Protein is an essential nutrient. The body needs it to build and repair tissues.
Although animal foods are usually highest in protein, some plants also contain high amounts.
Here are 10 healthful vegetables that contain a fair amount of protein.
Watercress is a cruciferous plant that grows in water. It is high in protein per calorie.
Watercress has the following protein content (1):
- One cup (34 grams [g]) of watercress contains 0.8 g of protein.
- 100 g of watercress contains 2.3 g of protein and 11 calories.
- Protein accounts for 84% of its calories.
Avoid boiling watercress in water, as this will decrease its antioxidant content. Instead, eat raw watercress in salads, stuff it into sandwiches, or blend it into smoothies (7).
Alfalfa sprouts are very low in calories but rich in nutrients.
Alfalfa sprouts have the following protein content (8):
- One cup (33 g) of alfalfa sprouts contains 1.3 g of protein.
- 100 g of alfalfa sprouts contains 4 g of protein and 23 calories.
- Protein accounts for 69% of their calories.
In an older study, from 1987, researchers gave 15 people with high blood lipid levels 40 g of alfalfa seeds three times daily for 8 weeks. These people had a 17% reduction in total cholesterol and an 18% reduction in low-density lipoprotein, or “bad,” cholesterol (11).
Spinach is one of the most nutrient-dense leafy green vegetables a person can eat.
Spinach has the following protein content (15):
- One cup (25 g) of raw spinach contains 0.7 g of protein.
- 100 g of spinach contains 2.9 g of protein and 23 calories.
- Protein accounts for 50% of its calories.
The protein in spinach contains all essential amino acids. One cup of spinach contains 121 mcg of vitamin K, which is just over 100% of a person’s daily needs (2).
Spinach is also a rich source of folate, vitamin A, and vitamin C. It is a good source of magnesium, iron, and potassium, and a decent source of calcium.
Spinach contains plant compounds that can increase antioxidant defense and reduce inflammation (16).
In one study, 10 athletes who took spinach supplements for 14 days showed reduced oxidative stress and reduced muscle damage after running a half-marathon, compared with those who took a placebo (17).
In another study, researchers gave nitrate-rich spinach to healthy participants and measured its effects on their levels of nitric oxide, which is a signaling molecule that widens the blood vessels. They also measured cell function and blood pressure.
They found that nitrate-rich spinach increased nitric oxide, improved endothelial cell function, and lowered blood pressure — all of which can improve heart health (18).
Chinese cabbage, which refers to the napa cabbage and bok choy, also has a high protein content per calorie.
Chinese cabbage has the following protein content (20):
- One cup (70 g) of shredded Chinese cabbage contains 1.1 g of protein.
- 100 g of Chinese cabbage contains 1.5 g of protein and 13 calories.
- Protein accounts for 46% of its calories.
Chinese cabbage is a rich source of vitamins A, C, and K. It is also a good source of folate and a decent source of calcium and potassium.
A number of cell studies have shown that Chinese cabbage is rich in compounds with antioxidant activity. Its outer leaves appear to contain the most antioxidants. It may also have anti-inflammatory properties (21, 22, 23)
People use Chinese cabbage in many Asian recipes, such as stir-fries, kimchi, soups, and spring rolls.
Asparagus is a very popular vegetable with a high nutrient content.
Asparagus has the following protein content (26):
- One cup (134 g) of asparagus contains 3 g of protein.
- 100 g of asparagus contains 2.2 g and 20 calories.
- Protein accounts for 44% of its calories.
Asparagus is a rich source of vitamin K and a good source of folate and riboflavin. It also contains some magnesium, phosphorous, and vitamin A.
Asparagus may also have anti-inflammatory and anticancer properties (27).
People can grill, boil, steam, or pan-fry asparagus, and it works in salads and as a side dish.
Mustard greens belong to the Brassica family. They are very similar to kale but have a distinct mustard flavor.
Mustard greens have the following protein content (30):
- One cup (56 g) of chopped mustard greens contains 1.6 g of protein.
- 100 g of mustard greens contains 2.9 g of protein and 27 calories.
- Protein accounts for 42% of their calories.
One cup also provides 144 mcg of vitamin K, which is more than 100% of a person’s daily needs (2).
They are a rich source of vitamin C and also contain calcium, potassium, and B vitamins. They are also a good source of vitamin E.
A test-tube study demonstrated that steaming mustard greens increases their ability to bind to bile acids. This may help them reduce cholesterol levels (32).
