Leafy Green Vegetables
Green leafy vegetables such as lettuce, kale and spinach, contain a high amount of nutrients. A cup of raw spinach, for example, has seven calories but contains 56 percent of an adult's daily value of vitamin A, 181 percent of the daily value of vitamin K and 14 percent of the daily value for vitamin C. It also contains needed minerals, including calcium and iron.
A cup of Romaine lettuce has 82 percent of the daily value of vitamin A but has only eight calories.
An adult should aim for about two and half cups of vegetables each day, according to the United States Department of Agriculture (USDA).