Beans are an awesome source of nutrition whether you’re vegan or not.
But…they aren’t perfect. You shouldn’t rely on them for all your protein needs, because as we’ll see, beans are deficient in certain types of amino acids.
Using detailed data from the USDA’s food database, I extracted the amount of each essential amino acid in the most common beans.
First, we’ll look at them altogether to spot some trends, then break down each bean one at a time.
Table of Contents
The Number of Servings Required to Meet Your RDA
This section alone will probably contain the answers you were most looking for when you stumbled across this post.
The RDA for all amino acids is in terms of mg per kg of bodyweight. So it’s different for everyone.
By using a 70 kg (154 lb) person as an example, I calculated the number of servings for each type of bean to meet the RDA of each essential amino acid. All servings are 1 cup of cooked beans.
Click the image below to open up the full-size version if it’s hard to see:
I applied some basic conditional formatting to the results where green means that it requires few servings, red requires many servings.
The biggest trends that we see are:
- All beans are great plant sources of tryptophan, threonine, and histidine.
- All beans have low amounts of methionine. It’s one of the hardest essential amino acids to get as a vegan.
- Many beans (but not all) have relatively low amounts of leucine and valine.
- Fava beans have a low amount of protein overall, and a low amount of all amino acids.
Essential Amino Acids That Beans Lack
I’ve compiled the top 30 vegan sources of methionine in another post.
But leucine and valine depend heavily on which types of beans you eat. You should be able to see from the image if the beans you eat are low in those two and whether or need alternative sources.
If you do, here are:
If you can’t tell from the image alone, scroll down to each bean’s individual section below that you’re concerned about.
Soybean Amino Acid Profile
I’ll start with soybeans, as soy products are the most popular. While products like tofu and tempeh might not have the exact same amino acid profile, it should be similar.
Here’s the amino acid profile of soybeans:
| RDA | RDA | Soybeans | |
|---|---|---|---|
| mg per kg | for 70 kg person | 1 cup | |
| Tryptophan (mg) | 4 | 280 | 270 |
| Threonine (mg) | 15 | 1050 | 886 |
| Isoleucine (mg) | 20 | 1400 | 977 |
| Leucine (mg) | 39 | 2730 | 1589 |
| Lysine (mg) | 30 | 2100 | 1330 |
| Methionine (mg) | 15 | 1050 | 270 |
| Phenylalanine (mg) | 25 | 1750 | 1006 |
| Valine (mg) | 26 | 1820 | 988 |
| Histidine (mg) | 10 | 700 | 598 |
For almost all amino acids, it takes only 1-2 servings of 1 cup of soybeans to reach the RDA for a 70 kg person, which is great.
The only weak point, as with every other type of bean, is methionine. It takes about 4 servings of soybeans to hit the RDA for methionine, which is quite a lot.
Overall, soybeans have one of the best bean amino acid profiles.
Kidney Bean Amino Acid Profile
My personal favorite bean to pair with rice, let’s take a look at the amino acid profile of kidney beans.
| RDA | RDA | Kidney Beans | |
|---|---|---|---|
| mg per kg | for 70 kg person | 1 cup | |
| Tryptophan (mg) | 4 | 280 | 182 |
| Threonine (mg) | 15 | 1050 | 646 |
| Isoleucine (mg) | 20 | 1400 | 678 |
| Leucine (mg) | 39 | 2730 | 1227 |
| Lysine (mg) | 30 | 2100 | 1053 |
| Methionine (mg) | 15 | 1050 | 230 |
| Phenylalanine (mg) | 25 | 1750 | 830 |
| Valine (mg) | 26 | 1820 | 804 |
| Histidine (mg) | 10 | 700 | 428 |
Again, weak in methionine (needs about 4 servings to hit RDA), but all other amino acid RDAs can be met with about 2 servings of kidney beans.
The only exception is that it takes ~2.5 servings to hit the valine RDA.
Black Bean Amino Acid Profile
Black beans are a very common type of legume to include in vegan recipes.
