Watercress snagged the No. 1 spot, and other leafy greens rank in the top 10, according to the study.
To be called a powerhouse, a 100-calorie serving of the food had to provide at least 10 percent, on average, of the daily recommended intake of 17 important nutrients. The foods that scored higher are those that provide more of these nutrients.
Here is the full list of all 41 foods, with their nutrient density scores:
Watercress: 100.00
Chinese cabbage: 91.99
Chard: 89.27
Beet greens: 87.08
Spinach: 86.43
Chicory: 73.36
Leaf lettuce: 70.73
Parsley: 65.59
Romaine lettuce: 63.48
Collard greens: 62.49
Turnip greens: 62.12
Mustard greens: 61.39
Endive: 60.44
Chive: 54.80
Kale: 49.07
Dandelion greens: 46.34
Red pepper: 41.26