Chicken soup is a soup made by boiling chicken parts or bones in water, with various vegetables and flavorings. The classic chicken soup consists of a clear broth, often served with small pieces of chicken or vegetables, or with noodles or dumplings, or grains such as rice and barley. Chicken soup has also acquired the reputation of a folk remedy for colds and flus, and in the United States is considered a classic comfort food. It is commonly eaten with saltines.
According to food historians, chicken soup was already being prescribed as a cure for the common cold in Ancient Egypt. The 10th century Persian physician Avicenna also referred to the curative powers of chicken soup in his writings. In the 12th century the Jewish sage Maimonides wrote that chicken soup "has virtue in rectifying corrupted humours", and recommended it as nutrition for convalescents; Maimonides also particularly recommended chicken soup for people suffering from hemorrhoids and the early stages of leprosy.
In modern medicine, research conducted by Dr. Stephen Rennard, professor of pulmonary and critical care medicine, and his colleagues at the University of Nebraska Medical Center in Omaha, suggests that there might be some scientific basis for the curative powers of chicken soup. They found that the particular blend of nutrients and vitamins in traditional chicken soup can slow the activity of certain white blood cells. This may have an anti-inflammatory effect that could hypothetically lead to temporary ease from symptoms of illness. Their research was published in 2000 in the scientific journal Chest (volume 118, pages 1150-1157: "Chicken Soup Inhibits Neutrophil Chemotaxis In Vitro"). This was not, however, an in vivo clinical trial, and did not demonstrate that chicken soup was the best foodstuff for this purpose.
Because it is simple to prepare, relatively cheap, nutritious, and easy on the digestive system, chicken soup is a good food for winter convalescents. Probably more significant, sipping warm soup can clear the sinuses because of the steam ventilating into the nasal passages, serving as a natural decongestant, which also relieves cold and flu symptoms. Last but not least, chicken soup can be beneficial due to the placebo effect of comfort foods.
The flavor of the chicken in chicken soup is most potent when the chicken is boiled in water with salt and only a few vegetables, such as onion, carrots, and celery. For a more vegetable-tasting dish, add root vegetables (such as parsnip, celery and parsley), zucchini, sweet potato, whole garlic cloves or tomatoes. Soup should be brought to a boil and then simmered in a covered pot on a very low flame for one to three hours, adding water if necessary. Seasonings such as black pepper can be added, as well as fresh herbs such as parsley. A clearer broth is achieved by skimming the film of congealed fat off the top of the soup as it is cooking; the broth can be further clarified by straining it through a strainer or cloth. Saffron or turmeric is sometimes added as a yellow colorant. It has also been said that the amount of scum can be reduced by first bringing the chicken to boil from a pot of cold water and discarding it before starting.
Chicken soup can be a relatively low fat food: fat can be removed by chilling the soup after cooking and skimming the layer of congealed fat from the top. The nutritional value of chicken soup can be boosted by adding turkey meat to chicken soup recipes: turkey is a richer source of iron. Research has also shown that the longer the cooking time of soups containing meat and bones, the higher the calcium content of the soup.