Protein is to the human body as water and sun are to plants. Proteins act as building blocks for bones, muscles, skin, and blood. The beneficial compound also helps encourage the growth and strengthening of enzymes, hormones, and vitamins. As one of three nutrients that provide calories, consider buying food rich in protein, which includes meat, fish, poultry, peas, beans, and nuts. If you have a busy schedule, protein bars make a convenient snack that you can work into your hectic day. A protein shake offers the same replenishment option for people who are always on the go. Whatever source you choose to enhance the intake of this important nutrient, you can find it online from the reliable sellers on eBay.