Chronic stress can reduce the body’s response to infections and vaccines while increasing inflammation.
Physician Dr Helen Chu at the University of Washington School of Public Health in the US, 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 experts say you can do to prepare ahead of 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 in the US who researches exercise, nutrition and immunology. In a study published in 2011, Nieman and his colleagues followed more than a 1,000 adults living in the US state of North Carolina for three months. 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 its severity.
“The No. 1 lifestyle factor that emerged was physical activity,” Nieman said. Those who exercised five days per week were 43 per cent less likely to be sick with an upper respiratory tract infection than those who exercised for less than one day a week. But even those who did a little bit of exercise 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 they can eliminate them. A few hours of moderate exercise spread across a week is enough to get your immune cells circulating optimally, Nieman 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.
Power of rest
Too much exercise, though, can tax the body and temporarily suppress the immune system, 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 the right quality — can reduce the capability of your body to fight off infections, said Kathi Heffner, a professor of nursing, medicine and psychiatry at the University of Rochester Medical Center in New York in the US. While not everyone requires the same amount of sleep, the general guidance for adults is six to eight hours each night.
Good sleep can also help regulate your stress levels. When stress occurs chronically, it can reduce the body’s response to not only infections but also vaccines and can also increase inflammation, “all of which can increase our susceptibility to infection as well as other kinds of chronic diseases”, Heffner said.
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 coloured fruits and vegetables are great sources of flavonoids, chemical compounds found in plants that can help the body fight inflammation and illness. 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 (preferably brightly coloured ones) 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 (active and passive) and drinking of alcohol in excess — more than two drinks a day for men and one drink a day for women — can suppress your immune system. Minimising your alcohol consumption (or at least keeping within the dietary guidelines) or quitting smoking can help reduce your risk of infections, Dr Chu said.