How to boost your immune system during cold and flu season
By Hannah Seo
As the days shorten and people trade their tank tops and shorts for sweaters and tights, the turn of autumn signals another new beginning: the start of flu and cold season, and COVID winter No. 3.
According to Dr. Helen Chu, a public health researcher and infectious-disease physician at the University of Washington School of Public Health, it’s a myth that simply being cold will make you more likely to get sick. But viruses do tend to transmit most efficiently in drier, colder conditions, leading to spikes in winter months. So now is the time to get serious about immune health.
Here are four things health experts say you can do to prepare ahead of fall and winter surges.
Exercise is a great way to bolster your health and reduce your susceptibility to disease, said David Nieman, a professor of biology at Appalachian State University who researches exercise, nutrition and immunology. In one study published in 2011, Nieman and his colleagues followed more than 1,000 adults living in North Carolina for three months in 2008. They logged their lifestyle habits — including diet, exercise and exposure to stressful events — as well as how often they were sick with upper respiratory tract infections, such as common colds or laryngitis, and the severity of their symptoms.
“The No. 1 lifestyle factor that emerged was physical activity,” Nieman said. Those who exercised five or more days per week were 43% less likely to be sick with an upper respiratory tract infection than those who exercised for less than one day per week. But even those who did a little bit of exercise — at least 20 minutes of moderate exercise (as simple as a brisk walk) at least one day per week — were better off than those who did none.
We see this effect in part because exercise stimulates immune cells to “patrol the body” for virus-infected cells so that it can identify and eliminate them, Nieman said. Just a few hours of moderate exercise spread across a week is enough to get your immune cells circulating optimally, he said. And the exercises don’t have to be intense — just walking, dancing or “vigorous yard work” is enough to experience a boost in your health.
Don’t underestimate the power of rest.
Too much exercise, though, can tax the body and temporarily suppress the immune system, Nieman said, increasing your risk of infections. There’s no simple formula for what constitutes too much exercise, the experts said, but if you’re suddenly feeling unwell or constantly tired, or if previously easy workouts are feeling hard, it might be a signal that you need to slow down.
Research has also shown that not getting enough sleep, or sleep of good quality, can reduce your body’s capability for fighting off infections, said Kathi Heffner, a professor of nursing, medicine and psychiatry at the University of Rochester Medical Center in New York. While not everyone requires the same amount of sleep, the general guidance for adults is six to eight hours each night, Heffner said.
Good sleep can also help regulate your stress, she added. When stress occurs chronically, it can reduce the body’s response to vaccines and infections and can increase inflammation, “all of which can increase our susceptibility to infection as well as other kinds of chronic diseases,” she said. Even day-to-day stressors — from your job, your commute or your care-taking responsibilities, for example — can weaken the immune system, she added.
Reducing that kind of stress is often difficult, Heffner said, but if you can find time to do so, whether via practicing mindfulness exercises like meditation or yoga or even just “finding time to do pleasurable activities,” that can reduce your stress and in turn help your immune health.
Follow a healthy diet.
What you choose to eat and drink is one of the most important lifestyle choices that can influence your immune health, Nieman said.
A variety of brightly colored fruits and vegetables — berries, citrus fruits, red cabbage and kale, for instance — are great sources of flavonoids, chemical compounds found in plants that can help the body fight inflammation and illness, he said. Tea, coffee, dark chocolate and certain grains, like buckwheat, are also good sources of flavonoids. In Nieman’s 2011 study, his team found that adults who ate at least three servings of fruit per day had fewer upper respiratory tract infections throughout the year than those who did not eat as much fruit.
Research has also shown that exposure to cigarette smoke and drinking of alcohol in excess — more than two drinks a day for men or one drink a day for women — can suppress your immune system. Minimizing your alcohol consumption (or at least keeping within the dietary guidelines) or quitting smoking can help reduce your risk of infections, Chu said.
If you’re tempted to try supplements that claim to improve immune health, she added, don’t — especially if you’re already following a healthy and balanced diet. For the most part, she said, “there’s really not much data at all to support the use of most supplements to prevent illness or to boost your immunity.”
Keep up the pandemic precautions.
“Probably the most important thing that people can do right now is to get both their up-to-date COVID booster shots and their flu vaccines as soon as possible,” Chu said, since flu and COVID-19 cases will almost certainly go up this fall and winter.
And while many people have stopped wearing masks in public indoor spaces, continuing to do so will help protect you against all sorts of viruses, not just the coronavirus. This is especially true if you have a weaker immune system. Using rapid COVID tests before gatherings or when you have symptoms, and asking others to do so as well, can also minimize everyone’s risk of infection, Chu said.
“One of the things we’ve learned through this pandemic is just how important hygiene is,” Heffner said. “Washing hands, keeping your distance when you have a cold — those kinds of things are highly effective for keeping people healthy.”
In fact, Chu said, good hygiene includes staying home when you have symptoms of any type of infection at all. “People tend to try to power through, even if they’re sick,” she said. “They want to continue to do their job, to continue to go to school, to continue to do what they were doing before.” But that behavior just increases exposure and risk of transmission to other people. Stay home and give yourself time to rest instead, Chu urged.