The Impact of Age on Your Immune Function

Your body is a complex, hardworking machine. It works best when all systems and internal mechanisms operate in concert to keep your body running at its peak—from your skin and skeletal structure to your cardiovascular and central nervous systems. But, like any machine, your body’s natural aging process will begin to affect many of these systems.

As your body’s natural defense, there is no one system that affects your entire body through natural decline more than an aging immune system. Over time, your immune system naturally deteriorates through a process called immunosenescence. While defined as the impact of age on immune function, it is a process that, like your immune system, is brought about by the workings—or lack thereof—of many smaller parts.

To make sense of what happens to immune health as you age, it might be important to have a quick summary of your immune system.

Innate vs Adaptive Immunity

Your immune system is made up of white blood cells, tissues, and organs that combine forces to defend the body against internal and external stressors. General immune system response is often broken down into two parts: innate and adaptive immunity.

The innate immune system (or non-specific immune system) is exactly what you’d think it is based on the name—this is what you are born with. Your innate immunity is developed with the help of your parents and genetically passed along to your offspring. It is made of physical and chemical immunity barriers, like your cough reflex, skin, mucous membranes, and stomach acid.

Your innate immune system is not as powerful as other parts of your overall system, but it is your first line of defense and rapidly attacks any and all foreign substances, called antigens. Any antigens that break through these defenses then go against your adaptive immunity.

Your adaptive immunity is individual to you and continually changing. As you are exposed to various antigens throughout your life, your immune system builds and catalogs a defense against those particular antigens. When your body is bombarded, B and T lymphocytes (B and T cells) are released from your thymus gland. B Cells produce antibodies and T cells directly attack the antigens. Together, these white blood cells work toward protecting your body from harm, including threats from viruses and infections, and remembers how to fight what you’ve already been exposed to.

Immunity and Age

As you naturally age, there are a few things that happen in your body as immunosenescence takes place. Your thymus—which is biggest in size throughout puberty—shrinks, limiting T-cell production. The number of T cells you have does not decrease as you age, but their function does. Because these cells are part of the team tasked with directly attacking antigens, the risk of becoming ill increases. They still remember how to fight what they’ve seen in the past, but you need new ones to fight new exposures—or even mutated types your body has already adapted to, like a new strain of influenza.

Not only are there fewer new cells created, but they are also slower to react to new threats. As a result, it takes longer for your body to figure out a plan of attack to deal with threats once they are detected. This is why infections and illnesses are more frequent and severe as you age than they were when you—and your immune system—were young.

But it isn’t just the adaptive immunity that slows down. Similarly, the innate system is slower to respond and react to internal and external frontline issues. Take, for example, a surface-level cut. When you’re young, white blood cells are quickly deployed to clot, scab, and remodel the skin. But, as you age, this process naturally slows, leaving some prone to inflammation and infections—two of the main factors in a weakened immune system.

Support an Aging Immune System

Although a slowed immune system is a natural part of aging, it doesn’t mean deterioration is inevitable. In fact, depending on certain factors, your body may be biologically younger than your calendar age.

While your chronological age is measured by counting the years since birth, biological age—or how you age—is a measure of your overall health when factors like lifestyle, diet, genetic risk of developing age-related ailments, and more, are all taken into account. This is why two people born on the same day may appear to age differently.

There are certain aspects you can’t control about how aging may naturally affect your immune system due to genetic factors, but you can add (or take away) some key lifestyle habits to support to your entire body system.

Eat a Well-Balanced Diet

A diet full of fresh fruits and vegetables, whole grains, healthy fats, and lean meats can help your immune system keep running strong. A variety of fruits, vegetables, and whole grains also provide necessary dietary fiber to support a healthy gastrointestinal tract. This is especially important in establishing a strong immune response to outside stressors. That’s because it’s directly impacted by pathogens and anything foodborne. Many of the foods most closely associated with the Mediterranean diet have been shown to help maintain your immune system.

Get Enough Sleep

A lack of adequate sleep means your body doesn’t produce as many infection- and inflammation-targeting proteins that help bolster and restore immune responses.


Being consistently active is one of the best ways to help your overall health. It is recommended adults complete about 150 combined minutes of moderate exercise each week. This is enough to aid blood flow and help immune cells migrate throughout your body.

Practice Good Hygiene

One of the easiest ways you can help your body fight against external stressors is to practice proper hygiene habits. Proper handwashing and other cleanliness habits help limit exposure to germs that could test your immunity.


Unchecked stress can impact your weight, sleep, and overall well-being, and it can also put added pressure on your immune system. Developing some simple stress management techniques can help you momentarily step away from stressful situations and reset.

Don’t Smoke

Smoking kills antibodies and antioxidants in your blood. It inflames your lungs, causing cells to divert from other uses.

Drink Alcohol in Moderation

Excessive drinking lowers your white blood cells’ ability to kill antigens and fight infection.

The bottom line is a healthy immune system and an overall healthy lifestyle go hand-in-hand. Preparing for the impact of age on immune function is a whole-body effort, and maintaining it takes a holistic approach.

For more, take an in-depth look at ways to further support your immune system, no matter your age.