The 12 healthiest lettuces and leafy greens for you, ranked

So which leaves and lettuces should you use in your salad to justify the croutons, bacon, and tasty dressing you add?

We're here to help you find the most nutritious ones.

In the past rankings, we've relied on the CDC's 2014 list of "powerhouse foods". But this time, we factored in how many nutrients (specifically potassium, fiber, protein, riboflavin, niacin, folate, B6, calcium, iron, zinc, and vitamins A, C, and B6) the greens pack per calorie.

Of course, none of the veggies on this list are bad for you, and you won't necessarily be worse off for picking one over another. With that said, here are the healthiest greens for your salads.

12. Arugula (sometimes called rocket)

Arugula's distinct peppery taste doesn't quite correlate with a high nutritional content. While it does have some vitamins, it lacks in other nutrients that other greens boast.

Calories per cup: 6

11. Iceberg lettuce

It's no surprise that iceberg lettuce is among the least nutritious greens to put in a salad. In fact, Chick-fil-A has even banned the veggie from its stores, allegedly because of its low nutritional value. Iceberg lettuce has about only 7% of your daily vitamin A per cup, and only 3% of daily vitamin C — among the lowest on this list.

Calories per cup: 10

10. Radicchio

Radicchio is a member of the chicory family. It's also packed with vitamin K, containing more than 100% of your daily value.

Calories per cup: 9

TIE - 8. Watercress

Watercress, with its little round leaves, was considered the top powerhouse food in the CDC study. However, by our metrics, it didn't pack in as many nutrients as others on the list. It's high in vitamins A, C, and K and incredibly low in calories.

It's also linked to a lower risk of type-2 diabetes and is not too hard to grow.

Calories per cup:

TIE - 8. Leaf lettuce

One of the more nutritious of the lettuce family, leaf lettuce is low in calories and high in potassium and vitamins A and K.

Calories per cup: 5

7. Endive

Endive, also a kind of chicory, is fill of vitamin K, and a cup has 20% of your daily vitamin A intake. The frisée — or curly endive — in your salads is also part of this plant.

Calories per cup: 8

6. Chard

With its defining red (or rainbow) stems, chard is among the top powerhouse foods because of its low calorie count and high levels of nutrients. It has the most vitamin K of any leafy green on this list, at nearly 300% of your daily value per cup. Chard also contains a fair amount of magnesium, which is important for things like muscle and nerve function, blood-glucose control, and blood-pressure regulation.

Calories per cup:

5. Butter lettuce

Also called Boston and bibb lettuce, butter lettuce is the most nutritious of the lettuces on this list. The leaves are higher in folate, iron and potassium than iceberg and leaf lettuces.

Calories per cup: 7

4. Romaine

Romaine ranked among the top 10 "powerhouse foods," by the CDC, which are classified based on their associations with reduced risk for chronic diseases. It's an especially great source of vitamin A — one cup has 81% of your daily intake — as well as some B vitamins.

Calories per cup: 8

3. Broccoli leaves

While most folks just eat the heads of broccoli (and maybe the stems) tossing some of the plant's nutrient-packed leaves into your salad can be a good decision. The leaves are high in protein, and have the highest fiber content and vitamin A of the greens on the list.

Popular chain Sweetgreen even started featuring them in seasonal salads after conversations with farmers.

Calories per cup: 13

TIE - 1. Spinach

Spinach is the staple green in many salads that feature sweet ingredients like beets or fruit, and it's also one of the top-ranking greens when it comes to all-around nutrition content. It's packed with vitamins and nutrients, particularly potassium and iron, which are important for regulating your blood cells and blood pressure — though it's not necessarily as high in protein as Popeye may have led you to believe.

Calories per cup: 7

TIE - 1. Kale

Trendy for a reason, kale kills it in vitamin content, especially A, C, and K. Vitamin K is especially important in helping blood to clot.

Calories per cup: 33