Dozens of plants contain meaningful amounts of protein, from legumes and grains to nuts, seeds, and even leafy greens. The highest concentrations are found in soybeans (29 grams per cooked cup), lentils, and other legumes, but you can also get protein from pseudocereals like quinoa, concentrated sources like seitan, and everyday vegetables.
Legumes: The Protein Heavyweights
Legumes consistently top the list of protein-rich plants. Common beans contain about 24 grams of protein per 100 grams dry weight, while lentils range from 25 to 29 grams per 100 grams. Chickpeas come in slightly lower at around 21 grams per 100 grams. Once cooked, a cup of most legumes delivers roughly 15 to 18 grams of protein, making them one of the most practical plant protein sources available.
The one nutritional gap in legumes is that they’re low in sulfur-containing amino acids (methionine and cysteine). Grains happen to be rich in exactly those amino acids, which is why rice and beans, lentils and bread, or hummus and pita are such effective pairings. You don’t need to eat them in the same meal, but eating both regularly throughout the day gives your body the full set of essential amino acids it needs.
Soy: A Complete Protein Source
Soybeans stand apart from other legumes because they provide all essential amino acids in significant quantities. A cup of cooked soybeans packs 29 grams of protein. Soy also scores a 91 out of 100 on the DIAAS scale, a measure of how well your body can actually digest and use a protein source. For comparison, pea protein scores around 70 and wheat protein only 48.
Soy shows up in several forms, each with a different protein density. Half a cup of tempeh (fermented soybeans) provides 16 grams of protein. Four ounces of tofu delivers about 9 grams. Edamame, which is simply young soybeans, falls somewhere between tofu and cooked soybeans depending on how much you eat. Tempeh tends to be the best choice if you’re optimizing for protein per serving, and its fermentation process can make the protein easier to absorb.
Seitan and Wheat Gluten
Seitan is made from vital wheat gluten, the protein fraction of wheat with the starch washed away. The result is remarkably protein-dense: a two-ounce serving contains about 17 grams, roughly matching the same amount of chicken breast. If you’re not sensitive to gluten, seitan is one of the most concentrated plant protein sources you can cook with, and it has a chewy, meat-like texture that works well in stir-fries and sandwiches.
Quinoa, Amaranth, and Buckwheat
These three pseudocereals (they look and cook like grains but are technically seeds) are notable for having well-balanced amino acid profiles. Unlike wheat or rice, which are low in certain essential amino acids, quinoa, amaranth, and buckwheat contain all nine essential amino acids in more useful proportions. A cooked cup of quinoa provides around 8 grams of protein, making it a solid base for meals, though not as protein-dense as legumes.
The real advantage of these pseudocereals is versatility. They work as side dishes, salad bases, or breakfast porridge, and they complement other plant proteins without creating amino acid gaps the way white rice or pasta might on their own.
Seeds and Nuts
Seeds pack a surprising amount of protein into small servings. Hemp seeds provide about 3 grams of protein per tablespoon, along with healthy fats. Pumpkin seeds contain roughly 2 grams per tablespoon. Scale that up to a few tablespoons sprinkled on oatmeal or salad and you’re adding a meaningful protein boost without much effort.
Nuts like almonds, peanuts (technically a legume), and pistachios typically contain 5 to 7 grams of protein per ounce. Peanuts and peanut butter are particularly accessible, with about 7 grams per two-tablespoon serving. The calorie density of nuts is high, so they work best as a protein supplement to meals rather than a primary source.
Spirulina and Microalgae
Spirulina and chlorella contain between 50% and 70% protein by dry weight, which is higher than virtually any other whole food. In practice, though, you eat them in tiny amounts. A tablespoon of spirulina powder adds a few grams of protein. It’s a useful addition to smoothies, but you’d need unrealistic quantities to rely on it as a major protein source. Think of it as a nutrient-dense bonus, not a foundation.
Vegetables With the Most Protein
Vegetables aren’t typically thought of as protein sources, but some contribute more than you’d expect, especially relative to their calorie count. Brussels sprouts lead common vegetables with 3.4 grams per 100-gram serving, followed by collard greens at 3 grams. Spinach and mustard greens each provide 2.9 grams, and broccoli comes in at 2.8 grams per 100-gram serving.
What makes certain vegetables interesting is their protein-to-calorie ratio. Watercress gets 84% of its calories from protein. Spinach gets 50%, and asparagus gets 44%. You won’t build a high-protein diet on vegetables alone, but if you’re eating several cups of greens and cruciferous vegetables daily, you could easily pick up an extra 8 to 12 grams of protein without trying.
How Cooking Affects Plant Protein
Raw legumes contain compounds called antinutritional factors that interfere with protein digestion. Soaking and cooking break down or deactivate these compounds, which significantly improves how much protein your body can actually absorb. Grinding legumes into flour or paste also helps by breaking up cell walls and giving digestive enzymes more surface area to work with.
There’s one trade-off worth knowing about: some water-soluble proteins leach into the cooking liquid. If you’re boiling beans or lentils and discarding the water, you lose a small fraction of the available protein. Using the cooking liquid in soups or stews, or choosing methods like pressure cooking with less water, helps you retain more of what the plant originally offered. Sprouting is another effective technique. It partially breaks down stored proteins into more digestible forms before you even start cooking.
Combining Plants for Complete Protein
Most plant proteins are “incomplete,” meaning they’re low in at least one essential amino acid. Legumes lack sulfur-containing amino acids. Grains and rice lack lysine. But these gaps are perfectly complementary: eating grains and legumes together, or at different points in the same day, provides your body with every amino acid it needs.
Soy, quinoa, amaranth, and buckwheat are exceptions that deliver a more complete amino acid profile on their own. If you eat a varied diet that includes legumes, whole grains, nuts, seeds, and vegetables, protein deficiency from plant sources is unlikely. The practical goal isn’t to obsess over individual amino acids but to eat a range of plant protein sources throughout the week.