cold medicines. One is an amino acid released from chicken during cooking that chemically resembles a drug prescribed for bronchitis and other respiratory disorders, acetylcyseine.

Dr. Stephan Rennard, professor of pulmonary and critical care medicine at University of Nebraska’s Medical Center and his colleagues researched the effect of chicken soup on inflammatory white blood cells, known as neutrophils. Cold symptoms such as congestion and coughing are often caused by the inflammation produced when neutrophils migrate to and accumulate in bronchial tubes.

Rennard demonstrated that neutrophils showed less tendency to congregate — even while retaining all their capabilities of fighting germs — after he added samples of chicken soup to them. Even when the soup was diluted up to 200 times, it still had that effect.

Rennard postulates that’s because of chicken soup’s combination of vitamins and nutrients. Of course, sipping any hot liquid can be beneficial to those suffering from colds and flu. The steam ventilating into the nasal passages acts as a natural decongestant. Also, cold and flu viruses are capable of surviving only within a narrow temperature range, and hot liquids can raise the ambient temperature above those thresholds.

There really is something special about chicken soup, though — especially if it’s homemade. For his initial experiments, Rennard used chicken soup made from a recipe of his wife’s Lithuanian grandmother.

Later he tested commercial varieties with wildly varying results. Chicken soup that someone makes for you when you’re sick not only gives you physical warmth and comfort — it also gives you the warmth and comfort of knowing you’re cared for.