Let’s look at their profile:
| RDA | RDA | Black beans | |
|---|---|---|---|
| mg per kg | for 70 kg person | 1 cup | |
| Tryptophan (mg) | 4 | 280 | 181 |
| Threonine (mg) | 15 | 1050 | 642 |
| Isoleucine (mg) | 20 | 1400 | 673 |
| Leucine (mg) | 39 | 2730 | 1218 |
| Lysine (mg) | 30 | 2100 | 1046 |
| Methionine (mg) | 15 | 1050 | 229 |
| Phenylalanine (mg) | 25 | 1750 | 824 |
| Valine (mg) | 26 | 1820 | 798 |
| Histidine (mg) | 10 | 700 | 425 |
Black beans have a very similar amino acid profile to kidney beans. Most amino acid RDAs are met within 2 servings, but valine needs a little more (again about 2.5 servings).
As with all beans, there is a low amount of methionine.
Navy Bean Amino Acid Profile
Navy beans are frequently used in BBQ bean recipes.
Here’s what the profile looks like:
| RDA | RDA | Navy Beans | |
|---|---|---|---|
| mg per kg | for 70 kg person | 1 cup | |
| Tryptophan (mg) | 4 | 280 | 182 |
| Threonine (mg) | 15 | 1050 | 526 |
| Isoleucine (mg) | 20 | 1400 | 704 |
| Leucine (mg) | 39 | 2730 | 1274 |
| Lysine (mg) | 30 | 2100 | 946 |
| Methionine (mg) | 15 | 1050 | 202 |
| Phenylalanine (mg) | 25 | 1750 | 857 |
| Valine (mg) | 26 | 1820 | 917 |
| Histidine (mg) | 10 | 700 | 375 |
Navy beans have arguably the most balanced amino acid profile of all the beans. It takes right around 2 servings to meet all RDAs with the typical exception of methionine.
Adzuki Bean Amino Acid Profile
Adzuki beans have the second highest protein content per serving of all the beans here, and one of the best profiles as well:
| RDA | RDA | Adzuki Beans | |
|---|---|---|---|
| mg per kg | for 70 kg person | 1 cup | |
| Tryptophan (mg) | 4 | 280 | 166 |
| Threonine (mg) | 15 | 1050 | 587 |
| Isoleucine (mg) | 20 | 1400 | 690 |
| Leucine (mg) | 39 | 2730 | 1454 |
| Lysine (mg) | 30 | 2100 | 1304 |
| Methionine (mg) | 15 | 1050 | 182 |
| Phenylalanine (mg) | 25 | 1750 | 915 |
| Valine (mg) | 26 | 1820 | 890 |
| Histidine (mg) | 10 | 700 | 455 |
Even the harder to get amino acids, like valine and leucine, are found in decent amounts (takes about 2 servings to reach the RDA).
But the methionine content is lower than the other beans we’ve looked at so far. That shouldn’t be a big deal because you should be getting methionine from other sources.
Mung Bean Amino Acid Profile
Here’s the amino acid profile for mung beans.
| RDA | RDA | Mung Beans | |
|---|---|---|---|
| mg per kg | for 70 kg person | 1 cup | |
| Threonine (mg) | 15 | 1050 | 465 |
| Isoleucine (mg) | 20 | 1400 | 600 |
| Leucine (mg) | 39 | 2730 | 1099 |
| Lysine (mg) | 30 | 2100 | 990 |
| Methionine (mg) | 15 | 1050 | 170 |
| Phenylalanine (mg) | 25 | 1750 | 858 |
| Valine (mg) | 26 | 1820 | 735 |
| Histidine (mg) | 10 | 700 | 414 |
It’s a little low in leucine and valine than the more popular beans, requiring almost 3 servings to meet the RDA.
It’s methionine content is also on the low side relative to most other beans.
Fava Bean Amino Acid Profile
Fava beans have the worst amino acid profile of any bean on this page:
| RDA | RDA | Fava Beans | |
|---|---|---|---|
| mg per kg | for 70 kg person | 1 cup | |
| Tryptophan (mg) | 4 | 280 | 122 |
| Threonine (mg) | 15 | 1050 | 459 |
| Isoleucine (mg) | 20 | 1400 | 520 |
| Leucine (mg) | 39 | 2730 | 972 |
| Lysine (mg) | 30 | 2100 | 826 |
| Methionine (mg) | 15 | 1050 | 105 |
| Phenylalanine (mg) | 25 | 1750 | 546 |
| Valine (mg) | 26 | 1820 | 575 |
| Histidine (mg) | 10 | 700 | 328 |
Compared to other foods in general, they’re still good nutritionally, but other beans are almost always a better choice.
