See main article: protein (nutrient) and protein combining.
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]
People who eat a varied diet generally do not have to consider the completeness of proteins of single foods. Different protein sources that are each incomplete on their own, typically are complete when combined.[6]
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] (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[8] | quinoa[9] | raw spinach[10] | |
|---|---|---|---|---|---|---|
| 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% | |
| 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% | ||
| 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% |
The second column in the following table shows the amino acid requirements of adults as recommended by the World Health Organization[11] calculated for a 62kg (137lb) adult. Recommended Daily Intake is based on per day,[12] which could be appropriate for a 70kg (150lb) adult.
| Essential amino acid | Required mg/day for a 62kg (137lb) adult | |
|---|---|---|
| Tryptophan | 248 | |
| Threonine | 930 | |
| Isoleucine | 1240 | |
| Leucine | 2418 | |
| Lysine | 1860 | |
| 930 | ||
| 1550 | ||
| Valine | 1612 | |
| Histidine | 620 | |
| Total | 11408mg | |
| Total Protein | 46g56g |