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Do free radicals play causal role in atherosclerosis? Low density lipoprotein oxidation and vitamin E revisited.

Niki E - J Clin Biochem Nutr (2010)

Bottom Line: Firstly low density lipoprotein oxidation proceeds by multiple pathways mediated not only by free radicals but also by other non-radical oxidants and vitamin E is effective only against free radical mediated oxidation.Secondly, in contrast to animal experiments, vitamin E is given at the latter stage where oxidation is no more important.Free radicals must play causal role in pathogenesis of atherosclerosis and vitamin E should be effective if given at right time to right subjects.

View Article: PubMed Central - PubMed

Affiliation: Department of Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto 602-8566, Japan.

ABSTRACT
Lipid peroxidation induced by free radicals has been implicated in the pathogenesis of various diseases. Numerous in vitro and animal studies show that oxidative modification of low density lipoprotein (LDL) is an important initial event of atherosclerosis. Vitamin E and other antioxidants inhibit low density lipoprotein oxidation efficiently in vitro, however, human clinical trials with vitamin E have not yielded positive results. The mixed results for vitamin E effect may be ascribed primarily to the two factors. Firstly low density lipoprotein oxidation proceeds by multiple pathways mediated not only by free radicals but also by other non-radical oxidants and vitamin E is effective only against free radical mediated oxidation. Secondly, in contrast to animal experiments, vitamin E is given at the latter stage where oxidation is no more important. Free radicals must play causal role in pathogenesis of atherosclerosis and vitamin E should be effective if given at right time to right subjects.

No MeSH data available.


Related in: MedlinePlus

Progress of atherosclerosis and vitamin E supplementation (see text).
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Related In: Results  -  Collection


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Figure 1: Progress of atherosclerosis and vitamin E supplementation (see text).

Mentions: Secondly, atherosclerosis is a chronic disease and its onset, that is, the oxidative modification of LDL may have taken place decades before the symptoms appear. The major difference between human trials and animal experiments is that, in general, human trials start often after the onset of oxidative modification of LDL at the age of 50 or above, whereas in animal studies vitamin E or other antioxidant is given usually at the same time as the onset of oxidative stress (Fig. 1). It may be unrealistic to expect that a few years of antioxidant supplementation can turn around the effects of oxidative stress on endothelium which lasted more than 30 years. In contrast to human trials, the animal studies are performed under the same lifestyle with the same diet, which may yield more consistent outcome than human trials.


Do free radicals play causal role in atherosclerosis? Low density lipoprotein oxidation and vitamin E revisited.

Niki E - J Clin Biochem Nutr (2010)

Progress of atherosclerosis and vitamin E supplementation (see text).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3022060&req=5

Figure 1: Progress of atherosclerosis and vitamin E supplementation (see text).
Mentions: Secondly, atherosclerosis is a chronic disease and its onset, that is, the oxidative modification of LDL may have taken place decades before the symptoms appear. The major difference between human trials and animal experiments is that, in general, human trials start often after the onset of oxidative modification of LDL at the age of 50 or above, whereas in animal studies vitamin E or other antioxidant is given usually at the same time as the onset of oxidative stress (Fig. 1). It may be unrealistic to expect that a few years of antioxidant supplementation can turn around the effects of oxidative stress on endothelium which lasted more than 30 years. In contrast to human trials, the animal studies are performed under the same lifestyle with the same diet, which may yield more consistent outcome than human trials.

Bottom Line: Firstly low density lipoprotein oxidation proceeds by multiple pathways mediated not only by free radicals but also by other non-radical oxidants and vitamin E is effective only against free radical mediated oxidation.Secondly, in contrast to animal experiments, vitamin E is given at the latter stage where oxidation is no more important.Free radicals must play causal role in pathogenesis of atherosclerosis and vitamin E should be effective if given at right time to right subjects.

View Article: PubMed Central - PubMed

Affiliation: Department of Gastroenterology and Hepatology, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto 602-8566, Japan.

ABSTRACT
Lipid peroxidation induced by free radicals has been implicated in the pathogenesis of various diseases. Numerous in vitro and animal studies show that oxidative modification of low density lipoprotein (LDL) is an important initial event of atherosclerosis. Vitamin E and other antioxidants inhibit low density lipoprotein oxidation efficiently in vitro, however, human clinical trials with vitamin E have not yielded positive results. The mixed results for vitamin E effect may be ascribed primarily to the two factors. Firstly low density lipoprotein oxidation proceeds by multiple pathways mediated not only by free radicals but also by other non-radical oxidants and vitamin E is effective only against free radical mediated oxidation. Secondly, in contrast to animal experiments, vitamin E is given at the latter stage where oxidation is no more important. Free radicals must play causal role in pathogenesis of atherosclerosis and vitamin E should be effective if given at right time to right subjects.

No MeSH data available.


Related in: MedlinePlus