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Complete protein foods supply all nine essential amino acids that MedlinePlus lists, in proportions that meet human needs. In USDA FoodData Central (SR Legacy) data, a cup of tempeh lists about 33.7 grams of protein, a cup of boiled soybeans about 31.3 grams and half a roasted chicken breast about 26.7 grams, ahead of cottage cheese, salmon, lean ground beef and tuna. The first table ranks 14 animal, soy and grain foods by protein per serving with three amino acids, lysine, methionine and tryptophan; the second compares 16 foods by amino acid per gram of protein, which is where incomplete proteins show up.
Peptide Labs does not sell foods. This article is general nutrition information, not medical advice.
Key Takeaways
- In USDA SR Legacy data, a cup of tempeh (33.7 grams of protein) and a cup of boiled soybeans (31.3 grams) list more protein per serving than half a roasted chicken breast (26.7 grams).
- Every food in both tables lists all nine essential amino acids in USDA data except unsweetened gelatin, which lists no tryptophan; elsewhere the differences are in proportions.
- Lentils, black beans and chickpeas list 67 to 70 milligrams of lysine per gram of protein in USDA data but only 9 to 15 milligrams of methionine, while brown rice lists 36 and 21: the patterns complement each other.
- Hemp seeds list about 40 milligrams of lysine per gram of protein in USDA data, the same figure as gelatin and under half the 85 milligrams for chicken breast.
- Under the FDA labeling rule (21 CFR 101.9), protein quality is scored by the PDCAAS method, and a label's protein %DV must use protein corrected by that score.
Complete protein foods ranked by USDA protein per serving
The table uses USDA SR Legacy entries and USDA household portions. Protein, lysine, methionine and tryptophan are grams per serving. There is no percent Daily Value column on purpose: the FDA labeling rule requires the protein %DV to be calculated from protein corrected for quality, a score that USDA SR Legacy does not report.
| Food (USDA FDC ID) | Serving | Protein | Lysine | Methionine | Tryptophan | Calories |
|---|---|---|---|---|---|---|
| Tempeh (174272) | 1 cup | 33.7 g | 1.51 g | 0.29 g | 0.32 g | 319 |
| Soybeans, mature, boiled (174271) | 1 cup | 31.3 g | 1.91 g | 0.39 g | 0.42 g | 296 |
| Chicken breast, meat only, roasted (171477) | 1/2 breast | 26.7 g | 2.27 g | 0.74 g | 0.31 g | 142 |
| Cottage cheese, lowfat 2% (172182) | 1 cup | 23.6 g | 1.98 g | 0.57 g | 0.31 g | 183 |
| Salmon, sockeye, cooked (173692) | 3 oz | 22.5 g | 2.19 g | 0.73 g | 0.28 g | 133 |
| Ground beef, 90% lean, broiled (174031) | 3 oz | 22.2 g | 1.84 g | 0.57 g | 0.11 g | 184 |
| Tofu, raw, firm, with calcium sulfate (172475) | 1/2 cup | 21.8 g | 1.11 g | 0.27 g | 0.30 g | 181 |
| Edamame, frozen, prepared (168411) | 1 cup | 18.5 g | 1.15 g | 0.22 g | 0.20 g | 188 |
| Tuna, light, canned in water, drained (173709) | 3 oz | 16.5 g | 1.45 g | 0.47 g | 0.18 g | 73 |
| Hemp seeds, hulled (170148) | 3 tbsp | 9.5 g | 0.38 g | 0.28 g | 0.11 g | 166 |
| Quinoa, cooked (168917) | 1 cup | 8.1 g | 0.44 g | 0.18 g | 0.10 g | 222 |
| Milk, 2% milkfat (171267) | 1 cup | 8.1 g | 0.67 g | 0.21 g | 0.10 g | 122 |
| Egg, whole, hard-boiled (173424) | 1 large | 6.3 g | 0.45 g | 0.20 g | 0.08 g | 78 |
| Buckwheat groats, roasted, cooked (170686) | 1 cup | 5.7 g | 0.29 g | 0.07 g | 0.08 g | 155 |
Per serving, tofu and edamame list 18.5 to 21.8 grams of protein in USDA data, close to salmon and tuna. The three non-soy plant foods list far less protein per serving in USDA data: about 9.5 grams in 3 tablespoons of hemp seeds, 8.1 grams in a cup of cooked quinoa and 5.7 grams in a cup of cooked buckwheat groats, the range of a cup of milk or one large egg.
