What does the lipoprotein oxidation phenomenon mean?

The evidence that oxidative lipid modification may be involved in the genesis of common diseases, such as atherosclerosis, is persuasive, but it was, until recently, conjecture based on in vitro findings, or investigation using experimental animal models. Recent clinical intervention studies in patients at high risk of cardiovascular events have been, at best, inconclusive. This has led to a general consensus that antioxidant supplements are of no value in the prevention of cardiovascular disease in subjects at high risk. However, epidemiological studies have demonstrated that the protective effects of antioxidant supplements, specifically vitamin E, were particularly evident amongst healthy subjects taking supplements. The picture is further clouded by the uncertain mechanism of lipoprotein modification within the artery wall, the possibility that some antioxidants may, under certain conditions, become pro-oxidants, the complex interactions between lipid- and water-soluble antioxidants, and the fact that free-radical-mediated events may only be important in the early stages of atherogenesis. Recent results also suggest that the biological efficacy of antioxidants, such as α-tocopherol, may be compromised by the conditions extant within the plaque. It is evidently important that the position on the benefits of antioxidants, whether in food or as supplements, in disease prevention is clarified.