Ot. Raitakari et al., Coenzyme Q improves LDL resistance to ex vivo oxidation but does not enhance endothelial function in hypercholesterolemic young adults, FREE RAD B, 28(7), 2000, pp. 1100-1105
Oxidative modification of low-density lipoprotein (LDL) may cause arterial
endothelial dysfunction in hyperlipidemic subjects. Antioxidants can protec
t LDL from oxidation and therefore improve endothelial function. Dietary su
pplementation with coenzyme Q (CoQ(10)) raises its level within LDL, which
may subsequently become more resistant to oxidation. Therefore, the aim of
this study was to assess whether oral supplementation of CoQ(10) (50 mg thr
ee times daily) is effective in reducing ex vivo LDL oxidizability and in i
mproving vascular endothelial function. Twelve nonsmoking healthy adults wi
th hypercholesterolemia (age 34 +/- 10 years, nine women and three men, tot
al cholesterol 7.4 +/- 1.1 mmol/l) and endothelial dysfunction (below popul
ation mean) at baseline were randomized to receive CoQ(10) or matching plac
ebo in a double-blind crossover study (active/placebo phase 4 weeks, washou
t 4 weeks). Flow-mediated (FMD, endothelium-dependent) and nitrate-mediated
(NMD, smooth muscle-dependent) arterial dilatation were measured by high-r
esolution ultrasound. CoQ(10) treatment increased plasma CoQ(10) levels fro
m 1.1 +/- 0.5 to 5.0 +/- 2.8 mu mol/l (p = .009) but had no significant eff
ect on FMD (4.3 +/- 2.4 to 5.1 +/- 3.6 %, p = 99), NMD (21.6 +/- 6.1 to 20.
7 +/- 7.8 %, p = .38) or serum LDL-cholesterol levels (p = .51). Four subje
cts were selected randomly for detailed analysis of LDL oxidizability using
aqueous peroxyl radicals as the oxidant. In this subgroup, CoQ(10) supplem
entation significantly increased the time for CoQ(10)H(2) depletion upon ox
idant exposure of LDL by 41 +/- 19 min (p = .04) and decreased the extent o
f lipid hydroperoxide accumulation after 2 hours by 50 +/- 37 mu mol/l (p =
.04). We conclude that dietary supplementation with CoQ(10) decreases ex-v
ivo LDL oxidizability but has no significant effect on arterial endothelial
function in patients with moderate hypercholesterolemia. (C) 2000 Elsevier
Science Inc.