistant to oxidative change in type 1 diabetic subjects than in
control subjects, and there was no evidence of oxidatively induced DNA or
LDL change in type 1 diabetes. This study does not support the hypothesis
of oxidative damage in these patients, and a dose of vitamin E (400 IU/day)
that reduced LDL oxidative susceptibility in control subjects did not do so
in patients with type 1 diabetes.