Endothelial dysfunction may be thought of as the failure of the cells lining the inside of arteries and veins to regulate properly blood vessel relaxation and contraction, blood clotting, immune function, and platelet adhesion.

Endothelial dysfunction prevents the blood vessels from dilating sufficiently and can lead to increased risk of atherosclerosis, heart attack, and stroke.

Coenzyme Q10 supplementation is associated with significant improvement in endothelial function.