Oestrogen and inhibition of oxidation of low-density lipoproteins in postmenopausal women.

Oxidative modification of low-density lipoprotein (LDL) may be atherogenic. We studied the time of onset of LDL oxidation (lag) in 18 postmenopausal women before and after intraarterial infusion of 17 beta-oestradiol, after 3 weeks' patch administration in 12 of these women, and 1 month after discontinuation in 10. The lag increased from baseline after acute infusion (from 134 [SD41] to 167 [36] min, p = 0.01) and after the patch (132 [31] to 178 [45] min, p = 0.009). After discontinuation of oestradiol, the lag returned to baseline. This study shows an antioxidant effect of physiological levels of 17 beta-oestradiol, which may contribute to an anti-atherogenic action.