She refused to eat or drink anything that was brought into her room. While she didn't believe the house-elves enslaved by the Lestrange family would ever hurt her on their own, she feared the orders they were given. They could be putting potions in her food and in her drink. Perhaps not enough to make it noticeable, but just enough that she would gradually feel the effects when it was too late. She was grateful that her beaded bag still contained an adequate supply of food.