Effect of caffeic acid dietary supplementation on the antioxidant defense system in rat: an in vivo study.

Dietary supplementation of caffeic acid (0.2 and 0.8% w/w) in rats resulted in a statistically significant increase of alpha-tocopherol both in plasma and lipoprotein. While caffeic acid was not detectable in plasma under fasting conditions, in postprandial plasma it was present at micromole concentrations, doubling plasma total antioxidant capacity. Lipoproteins from caffeic acid-fed rats were more resistant than control to Cu2+-catalyzed oxidation, despite the lack of incorporation of caffeic acid in the particles. No significant effects on plasma and liver copper concentration, nor the increase in liver of Mn-superoxide dismutase reported in copper deficiency, were detected. These results demonstrate the physiological relevance of caffeic acid and its antioxidant action in vivo, through both a direct contribution to the antioxidant defense system and a sparing effect on alpha-tocopherol.