Lettuce is a green, cool weather vegetable commonly used in salads. The history of lettuce in America began when colonist John Winthrop brought lettuce seeds to the New World. Today, common lettuce varieties include romaine, green leaf, iceberg and butter. The average American diet includes 25 lbs. of the varying lettuce types each year. The nutrients in lettuce provide several dietary benefits.
The minerals lettuce provides include calcium, iron and potassium. The Food and Drug Administration recommended daily values for the nutrients are 1,000 mg of calcium, 18 mg of iron and 3,500 mg of potassium. A 1-cup serving of shredded green leaf and iceberg provide 13 mg of calcium, romaine provides 16 mg and butter provides 19 mg. The iron content in lettuce is .3 mg for green leaf and iceberg, .7 mg for butter and 5 mg for romaine. Green leaf lettuce provides 70 mg of potassium, iceberg provides 102 mg, romaine provides 116 mg and butter provides 131 mg. Calcium is an important structural component of bones, iron transports oxygen from the lungs to the body's organs and potassium regulates electrolyte and fluid levels in the body that influence blood pressure health.
Lettuce provides a significant amount of vitamin A. The FDA recommends consuming 5,000 IU each day. A 1-cup serving of shredded Iceberg provides 361 IU, butter provides 1,822 IU, green leaf provides 2,666 IU and romaine provides 4,094 IU vitamin A. Vitamin A supports skin, eye and immune system health.
Carbohydrates and Protein
The various lettuce varieties provide trace amounts of carbohydrates and protein. The FDA daily value of protein is 50 g and carbohydrates is 300 g. A 1-cup serving of green leaf provides .5 g protein, romaine provides .6 g and butter and iceberg provide .7 g. Green leaf lettuce contains 1 g of carbohydrates, butter contains 1.2 g, romaine contains 1.6 g and iceberg contains 2.1 g carbohydrates.
The fiber daily value is 25 g each day. One cup of green leaf provides .5 g, butter provides .6 g and romaine and iceberg provide 1 g. Fiber is an important nutrient for digestive health. It also regulates the absorption of carbohydrates. Carbohydrates often enter the bloodstream at a fast rate, increasing blood glucose abnormally and contributing to diabetes and weight gain.