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."
Vegetarianism
Protein intake in vegetarian diets is lower than in meat diets but can meet the daily requirements for most people. Studies at Harvard University as well as other studies conducted in the United States, United Kingdom, Canada, Australia, New Zealand and various European countries,
confirmed vegetarian diets provide sufficient protein intake as long as a variety of plant sources are available and consumed. Pumpkin seeds, peanut butter, hemp seed, almonds, pistachio nuts, flaxseed, tofu, oats, soybeans, walnuts, are great sources of protein for vegetarians. Proteins are composed of amino acids, and a common concern with protein acquired from vegetable sources is an adequate intake of the essential amino acids, which cannot be synthesised by the human body. While dairy and egg products provide complete sources for ovo-lacto vegetarian, several vegetable sources have significant amounts of all eight types of essential amino acids, including lupin beans, soy, hempseed, chia seed, amaranth, buckwheat, pumpkin seeds spirulina, pistachios, and quinoa. However, the essential amino acids can also be obtained by eating a variety of complementary plant sources that, in combination, provide all eight essential amino acids (e.g. brown rice and beans, or hummus and pita, though protein combining in the same meal is not necessary). A 1994 study found a varied intake of such sources can be adequate.