Salad is a form of food composed principally of uncooked edible leaves, vegetables, and fruit such as tomatoes and cucumbers, often with the addition of egg, cheese, nuts, meat or fish. Salads are generally served cold, although warm salads have become popular in recent years. Examples of traditional salads are the potato salad of Germany and the green papaya salad of Thailand. A fruit salad is a mixture of chopped raw fruit. A tuna salad is made with tuna fish, onion, and mayonnaise; while a chicken salad has the same ingredients as tuna salad but with cooked chicken in place of the tuna. Salads are usually garnished with salad dressing, a liquid mixture that adds flavor and usually has a base of vinegar and olive oil. Slaws such as cole slaw are another kind of salad, usually with a cabbage base instead of lettuce. Salad is usually praised for its high fiber and beta carotene, as well as its low calorie count and trans fat content. However, these nutritional values depend on the ingredients, dressing, and quantity. Another health consideration is the frequent occurrence of E. coli, salmonella, and drosophila eggs in salad.