Seeing the Light: The Greener Leaves of Lettuce and Cabbage are Much More Nutritious

An article in Current Nutrition & Food Science has pointed out that "open leaf" type lettuces such as romaine are much richer in nutrients than crisp head types, like ice-berg. The main reason for this difference is the ability of the leaves to absorb light, and thereby synthesize more vitamins. Take a look at the nutrient profile comparison of romaine lettuce to ice-berg.

Complete nutrient comparison of Romaine vs. Ice-berg/Crisp Head Lettuces

Here we see that the difference can be as much as 10 fold for vitamin A foods and over 8 times for vitamin C foods. Further, comparing the romaine to the ice-berg, we see romaine has more protein, fiber, calcium, and iron.

The same phenomenon also holds true for cabbage, take a look at a comparison of Collard Greens (open leaf cabbage) vs. a typical head of cabbage:

Complete nutrient comparison of Collard Greens vs. Cabbage

While the amounts of vitamin C and Iron are slightly higher in cabbage, the collards still maintain higher protein levels, about 3 times the calcium, and over 50 times the vitamin A. The rule of thumb is to choose and prepare the outer dark green leaves of all leaf vegetables you consume. The darker the better.