Lupini beans top the list at 26 grams of protein per cooked cup, making them the highest-protein legume you can eat. But several other legumes come close, and the “best” choice depends on more than just the number on the label. Protein quality, how well your body absorbs it, and what you pair it with all matter.
Protein Per Cup, Ranked
These numbers reflect one cup of cooked legumes, which is the most practical way to compare since it represents a typical serving.
- Lupini beans: 26 g per cup
- Soybeans (edamame): 22–24 g per cup
- Lentils: 18 g per cup
- Black beans: 15 g per cup
- Chickpeas: 15 g per cup
- Kidney beans: 15 g per cup
- Pinto beans: 15 g per cup
- Lima beans: 12 g per cup
- Green peas: 9 g per cup
The gap between the top two and everything else is significant. Lupini beans and soybeans deliver roughly 50–70% more protein per serving than the cluster of common beans sitting around 15 grams. Lentils land in a strong middle position, and they cook faster than nearly every other legume on this list, which makes them a practical daily option.
Why Soybeans and Peas Win on Quality
Raw protein count tells you how much is there, but not how much your body can actually use. Scientists measure this with a score called PDCAAS, which rates protein on a scale from 0 to 1.0 based on its amino acid profile and digestibility. For context, egg protein scores a perfect 1.0 and beef scores 0.92.
Soy protein scores between 0.91 and 1.0, depending on how it’s processed. Soy protein isolate (the kind used in tofu and protein powders) hits a perfect score. Pea protein concentrate scores 0.89. Most other legumes fall in the 0.5 to 0.7 range, meaning your body can use a smaller fraction of their total protein.
This changes the math. A cup of lentils has 18 grams of protein on paper, but your body may effectively use only 10–13 grams. A cup of edamame has 22–24 grams, and your body uses nearly all of it. If you’re counting on legumes as a primary protein source, soy and pea-based options give you the most usable protein per bite.
The Amino Acid Gap in Legumes
All legumes share the same nutritional blind spot: they’re low in sulfur-containing amino acids (methionine and cysteine) and tryptophan. These are essential amino acids your body can’t make on its own. On the flip side, legumes are rich in lysine, which is exactly the amino acid that grains lack.
This is why the classic combination of beans and rice, lentils and bread, or hummus and pita works so well nutritionally. You don’t need to eat them at the same meal. As long as you’re eating both legumes and grains over the course of a day, your body gets the full set of amino acids it needs. Soy is the notable exception here. Its amino acid profile is complete enough on its own that pairing isn’t necessary.
Cooking and Preparation Matter
Legumes contain compounds called lectins that can interfere with protein absorption by disrupting the intestinal lining. They also contain phytates, which bind to minerals like iron and zinc and make them harder to absorb. The good news is that standard cooking methods neutralize most of these compounds.
Boiling is the most effective step. Heat permanently breaks down lectins, which is why properly cooked beans cause no issues while undercooked kidney beans can make you sick. Soaking before cooking helps too, reducing phytate levels by roughly 20–28% depending on the legume. A simple overnight soak followed by thorough boiling is enough to maximize what your body gets from the protein and minerals in the beans.
Sprouting takes this a step further. When legumes sprout, their protein content actually increases. Lupine sprouts contain about 48 grams of protein per 100 grams of dry weight, compared to 44 grams in unsprouted seeds. Soybean sprouts show a similar jump, rising from about 39 to 43 grams per 100 grams dry weight. Sprouting also breaks down some of the compounds that interfere with digestion, so you absorb more of what’s there.
Practical Picks for Different Goals
If your goal is maximum protein per serving with minimal effort, lupini beans are hard to beat. They’re commonly sold jarred in brine, ready to eat as a snack. The taste is bitter if they haven’t been properly brined, so look for prepared versions rather than trying to process raw lupini at home.
For everyday cooking, lentils offer the best balance of high protein, fast prep time, and versatility. Red lentils cook in about 15 minutes and dissolve into soups and sauces. Green and brown lentils hold their shape better for salads and grain bowls.
If protein quality matters most to you, soy-based foods (edamame, tofu, tempeh) deliver both high quantity and a near-perfect amino acid profile. Tempeh has the added benefit of fermentation, which further improves digestibility. Among processed options, pea protein and soy protein isolate score closest to animal proteins on digestibility.
For budget and accessibility, the common beans (black, pinto, kidney, chickpea) all land around 15 grams per cup and cost very little when bought dried. They’re not the highest in protein, but eaten regularly alongside grains, they contribute meaningful amounts to your daily intake. A cup of black beans over rice gives you a complete amino acid profile and roughly 20 grams of protein from the beans and grain combined.