Discussion
The present randomized, placebo controlled study demonstrates
that antioxidant supplementation with vitamin
C, vitamin E, coenzyme Q10 and selenium significantly
increased large and small artery elasticity in patients with
multiple cardiovascular risk factors. This beneficial vascular
effect was associated with an improvement in glucose
and lipid metabolism as well as significant decrease
in blood pressure.
Assessment of arterial function and structure can serve
as a surrogate endpoint for prediction of morbid events
and for estimation of success of treatment. Pulse wave
contour analysis using the modified Windkessel model is
one of several noninvasive methods for estimation of
arterial properties. Numerous studies performed with the
HDI CR-2000 equipment have shown good correlation to
age, cardiovascular risk factors and markers of disease
[13]. Therapeutic interventions with medications like statins,
angiotensin II receptor blocking agents as well as
weight loss, have also shown improvement in LAEI and
SAEI which may suggest lowering of cardiovascular risk.
Nevertheless, no major prospective study associating
arterial elasticity with cardiovascular events has been
performed. Although PWA using the modified Windkessel
model has some limitations, this method provides
complementary information about vascular health.
The favorable vascular effect of antioxidants has been
observed in vitro and in animal models of atherosclerosis
[14-16]. However, data on long-term vascular impact of
antioxidant supplementation in humans are limited and
controversial. The findings of the present study concur
with those of previous study that has shown substantial
reduction in the progression of common carotid atherosclerosis
during three year treatment with combined supplementation
of both vitamin E and vitamin C [17].
Additionally, the beneficial effect of antioxidant supplementation
on LDL oxidation and endothelial flow has
been demonstrated [18,19]. Moreover several prospective
randomized controlled clinical trials such as Cambridge
Heart Antioxidant Study, Secondary Prevention with
Antioxidants of Cardiovascular Disease in End-stage