1 cup of shredded green leaf lettuce has 5 calories. The calorie breakdown is as follows: 8% fat, 62% carbohydrates, and 30% protein. Green leaf lettuce is high in fiber and low in sodium. Lettuce is a very low-calorie food that packs a lot of nutrition into a small volume. A cup of shredded green leaf lettuce contains only 5 calories. Lettuce is high in fiber and low in sodium. Lettuce is one of the most nutritious foods you can eat. It's loaded with vitamins A and C and potassium. It also provides folate and calcium. Lettuce belongs to the brassica family which includes cabbage, broccoli, and brussels sprouts. These vegetables are rich in cancer-fighting compounds called glucosinolates that my body converts into isothiocyanates after digestion. I love eating fresh salads during the summer time when lettuce is at its best! Lettuce is available in many different colors and varieties. The most popular types include iceberg, butterhead, and romaine. Iceberg has a large head of white flesh with a core of crisp dark green leaves and a thick stem. Butterhead has a large head of yellowish green flesh with a core of creamy white leaves and a thin stem.