Many foods contain all nine essential amino acids, and they’re not limited to meat. Animal proteins like eggs, dairy, poultry, pork, and fish are the most familiar complete proteins, but several plant foods qualify too, including soy, quinoa, buckwheat, pistachios, and potatoes. Your body can’t make these nine amino acids on its own (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine), so every gram has to come from what you eat.
Animal Foods With Complete Protein
Nearly all animal-based foods deliver the full set of essential amino acids in proportions your body can readily use. A single egg provides about 6 grams of protein with no limiting amino acid, meaning none of the nine falls short of what your body needs. One ounce of chicken, beef, pork, turkey, or lamb provides roughly 7 grams of protein. An 8-ounce glass of milk has about 8 grams, while a 5-ounce serving of plain nonfat Greek yogurt packs 12 to 18 grams. Hard cheeses deliver around 7 grams per ounce, and a half cup of cottage cheese provides about 14 grams.
These animal sources also score exceptionally well on protein quality metrics. Using the Digestible Indispensable Amino Acid Score (DIAAS), which measures how well your body can actually absorb and use each essential amino acid, pork scores 117, casein (the main protein in cheese and milk) scores 117, and whole egg scores 101. Any score above 100 is considered excellent quality, meaning no amino acid limits what your body can use from that food.
Plant Foods That Are Naturally Complete
The idea that plants can’t provide complete protein is outdated. Several plant foods contain all nine essential amino acids in meaningful amounts.
Soy is the most well-known plant-based complete protein, with a DIAAS of 91, classified as high quality. Tofu, tempeh, edamame, and soy milk all count. Its only slight weakness is in sulfur-containing amino acids (methionine and cysteine), but levels are still high enough for it to qualify as a complete protein.
Quinoa and buckwheat stand out among grains because they’re rich in lysine and sulfur-containing amino acids, exactly the amino acids most cereals lack. Both provide all essential amino acids at levels close to those recommended by the Food and Agriculture Organization. They’re technically pseudocereals (seeds, not grasses), which is part of why their amino acid profiles differ so sharply from wheat, rice, or oats.
Pistachios provide all nine essential amino acids with 8.2 grams of total essential amino acids per 100 grams. Their DIAAS is above 75, placing them in the “good quality” category. Per 100 grams, they deliver 1.7 grams of leucine, 1.3 grams of valine, and 1.2 grams of lysine, with an overall amino acid spread comparable to some animal products.
Potatoes are a surprising entry. Despite their reputation as a simple carbohydrate, potato protein scores a DIAAS of 100 with no limiting amino acid. The catch is that potatoes are low in total protein (about 2 grams per medium potato), so you’d need to eat a lot to meet your daily needs from potatoes alone.
Mycoprotein, sold under the brand name Quorn, is made from a type of fungus and contains all nine essential amino acids. Its total essential amino acid content is 21.1 grams per 100 grams, which is actually higher than lean cooked beef (14.8 g) or skinless cooked chicken (14.1 g). Its digestibility score is nearly perfect at 0.996 out of 1.
Why Some Plant Proteins Fall Short
Most grains, legumes, and nuts contain some of every essential amino acid but not enough of one or two to meet your body’s needs. That shortfall is called the “limiting amino acid,” and it varies by food group. Rice, wheat, corn, oats, and hemp are all limited by lysine. Their DIAAS scores reflect this: corn scores just 36, rice 47, wheat 48, and oats 57. Legumes like peas and fava beans have a different gap. They’re limited by sulfur-containing amino acids (methionine and cysteine), scoring around 55 to 70.
This pattern is actually useful, because the weakness of one group is the strength of the other. Grains are low in lysine but adequate in methionine. Beans are low in methionine but rich in lysine. Combine them and you get a complete amino acid profile. Rice and beans is the classic example, recognized by the American Heart Association as a complete protein pairing. You don’t need to eat them in the same meal. As long as you’re getting both throughout the day, your body can use the amino acids from each.
How Your Body Uses These Proteins
Having all nine amino acids present in a food is only part of the picture. Your body also has to digest and absorb them, and that’s where animal and plant proteins diverge. Plant proteins are generally less digestible than animal proteins. Plant cell walls contain fiber and other compounds that slow enzyme access to the protein inside, reducing how much actually reaches your bloodstream. Cooking helps significantly: heat-treated plant protein sources show about 18% higher digestibility than raw ones. Processed forms like pea protein concentrate can match the digestibility of milk protein.
Once amino acids reach your muscles, leucine plays a special role. It acts as a trigger for muscle protein synthesis, the process that builds and maintains muscle tissue. The threshold for maximum stimulation is roughly 3 to 4 grams of leucine per meal, which corresponds to about 25 to 30 grams of total protein. This is relatively easy to hit with animal sources but requires larger servings of most plant proteins, since they contain less leucine per gram.
How Much You Actually Need
The World Health Organization sets recommended intakes for each essential amino acid based on body weight. For a 70-kilogram (154-pound) adult, the daily requirements break down roughly as follows: 2.7 grams of leucine (the highest requirement), 2.1 grams of lysine, 1.8 grams of valine, 1.4 grams of isoleucine, 1.1 grams of threonine, about 0.7 grams each of histidine and methionine, and just 0.3 grams of tryptophan.
In practical terms, anyone eating a reasonable amount of protein from varied sources will meet these targets without tracking individual amino acids. Where it matters most is if you rely heavily on a single protein source, especially a plant one with a limiting amino acid. Eating only rice for your protein, for instance, would leave you short on lysine. But adding beans, tofu, or even a glass of milk throughout the day fills that gap easily. The goal isn’t to obsess over amino acid math. It’s to eat a mix of protein sources, which most people already do.