Protein sources contain different quantities of this macronutrient. To plan our diets with healthy protein, we need to understand the best sources to ensure adequate supply to every cell or tissue in our bodies. There are nine amino acids that the body must obtain from food. Studies show that it is the protein package (source) rather than the quantity that matters that matter to our health. Which foods can supply us with the best protein? We get protein from plants, poultry, and animals, as discussed below.