Should you really feed a cold?

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?

Whoever first advised people to feed a cold probably did it for the wrong reasons. Colds aren't the result of being chilled, and eating raises body temperature only slightly for only about 20 to 30 minutes (which is why experts advise you to wait that long before sticking a thermometer under your tongue). But that anonymous sage got the most important thing right: Eating well is an important part of nursing a cold.

Research shows that your immune system needs to be properly nourished to function properly, and that's especially important when you're run down. In the mid-1990s, for example, the U.S. Army noticed that Ranger trainees were succumbing to infections during training [source: McBride]. Government researchers discovered the problem wasn't the stress of hard exercise, but rather an inadequate diet. When male soldiers didn't consume enough calories to meet their daily needs, their T cells' ability to attack invading microbes decreased by as much as 60 percent [source: McBride].

Studies on animals also indicate that being undernourished makes it tougher to fight off an infection. In a study published in 2008, for example, Michigan State University nutritional immunology researcher Elizabeth Gardner found that mice with a calorie-restricted diet were more likely to die during the first few days of infection than mice with a normal diet, and they took longer to recover from the illness [source: MSU News].

Conversely, a 2002 study by Dutch researchers found that eating actually stimulates the type of immune response that destroys the viruses that cause colds. Six hours after a meal, human subjects' levels of gamma interferon, a substance involved in the process by which T cells destroy cells invaded by pathogen, more than quadrupled. In contrast, a group who drank only water saw their gamma interferon levels drop slightly [source: van den Brink].

But just stuffing your face with fast food or whatever happens to be in your refrigerator isn't necessarily a good idea, either. What are the best menu items for cold sufferers?

Your immune system needs calories, but the right nutrients are important, too. Protein helps your body to repair itself and fight infections. Anti-inflammatory chemicals called bioflavenoids -- found in many citrus fruits -- can help reduce the severity of cold symptoms. Foods rich in beta-carotene and vitamins C and E, which are found in many fruits and vegetables, can help reduce the cell damage that cold viruses cause [source: WebMD]. Zinc is another important nutrient, since a deficiency can reduce production and activity of the white blood cells that attack and kill viruses.

Dietician H.K. Jones, in an article for HealthCastle.com, recommends a menu for cold sufferers that emphasizes healthy, nutrient-rich foods -- fruits, vegetables, complex carbohydrates for energy -- and plenty of liquids to keep you hydrated [source: Jones]. A good breakfast, for example, would consist of oatmeal made with water and topped with mixed berries, some whole-grain toast, orange juice and a cup of hot decaffeinated tea. Lunch would include a bowl of soup, a mixed green salad, mandarin orange sections, a glass of tomato juice and more tea. For dinner, have steamed mixed vegetables, whole wheat pasta with tomato sauce, applesauce, sliced fruit and still more tea [source: Jones].

As it turns out, Grandma was right: A scientific study confirms that one of the best things to eat when you have a cold is a nice steaming bowl of chicken soup. University of Nebraska Medical Center researcher Dr. Stephen Rennard analyzed several chicken soup recipes, including his grandmother's, and found that the popular comfort food had anti-inflammatory properties. In particular, chicken soup reduced the movement of neutrophils, the white blood cells whose activity in the upper respiratory tract can cause the congestion and other symptoms that we associate with colds. On the other hand, if what you're really craving is a spicy bowl of chili, indulge yourself. According to nutritionist, dietician and radio host Susan Mitchell, hot and spicy foods help open up the sinuses and reduce congestion [source: Cerino].