The same study also found that steaming may have similar positive effects on collard greens, kale, cabbage, green peppers, and broccoli.
People can steam, boil, or saute mustard greens, or they can simply eat them raw.
Collard greens are dark green, loose leafed vegetables from the same family as kale, broccoli, and cauliflower.
Collard greens have the following protein content (33):
- One cup (36 g) of chopped collard greens contains 1.1 g of protein.
- 100 g of collard greens contains 3 g of protein and 32 calories.
- Protein accounts for 38% of their calories.
Their vitamin K content is particularly remarkable, with 157 mcg in a single cup. This is around 131% of a person’s daily needs (2).
They are also rich in vitamin C and folate, are a good source of calcium, and contain some potassium.
Research has linked the high levels of antioxidants in collard greens with a decreased risk of developing prostate cancer (24).
One study reported that people who eat cruciferous vegetables, such as collard greens, are less likely to receive a diagnosis of breast cancer (35).
Collard greens can also bind to bile acids in the gut, which helps reduce cholesterol levels. One study showed that steam cooking boosts this benefit (32).
Broccoli is a very popular vegetable that also happens to contain protein with all the essential amino acids. People can enjoy it either raw or cooked.
Broccoli has the following protein content (36):
- One cup (88 g) of chopped broccoli contains 2.5 g of protein.
- 100 g of broccoli contains 2.8 g of protein and 34 calories.
- Protein accounts for 33% of its calories.
Broccoli is a very rich source of vitamins C and K, a good source of folate, and a decent source of phosphorous and potassium. It also contains some calcium.
Broccoli also provides high amounts of plant compounds and flavonoids, such as kaempferol. These may have antioxidant, anti-inflammatory, and anticancer effects (37).
Like all cruciferous vegetables, broccoli is high in glucosinolates. These are compounds that may help reduce the risk of cancer (38).
Also, like mustard greens, broccoli has a higher capacity to bind to bile acids when steamed, so eating steamed broccoli may help reduce cholesterol levels in the blood (32).
Additionally, broccoli can help improve liver health by stimulating detoxification and the production of antioxidant compounds in the liver (39).
People can steam, roast, bake, or saute broccoli. It also works well in soups and sauces or as a side dish.
Brussels sprouts are a great addition to most diets. They are a good source of protein, fiber, and vitamins.
Brussels sprouts have the following protein content (40):
- One cup (88 g) of Brussels sprouts contains 3 g of protein.
- 100 g of Brussels sprouts contains 3.4 g of protein and 43 calories.
- Protein accounts for 31% of their calories.
One cup contains 3.3 g of fiber. Brussels sprouts are also very rich in vitamins C and K and are a good source of folate and vitamin B-6. They are also a decent source of iron and potassium.
One animal study reported that eating Brussels sprouts promoted the growth and health of intestinal bacteria and stimulated the production of short-chain fatty acids in the gut (41).
People can cook Brussels sprouts by boiling, steaming, grilling, or roasting them. They work well as a side dish.
Like broccoli, cauliflower provides a high amount of protein for the number of calories it delivers.
Cauliflower has the following protein content (42):
- One cup (107 g) of cauliflower contains 2 g of protein.
- 100 g of cauliflower contains 1.9 g of protein and 25 calories.
- Protein accounts for 31% of its calories.
Cauliflower is a very rich source of vitamin C and a good source of vitamin K. It also contains some calcium, iron, magnesium, and phosphorous.
Cauliflower also contains a high amount of a particular glucosinolate compound called sinigrin, which may have anticancer, antioxidant, and anti-inflammatory properties (43).
The glucosinolate content of cauliflower may drop significantly when a person cooks it. Therefore, cauliflower may be better raw (44).
However, cauliflower is also high in other antioxidants that are preserved during cooking and may even increase after a person steams or microwaves the vegetable (45).
Like several other vegetables on this list, cauliflower has the potential to reduce cholesterol levels due to its ability to bind to bile acids. Steaming cauliflower increases this capacity (46).
Cauliflower is a versatile vegetable suited to a variety of recipes. In many cases, it can act as a substitute for starchy carbohydrates, such as pasta or bread.
Even though vegetables are not very high in protein compared with some other foods, many contain good amounts of protein relative to their calorie content.
Also, the vegetables on this list are high in many other nutrients that scientists have linked to all sorts of health benefits.
Consuming these protein-rich vegetables is a great way to increase the protein and nutrient content of any diet without adding many calories.