There's very little research on how what you eat (or don’t eat) affects your body’s infection-fighting capabilities. Photo / Eric Helgas, The New York Times
Q: I often hear people say that when you’re sick, you should “feed a cold and starve a fever”. Does that work?
A: People often repeat this catchy bit of sick-day wisdom. Fuel your body when you have the sniffles, the saying implies, and hold back when your temperature climbs.
But should you really skip dinner when you spike a temperature? There is very little research on how what you eat (or don’t eat) affects your body’s infection-fighting capabilities. Yet based on what experts do know about biology, they say you can probably ignore this advice.
It’s most likely “just an old wives’ tale”, said Dr David Schneider, chair of the department of family and community medicine at the University of Texas Southwestern Medical Center in Dallas.
Still, there are a few food- and drink-related guidelines to keep in mind when you’re feeling lousy.
One reason to question this advice is that it fundamentally doesn’t make sense, said Benjamin Hurrell, an assistant professor of nutrition and immunology at the University of California, Davis.
For instance, he said, it’s possible to have a fever and a cold at the same time. When that happens, how might someone feed their cold but starve their fever?
Another reason to be sceptical is that being well-nourished helps support the immune system. Research suggests that people who are chronically undernourished or who have certain severe nutritional deficiencies have a harder time fighting various infections, including pneumonia and gastrointestinal infections, said Dr Geeta Sood, assistant professor of medicine at Johns Hopkins University in Baltimore. People who are chronically undernourished may produce fewer infection-fighting immune cells, for instance.
But if you’re meeting your nutrient needs, Sood said, “there’s not a lot of hard science” suggesting that what you eat while you’re sick — whether with a cold or something worse — will make much of a difference in your recovery.
When you’re sick, eating nutritious foods such as fruits and vegetables can help fulfil your body’s energy needs, said Dr Michael Hanak, a family medicine physician at Rush University Medical Center in Chicago. This can be especially helpful if you have a fever, which your body needs extra energy to maintain.
However, if you have no appetite for a day or two, don’t force yourself to eat, Hanak said. Your body can most likely fuel itself with its existing energy reserves, but if you’re feeling very weak, seek medical attention.
Vitamin or mineral supplements probably won’t help you recover more quickly either, Sood said. There is some research suggesting that zinc supplements, taken before or soon after cold symptoms appear, can slightly reduce the length of your illness. But other studies suggest it offers no benefit. And despite popular claims that vitamin C can stave off colds, research does not suggest that this is true.
Honey may help soothe a cough, though, Sood said. In a 2021 review of 14 clinical trials, some of which involved only children, researchers found that consuming honey in various forms — straight out of the jar, with milk or coffee, or in a syrup mixed with other ingredients — reduced cough severity and frequency when compared with a placebo or another common treatment like diphenhydramine (often known as Benadryl).
There is one other situation in which food — and the body’s response to it — could affect infection susceptibility and recovery. Research suggests that people with high blood sugar, such as those who have unmanaged diabetes, have a harder time fighting bacterial infections, in part because the high levels of glucose in their blood may feed the bacteria and help them thrive, Sood said.
The experts we spoke with agreed that when sick with any illness, it’s important to stay hydrated, even if you’re not thirsty.
When you have a cold, you may lose extra fluids through the mucus you’re producing, Hanak said. Staying hydrated also helps to thin your mucus, which makes it easier to blow your nose and ease congestion. While everyone’s hydration needs are different, Hanak recommended drinking 2 to 4 litres (7 to 14 cups) of fluids every day, and avoiding alcohol, which can be dehydrating.
Staying hydrated is especially important when you have a fever, because you may lose fluids through sweat or diarrhea, Sood said. She recommended consuming electrolyte drinks, which can help replenish lost minerals. If your fever is above 103 degrees Fahrenheit (39.4C), or if you have a heart condition or seizure disorder, you may also want to consult a doctor and try to reduce your fever with pain relievers like acetaminophen or ibuprofen.
Typically, though, fluids and rest are the only real remedies you need when fighting a cold or a mild fever, Hanak said.
“More often than not, you will get better,” he said. “The more appropriate adage with colds and flu may simply be: ‘Time heals all wounds.’”
This article originally appeared in The New York Times.
Written by: Melinda Wenner Moyer
Photograph by: Eric Helgas
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