Human nutrition
The protein requirement for each individual differs, as do opinions about whether and to what extent physically active people require more protein. The 2005 Recommended Dietary Allowances (RDA), aimed at the general healthy adult population, provide for an intake of 0.8 grams of protein per kilogram of body weight. A review panel stating that "no additional dietary protein is suggested for healthy adults undertaking resistance or endurance exercise."
Vegetarian and vegan dog diet
A good source of protein provides a dog with a balanced and complete profile of amino acids, and is essential for growth, muscle maintenance, and various cellular functions. Conventionally, these amino acids are primarily provided through either a singular or a combination of animal meats, meals, and by-products. A vegan diet provides the same amino acids through plants such as legumes, peas, beans, nuts, seeds and grains. While all plants contain some amount of protein, some plant sources contain more than others. However, plant sources generally do not have as complete an amino acid profile, as they are often limiting in one or more essential amino acids.  Good sources of plant protein include chickpeas, green peas, soybeans, potatoes, rice, lentils, beans, and quinoa. In dog food, the protein composition can be sourced from a variety of ingredients, including grains, rice, corn, wheat, and/or barley. Soybeans, one of the most common plant-based protein sources in dog foods, provide a concentrated and complete protein source, meaning that they provide all the essential amino acids in adequate amounts. If soy is excluded for hypoallergenic purposes, chickpeas, green peas, rice, and potatoes are also common ingredients in commercial vegan dog foods. Nutritional yeast is another good source of complete protein, and can also be added to complement the amino acid profile.