Flavonoids and tannins: plant-based antioxidants with vitamin character.

Persistent activation of the neuroendocrine stress axis is the major cause of a continuous catabolic alteration of the metabolism. This often causes an oxidative stress situation with increased release of O2 and NO radicals and pro-inflammatory cytokines. For the correction of these metabolic states, an adequate supply of plant-based antioxidants, especially flavonoids and tannins, is indicated. These are plant-based polyphenols which, like vitamins cannot be synthesized by the animal organism. Vitamin E in combination with vitamin C and beta-carotene are currently considered worldwide as the standard antioxidative therapy. However, it has recently been shown that, depending on the iron status of the recipient, pharmacological doses of these vitamins sometimes have beneficial, but often also no effect or harmful effects, so that, for a more reliable antoxidative action, adequate dietary supply of a mixture of flavonoids and tannins seems preferable.