Aging and the immune system

The immune system is a network of organs, tissues, and cells that protect the body from illness and injury. This includes fighting off infections, such as viruses and harmful bacteria that make their way into the body. It also includes clearing away abnormal cells and repairing damaged tissues.

Like every other part of the body, the organs, tissues, and cells that make up the immune system change as a person gets older. As age increases, the immune system begins to work less effectively. As a result, wounds may be slower to heal, and a person will be at greater risk of becoming sick (and more severely ill) from common infections like the flu and COVID-19.

This decline in immune function is also one of several reasons why the risk of many diseases increases with age, including the risk of many types of cancer, cardiovascular disease, diabetes, osteoarthritis, eye problems (like cataracts and macular degeneration), and dementia.

Understanding how the immune system changes with age can help a person understand how to support good immunity as they age.

The body ages at the cellular level

Senescence is the medical term for becoming old. It is a process that occurs at the cellular level, with cells that no longer multiply and also no longer expire when they should. This results in fewer younger cells that function well, and a greater number of senescent cells, cells that have lingered beyond a healthy expiration date. Senescent cells release chemicals that promote inflammation, which can damage nearby cells. This creates an environment within the body where disease is more likely to occur.

This process affects many systems throughout the body, including the immune system. Immunosenescence is the term for senescent changes that affect the immune system. As this process occurs, the organs that produce immune cells function at a reduced capacity. White blood cells become senescent and promote harmful inflammation. The immune system is slower and weaker when it responds to infections and injuries. Keep in mind that this is a simplified explanation of a complex process that medical researchers are still learning more about.

Not all senescent cells are unhealthy

It’s important to note that not all senescent cells are bad. Senescence occurs at all stages of a person’s life, and senescent cells help guide normal growth and development. Problems begin to occur as the percentage of senescent cells increases.

Keeping the immune system healthy with age

While aging and changes to the immune system are unavoidable, there are steps you can take to stay healthy and keep your immune system working as well as possible as you age. These include:

• Exercise. Leading a physically active lifestyle helps promote better immune system function at any age, including older age.
• Avoid unhealthy habits. Habits like smoking and consuming alcohol in excess amounts contribute to many health problems, including chronic infections and cancer.
• Good nutrition. Generally, you’ll want a diet that consists mostly of vegetables, fruit, whole grains, and lean proteins. You’ll also want to avoid unhealthy fats and sugary foods. Talk to a healthcare provider about the foods you eat, the foods you should be avoiding, and the foods you should be eating.
• Stay up to date on vaccines. Check with a healthcare provider or pharmacist about the vaccines recommended for your age group. If you are behind, ask about the best way to get caught up.
• Prevent injuries. Take steps to avoid falls and injuries, such as safety measures around the home or using devices to assist with mobility.

Your healthcare provider will always be your best source of information. For example, you may want to ask your healthcare provider about strategies for exercising safely, what amount of alcohol is safe to consume, and ways to improve your overall health and reduce your risk of health problems.