Humans do indeed require protein, as it is one of the three macronutrients we need to attain from our diet. Protein is involved in virtually all of the body’s structural and functional mechanisms. All of our cells contain protein and it constitutes the building blocks of muscles, hair, nails, organs, skin, tendons, ligaments, enzymes, membranes, some hormones, hemoglobin, antibodies, enzymes, and much more. However, just because something is critical doesn’t mean that more is better. In fact, when it comes to protein, consuming an excess of what we need may promote disease.
The other popular misconception is that animal products are the best source of protein. One important reason this myth has been perpetuated is because the amino acids—the building blocks of protein—are assembled in a way in animal foods that more closely resembles what humans actually utilize. However, we now know that this is inconsequential. When you consume any protein, it is broken down via digestion into its separate amino acid constituents and is pooled in the blood for further use. When the body needs to construct a protein for an enzyme or to repair muscles tissue, it collects the necessary amino acids and strings them back together in the sequence appropriate for what it is currently creating. This occurs regardless whether you consume animal or plant protein.
Humans need about 10 percent of calories from protein. Virtually all whole plant foods contain at least this amount, so if you consume enough volume and variety of whole plant foods, your protein requirement will easily be met. This applies to athletes too, who are often thought to require larger amounts of protein to sustain muscle size and optimize performance. However, athletes have increased overall calorie requirements, so when they boost their intake of whole plant foods, they automatically meet their greater need for all of the macronutrients, including protein.