Protein is an essential nutrient that helps in building lean muscle, and helps maintain a healthy weight. Vegetarians often lose out on protein because of the misinformation that animal sources have more protein. Here are good protein rich vegetarian sources. Protein is an essential nutrient that helps in building lean muscle, and helps maintain a healthy weight. Vegetarians often lose out on protein because of the misinformation that animal sources have more protein. Here are good protein rich vegetarian sources.