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Essential Amino Acid Profile of Beans

By: by Amy Lucas
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As a source of dietary fiber and plant-based protein, beans have a ton of bang for the buck. But if you’re subsisting on beans as your sole source of protein, then you’re likely missing out on some key essential amino acids. Let’s get to know beans a little better, including the amino acid profile of beans with the highest protein content.

Protein in Beans

Dietary protein, whether it comes from animal or plant foods, is made up of 20 amino acids linked together in different combinations, which is why amino acids are referred to as the building blocks of protein. Eleven of these are nonessential amino acids that the body can synthesize on its own. Nonessential amino acids become conditionally essential in times of stress and illness. The other nine are essential amino acids, and the body cannot make them. These in-demand aminos must be obtained from a food source. 

The nine essential amino acids are:

  • Histidine
  • Isoleucine
  • Leucine
  • Lysine
  • Methionine
  • Phenylalanine
  • Threonine
  • Tryptophan
  • Valine

When dietary protein is digested, it’s broken down into its component amino acids, which get to work performing various functions in the body—building and repairing tissue, producing neurotransmitters and hormones, boosting mental and physical performance, improving mood, and strengthening the immune system.

Are Beans a Complete Protein?

A complete protein contains sufficient amounts of all nine of the essential amino acids. Most beans are incomplete proteins, as they tend to be too low in certain essential amino acids, particularly the sulfur-containing amino acid methionine.

That’s the case for most plant-based sources of protein. They are limited in certain essential amino acids (EAAs), including lysine and leucine. Even if they are considered complete by some accounts, they don’t have the anabolic, or muscle building, capacity that high-quality animal-based proteins do, such as meat and eggs.

That doesn’t mean they aren’t an important part of your diet, but knowing the essential amino acid profile of beans can help you get a more complete essential amino acid makeup in your diet.

Beans and Legumes High in Protein

Amino Acid Composition of Common Legumes

Many of the most popular types of beans come from the edible ripe fruit or dry seeds of the Phaseolus vulgaris plant, or the common bean. Types of common beans include kidney beans, pinto beans, navy beans, and black beans. One cup of each of these cooked beans renders approximately 15 grams of protein. Soybeans, chickpeas, mung beans, adzuki beans, and lentils are common varieties of nutrient-dense legumes that are high in protein and fiber.

Essential Amino Acid Content of Kidney Beans

A 2018 study in the journal Nutrients determined that household-cooked kidney beans are the highest in protein of five beans studied: kidney beans, white beans, chickpeas, brown and green lentils, and flageolets. In all the beans lysine, leucine, and valine were the most plentiful EAAs, but methionine levels were inadequate (1). 

One cup of boiled kidney beans has the following essential amino acid profile.

Histidine 421 mg 66% RDI
Isoleucine 726 mg     52% RDI
Leucine 1303 mg 48% RDI
Lysine 1074 mg 51% RDI
Methionine 200 mg 27% RDI
Phenylalanine 904 mg     103% RDI
Threonine 565 mg 54% RDI
Tryptophan 84 mg 66% RDI
Valine 885 mg 49% RDI

Essential Amino Acid Content of Navy Beans

Given the name navy beans when they became a staple of the U.S. Naval diet in the second half of the 19th century, these small white beans have the following essential amino acid content in 1 cup:

Histidine 375 mg 54% RDI
Isoleucine 704 mg 50% RDI
Leucine 1274 mg 47% RDI
Lysine 946 mg 45% RDI
Methionine 202 mg 28% RDI
Phenylalanine 857 mg 98% RDI
Threonine 526 mg 50% RDI
Tryptophan 182 mg     65% RDI
Valine 917 mg 50% RDI

Essential Amino Acid Content of Black Beans

Also known as turtle beans, black beans are a featured bean of Latin cuisine. Here’s the essential amino acid breakdown of black beans:

Histidine 425 mg 61% RDI
Isoleucine 673 mg 48% RDI
Leucine 1218 mg 45% RDI
Lysine 1046 mg 50% RDI
Methionine  229 mg 31% RDI
Phenylalanine 824 mg 94% RDI
Threonine 642 mg 61% RDI
Tryptophan 181 mg 65% RDI 
Valine 798 mg 44% RDI

Essential Amino Acid Content of Pinto Beans

When you dig into a serving of refried beans, you’re eating pinto beans and getting these proportions of essential amino acids:

