Protein is essential to human life. Your skin, bones, muscles and organ tissue all contain protein. It's found in your blood, hormones and enzymes too. Protein is found in many plant foods. It comes from animal sources as well. Legumes, poultry, seafood, meat, dairy products, nuts and seeds are your richest sources of protein.
Between 10 percent and 35 percent of your total daily calories — 50 to 175 grams a day — can come from protein. This recommendation is based on a 2000-calorie diet.