Although Geralt does not need to eat or drink during the game, if he has no healing potions, then he could use some food to help increase his vitality. Below is a table of all food items in The Witcher. All of these items can be consumed, and if so, provide 9 minutes of vitality regeneration each.
Note: When consuming food for the purpose of increasing vitality regeneration, it is important to avoid eating the same type of food if you want to gain several bonuses at once. For example, eating two blueberries will only show one regeneration effect in the HUD, but eating a blueberry and a loaf of bread would show two.