Varying in color, size, texture, shape and taste, the leaves of iceberg and romaine lettuce also have differences in nutritional value, offering a range of vitamins, minerals and fiber. Get the most out of your salads, sandwiches and wraps by choosing a lettuce that will provide the most nutritional benefit per serving.
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Per cup, romaine lettuce provides more than 10 times the vitamin A that's available in iceberg lettuce, with 4,094 international units in romaine vs. only 361 international units in iceberg. Vitamin A is important for healthy skin, teeth and other body tissue. It also plays a role in enhancing vision, especially in low light.
Vitamin K in the body is important for protein building that supports healthy bones and other tissues. Additionally, vitamin K is necessary for adequate blood clotting. Most types of lettuce contain vitamin K. The darker-colored romaine lettuce contains 48 micrograms of vitamin K, while iceberg lettuce contains 17 micrograms.
Adequate intake of folate, a B vitamin, by women of child-bearing age has been linked to a decrease in neural tube defects in newborns. And people who consume adequate amounts of folate, or folic acid, may be at decreased risk for developing cancer. It may also help treat depression and anemia. Romaine lettuce, with 64 micrograms of folate per cup, provides about 16 percent of the daily value for folate. Iceberg lettuce provides about 21 micrograms of folate per 1-cup serving.
Both romaine and iceberg lettuces provide approximately 1 gram of fiber per cup. Dietary fiber is important for intestinal health by normalizing bowel function. Eating lettuce as part of a high-fiber diet may also help control blood cholesterol levels, maintain blood sugar levels and aid in weight management.
Romaine and iceberg lettuce contribute a significant amount of other nutrients to the diet, including vitamin C, calcium, phosphorus and potassium. Although both types of lettuce contain these vitamins and minerals, romaine lettuce contains more per serving than iceberg. One cup of lettuce provides 8 to 10 calories and 1 gram of protein. Iceberg lettuce has nearly 2 ounces of water per serving, while romaine contains about 1.5 ounces.