According to the comments of HAZRAT IMAM SADIQ (AS), here in this verse, by the food of the people of the Book, grains, cereals, and fruits are meant. In the matter of meat; it should be slaughtered in the name of Allah, with some ritual observances. This is opposed to animals butchered by Pagans with their superstitious rites. EATING THE FOODS OF THE PEOPLE OF THE BOOK.
(VERSE NO. 5)