Exploring Nutrition: Which leafy green is highest in protein?

October 28, 2025 •

4 min read

For those focusing on plant-based nutrition, a common query is which leafy green is highest in protein? While many greens are not considered primary protein sources, one stands out per 100g, offering a significant nutritional boost alongside a host of other vitamins and minerals. Surprisingly, the answer can depend on whether the green is measured raw or cooked.

Quick Summary

Alfalfa sprouts and Brussels sprouts provide the most protein per 100g among common leafy greens, followed closely by spinach and mustard greens. The protein density of cooked greens increases as water is removed, altering the nutritional comparison. A balanced intake of diverse leafy greens is recommended for a broad spectrum of nutrients.

Key Points

Alfalfa Sprouts Are King (by raw weight): Per 100 grams, alfalfa sprouts pack the most protein among common raw leafy greens.
Cooking Concentrates Nutrients: While raw greens are low in protein by volume, cooking removes water, significantly increasing the protein concentration per cup in vegetables like spinach and collards.
Don't Forget About Brussels Sprouts: Technically a leafy green, Brussels sprouts are very protein-dense, containing 3.4g of protein per 100g.
A Balanced Approach is Best: Relying on a variety of leafy greens ensures a broad spectrum of vitamins, minerals, and antioxidants, alongside their protein contribution.
Not Just Protein: High-protein greens like spinach and kale are also loaded with other vital nutrients like Vitamin K, Iron, and Vitamin C.

The Top Contender: Alfalfa Sprouts

While not the first vegetable that comes to mind for protein, alfalfa sprouts generally top the list when comparing protein content by weight among common raw leafy greens. A 100-gram serving of alfalfa sprouts contains approximately 4 grams of protein, making it a surprisingly potent option. These small, tender sprouts are also very low in calories but rich in other vital nutrients, including vitamin K and vitamin C. Alfalfa sprouts are highly versatile and can be added raw to sandwiches, salads, or smoothies for an easy nutritional boost.

The Cooking Conundrum: Raw vs. Cooked Greens

When assessing protein content in leafy greens, comparing raw and cooked versions is crucial. Cooking greens, such as spinach or collard greens, causes them to lose a significant amount of water and shrink in volume. This concentration effect means a cup of cooked greens contains more protein than a cup of the same greens raw. For example, one cup of raw spinach contains 0.9g of protein, whereas one cup of cooked, chopped collard greens contains 5.2g of protein, though the cooked portion weighs more. While this is a practical consideration, comparing based on raw weight (per 100g) offers a more consistent and direct metric for raw ingredients.

A Head-to-Head Comparison of Protein-Rich Greens

To provide a clearer picture, here is a comparison of the protein content and other nutritional highlights for several popular leafy greens, based on approximately 100g of the raw vegetable:


Leafy Green	Protein (per 100g, raw)	Key Nutrients (in addition to protein)
Alfalfa Sprouts	~4.0g	Vitamin K, Vitamin C, Folate
Brussels Sprouts	~3.4g	Very high in Vitamin C & K, Fiber
Spinach	~2.9g	Iron, Calcium, Vitamin A, Vitamin K, Folate
Mustard Greens	~2.9g	Vitamin K, Vitamin C, Calcium
Collard Greens	~2.7g	Very high in Vitamin K, Vitamin A, Calcium
Kale	~2.0g	Very high in Vitamins A, C, and K, Calcium
Watercress	~2.3g	Vitamin K, Vitamin C, Antioxidants

It is worth noting that while Kale may be slightly lower in protein per 100g than spinach, a different type of comparison shows it has a higher percentage of protein per serving size, depending on how it's prepared and served. However, spinach contains more iron, folate, and magnesium. Ultimately, a variety of greens offers the greatest range of health benefits.

Maximizing Protein and Nutrient Absorption

To get the most out of your leafy greens, consider a few simple preparation and pairing techniques:

Pair with Vitamin C: The non-heme iron found in plant-based sources like spinach is best absorbed when consumed with a source of vitamin C. A squeeze of lemon on your spinach or adding citrus to a smoothie can significantly boost iron absorption.
Add Healthy Fats: For fat-soluble vitamins like A, E, and K (all plentiful in leafy greens), consuming them with a source of healthy fat, such as avocado or olive oil, can increase their absorption.
Embrace Cooking: For nutrients like calcium and beta-carotene, cooking can actually increase bioavailability by breaking down the greens' structure and reducing oxalic acid content, which can inhibit mineral absorption.

Health Benefits Beyond Protein

Beyond their modest protein content, leafy greens are celebrated as superfoods for their impressive nutrient profiles. They are a cornerstone of healthy eating and offer numerous health advantages, including:

Rich in Antioxidants: Leafy greens are packed with powerful antioxidants, such as carotenoids and flavonoids, that help protect cells from damage and reduce inflammation. This can lower the risk of chronic diseases like heart disease and cancer.
Heart Health: High levels of potassium and nitrates in many leafy greens can help relax blood vessels and lower blood pressure, promoting cardiovascular health.
Bone Health: Many greens, including kale, spinach, and collard greens, are rich in vitamin K, which is essential for blood clotting and bone health.
Digestive Regularity: The high fiber and water content aid digestion and help prevent constipation.
Brain Function: Studies have shown that consuming leafy greens daily can help slow age-related memory decline, with folate and antioxidants protecting brain cells.

Conclusion: Embracing a Variety of Greens

While alfalfa sprouts can claim the title of which leafy green is highest in protein? per 100g of raw product, the takeaway for a healthy diet is more nuanced. Greens like spinach, Brussels sprouts, kale, and collard greens also provide significant protein and a wealth of other essential nutrients, especially when considering the concentration that occurs during cooking. Instead of focusing on a single winner, incorporating a diverse range of these vegetables ensures you benefit from a wide spectrum of vitamins, minerals, and antioxidants. Whether raw in a salad or cooked into a hearty soup, adding more leafy greens is a simple and effective strategy for boosting overall health. For further information on food composition, reference the official USDA FoodData Central at https://fdc.nal.usda.gov.

Frequently Asked Questions

While it can depend on preparation, many sources indicate that per 100g, spinach has slightly more protein than kale, though both are excellent nutritional choices. Spinach is also richer in iron and folate, while kale is higher in Vitamin C.

No, leafy greens are not a complete protein source and do not provide sufficient protein to meet daily needs alone. They are best consumed as part of a varied diet that includes other protein sources like legumes, nuts, and seeds.

No, cooking does not destroy the protein. In fact, by reducing the water content, it concentrates the protein, meaning a cup of cooked spinach has more protein than a cup of raw spinach.

High-protein leafy greens are typically rich in vitamins A, C, and K, as well as minerals like iron, calcium, and magnesium and beneficial antioxidants.

Pair iron-rich leafy greens like spinach with a source of vitamin C, such as a squeeze of lemon juice or citrus fruits, as this enhances non-heme iron absorption.

Alfalfa sprouts are young, sprouted alfalfa plants. They are typically eaten raw in sandwiches, salads, or mixed into soups or smoothies.

For most people, consuming leafy greens is safe and healthy. However, those on blood thinners must monitor their intake of high-vitamin K greens (like spinach and kale), and those prone to kidney stones should be mindful of high-oxalate greens like spinach.