Protein is an essential part of the human diet. The National Institutes of Health points out that every cell in the human body contains protein, as do all human fluids except urine and bile. Protein helps repair damaged cells and create new ones. While meat is a major source of protein, there are plenty of protein sources that are not derived from animal sources.
Tofu is a sensible protein substitute for those wanting to avoid animal products. According to the Vegetarian Society, it is recommended that the average individual consume 45 to 55 g of protein a day. A 5 oz. serving of tofu, which is derived from soy plants, contains 10.3 g of protein. Tofu can be mixed with vegetables and sauces to make it part of a complete meal.
The Harvard School of Public Health calls beans a "best bet" if you're looking for a food that will deliver protein. A 8 oz. serving of baked beans contains 11.5 g of protein. You can alternate bean varieties for flavor and for use in different recipes. Garbanzo, kidney, black and other beans are all excellent protein sources.
The Harvard School of Public Health also recommends nuts if you are on an animal-free protein diet. Not only do nuts provide a protein source, they contain vitamins, minerals and natural fiber. Although different nuts vary in their protein content, they are all a good source. A single ounce of peanuts, for example, contains 7.3 g of protein.
The Vegetarian Society also recommends muesli as a protein source. A 4.5 oz. serving of this mix of oats, nuts, wheat and fruit usually contains 7.7 g of protein. This is a good breakfast option if you're looking for a protein boost in the morning.