A complete protein (or whole protein) is a source of protein that contains an adequate proportion of all nine of the essential amino acids necessary for the dietary needs of humans or other animals.
According to the Food and Nutrition Board of the Institute of Medicine, complete proteins are supplied by meat, poultry, fish, eggs, milk, cheese, or yogurt. Since the amino acid profile of protein in plant food may be deficient in one or more of the following types, plant proteins are said to be incomplete. Vegetarian meals may supply complete protein by the practice of protein combining which raises the amino acid profile through plant variety.
The following table lists the optimal profile of the essential amino acids, which comprises complete protein, as recommended by the Institute of Medicine's Food and Nutrition Board:
The second column in the following table shows the amino acid requirements of adults as recommended by the World Health Organization calculated for a 62-kilogram (156 pounds) adult. Recommended Daily Intake is based on 2,000 kilocalories per day., which is also an appropriate daly calorie allowance for a fairly sendentary, 156-pound adult. The third column in the following table shows the amino acid profile of 2,000.14 kilocalories of baked potatoes (2,652 grams).
From the chart, you can see that if you ate nothing but baked potatoes all day, you would have plenty of every essential amino acid. Therefore, potatoes are a source of complete protein.
Nearly all whole foods contain all essential amino acids in sufficient quantity. The concept that plant proteins are incomplete or inferior has been dismissed by the nutrition community as myth. While many plant proteins are lower in one or more essential amino acids than animal proteins, especially lysine, and to a lesser extent methionine and threonine, eating a variety of plants can serve as a well-balanced and complete source of amino acids.
Consuming a mixture of plant-based protein sources can increase the biological value (BV) of food. For example, to obtain 25 grams of high BV protein requires 492 grams of canned pinto beans (USDA16044) for a total calorie intake of 423 kcal. When paired with 12 g of Brazil nuts (USDA12078), we require only 364 g of canned pinto beans, for a total of 391 kcal. This small addition of Brazil nuts yields a 23% reduction in the total food mass and a 7.5% reduction in calories. Complementary proteins need not be eaten at the same meal for your body to use them together. Your body can combine complementary proteins that are eaten over the course of the day.
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