Eating anything sweet will disguise the bitterness momentarily but then the harshness will kick back in with a vengeance after the sweet flavor disappears.  Eating acidic food will make the wine worse, since acidity and bitterness reinforce each other.  The only substance that can improve strongly tannic wine is diary.  Milk’s fat and protein can effectively camouflage the bitterness and make the tannins taste softer.  So, pairing strongly tannic wine with cheese will taste better.

Source: The Wine Bible by Karen MacNeil