Green Romaine Lettuce

This grows in a tall head of sturdy leaves with a firm rib down the center. As with other dark leafy greens, the antioxidants contained within romaine lettuce are believed to help prevent cancer. According to the 2011 edition of the Old Farmer's Almanac, the chlorophyll pigment in dark leafy greens, such as Romaine lettuce, may reduce levels of colon and liver cancer carcinogens.