Complete protein
A complete protein or whole protein is a food source of protein that contains an adequate proportion of each of the nine essential amino acids necessary in the human diet.[1][2][3][4][5]
Concept
[edit]Protein nutrition is complex because any proteinogenic amino acid may be the limiting factor in metabolism. Mixing livestock feeds can optimize for growth, or minimize cost while maintaining adequate growth. Similarly, human nutrition is subject to Liebig's law of the minimum: The lowest level of one of the essential amino acids will be the limiting factor in metabolism.
- If the content of a single indispensable amino acid in the diet is less than the individual's requirement, then it will limit the utilization of other amino acids and thus prevent the normal rates of synthesis even when the total nitrogen intake level is adequate. Thus the "limiting amino acid" will determine the nutritional value of the total nitrogen or protein in the diet.[6]
Protein sources are thus rated by their limiting amino acids.[7]
Most people eat a varied diet with multiple sources of protein. Incomplete sources can complement each other and become complete when combined.[8] Combining does not need to happen for every single meal: so long as the diet is varied and meets caloric needs, even vegans and vegetarians – people who tend to have more "incomplete protein" in their diet – can easily meet their amino acid needs. In other words, most people do not need to consider the completeness of proteins of single foods.[9]
Amino acid profile
[edit]The following table lists the optimal profile of the nine essential amino acids in the human diet, which comprises complete protein, as recommended by the US Institute of Medicine's Food and Nutrition Board. The foodstuffs listed for comparison show the essential amino acid content per unit of the total protein of the food; 100g of spinach, for example, only contains 2.9g of protein (6% Daily Value), and of that protein 1.36% is tryptophan.[2][10](note that the examples have not been corrected for digestibility)
| Essential amino acid | mg/g of protein | percentage of total protein | raw, whole chicken egg[11] | quinoa[12] | raw spinach[13] |
|---|---|---|---|---|---|
| Tryptophan | 7 | 0.7% | 1.33% | 1% | 1.36% |
| Threonine | 27 | 2.7% | 4.42% | 3.2% | 4.27% |
| Isoleucine | 25 | 2.5% | 5.34% | 4.2% | 5.14% |
| Leucine | 55 | 5.5% | 8.65% | 7.3% | 7.8% |
| Lysine | 51 | 5.1% | 7.27% | 6.1% | 6.08% |
| Methionine+Cystine | 25 | 2.5% | 5.18% | 2.7%+1.3% | 1.85%+1.22% |
| Phenylalanine+Tyrosine | 47 | 4.7% | 9.39% | 4.3%+3.6% | 4.51%+3.78% |
| Valine | 32 | 3.2% | 6.83% | 5% | 5.63% |
| Histidine | 18 | 1.8% | 2.45% | 3.1% | 2.24% |
| Total | 287 | 28.7% | 50.86% | 41.8% | 43.88% |
Total adult daily intake
[edit]The second column in the following table shows the amino acid requirements of adults as recommended by the World Health Organization[14] calculated for a 62 kg (137 lb) adult. Recommended Daily Intake is based on 2,000 kilocalories (8,400 kJ) per day,[15] which could be appropriate for a 70 kg (150 lb) adult.
| Essential amino acid | Required mg/day for a 62 kg (137 lb) adult |
|---|---|
| Tryptophan | 248 |
| Threonine | 930 |
| Isoleucine | 1240 |
| Leucine | 2418 |
| Lysine | 1860 |
| Methionine+Cystine | 930 |
| Phenylalanine+Tyrosine | 1550 |
| Valine | 1612 |
| Histidine | 620 |
| Total | 11,408 milligrams (11.408 g) |
| Total Protein | 46 to 56 grams (46,000 to 56,000 mg) |
See also
[edit]References
[edit]- ^ "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.
- ^ a b Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Food and Nutrition Board of Institute of Medicine, National Academies Press. 2005. p. 691. doi:10.17226/10490. ISBN 978-0-309-08525-0.
- ^ "All About the Protein Foods Group". US Department of Agriculture. 3 November 2017. Retrieved 20 May 2018.
- ^ Mariotti, François; Gardner, Christopher D. (Nov 2019). "Dietary Protein and Amino Acids in Vegetarian Diets—A Review". Nutrients. 11 (11): 2661. doi:10.3390/nu11112661. PMC 6893534. PMID 31690027.
- ^ Young, VR; Pellett, PL (May 1994). "Plant proteins in relation to human protein and amino acid nutrition". The American Journal of Clinical Nutrition. 59 (5 Suppl): 1203S – 1212S. doi:10.1093/ajcn/59.5.1203S. PMID 8172124.
- ^ Food and Nutrition Board of Institute of Medicine (2005) Dietary Reference Intakes for Protein and Amino Acids, page 685, from National Academies Press
- ^ 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. doi:10.1093/ajcn/59.5.1203s. PMID 8172124.
- ^ "What's a Complete Protein and Should You Care?". Cleveland Clinic. Retrieved 2024-04-19.
- ^ Melina, Vesanto; Craig, Winston; Levin, Susan (2016-12-01). "Position of the Academy of Nutrition and Dietetics: Vegetarian Diets". Journal of the Academy of Nutrition and Dietetics. 116 (12): 1971. doi:10.1016/j.jand.2016.09.025. ISSN 2212-2672. PMID 27886704. S2CID 4984228. PDF
- ^ "Protein quality". Conde Nast, Nutritiondata.com. 2018. Retrieved 13 April 2020.
- ^ "Egg, whole, raw, fresh, nutrition facts per 100 grams". Conde Nast, Nutritiondata.com. 2018. Retrieved 13 April 2020.
- ^ "Quinoa, cooked, nutrition facts per 100 grams". Conde Nast, Nutritiondata.com. 2018. Retrieved 13 April 2020.
- ^ "Spinach, raw, nutrition facts per 100 grams". Conde Nast, Nutritiondata.com. 2018. Retrieved 13 April 2020.
- ^ "Protein and Amino Acid Requirements in Human Nutrition" (PDF). World Health Organization. 2007. Retrieved January 21, 2021.
- ^ "Guidance for Industry: A Food Labeling Guide". U.S. Food & Drug Administration. US FDA. Archived from the original on 2017-10-31. Retrieved 14 January 2017.