These Are 4 of the Most Nutrient Dense Vegetables to Add to Your Diet, According to the CDC

You may have heard recently that watercress is considered the healthiest vegetable, according to the Centers for Disease Control and Prevention (CDC), and made a mental note to add it to your grocery list as a result. But watercress isn’t for everyone, and it can be tricky to find in some stores, putting this leafy green out of reach for some. 

But know this: The CDC also flagged other “powerhouse” vegetables for their high nutritional value, giving you options to choose from. Those include Chinese cabbage (such as bok choy, Napa cabbage, and tatsoi), chard, beet greens, and spinach. While these don’t match the perfect 100/100 nutrient density score of watercress, they come close — all of these have a nutrient density score of 86 or higher. 

Turns out, these vegetables have a few things in common beyond being packed with nutrients. Here’s why they’re so impactful, according to nutritionists. 

What is a nutrient density score?

Nutrient density score is a measure that evaluates the amount of essential nutrients in a food relative to its calorie content, explains Keri Gans, RD, author of The Small Change Diet. “It is typically calculated by dividing the total amount of key nutrients — like vitamins, minerals, and fiber — by the number of calories in a food item,” she says. 

The CDC calculates nutrient density score based on the mean percentage of daily values of 17 essential nutrients, including potassium, fiber, protein, calcium, iron, vitamins A, B6, C, E, and K, found in 100 grams of the food, says Scott Keatley, RD, co-owner of Keatley Medical Nutrition Therapy.

“The score reflects the balance of these nutrients per 100 calories of food,” Keatley says. “Foods scoring above 100 are capped at 100, indicating they provide, on average, 100% of the daily value for these nutrients per 100 calories.” 

This method “highlights foods that are nutrient-dense, yet low in calories, making them highly efficient at delivering essential nutrients without excessive energy intake,” Keatley explains. 

What do these vegetables have in common?

These vegetables are all leafy greens. “Leafy greens are well-known for their high nutrient density, meaning they provide a significant amount of essential vitamins and minerals per calorie,” Keatley says. 

These vegetables also have a few key nutrients in common. “The amount of vitamins A, C, and K in Chinese cabbage, chard, beet greens, and spinach set these foods apart from other powerhouse fruits and vegetables,” says Kathleen Moore, RDN, a nutritionist at The Ohio State University Wexner Medical Center.

What are the different kinds of Chinese Cabbage?

Chinese cabbage — which can refer to Napa cabbage, bok choy, and tatsoi — are all subspecies of Brassica rapa but differ nutritionally, according to Keatley. "Bok choy and tatsoi are higher in calcium, iron, and vitamins A, C, and K, making them more nutrient-dense than Napa cabbage, which offers more folate and fiber," he says. "While all three are great for a balanced diet, tatsoi packs the biggest punch in vitamins and minerals."

Napa cabbage

Napa cabbage, which was first cultivated in the 15th century along the Yangtze River in China, is nutritionally beneficial in that it's a "good source of fiber, Vitamin C, and folate," says Keatley.

Bok choy and baby bok choy

Boy choy — also often referred to as "pak choi" — and baby bok choy are powerhouses of nutrients and minerals. "Boy choy stands out for its higher calcium and Vitamin A content, which support bone health and immune function. It’s also rich in Vitamin C and antioxidants like beta-carotene," Keatley says. "Meanwhile, baby bok choy offers a rich source of Vitamins A, C, and K. Its nutritional profile is similar to bok choy but is typically more concentrated due to its smaller, darker leaves."

What makes Chinese cabbage, chard, beet greens, and spinach so healthy?

In addition to vitamins A, E, and K, these vegetables have vitamin C, along with minerals like calcium, magnesium, and iron. “Their cellular structure and phytonutrient profile contribute to their exceptional nutrient density, which supports a wide range of physiological functions, from antioxidant activity to bone health,” Keatley says. 

These nutrients are “highly bioavailable,” which means they’re easy to digest and absorb in the body, Moore says. “Additionally, leafy greens like these tend to have low natural sugar content and a broad array of bioactive compounds, such as glucosinolates in cabbage and carotenoids in spinach, which have additional health benefits like cancer prevention and improved metabolic health,” Keatley says.

Do the benefits go away when they’re heated or cooked? 

It depends. “Cooking does lead to some loss of certain heat-sensitive nutrients, particularly vitamin C and certain antioxidants,” Keatley says. “For instance, boiling can reduce vitamin C content by up to 50%, while steaming tends to preserve more nutrients.” 

But cooking can also enhance the bioavailability of other nutrients, like beta-carotene in spinach and calcium in kale, Keatley says. “Additionally, cooking may reduce oxalate levels in some of these greens, which can increase the absorption of minerals like calcium and magnesium,” he says. 

If you’re unsure, he suggests “light steaming” or sautéing to preserve nutrient content while making the foods easier to digest and absorb.

What serving sizes should you aim for?

It’s important to aim for three to five servings of vegetables a day and two to four servings of fruits a day, according to the U.S. Department of Agriculture. “A serving size is typically one cup of raw leafy greens or a half cup of cooked greens — a cup is about the size of a fist,” Keatley says. 

But while these vegetables are called out by the CDC for their nutritional value, they’re not the only ones to have in regular rotation on your plate. “All vegetables have value,” Moore says.