[Vitamin E and coronary heart disease--why the lack of effect in large clinical trials?].
BACKGROUND
Oxidative modification of low-density lipoprotein (LDL) is likely to play a role in the development of atherosclerosis and coronary heart disease. In vitro studies, animal experiments and several observational investigations suggest that vitamin E is an effective preventive agent. Unfortunately, large clinical studies have failed to confirm these findings.


METHODS
On the basis of literature studies, I discuss the lack of effect.


RESULTS
The hypothesis that LDL must be oxidised to be really harmful, could be wrong. If oxidised LDL is an important atherogenic factor, vitamin E (alpha-tocopherol) might not be a powerful enough antioxidant, especially in the later stages of atherosclerosis. Maybe one needs to use a mixture of different kinds of vitamin E and co-antioxidants that can regenerate vitamin E to achieve an effect that is powerful enough? The effect of vitamin E might have been masked by n-3 fatty acids in some studies. The most plausible hypothesis is that only people with extraordinarily high oxidative stress will benefit from vitamin E supplementation.


CONCLUSIONS
Further research is needed to understand how oxidised LDL and vitamin E affect the development of coronary heart disease. In the meantime it is important to point out that a healthy diet with balanced amounts of antioxidants and enough n-3 fatty acids has been proven effective.
Andersen
J R
JR
Avdeling for helsefag Høgskulen i Sogn og Fjordane 6800 Førde. johnra@hisf.no
D000818:Animals; D000975:Antioxidants / Q000009:adverse effects*; D018849:Controlled Clinical Trials as Topic; D003324:Coronary Artery Disease / Q000097:blood / Q000209:etiology / Q000517:prevention & control; D003327:Coronary Disease / Q000097:blood / Q000209:etiology / Q000517:prevention & control*; D006801:Humans; D008077:Lipoproteins, LDL / Q000097:blood; D018384:Oxidative Stress; D016032:Randomized Controlled Trials as Topic; D014810:Vitamin E / Q000008:administration & dosage*
D000975:Antioxidants; D008077:Lipoproteins, LDL; D014810:Vitamin E