Chicken soup for a cold
Research hints that chicken soup remedy may have scientific validity in reducing cold symptoms.
October 21, 2008
Since releasing his research findings on the benefits of chicken soup in 1993, University of Nebraska Medical Center researcher, Stephen Rennard, M.D., has been cited by thousands of media outlets around the world.
“When I’m gone, out of all the research I’ve done, I’ll probably be remembered most for my research on chicken soup,” Dr. Rennard said.
In his research study, Dr. Rennard found that chicken soup may contain a number of substances, including an anti-inflammatory mechanism, that could ease the symptoms of upper respiratory tract infections. The suspected benefits of chicken soup were reported centuries ago. The Egyptian Jewish physician and philosopher, Moshe ben Maimonides, recommended chicken soup for respiratory tract symptoms in his 12th century writings which were, in turn, based on earlier Greek writings. But, there’s little in the literature to explain how it works.
A challenge outside of the normal realm of scientific research, and curiosity about the long-touted folk medicine, first led a University of Nebraska Medical Center (UNMC) physician/researcher to embark upon an off-beat study to see if the soup may indeed have medicinal value.
In 1993, Stephen Rennard, M.D., conducted an informal laboratory study and submitted the results as an abstract mostly because of its amusement value. Seven years later, his chicken soup research was published in the Oct. 17 issue of CHEST, the peer-reviewed journal of the American College of Chest Physicians. It is titled, “Chicken Soup Inhibits Neutrophil Chemotaxis In Vitro.”
Dr. Rennard, Larson Professor of Medicine in the Pulmonary and Critical Care Medicine Section at UNMC, had for years watched his wife, Barbara, cook her Lithuanian grandmother’s chicken soup recipe when a cold was going around her family of 10.
“She told me the soup was good for colds,” Dr. Rennard said. “I’ve heard that a zillion times. Then I started to think, ‘well, maybe it has some anti-inflammatory value.’ Everyone’s heard this from their mother in many cultures. No one seems to have a monopoly on the insight of the value of chicken soup.”
Three batches of soup prepared in the home of Dr. Rennard were studied in the laboratory under controlled conditions. Researchers collected neutrophils from blood donated by healthy, non-smoking volunteers.
The study focus was to find out if the movement of neutrophils – the most common white cell in the blood that defends the body against infection – would be blocked or reduced by chicken soup. Researchers suspect the reduction in movement of neutrophils may reduce activity in the upper respiratory tract that can cause symptoms associated with a cold.
Colds are the result of infection in the upper respiratory tract, which causes inflammation. Although colds are not completely understood, it is believed the inflammation contributes to cold symptoms. Dr. Rennard theorized if soup can stop or reduce inflammation, it might reduce the symptoms of a cold.
In the laboratory, UNMC scientists diluted the soup and subjected the neutrophils to several variations of the soup, including vegetables, chicken and a combination of the ingredients. The team found the movement of neutrophils were reduced. Samples taken during the initial stages of the soup with chicken broth alone were not found effective in inhibiting neutrophil movement.
The researchers were not able to identify the exact ingredient or ingredients in the soup that made it effective against fighting colds but theorize it may be a combination of ingredients in the soup that work together to have beneficial effects. “All vegetables and the soup had activity,” Dr. Rennard said. “I think it’s the concoction.”
Known as “Grandma’s Soup,” the recipe includes chicken, onions, sweet potatoes, parsnips, turnips, carrots, celery stems, parsley, salt and pepper. For comparison purposes, commercial soups were obtained from a local supermarket and prepared according to the directions on the label. Many of the soups had the same inhibitory effect.
“A variety of soup preparations were evaluated and found to be variably, but generally, able to inhibit neutrophil chemotaxis,” Dr. Rennard said. “The current study, therefore, presents evidence that chicken soup might have an anti-inflammatory activity, namely the inhibition of neutrophil migration.”
Researchers noted that “Grandma’s soup” has several unusual features. It contains strained vegetables. Dr. Rennard noted, however, that the inhibitory activity was observed with several other recipes that lack the particles from vegetables. “Thus,” he said, “while the identity of the biologically active materials is unknown, it seems likely they are water-soluble or extractable. Pureed carrots or other vegetables are not recommended as a remedy while chicken soup is.”
He said the soup also may improve rehydration and nutrition in the body. The psychological and physical comfort soup provides may also have a placebo effect for those who are feeling ill.
Ronald Ertl, research coordinator of the lung biology laboratory at UNMC, said colleagues working near the lab wondered about the aroma coming from the lab. “It was the only time in my life when I could work in the lab and taste the samples,” Ertl said. “The lab shouldn’t smell like your kitchen.”
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