There was never a sanction that prohibited food or medicine trade. The people starved because Saddam took the goods from 'oil for food' and sold them to pay cronies. The 'food for oil' was not a substiute for food-aid (or food-trade in the open market), but an additional method of trying to help common Iraqis - which he subverted, resulting in the direct deaths of 400,000 children, just by quantifying the food he diverted.