It depends upon how much oxidized cholesterol, UFAs (especially
PUFAs), iron, antioxidant-rich foods, etc. you are ingesting.  If you
avoid the first two, and don't get too much of the third, then you
don't have to ingest much cocoa at all.  I drink diluted coffee and
tea, and eat small amounts of dark chocolate each day, though I
probably don't need to (since I avoid those dangerous substances) - I
mostly do it because I like the taste.