[Recent changes in concepts of antioxidant treatment].
The promising theoretical possibilities of antioxidant prevention and protection against vascular diseases and neoplasms could not have been realized as yet. The author searches into the causes of this failure by analyzing data of recent literature. Previous preventive trials as well as newly discovered pharmacological and molecular biological effects of antioxidants are reviewed. Results of meta-analyses on prevention trials of vascular disease by vitamin-E and those of gastrointestinal cancers are also included. The lately recognized properties of antioxidants are surveyed with special regard to their capability of modulating apoptosis, inducing gene expressions and their transformation into pro-oxidants. The harmful consequence of high doses of a single antioxidant is emphasized. The retinoids, vitamins D and K possess both pro-apoptotic and antiproliferative activity, while N-acetylcysteine exerts mainly anti-apoptotic effects. Since the effects of the eight vitamin E homologues are different in many respects, alpha-tocopherol can not be regarded as vitamin E of full value. Antioxidant supply from natural sources does not seem to be sufficient for an adequate preventive effect. The author recommends such a combination in which physiological amounts of vitamins C, D, K and B-complex, N-acetylcysteine, vitamin E of natural origin might be complemented by allopurinol, co-enzyme Q-10 and alpha-lipoic acid. A diet rich in flavonoids and carotenoids is essential. Application of appropriate laboratory methods is of great value in the individualization, monitoring and control of antioxidant treatment.