What leafy vegetable has the most protein?

December 20, 2025 •

5 min read

While protein is often associated with meat and legumes, the truth is that all plants contain protein, and leafy greens are surprisingly potent sources. In fact, watercress was ranked the number one powerhouse vegetable for nutrient density by the CDC.

Quick Summary

Watercress contains the highest protein content per calorie, while cooked spinach and collard greens offer significant protein per serving, making them excellent choices for boosting intake.

Key Points

Watercress Leads in Protein Density: Watercress provides the most protein per calorie among leafy vegetables, making it highly nutrient-dense.
Cooked Spinach is a Protein Powerhouse: A single cooked cup of spinach offers a significant protein boost, around 5.35 grams, due to its reduced volume.
Cruciferous Greens are Top Contenders: Kale and collard greens are also excellent sources of plant protein and come packed with vitamins and antioxidants.
Measure Matters for Protein Content: The 'most protein' title can vary depending on whether you measure by raw weight, cooked volume, or per calorie basis.
Variety is Key for Complete Protein: Eating a wide variety of plant-based protein sources, including greens, ensures you get all the essential amino acids your body needs.
Cooking Increases Protein Concentration: While raw greens offer great nutrition, cooking reduces water content, concentrating the protein and nutrients per serving.
Greens Offer Added Health Benefits: In addition to protein, leafy greens provide fiber, vitamins, and minerals that support overall health and weight management.

Protein Powerhouses: Beyond the Cliche

When people think of protein, they often turn to animal products, beans, or lentils. However, leafy greens offer a fantastic, low-calorie way to supplement your protein intake with the added benefit of essential vitamins, minerals, and antioxidants. The question of which leafy vegetable has the most protein is nuanced and depends on whether you measure by volume, cooked weight, or protein per calorie. By all accounts, a few key contenders rise to the top, with the unexpected watercress leading the charge for its exceptional nutrient density relative to its caloric load.

The Surprising Star: Watercress

Watercress is a standout cruciferous vegetable, praised for its peppery flavor and incredible nutritional profile. When measured for protein per calorie, it is often ranked highest among leafy greens. A 100-gram serving of watercress contains about 2.3 grams of protein and only 11 calories, meaning protein accounts for a significant portion of its total calories. This low-calorie, high-protein combination makes it an excellent choice for weight management and overall health. Its nutritional benefits extend beyond protein, offering more than 100% of the daily recommended intake for vitamin K in just one cup, along with vitamins A and C.

Easy Ways to Add Watercress to Your Diet:

Blend it into a smoothie with fruit and other greens.
Use it as the base for a vibrant salad.
Stir it into soups or stews right before serving to preserve its texture and nutrients.
Add a handful to your sandwiches or wraps for a peppery kick.

The Classic Contender: Spinach

Popeye's favorite vegetable is a nutritional champion for good reason. Spinach is one of the most widely consumed leafy greens and offers a robust protein content, especially when cooked. While one cup of raw spinach contains less than a gram of protein, a cooked cup is a different story entirely. Because it shrinks so much, a cooked cup of spinach contains about 5.35 grams of protein, making it a very effective source. Spinach is also an excellent source of iron, folate, and vitamins A, C, and K, contributing to its status as a nutrient-dense superfood.

Quick Tips for Cooking with Spinach:

Sauté it with garlic and olive oil for a simple, healthy side dish.
Mix it into eggs for a protein-packed breakfast scramble.
Use it as a base for pasta sauces or lasagna fillings.
Fold it into dips, like a classic spinach and artichoke dip.

The Hearty Green: Kale

Kale, another cruciferous superstar, is prized for its hearty texture and impressive nutritional content. Its protein count is respectable, with a cooked cup providing approximately 3.5 grams. A 100-gram serving of raw kale has about 3.3 grams of protein, a higher raw volume content than spinach. Kale is also an excellent source of vitamins C, A, and K, as well as fiber and various antioxidants.

Other Notable Leafy Greens with High Protein

Collard Greens: Like kale, collard greens are part of the cabbage family and boast a high protein content, particularly when cooked. One cup of cooked collard greens can provide over 5 grams of protein, along with significant amounts of folate, vitamin C, and calcium.
Mustard Greens: Similar to kale, these greens have a peppery flavor and offer a notable protein boost, with a cooked cup containing about 3.5 grams.
Swiss Chard: This vibrant leafy green offers a good amount of protein, along with vitamins A, C, E, and K, and a variety of minerals.

