Legumes dominate the list of highest-protein plants, with dried field peas, beans, and lentils packing 20 to 26 grams of protein per 100 grams. But the full picture depends on whether you’re comparing dried seeds, cooked foods, or processed plant proteins, and on how well your body actually absorbs what you eat.
Legumes: The Protein Heavyweights
Dried legumes consistently rank at the top of any plant protein list. Field peas lead with about 26 grams of protein per 100 grams, followed closely by cowpeas and common beans at 24 grams, mung beans at 23 grams, pigeon peas at 22 grams, and chickpeas at 21 grams. These numbers reflect dried, uncooked legumes. Once you cook them, water absorption roughly doubles or triples their weight, so the protein per 100 grams of cooked beans drops to around 7 to 9 grams. That’s still substantial for a plant food, especially considering the fiber and minerals you get alongside it.
Soybeans deserve special mention. While their raw protein content (about 13 grams per 100 grams of fresh edamame) looks modest next to dried beans, processed soy products tell a different story. Tofu, tempeh, and soy protein isolates concentrate that protein significantly. Tempeh delivers around 20 grams per 100 grams, and soy protein is one of the few plant proteins that scores a perfect 1.0 on the PDCAAS scale, a measure of protein quality that puts it on par with meat and dairy.
Lupin beans are a less familiar legume worth knowing about. They contain roughly 36 grams of protein per 100 grams of dried seeds, along with 19 grams of fiber. Lupin flour and lupin-based snacks are becoming easier to find in health food stores, and they offer one of the best protein-to-calorie ratios in the legume family.
Seeds, Nuts, and Pseudocereals
Seeds pack a surprising amount of protein for their size. Sunflower seeds provide about 19 grams per 100 grams, and hemp seeds and pumpkin seeds fall in a similar range. Because seeds are calorie-dense, you typically eat smaller portions (a handful is roughly 30 grams), so a realistic serving gives you 5 to 7 grams of protein. That makes them a useful addition to meals rather than a primary protein source.
Quinoa, amaranth, and buckwheat are often called pseudocereals because they’re seeds that cook like grains. Their protein content is moderate (12 to 16 grams per 100 grams, dry), but what sets them apart is amino acid balance. Unlike true cereals such as rice and wheat, these pseudocereals are not limited in lysine, one of the amino acids most commonly lacking in plant-based diets. Quinoa in particular is rich in leucine, an amino acid important for muscle repair.
Seitan and Processed Plant Proteins
Seitan, made from vital wheat gluten, is one of the most protein-dense plant foods you can buy. It contains about 25 grams of protein per 100 grams, which rivals chicken breast. The texture is chewy and meat-like, which makes it popular in stir-fries and sandwiches. The catch is that seitan is essentially pure wheat protein, so it’s off the table if you avoid gluten. It’s also low in the amino acid lysine, so pairing it with legumes throughout the day helps round out your amino acid intake.
Spirulina and Chlorella
Dried spirulina is roughly 62% protein by weight, and chlorella comes in around 56%. On paper, these algae are the most protein-dense plants on the planet. In practice, though, most people consume them in small doses (a teaspoon or two mixed into smoothies), which translates to just 3 to 6 grams of protein per serving. They’re better understood as nutrient-dense supplements than as primary protein sources.
Why Protein Quality Matters
Not all plant protein is absorbed equally. The PDCAAS scale, long used to rate protein quality, gives soy a perfect score of 1.0. But a newer and more precise measure called DIAAS tells a slightly different story. Under DIAAS, unprocessed soy scores around 86%, and many plant-heavy diets score between 71% and 88% overall. This doesn’t mean plant protein is inadequate. It means your body may need somewhat more total protein from plants to get the same usable amount it would extract from animal sources.
The practical difference is smaller than it sounds. Eating a variety of legumes, grains, seeds, and vegetables throughout the day covers all essential amino acids without any careful combining at individual meals. The old idea that you need to pair “complementary proteins” at every sitting has largely been set aside by nutrition researchers.
How Preparation Affects What You Absorb
High-protein plants, especially legumes, seeds, and whole grains, contain compounds called antinutrients that can interfere with mineral and protein absorption. Phytic acid in beans and grains binds to minerals like iron, zinc, and calcium during digestion, reducing how much your body takes in. Lectins, found in raw or undercooked legumes, can also impair nutrient absorption.
The good news is that common kitchen techniques dramatically reduce these compounds. Soaking dried beans overnight activates enzymes that break down phytic acid and trypsin inhibitors (compounds that slow protein digestion). Cooking further degrades lectins, which is why properly cooked beans cause far fewer digestive issues than underprepared ones. Sprouting and fermmentation go even further: sprouting grains and legumes increases amino acid availability, and fermentation (as in tempeh or traditional soy sauce) partially pre-digests proteins, making them easier to absorb.
For the highest protein absorption from plant foods, your best bet is to soak legumes before cooking, choose fermented options like tempeh over raw soy, and sprout grains and seeds when practical. These aren’t just folk traditions. They meaningfully shift how much protein your body actually extracts from what you eat.
Quick Comparison by Protein Content
- Spirulina (dried): ~62 g per 100 g (tiny typical serving)
- Lupin beans (dried): ~36 g per 100 g
- Field peas (dried): ~26 g per 100 g
- Seitan: ~25 g per 100 g
- Common beans (dried): ~24 g per 100 g
- Chickpeas (dried): ~21 g per 100 g
- Tempeh: ~20 g per 100 g
- Sunflower seeds: ~19 g per 100 g
- Quinoa (dried): ~14 g per 100 g
- Soybeans (fresh edamame): ~13 g per 100 g
Keep in mind that dried legumes and grains absorb water during cooking, so their cooked protein density drops by roughly half to two-thirds. Seitan and tempeh are listed in their ready-to-eat form, making their numbers directly comparable to what ends up on your plate.