Acomplete protein orwhole protein is a food source ofprotein that contains an adequate proportion of each of the nineessential amino acids necessary in the humandiet.[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 arecomplete 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 USInstitute 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% istryptophan.[2][7](note that the examples have not been corrected fordigestibility)
| 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% |
| 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% |
The second column in the following table shows the amino acid requirements of adults as recommended by theWorld Health Organization[11] calculated for a 62 kg (137 lb) adult. Recommended Daily Intake is based on 2,000 kilocalories (8,400 kJ) per day,[12] 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) |
In aplant-based diet there is the perceived issue ofamino acid content of various individual foods. A satisfying diet however, will include minimum requirements of allessential amino acids.
In addition to grains, such as corn, rice, or wheat, vegetable protein also occurs in legumes, which include beans and peanuts. Grains tend to be deficient intryptophan andlysine, whereas legumes lackmethionine Thus a meal combining grains and legumes such as the Mexican peasant dish ofcorn tortillas andrefried beans is basically complete in amino acid content.
— Stanley E. Manahan,General Applied Chemistry 1978,82 , page 474