The most nutrient-dense calcium food source is?

Vegetables, especially leafy green vegetables, are the most nutrient dense foods for calcium. The following are the calcium contents for 200 calories worth of common vegetables:

Watercress, 2181mg

Bok choy, 1615mg

Arugula, 1280mg

Turnip greens, 1187mg

Beet greens, 1064mg

Broccoli raab, raw [Broccoli rabe, Rapini], 982mg

Kale, scotch, 976mg

Collards, 966mg

Cabbage, Chinese (pe-tsai), 962mg

Chicory greens, 870mg

Spinach, 861mg

Mustard greens, 792mg

Seaweed, kelp, 781mg

Parsley, 767mg

Seaweed, wakame, 667mg

Endive, 612mg

Kale, 540mg

Chard, swiss, 537mg

Celery, 500mg

Lettuce, green leaf, 480mg

Lettuce, red leaf, 413mg

Seaweed, laver, 400mg

Cabbage, common (danish, domestic, and pointed types), 392mg

Lettuce, cos or romaine, 388mg

Radishes, white icicle, 386mg

Broccoli, flower clusters, 343mg

(1,000 mg per day is the Daily Value)