Complete proteins: what the term means
MedlinePlus lists nine essential amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. MedlinePlus explains that the body cannot make them, so they must come from food, while the nonessential amino acids can be made by the body, and some of those become conditionally essential at certain times, such as illness. The 2019 collagen review by Paul, Leser and Oesser cited below uses the other common name, indispensable amino acids.
A complete protein supplies all nine in proportions that cover human requirements, the framing a 1994 review by Young and Pellett in the American Journal of Clinical Nutrition used when it concluded that mixtures of plant proteins can serve as a complete and well-balanced source of amino acids for meeting human physiological requirements.
On U.S. food labels the FDA yardstick is the protein digestibility-corrected amino acid score, or PDCAAS. Under 21 CFR 101.9(c)(7), the score is determined by methods in a report of an FAO/WHO expert consultation on protein quality evaluation, the corrected amount of protein is the grams of protein multiplied by that score, and a score above 1.00 is set at 1.00. When a food for adults and children 4 and older has a PDCAAS below 20 percent, FDA requires either the statement “not a significant source of protein” or a corrected %DV next to the grams of protein. The FDA Daily Reference Value for protein is 50 grams.
Incomplete proteins: the amino acid per gram table
An incomplete protein falls short on at least one essential amino acid, and USDA data show the clearest case: unsweetened gelatin lists no tryptophan at all. A 2019 review in Nutrients by Paul, Leser and Oesser, written by authors affiliated with gelatin and collagen businesses, states that under PDCAAS collagen protein lacks tryptophan and is therefore categorized as an incomplete protein source (see our gelatin guide).
Most plant proteins fall short in a milder way: all nine amino acids are present, but one is low next to animal proteins. A 2018 analysis in Amino Acids by Gorissen and colleagues measured protein isolates, which are concentrated protein ingredients rather than whole foods, and found methionine and lysine typically lower in the plant proteins (about 1.0 and 3.6% of protein) than in the animal proteins (about 2.5 and 7.0%). Gorissen and colleagues also reported essential amino acid contents of 21% for oat and lupin protein and 22% for wheat protein, against 32% for egg, 34% for casein, 39% for milk and 43% for whey.
| Food (USDA FDC ID) | Lysine per g protein | Methionine per g protein | Tryptophan per g protein |
|---|---|---|---|
| Chicken breast, meat only, roasted (171477) | 85 mg | 28 mg | 12 mg |
| Cottage cheese, lowfat 2% (172182) | 84 mg | 24 mg | 13 mg |
| Egg, whole, hard-boiled (173424) | 72 mg | 31 mg | 12 mg |
| Lentils, boiled (172421) | 70 mg | 9 mg | 9 mg |
| Black beans, boiled (173735) | 69 mg | 15 mg | 12 mg |
| Chickpeas, boiled (173757) | 67 mg | 13 mg | 10 mg |
| Soybeans, mature, boiled (174271) | 61 mg | 12 mg | 13 mg |
| Quinoa, cooked (168917) | 54 mg | 22 mg | 12 mg |
| Buckwheat groats, roasted, cooked (170686) | 51 mg | 13 mg | 14 mg |
| Oats, regular and quick, dry (173904) | 48 mg | 16 mg | 14 mg |
| Hemp seeds, hulled (170148) | 40 mg | 30 mg | 12 mg |
| Gelatin, dry powder, unsweetened (169599) | 40 mg | 7 mg | 0 mg |
| Brown rice, long-grain, cooked (169704) | 36 mg | 21 mg | 12 mg |
| Peanuts, dry-roasted (173806) | 35 mg | 12 mg | 9 mg |
| Bulgur, cooked (170287) | 28 mg | 16 mg | 16 mg |
| Almonds, dry roasted (170158) | 27 mg | 7 mg | 10 mg |
The three animal rows combine high lysine with high methionine. Lentils, black beans and chickpeas match them on lysine, at 67 to 70 milligrams per gram of protein in USDA data, but list only 9 to 15 milligrams of methionine. Brown rice, bulgur, peanuts and almonds list 27 to 36 milligrams of lysine per gram of protein in USDA data, while the rice row lists 21 milligrams of methionine, more than twice the lentil figure. Soybeans, quinoa and buckwheat sit in between at 51 to 61 milligrams of lysine in USDA data, and the hemp row pairs a high methionine figure with lysine as low as gelatin’s.