Histidine 422 mg 60% RDI
Isoleucine 728 mg 52% RDI
Leucine 1308 mg 48% RDI
Lysine 1077 mg 51% RDI
Methionine 200 mg 27% RDI
Phenylalanine 908 mg 98% RDI
Threonine 566 mg 54% RDI
Tryptophan 185 mg 66% RDI
Valine 887 mg 49% RDI

Essential Amino Acid Content of Chickpeas

Otherwise known as garbanzo beans, chickpeas are used in salads and soups and bring us everyone’s favorite pita dipper—hummus! Here’s the EAA composition of chickpeas:

Histidine 400 mg 57% RDI
Isoleucine 623 mg 45% RDI
Leucine 1035 mg 38% RDI
Lysine 973 mg 46% RDI
Methionine 190 mg 26% RDI
Phenylalanine 779 mg 89% RDI
Threonine 540 mg 51% RDI
Tryptophan 139 mg 50% RDI
Valine 610 mg 34% RDI

Essential Amino Acid Content of Mung Beans

Although lower in methionine and valine then some of the other popular beans, mung beans can be enjoyed sprouted or dried and are a versatile cooking staple. Here’s what you get in 1 cup of mung beans:

Histidine 414 mg 59% RDI
Isoleucine 600 mg 43% RDI
Leucine 1099 mg 40% RDI
Lysine 990 mg 47% RDI
Methionine 170 mg 23% RDI
Phenylalanine 859 mg 98% RDI
Threonine 465 mg 44% RDI
Tryptophan 154 mg 55% RDI
Valine 735 mg 40% RDI

Essential Amino Acid Content of Soybeans

When it comes to plant-based protein sources, soybeans are a shining star. You can enjoy them as edamame or turn them into soy milk, soy protein powder, tofu, and tempeh. One cup of cooked green soybeans has an impressive essential amino acid profile, but is still lacking in methionine.

Histidine 598 mg 85% RDI
Isoleucine 977 mg 70% RDI
Leucine 1589 mg 58% RDI
Lysine 1330 mg 63% RDI
Methionine 270 mg 37% RDI
Phenylalanine 1006 mg 115% RDI
Threonine 886 mg 84% RDI
Tryptophan 270 mg 96% RDI
Valine 988 mg 85% RDI

Essential Amino Acid Content of Adzuki Beans

Adzuki beans are fitting for bean bowls, pastes, and even flour! And they can hold their own in terms of beans with admirable EAA compositions. One cup of adzuki beans delivers the following EAAs:

Histidine 455 mg 65% RDI
Isoleucine 690 mg 49% RDI
Leucine 1454 mg 53% RDI
Lysine 1404 mg 62% RDI
Methionine 182 mg 25% RDI
Phenylalanine 915 mg 105% RDI
Threonine 587 mg 56% RDI
Tryptophan 166 mg 59% RDI
Valine 890 mg 49% RDI

Essential Amino Acid Content of Lentils

Lentils offer up an impressive 18 grams of protein in 1 cup and are a terrific source of iron. Protein and iron are two nutrients that can be lacking in vegetarian diets, which make lentils a nutrient-dense ally for plant-based eaters.

Histidine 503 mg 72% RDI
Isoleucine 772 mg 55% RDI
Leucine 1295 mg 47% RDI
Lysine 1247 mg 59% RDI
Methionine 152 mg 21% RDI
Phenylalanine 881 mg 108% RDI
Threonine 640 mg 61% RDI
Tryptophan 160 mg 67% RDI
Valine 887 mg 49% RDI

Don’t Miss Out on the Essentials

As mentioned at the beginning of this article, the protein quality of beans, even soybeans, isn’t as high as that of animal food sources. Beans also contain phytates, which are anti-nutrients that can impair protein digestibility. While beans confer many health benefits—antioxidants, heart health, cancer protection, and appetite control to name a few—it’s important to complement your protein intake with other plant-based foods, such as quinoa, in addition to animal foods.

If you are vegan or vegetarian, you can get your essential amino acids from a vegetarian or vegan essential amino acid supplement rather than from dietary protein from meat or animal byproducts. 

All Amino Co blends are vegetarian approved, gluten-free, non-GMO, halal, and free of additives and artificial sweeteners, and our Life blend is also vegan. You can supplement your diet with the essentials here

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