Should you really feed a cold?

What is a cold, anyway?

The common cold and its symptoms -- scratchy throat, stuffed-up nose, coughing and sneezing --have bedeviled humans for ages. According to David Arthur John Tyrrell and Michael Fielder's 2002 book "Cold Wars: The Fight Against the Common Cold," the ancient Egyptians had hieroglyphic symbols for colds and coughing, and the ailment was described in detail by the Greek physician Hippocrates about 2,500 years ago.

Over the centuries, people have tried all manner of cures. The Egyptians' painted their noses with lead sulfide ore, dry incense and honey, while the Greeks favored bloodletting, exercise and herbs, and the Romans recommended wine. The medieval Saxons and Normans, who thought colds were caused by evil spirits, uttered magical incantations. In the mid-18th century, Methodist church founder John Wesley advised cold sufferers to drink hot water mixed with oatmeal and honey, soak their feet in hot mustard baths and put orange rinds up their nostrils.

People had no choice but to rely on crazy remedies because it wasn't until after World War II that scientists discovered colds were viral. According to the National Institutes of Health, cold symptoms may be caused by any of more than 200 different viruses [source: NIH]. The most common culprits are rhinoviruses, a word that comes from "rhin," the Greek word for nose, a part of the body that these viruses find particularly inviting for reproduction. You can catch a rhinovirus when an infected person sneezes in your vicinity or touches something that you touch [source: Tolan]. After that, it usually takes two to four days for you to start feeling yucky. Cold symptoms can last from two to 14 days, but most people recover in a week.

What the common cold lacks in seriousness, it makes up for by being -- well -- common. A 2003 University of Michigan study found that three quarters of Americans caught at least one cold per year, and on average, they suffered 2.5 of them [source: Hagen]. And in addition to making our existences temporarily unpleasant and stressful, they cost money. The 2003 University of Michigan study found that Americans spent $2.9 billion a year on over-the-counter medicines, and another $7.7 billion for doctor visits [source: Hagen].

So why's it so important to eat when you're feeling ill?