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Feed a cold? Maybe Dr. Mom was right

March 12, 2007|Susan Bowerman | Special to The Times

Along with the cold and flu season, old-time beliefs and adages come around every year too.

Mothers admonish their children not to go out of the house with wet hair, and to remove wet socks after coming in from the rain, for fear the kids will catch their death of cold. They offer up chicken soup as a cure-all.

And, of course, most of us have heard that we should "feed a cold and starve a fever."

This maxim, apparently first written in the 1500s as "fasting is a great remedie of fever," has intrigued a few scientists enough to investigate its merit.

It's unclear where the idea originated -- but the most likely source is American/European popular wisdom, which suggested that if you had a chill you needed to stoke the interior fires by "feeding the cold." Conversely, cutting back on food -- fuel -- when the body temperature was raised by a fever was believed to help bring elevated body temperatures back to normal.

Addressing one part of this notion, in 2002, a group of Dutch scientists tested the hypothesis that fasting or feeding could differently affect the immune response -- and thus the body's ability to fight infection. Specifically, they measured effects on the balance of two types of white blood cells called Th1 and Th2. Each stimulates different parts of the body's immune response: Th1 cells are primarily called into play when viruses attack; Th2 cells preferentially respond to bacterial infection.

After an overnight fast, six healthy men were given either a liquid meal or an equal volume of plain water. Then their Th1 and Th2 activities were measured. After six hours, in those who'd had the liquid meal, blood levels of a chemical marker of the Th1 response more than quadrupled, indicating a response aimed at viral invaders, such as those causing the common cold.

After drinking only water, a different chemical messenger, and marker of Th2 response, went up nearly four-fold. This response helps battle bacterial intruders -- the ones, for the most part, more likely to cause a fever.

The study, published in Clinical and Diagnostic Laboratory Immunology, has not been replicated in a larger group of subjects. Yet the authors speculate that these differing responses may have been adaptive to our species. The ability to fight acute bacterial infection during times of food scarcity would have been an advantage in ancient times, since bacterial pathogens at that time were much more widespread than viruses and would have posed a greater threat.

In another recent article published in the journal Medical Hypotheses, a research group at Stanford noted that the loss of appetite that often accompanies a fever may represent a prehistoric adaptation by the body to favor the Th2 response and thus fight back against bacteria.

But modern humans live in a world in which the Th2 response may be less adaptive. Fever-causing viral diseases are more prevalent now than they were in prehistory, the Stanford scientists say. (A ramped-up Th2 response isn't going to be of help when the influenza virus comes calling.)

Nonetheless, these studies suggest that "feeding a cold" or "starving a fever" could have some logic behind it. But until further studies are done, common sense still prevails -- bed rest, fluids and diet as tolerated.

What about that hot chicken soup? One study has shown that while the vapors from any hot liquid seems to help relieve a stuffy nose, hot chicken soup increases "mucus velocity" -- accelerating the flow of mucus out of the nasal passages -- significantly more than plain hot water. Aromatic chicken soup seasonings, such as pepper and onion, travel in the vapors, also helping to open clogged passages.

So go dry your hair and drink your soup. Maybe Mom was right after all.


Susan Bowerman is a registered dietitian and assistant director of the UCLA Center for Human Nutrition.

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