We all have that one friend who sniffles their way through the winter (or perhaps it’s you?), popping cough drops for months on end. And then there’s that other friend—you know, the one with the golden immune system who makes it ‘til spring without so much as a sore throat. What gives?
“We estimate there’ll be a billion colds every year in the U.S., caused by more than 200 viruses,” says Neil Schachter, M.D., professor of medicine at Mount Sinai Medical Center. “While our susceptibility to getting sick is partially decided by genetics, other aspects of our lives are important, too.”
We asked the experts to explain what makes the difference between those with Kleenex costs through the roof and those who never miss a day of work. They shared five major factors:
A crummy diet that lacks key nutrients might affect how often you fall under the weather. “The vitamins and minerals in fruits and vegetables can help support your immune system, which helps your body fend off harmful microorganisms,” says Torey Armul, M.S., R.D., C.S.S.D., spokesperson for the Academy of Nutrition and Dietetics. On the flipside, nutrient deficiencies can have a negative impact on your immune system, she says.
Vitamin A—known as beta-carotene when plant-derived, and also an antioxidant—contributes to mucus barriers in our respiratory system and gut that help protect them from absorbing harmful substances, says the British Journal of Nutrition paper. Good sources of beta-carotene include sweet potatoes, carrots, and leafy greens, says Armul.
Vitamin C gets lots of buzz for its role in immune function—and rightly so. The antioxidant may stimulate leukocyte (a.k.a. white blood cell) function, which plays a crucial role in your immune system’s power to ward off trouble, says a paper published in the British Journal of Nutrition. To support your immune system year-round, make sure your diet is chock-full of produce like citrus fruits, strawberries, and bell peppers, says Armul.
Vitamin E (you guessed it, another antioxidant!) also promotes a healthy immune system by supporting the production of another type of white blood cell called T cells, says the British Journal of Nutrition. Get your fill of vitamin E by making sure foods like almonds, beans, and lentils are in regular rotation in your diet, says Armul.
Last, but not least: zinc. This trace element contributes to the creation of new cells in our bodies, including many in our immune systems, says the British Journal of Nutrition. Zinc can be found in lean proteins like poultry and fish, so while many Americans tend to meet their daily needs, vegans and vegetarians may have a harder time, says Armul. According to the American Journal of Clinical Nutrition, good plant-based sources of zinc include legumes, nuts, and seeds.
Who knew your morning run could actually boost your immune system? A lifestyle that involves moderate, regular exercise can strengthen your defenses against illness in a few ways, like circulating harm-fighting white blood cells and flushing bacteria from your respiratory system, says the U.S. National Library of Medicine. “Try to hit a base of 30 minutes of exercise, three times a week,” says Schachter.
Plus, exercise promotes a healthy body weight—but more on that later.
When it comes to sleep and immune function, it’s all about rhythm—circadian rhythm. “It’s important to strive for seven hours of quality sleep every night,” says Schachter. “But you also want to wake up and go to bed at the same times every day to keep your wake-sleep cycle regular.” Ever heard ‘sleep helps healing’’ During rest, your production of cytokines (proteins used throughout your immune system) kicks up, as do the levels of T cells in your blood, says a review published in the European Journal of Physiology. Skimp on sleep and you screw with your body’s ability to recover and revamp.
Constant nail-biting does more than wreck a manicure: Stress may actually depress your immune system, says Schachter. For example, a study published in Psychosomatic Medicine found that med students who reported higher levels of stress showed a poorer immune response when given a hepatitis B vaccine during exam time. Yikes.
A review published in TRENDS in Immunology concluded that adrenal hormones (such as epinephrine, a.k.a. adrenaline) our body releases in response to stress can affect the function of immune cells like lymphocytes (white blood cells) over time.
To keep stress at a minimum, Schachter recommends carving out time—even if it’s just a few 15-minute intervals—every day for activities you enjoy. Whether your ‘thing’ is online shopping or guitar lessons, make it a priority.
5. Extra Pounds
With cold weather making us crave warm mac and cheese every other day, we all seem to pack on a few pounds throughout the winter. But when weight gain reaches the point of obesity, it can negatively impact your immune system, says Schachter. “The accumulation of fat is associated with higher levels of cortisol and adrenaline—two stress-response hormones—that can depress the immune system long-term,” he explains. Luckily, bringing your weight back down to a healthy range, identified by CDC as a body mass index (BMI) between 18.5 and 29.9, can help promote proper immune function.