A 2004 paper in the Food and Nutrition Bulletin by Hussain and colleagues describes lysine as the first limiting amino acid in wheat and names legumes and animal protein as foods that could complement its amino acid pattern. Our list of foods high in lysine ranks the lysine values per serving.
Complementary proteins as a concept
Because legumes run low in methionine and grains run low in lysine, eating both supplies a fuller set of amino acids than either alone. The 2025-2030 Dietary Guidelines for Americans advise vegetarians and vegans to diversify plant protein sources for amino acid balance. MedlinePlus adds that a diet based on a single plant item will not be adequate, and that pairing proteins such as beans with rice at a single meal is no longer a concern, because adequacy is judged over the whole diet throughout the day.
Gorissen and colleagues reached a similar conclusion for isolates: blends of plant proteins, or of plant and animal proteins, can come close to animal proteins. Our list of plant based protein sources ranks beans, lentils, soy foods, nuts, seeds and grains by protein per serving.
Notes on the data
- Values vary: USDA SR Legacy figures are averages for generic foods; the Nutrition Facts label on a packaged food is the figure for that product, and the FDA rule (21 CFR 101.9) lets a label round protein to the nearest gram.
- Single amino acids: our lists of foods high in leucine and foods high in tryptophan rank those amino acids per serving in USDA data, and the high protein foods guide ranks protein across every food group.
Frequently Asked Questions
What are complete proteins?
Proteins that supply all nine essential amino acids MedlinePlus lists, in proportions that cover human requirements. In USDA data, the animal foods in both tables list high amounts of both lysine and methionine per gram of protein.
Is gelatin a complete protein?
No. USDA lists no tryptophan for unsweetened gelatin, and a 2019 review in Nutrients notes that under PDCAAS collagen protein is categorized as an incomplete protein source.
Do incomplete proteins have to be combined at the same meal?
MedlinePlus says pairing proteins such as beans with rice at a single meal is no longer a concern, and that adequacy is judged over the whole diet throughout the day.
Where does quinoa fall in the amino acid table?
USDA lists about 54 milligrams of lysine and 22 milligrams of methionine per gram of protein for cooked quinoa, a lysine figure between the legumes and brown rice. USDA does not report a PDCAAS, the score FDA uses, so the table shows the pattern rather than a score.
Does the protein %DV on a label account for quality?
Yes. Under the FDA rule at 21 CFR 101.9, the protein %DV is calculated from protein multiplied by its PDCAAS, capped at 1.00, and the Daily Reference Value is 50 grams.
Questions about a label? Contact us or read our Buyer’s Guide. Food comes first; follow the label and ask a healthcare provider before starting a supplement, especially if you take medicines, are pregnant or have a health condition. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Last reviewed October 2026.
Related guides: Plant-Based Protein Sources: USDA Protein per Serving, High Protein Foods: USDA Values for Meat, Dairy and Plant Sources, Quinoa Benefits: USDA Nutrition, Protein and How It Compares to Rice, Foods High in Lysine: USDA Values per Serving.