Cooking's Effect on Protein and Nutrients

Cooking methods can alter the nutrient profile of leafy greens. For instance, boiling can cause some water-soluble vitamins, like vitamin C, to leach into the water. However, cooking is often beneficial for protein intake in leafy greens like spinach because it significantly reduces the volume, allowing for more protein per serving. In the case of spinach, a large volume of raw leaves cooks down into a much more compact, protein-dense portion. For preserving nutrients, lightly steaming or sautéing is often recommended.

Comparison of High-Protein Leafy Greens


Vegetable	Protein (Cooked, per 100g)	Protein (Raw, per 100g)	Key Nutritional Highlights
Watercress	~2.3g	~2.3g	Highest protein per calorie, rich in vitamins K, A, C.
Spinach	~5.35g	~2.9g	Excellent source of iron, folate, and vitamins.
Collard Greens	~3.0g	~3.0g	Significant source of folate, vitamin C, and calcium.
Kale	~3.5g	~3.3g	Hearty, high in vitamins C, A, K, fiber.
Mustard Greens	~2.9g	~2.9g	Peppery flavor, similar to kale.

Note: Protein content can vary based on growing conditions and specific varieties. Cooked figures often reflect a denser serving size than raw.

Boosting Your Plant-Based Protein Intake

While leafy greens offer a valuable protein contribution, they work best as part of a varied diet that includes other plant-based protein sources like legumes (beans, lentils), nuts, and seeds. Combining these foods ensures you receive a full spectrum of essential amino acids throughout the day. For example, pairing spinach with chickpeas in a salad or adding kale to a lentil stew creates a well-rounded meal.

For a delicious, protein-packed recipe, consider a wilted spinach and lentil salad. Simply sauté lentils with some onion and garlic, then toss with fresh spinach, a squeeze of lemon juice, and some nuts for extra crunch and protein. Or, for a quick snack, blend watercress, a ripe avocado, and a scoop of your favorite plant-based protein powder for a nutrient-dense, filling smoothie.

Conclusion: The Green Protein Verdict

Pinpointing a single winner for "most protein" depends on the metric. Watercress stands out for its high protein-per-calorie ratio, making it incredibly nutrient-dense. However, when considering cooked volume, greens like spinach and collard greens can offer a higher absolute protein amount per serving. For the average person, focusing on variety is the best strategy. Incorporating a mix of these protein-rich leafy greens, along with other plant-based protein sources, is the most effective way to reap their extensive health benefits and meet your daily protein goals. Ultimately, the best leafy green for protein is the one you enjoy eating consistently. For further nutritional insights, consult the official guidelines from authoritative sources like the American Heart Association (AHA).

Frequently Asked Questions

Most individual leafy greens are not considered 'complete' protein sources because they may lack sufficient levels of one or more essential amino acids. However, eating a diverse range of plant-based foods throughout the day, including greens, ensures your body receives all necessary amino acids.

Cooking leafy greens like spinach causes them to wilt and shrink significantly due to water loss. This concentrates the nutrients, including protein, so a cooked cup contains more protein than a raw cup.

While leafy greens are a valuable source of protein, they are low in calories. It would be challenging to meet your daily protein needs from greens alone without consuming an unfeasibly large volume. They should be part of a balanced diet with other protein sources like legumes, nuts, and seeds.

For maximizing protein per serving, cooking methods that reduce volume, like sautéing or steaming, are most effective for greens like spinach and kale. Blending into smoothies is another great way to consume a higher quantity.

Per 100 grams, raw kale contains slightly more protein (3.3g) than raw spinach (2.9g). However, raw watercress has the highest protein-per-calorie ratio.

Yes, collard greens are an excellent source of protein, especially when cooked. A cup of cooked collard greens provides a notable amount of protein, along with plenty of vitamins and minerals.

Leafy greens are loaded with nutrients. Watercress is high in vitamins K, A, and C. Spinach offers iron and folate. Kale and collard greens provide high levels of vitamins C, A, and K, as well as fiber and calcium.