Include physical structure of food too, although this is less nutrition than the actual chemicals and substances inside the food this is the biology and chemistry of the food that we call the nutrition. All these foods are made up of a few things- protein, carb, fats, and water, plus other substances such as salt. These substances contain mineral content and vital cels- vitamins, because the structures they come from - plants and living things, are alive and have many chemical reactions inside them due to sunlight, blood matter, and other liquids in the flesh and body of the food item. SO, we can tell how much vitamin C is in orange foods, and how much potassium is in a fruit that has green spots as opposed to one that has black spots.