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Doctor, How Can I Boost My Immune System?

How to strengthen your body’s defense systems against illness this winter


spinner image two people sit on a bench as one of them starts coughing
James Yates

You’re right to want to boost your immune system, especially around this time of year. Several simple steps can help you make it happen. But before we look into them, let’s talk about what your immune system is and how it helps your body to fight illness.

The immune system is your defense against infections caused by bacteria, viruses and parasites. It also protects your healthy cells from cancer by identifying and then destroying abnormal cells. Your immune system is amazing.

Our immune system is active 24 hours a day, all year long. But as we age, it’s not as strong as it was when we were younger. Not only do we have fewer immune cells as we get older, but the ones we have don’t communicate as well with each other. It’s the reason the immune system takes longer to react to germs and why we’re slower to heal.

Certain conditions can weaken an immune system including cancer, diabetes and obesity, as can some fairly common medications including steroids, some medications that treat inflammatory conditions and others that suppress the immune system.  ​No matter how old you are, or what may be depleting your immune system, you can boost your defenses by choosing healthy behaviors. What are they? Well, you’ve probably read it before — eating a healthy diet with plenty of fresh fruits and vegetables, whole grains and lean protein, not smoking, getting between seven and eight hours of sleep a night, avoiding alcohol, reducing stress, maintaining a healthy weight and exercising regularly.

spinner image Dr. Adam

Ask Dr. Adam

Adam B. Rosenbluth, M.D., is an internist and cardiologist in New York City. Each Monday, he’ll weigh in on your questions about how to make your body work better for you. His AARP book will be published in 2027.

Email your questions for Dr. Adam to dradam@aarp.org

In general, my older patients who stay active have a stronger immune system and get sick less often. On the other hand, I have some patients who tell me “Oh, I’m not going to go out because I’m too afraid of catching something.”

Since our bodies are designed to interact with the environment, isolation is not necessarily a good way to protect yourself. If you stay on the couch, you can still develop pneumonia. In fact, a few years ago, an analysis of 10 different studies showed that regular physical activity is linked to a lower risk of getting pneumonia.

Another thing I hear from patients is that when winter rolls around, they increase their vitamin C intake. OK, but if you’re still smoking or staying awake until three in the morning, more vitamin C won’t do much to protect you. A healthy lifestyle is the single best way to boost your immune system.

What else? Vaccines. If someone who is 30 years old asks me: “Should I get the flu shot?” and I say “Yes” but they decide not to do it, I’m not so worried. It’s their choice. But if someone is 80, it’s a different story. More than 3,000 people over the age of 65 died from the flu in the 2022–23 flu season and many more were hospitalized.

The idea that vaccines diminish the immune system is not true. Many vaccines are made of very small amounts of weak or dead germs. Although a vaccine won’t make you sick, it does trigger your immune response. So, if your body is exposed to that particular germ again, it recognizes it and goes on the attack. Some of the COVID-19 vaccines work in a slightly different way. They deliver instructions to your cells to help them build protection against the virus. ​

All adults should get the flu vaccine and the latest COVID-19 vaccine, according to the Centers for Disease Control. Everyone age 50 and older should get a shingles vaccine. People 65 and older should get the pneumonia vaccine and those 75 and older should get the RSV vaccine.

One of my favorite protective measures against contagious diseases like the flu, or even COVID, is to avoid touching your face. I read an Australian study reporting that most of us touch our faces 23 times an hour; almost half of those touches involve the mouth, nose or eyes. These are all easy places for viruses and bacteria that catch a ride on our hands to enter our bodies.

Not touching your face takes some practice. Washing your hands with scented soap acts as a good reminder. When you raise your hand to your face, the scent will give you the clue to put your hand down.

It’s likely some people are just born with stronger immune systems, but for most of us, it’s in our hands. We can make a difference and boost our defense system by getting our vaccines and committing to a healthier lifestyle.

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