The high antioxidant capacity of dietary flavonoids found in cocoa and chocolate may have beneficial effects in the treatment of degenerative diseases such as atherosclerosis, but the link between dietary habits and the protective effects of flavonoid-rich foods has been unclear. In a Brief Communication in the August 28 Nature, Mauro Serafini and colleagues from National Institute for Food and Nutrition Research show that milk may interfere with the absorption of antioxidants from chocolate in vivo and may therefore negate the potential health benefits that can be derived from eating moderate amounts of dark chocolate (Nature, 424:1013, August 28, 2003).

Serafini et al. tested different chocolate varieties on 12 health volunteers and measured their total plasma antioxidant capacities and plasma levels of the flavonoid (-)epicatechin. They observed that absorption of (-)epicatechin into the bloodstream and plasma antioxidant capacity was significantly reduced following ingestion of chocolate accompanied by milk or chocolate containing milk.

"Our findings highlight the possibility that the in vivo antioxidant activity of flavonoids could be impaired by other dietary constituents… and this needs to be taken into account when designing studies to assess the association between flavonoid rich foods, antioxidant activity and degenerative diseases," concluded the authors.