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.
Concept
Protein nutrition is complex because any proteinogenic amino acid may be the
limiting factor in
metabolism. Mixing
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.
[Food and Nutrition Board of Institute of Medicine (2005) Dietary Reference Intakes for Protein and Amino Acids, page 685, from National Academies Press]
Protein sources are thus rated by their limiting amino acids.
Most people eat a varied diet with multiple sources of protein. Incomplete sources can complement each other and become complete when combined.[ PDF]
Amino acid profile
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.
|
|
| 7 | 0.7% | 1.33% | 1% | 1.36% |
| 27 | 2.7% | 4.42% | 3.2% | 4.27% |
| 25 | 2.5% | 5.34% | 4.2% | 5.14% |
| 55 | 5.5% | 8.65% | 7.3% | 7.8% |
| 51 | 5.1% | 7.27% | 6.1% | 6.08% |
| 25 | 2.5% | 5.18% | 2.7%+1.3% | 1.85%+1.22% |
| 47 | 4.7% | 9.39% | 4.3%+3.6% | 4.51%+3.78% |
| 32 | 3.2% | 6.83% | 5% | 5.63% |
| 18 | 1.8% | 2.45% | 3.1% | 2.24% |
| Total | 287 | 28.7% | 50.86% | 41.8% | 43.88% |
Total adult daily intake
The second column in the following table shows the amino acid requirements of adults as recommended by the World Health Organization
calculated for a adult. Recommended Daily Intake is based on per day,
which could be appropriate for a adult.
|
|
|
| 248 |
| 930 |
| 1240 |
| 2418 |
| 1860 |
| 930 |
| 1550 |
| 1612 |
| 620 |
| Total | |
| Total Protein | |
See also