Fava beans take more than 2 servings to reach the RDA in tryptophan, isoleucine, leucine, lysine, methionine, phenylalanine, valine, and histidine.
So basically all of them…
Lima Bean Amino Acid Profile
Finally, we have the amino acid profile of lima beans:
| RDA | RDA | Lima Beans | |
|---|---|---|---|
| mg per kg | for 70 kg person | 1 cup | |
| Tryptophan (mg) | 4 | 280 | 139 |
| Threonine (mg) | 15 | 1050 | 540 |
| Isoleucine (mg) | 20 | 1400 | 623 |
| Leucine (mg) | 39 | 2730 | 1035 |
| Lysine (mg) | 30 | 2100 | 976 |
| Methionine (mg) | 15 | 1050 | 190 |
| Phenylalanine (mg) | 25 | 1750 | 779 |
| Valine (mg) | 26 | 1820 | 610 |
| Histidine (mg) | 10 | 700 | 400 |
It also has one of the weakest overall profiles.
It’s low in leucine, lysine, methionine, phenylalanine, and valine.
It’s still good to add to meals, but I wouldn’t heavily rely on it over other beans if possible.
Lentils Amino Acid Profile
I didn’t realize until after I originally published this that I also should have included lentils on the list.
So here is essential amino acid profile of lentils, better late than never.
| RDA | RDA | Lentils | |
|---|---|---|---|
| mg per kg | for 70 kg person | 1 cup | |
| Tryptophan (mg) | 4 | 280 | 160 |
| Threonine (mg) | 15 | 1050 | 640 |
| Isoleucine (mg) | 20 | 1400 | 772 |
| Leucine (mg) | 39 | 2730 | 1,295 |
| Lysine (mg) | 30 | 2100 | 1247 |
| Methionine (mg) | 15 | 1050 | 152 |
| Phenylalanine (mg) | 25 | 1750 | 881 |
| Valine (mg) | 26 | 1820 | 887 |
| Histidine (mg) | 10 | 700 | 503 |
Lentils have a similar profile to all other legumes.
Most RDAs can be reached in 2-3 cups of cooked lentils, but they’re quite low in methionine.
Garbanzo Bean (AKA Chickpea) Amino Acid Profile
Another one I forgot was chickpeas, despite it being the bean that I eat the most myself.
Here’s the essential amino acid profile for garbanzo beans (which is a different name for chickpeas, but the same):
| RDA | RDA | Chickpeas | |
|---|---|---|---|
| mg per kg | for 70 kg person | 1 cup | |
| Tryptophan (mg) | 4 | 280 | 151 |
| Threonine (mg) | 15 | 1050 | 491 |
| Isoleucine (mg) | 20 | 1400 | 745 |
| Leucine (mg) | 39 | 2730 | 909 |
| Lysine (mg) | 30 | 2100 | 765 |
| Methionine (mg) | 15 | 1050 | 116 |
| Phenylalanine (mg) | 25 | 1750 | 571 |
| Valine (mg) | 26 | 1820 | 723 |
| Histidine (mg) | 10 | 700 | 393 |
As expected, they follow the same trends as most other beans.
Decent for most amino acids, but very low in methionine. However, they’re also relatively low in leucine, and phenylalanine compared to other legumes.
What to Pair With Beans
You can reach your RDA for most essential acids with 2-3 servings of most beans.
The exception is that certain beans are low in valine and leucine, and that all beans are low in methionine.
So you’ll want to get methionine from other foods (it’s not like anyone eats 100% beans anyways). It doesn’t necessarily have to be in the same meal, but here are some of the top plant-based sources of methionine that could be good options to eat:
- Vital wheat gluten (seitan)
- Nuts and seeds (most nuts and seeds are high in methionine)
- Grains (oats, rye, and quinoa have a good amount)
Methionine is the most challenging essential amino acid to get on a vegan diet, but you can typically reach your RDA as long as you eat a variety of foods.
Summary
The best beans overall are soybeans, followed by kidney, black, navy, and adzuki beans, which all have similar amino acid profiles.
Fava and lima beans had by far the weakest amino acid profiles, with mung beans not too far behind.
If you want to diversify your protein sources, here’s a list of the best vegan sources of protein.
Finally, protein isn’t everything. If you want to see more about what else beans have to offer, see my bean nutrition comparison.
