Complete protein

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Main article: Protein (nutrient)

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.[1]

According to the Food and Nutrition Board of the Institute of Medicine, complete proteins are supplied by meat, poultry, fish, eggs, milk, cheese, yogurt, quinoa, or soybean. Since the amino acid profile of protein in plant food may, except for few cases, be deficient in one or more of the following types, plant proteins are said to be incomplete, although it is a myth.[2][3] 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:[2][4]

Essential Amino Acid mg/g of Protein
Tryptophan 7
Threonine 27
Isoleucine 25
Leucine 55
Lysine 51
Methionine+Cystine 25
Phenylalanine+Tyrosine 47
Valine 32
Histidine 18

The second column in the following table shows the amino acid requirements of adults as recommended by the World Health Organization[5] calculated for a 62-kilogram (156 pounds) adult. Recommended Daily Intake is based on 2,000 kilocalories per day.,[6] which is also an appropriate daly calorie allowance for a fairly sendentary, 62-kilogram adult. The third column in the following table shows the amino acid profile of 2466 kilocalories of baked potatoes (2,652 grams).[7]

Essential Amino Acid Requirement /day/62 kg adult 2652 grams baked potatoes[7]
mg mg
Tryptophan 248 796
Threonine 930 1883
Isoleucine 1240 2122
Leucine 2418 3129
Lysine 1860 3156
Methionine+Cystine 930 1485
Phenylalanine+Tyrosine 1550 4243
Valine 1612 2917
Histidine 620 1140

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.[3]

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.[8] 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.[3]

Sources of complete protein[edit]

See also[edit]


  1. ^ a b "Protein in diet". Medline Plus Medical Encyclopedia. U.S. National Library of Medicine and National Institute of Health. September 2, 2003. Retrieved 2006-10-28. 
  2. ^ a b c Food and Nutrition Board of Institute of Medicine (2005) Dietary Reference Intakes for Protein and Amino Acids, page 691, from National Academies Press
  3. ^ a b c Young VR, Pellett PL (1994). "Plant proteins in relation to human protein and amino acid nutrition" (PDF). American Journal of Clinical Nutrition. 59 (5 Suppl): 1203S–1212S. PMID 8172124. 
  4. ^
  5. ^ World Health Organization, Protein and Amino Acid Requirements in Human Nutrition, p. 245
  6. ^ "Guidance for Industry: A Food Labeling Guide". U.S. Food & Drug Administration. US FDA. Retrieved 14 January 2017. 
  7. ^ a b National Nutrient Database for Standard Reference Release 28, Nutrient data for 11336, Potatoes, white, flesh and skin, baked
  8. ^ Woolf, P. J.; Fu, L. L.; Basu, A. (2011). Haslam, Niall James, ed. "VProtein: Identifying Optimal Amino Acid Complements from Plant-Based Foods". PLoS ONE. 6 (4): e18836. doi:10.1371/journal.pone.0018836. PMC 3081312Freely accessible. PMID 21526128. 
  9. ^ Greger, Miichael. "The Protein-Combining Myth". Retrieved 12 January 2017. 
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  23. ^ "Tillery points out that a number of popular ethnic foods involve such a combination, so that in a single dish, one might hope to get the ten essential amino acids. Mexican corn and beans, Japanese rice and soybeans, and Cajun red beans and rice are examples of such fortuitous combinations."
  24. ^ "Quinoa: An emerging "new" crop with potential for CELSS (NASA Technical Paper 3422)" (PDF). NASA. November 2003. Retrieved 2006-10-28.