
Some say the steam is the real benefit. Sipping the hot soup and breathing in the steam helps clear up congestion. Irwin Ziment, M.D., pulmonary specialist and professor at the UCLA School for Medicine, says chicken soup contains drug-like agents similar to those in modern cold medicines. For example, an amino acid released from chicken during cooking chemically resembles the drug acetylcysteine, prescribed for bronchitis and other respiratory problems.
Spices that are often added to chicken soup, such as garlic and pepper (all ancient treatments for respiratory diseases), work the same way as modern cough medicines, thinning mucus and making breathing easier.
Another theory, put forth by Stephen Rennard, M.D., chief of pulmonary medicine at the University of Nebraska Medical Center in Omaha, is that chicken soup acts as an anti-inflammatory. The soup, he says, keeps a check on inflammatory white blood cells (neutrophils). Cold symptoms, such as coughs and congestion, are often caused by inflammation produced when neutrophils migrate to the bronchial tubes and accumulate there. In his lab, Rennard tested chicken soup made from the recipe of his wife's Lithuanian grandmother. He demonstrated that neutrophils showed less tendency to congregate - but were no less able to fight germs - after he added samples of the soup to the neutrophils. Diluted 200 times, the soup still showed that effect.
Rennard based his chicken soup research on a family recipe, which he referred to in his article as Grandma's Soup.
Dr. Stephen Rennard's Recipe for Grandma's Soup
Clean the chicken, put it in a large pot, and cover it with cold water. Bring the water to a boil. Add the chicken wings, onions, sweet potato, parsnips, turnips and carrots. Boil about 1.5 hours. Remove fat from the surface as it accumulates. Add the parsley and celery. Cook the mixture about 45 minutes longer. Remove the chicken. The chicken is not used further for the soup. (The meat makes excellent chicken parmesan.) Put the vegetables in a food processor until they are chopped fine or pass through the strainer. Both were performed in the present study. Salt and pepper to taste. (Note: this soup freezes well.)