Watercress: What Leafy Green is Highest in Protein?

January 3, 2026 •

4 min read

According to the Centers for Disease Control and Prevention, watercress ranks as the most nutrient-dense powerhouse fruit and vegetable, boasting an exceptionally high protein-to-calorie ratio. This spicy green answers the question: what leafy green is highest in protein?

Quick Summary

This article explores why watercress is considered the leafy green with the highest protein density, comparing its nutritional profile to other popular greens like spinach and kale. It details the extensive health benefits of high-protein leafy greens, and offers practical tips for incorporating them into daily meals.

Key Points

Watercress Leads in Protein Density: Watercress has the highest protein-to-calorie ratio of all leafy greens, with protein comprising up to 84% of its calories.
Cooked Spinach Offers More Protein by Volume: While raw spinach has less protein, cooking it significantly reduces volume, making a cup of cooked spinach a potent protein source.
Vitamins and Antioxidants: Leafy greens are packed with vitamins A, C, and K, along with potent antioxidants that combat chronic disease.
Versatile in the Kitchen: You can easily incorporate high-protein greens into your diet through smoothies, salads, soups, and sautéed dishes.
Supports Overall Health: Regular consumption of nutrient-dense greens boosts immune function, strengthens bones, and aids in weight management.
Variety is Best: Incorporating a mix of greens like spinach, kale, and watercress provides a wider spectrum of flavors and nutritional benefits.

Watercress: The Protein Powerhouse Per Calorie

While spinach often receives a reputation for being high in protein, watercress earns the top spot when looking at protein content relative to its low-calorie count. A 100-gram serving of watercress offers 2.3 grams of protein for only 11 calories, meaning protein accounts for a remarkable 84% of its total calories. This exceptional nutrient density is why it often outperforms other greens in a head-to-head comparison.

Comparing Leafy Greens by Protein Density

To understand why watercress is the leader, it's helpful to look at its protein density compared to other popular choices. While greens like collards and spinach may have a higher raw protein quantity by weight, watercress provides a significantly higher percentage of protein per calorie, making it highly efficient for those focused on nutrient intake.

A Deeper Dive into Watercress's Nutritional Profile

Beyond its high protein ratio, watercress is a nutritional superstar packed with an array of vitamins and minerals. It is particularly high in vitamin K, offering over 100% of the recommended daily intake in just one cup. This vitamin is crucial for blood clotting and bone health. Watercress is also an excellent source of vitamins A and C, as well as several beneficial antioxidant compounds called flavonoids, which help protect the body from cellular damage. Its high concentration of antioxidants may help lower the risk of chronic diseases such as heart disease and certain cancers.

The Health Benefits of Nutrient-Dense Leafy Greens

Incorporating a variety of leafy greens into your diet offers a wide range of health advantages. These vegetables are low in calories and fat while providing essential nutrients like fiber, vitamins, and minerals that support overall wellness.

Supports Cardiovascular Health: High levels of antioxidants and dietary nitrates found in watercress and other greens can help reduce inflammation, lower blood pressure, and decrease cholesterol, all contributing to a healthier heart.
Enhances Immune Function: Many greens, including watercress, are rich in vitamin C, which is known to boost the immune system by supporting the production of white blood cells that fight off infections.
Aids in Digestion and Weight Management: High-fiber greens promote regular bowel movements and help you feel full, which can assist with weight management. Watercress, being incredibly low in calories, is an excellent addition to a weight-loss diet.
Strengthens Bones: Nutrients like vitamin K, calcium, and magnesium found in leafy greens are essential for maintaining strong and healthy bones throughout your life.

Cooking with High-Protein Leafy Greens

From fresh salads to savory soups, integrating these powerful greens into your meals is simple and delicious. The key is to avoid overcooking them to preserve their nutritional integrity.

Delicious Ways to Use High-Protein Greens

Salads: Use raw watercress or a mix of watercress, baby spinach, and arugula as the base for a vibrant and peppery salad. Add ingredients like nuts, seeds, and a light vinaigrette.
Smoothies: A handful of fresh spinach or kale blends seamlessly into a fruit smoothie, boosting its protein and nutrient content without significantly altering the flavor.
Sautéed Sides: Sautéed collard greens, Swiss chard, or spinach with a bit of garlic and olive oil make a quick, nutrient-packed side dish. Remember, cooking wilts the leaves significantly, allowing you to consume a larger quantity of nutrients easily.
Soups and Stews: Add leafy greens to soups, curries, or stews near the end of cooking. The greens will wilt quickly while retaining their nutritional value.
Pesto and Sauces: Blend greens like watercress, spinach, or basil with nuts, garlic, olive oil, and nutritional yeast for a vegan, protein-rich pesto or sauce for pasta.

Comparison of High-Protein Leafy Greens


Leafy Green	Protein (g) per 100g	Calories per 100g	Protein per Calorie (%)	Notes
Watercress	2.3	11	84%	Highly nutrient-dense with a peppery flavor.
Spinach (Cooked)	5.3	20	50%	Cooked spinach is more protein-dense than raw due to volume reduction.
Kale (Cooked)	3.5	43	33%	Very high in vitamins A, C, and K.
Collard Greens (Cooked)	5.2	62	33%	Excellent source of vitamin K and calcium.
Mustard Greens	2.9	27	42%	Distinct spicy, mustard-like flavor.
Alfalfa Sprouts	4.0	23	69%	Very low in calories and rich in nutrients.

Conclusion: Making the Best Green Choice

While the absolute quantity of protein might not be the highest in leafy greens compared to legumes or meat, their remarkable protein density per calorie is a compelling reason to include them in your diet. Watercress, with its leading protein-per-calorie ratio, stands out as a prime choice for maximizing nutritional intake. However, for those seeking higher total protein from greens, cooked spinach and collard greens offer substantial amounts, especially when prepared in larger quantities. By understanding the unique nutritional profiles of different leafy greens, you can make informed decisions to enrich your diet with a variety of flavors and health benefits. Don't be fooled by small numbers; these leafy powerhouses provide an efficient and delicious path to better health.

For more nutritional details, the USDA's FoodData Central is a highly reliable resource for information on thousands of foods.

Frequently Asked Questions

When cooked and compared by volume or weight, spinach and collard greens often provide more total protein than watercress. For example, a cup of cooked collard greens contains around 5.2 grams of protein.

Watercress, like many plant-based protein sources, contains all nine essential amino acids. However, the amino acid profile may be less concentrated than in animal proteins, so combining it with other plant sources is recommended for a balanced diet.

Cooking does not destroy the protein in leafy greens. Instead, by reducing the volume of the leaves, cooking concentrates the nutrients, including protein, allowing you to consume a greater quantity in a single serving.

No, leafy greens should be part of a balanced diet but are not intended as a sole protein source. They contribute to your overall protein intake but should be supplemented with other high-protein foods like legumes, nuts, and seeds.

Protein density refers to the amount of protein a food contains relative to its calorie count. Watercress is known for its high protein density because it packs a significant amount of protein into very few calories.

Yes, different greens contain varying concentrations of essential amino acids. A varied intake of greens, along with other plant proteins, ensures your body receives a comprehensive array of amino acids for optimal health.

To maximize your intake, consider blending a large amount of raw spinach into a smoothie or sautéing a full bag of greens down to a smaller, more concentrated portion. This increases your nutrient density per serving.