What Green Lettuce Is the Most Nutritious?

by Sandi Busch, Demand Media

Americans eat about 33 pounds of lettuce per person every year, according to the U.S. Department of Agriculture. For many years iceberg was the most popular lettuce at the dinner table, but its consumption has declined while demand for romaine and leaf lettuce has more than doubled. A good rule of thumb is that nutritional value goes up as the green in the leaves gets darker, making iceberg easy to identify as the least nutritious.

Macronutrients

The four most common types of green lettuce -- green leaf, romaine, butterhead and iceberg -- have 13 to 17 calories in 100 grams, which is about a 1/2-cup serving of shredded lettuce. They deliver 1 gram of protein, or about 2 percent of the recommended daily intake. Green leaf, butterhead and iceberg have 1 gram of dietary fiber; romaine has 2 grams.

Vitamins

Green leaf, romaine and butterhead are all good sources of vitamins A and K, but romaine delivers significantly more vitamin A, while green leaf is the best source of vitamin K. In a 100-gram serving, romaine has almost 300 percent of the recommended daily intake of vitamin A, compared with 247 percent in green leaf and 110 percent in butterhead. Green leaf lettuce contains 105 percent of the daily value of vitamin K, while romaine and butterhead have 85 percent. Green leaf lettuce also delivers 10 percent of the recommended daily intake of vitamin C, which is twice the amount in romaine or butterhead lettuce. Iceberg has 3 to 7 percent fewer B vitamins. It’s also much lower in vitamins A and K, but you’ll still get 17 percent of the daily intake of both from iceberg.

Minerals

You’ll get 1 gram of iron from 100 grams of green leaf, romaine and butterhead lettuce. Since men and women have different iron needs, that’s 12 percent of the recommended daily intake for men and 5 percent for women. Iceberg only has half the amount of iron. The same serving size of green leaf, romaine or butterhead lettuce provides 3 to 5 percent of the recommended daily intake of calcium, magnesium, phosphorus and potassium. Iceberg has 1 to 2 percent less of each mineral. Even though all lettuce varieties are low in sodium, the mineral's content ranges from a low of 5 milligrams in butterhead lettuce to a high of 28 milligrams in green leaf lettuce.

Considerations

Since all lettuce is low in calories and delivers fiber, as well as 2 to 11 percent of essential vitamins and minerals in just 1/2 cup, include any variety as part of your regular diet regardless of whether your favorite is the most nutritious. Iceberg has the least nutrients overall because it grows in a tighter head, so the inner leaves get less sunlight, remain lighter green and have fewer nutrients. If you disregard minimal differences in nutrients, green leaf lettuce has more protein, calcium and seven out of nine vitamins, so it could be considered the most nutritious.