As medical and public health experts around the world continue to warn about the dangers of the coronavirus that causes Covid-19, one message is abundantly clear—if you’re an older adult, you’re at increased risk of severe disease and death if you contract it. That’s because your immune system doesn’t function as well as you grow older, making you more vulnerable to infection. What’s more, older people often have chronic medical conditions that can further weaken the immune system or make it harder to fight the infection.

All of this may have you wondering if there’s anything you can do to strengthen your body’s natural defenses. Although nothing is guaranteed to shield your immune system from the effects of aging, research suggests there are ways to enhance it.

Meet your immune system
Your immune system is a remarkably effective and highly complex network of specialized white blood cells, tissues, and organs (including the skin, spleen, tonsils, and appendix). It’s designed to protect and defend you from unwanted daily intrusions of millions of viruses, bacteria, fungi, and other pathogens that do their best to enter your body. We’re all born with some innate immunity. As we interact with our environment, the immune system becomes more effective at protecting us. This is called acquired immunity.

The immune system’s basic task is to recognize “self” (the body’s own cells) and “nonself” (any substances the body perceives as a threat—called antigens—such as those found on a virus, fungus, bacterium, toxin, or piece of foreign tissue). In response to these markers of a foreign invader, the immune system manufactures white blood cells (leukocytes) that can recognize these infiltrators and eliminate them.

Various kinds of white blood cells are key components of the immune system. Lymphocytes are a type of white blood cell that includes B cells and T cells. B cells manufacture antibodies to attack antigens, while T cells direct and regulate immune responses and attack infected cells. Macrophages (large cells that develop from certain white blood cells) recognize, ingest, and kill invading microorganisms in tissue and the bloodstream and alert certain T cells to the presence of antigens.

Thanks to the lymphocytes, the immune system possesses a memory, or a sense of history. For example, once the lymphocytes have produced antibodies to a certain microbe, that particular virus won’t sicken you for months or years—and sometimes for life—because you have cells that immediately recognize it and produce the antibodies that destroy it. However, at this time, scientists do not yet know if this will be the case with Covid-19.

How aging takes a toll
Immune function gradually starts to decline after age 40. By the time people reach ages 60 to 65, most of them—but not all—have immune systems that respond less effectively than before. Doctors refer to this as immunosenescence.

Immunosenescence causes older adults to become increasingly susceptible to infections, including the flu, pneumonia, urinary tract infections, and skin infections. When older adults contract these infections, the infections are more frequently severe and the ill person more prone to complications. Immunosenescence also increases the risk of developing cancer and autoimmune disorders such as rheumatoid arthritis and lupus. Following are some examples of age-related changes to the immune system:

• The body produces fewer white blood cells, including B and T cells, capable of attacking antigens.
• T cells become less capable of responding to new antigens, especially in people older than age 65.
• The ability of B cells to produce antibodies decreases.
• Macrophages are slower to destroy antigens such as bacteria and cancer cells than they once were.

In addition to aging, some medical conditions and other health-related factors can put you at risk for a weakened immune system. These include heart disease, high blood pressure, diabetes, lung disease, cancer, sickle cell disease, HIV infection, and certain medications, including immunosuppressive drugs.

Give your immune system a helping hand
You may have been tempted by ads touting the immune-enhancing benefits of certain nutritional supplements. One supplement manufacturer goes so far as to claim that you can multiply your immunity and live longer and free of illness if you take their products. These claims are all fanciful and unsubstantiated. Nevertheless, you can still take some sound measures to help fortify your aging immune system:

1. Eat a healthful diet and don’t think that supplements can help you. No single food or vitamin can, by itself, boost your immunity. Overall, vitamins A, C, D, E, B6, B12, and folate, and the minerals selenium, zinc, copper, and iron, are essential for normal immune function. To help keep your immune system functioning properly, make your diet a healthful one. Foods derived from plants—vegetables, fruits, whole grains, and legumes (such as beans and lentils)—should make up the bulk of the calories you consume.

Consistent and robust evidence showing that taking vitamin and mineral supplements can fortify the immune system is lacking. There’s no reason to believe supplements will boost immunity in healthy people, except in the malnourished and those deficient in such nutrients as vitamin C, certain B vitamins, and zinc. Contrary to the claims of those touting supplements for improved immune function in healthy people of any age, other research suggests that megadoses of certain nutrients can significantly suppress some immune responses.

2. Get vaccinated. An annual flu shot is one of the best ways to garner protection against the influenza virus. Two vaccines are specifically formulated to compensate for the declining immune response in people ages 65 or older. Doctors also recommend boosters that protect against tetanus, pertussis (whooping cough), and diphtheria every 10 years; a pneumonia vaccine for people 65 and older; and a zoster (shingles) vaccine for everyone 50 and older. However, your doctor may recommend a different schedule if you have any risk factors, such as a chronic health condition, that make you more prone to infection. As of yet, there’s no vaccine to protect against Covid-19.

3. Exercise. Some evidence suggests that long-term, moderate exercise may be associated with improved immune function in older adults. The Physical Activity Guidelines for Americans recommend that adults, including those ages 65 and older, get at least 150 minutes each week of moderate-intensity physical activity, such as brisk walking, swimming, or cycling. One caveat: Don’t overdo it. Strenuous exercise can suppress the immune system’s activity.

4. Stop smoking or vaping. Research has shown that smoking suppresses immune cells. One potential reason comes from a study published online in August 2018 in Thorax. The authors found that e-cigarette vapors impair the function of the immune system’s debris-eating white blood cells. The good news: When smokers quit, immune function begins to improve within 30 days.

The National Institutes of Health warns that because the coronavirus attacks the lungs, it could be an especially serious threat to those who smoke tobacco or marijuana or who vape. If you need help quitting, talk with your doctor. You can also call 1-800-QUIT-NOW or go to www.smokefree.gov for help.

5. Reduce stress. Research shows that stress affects the immune system, and some evidence suggests that age-related changes in the immune system accelerate when a person is under constant stress, such as caring for a chronically ill loved one.

Fortunately, research also suggests that managing chronic stress helps strengthen immunity. Studies on the impact of stress reduction techniques on the immune system are ongoing. In the meantime, experts say practices such as mindful meditation and yoga can help you de-stress. Meeting with a counselor or therapist can also help you find more effective ways to cope with life’s stressors.