Get to know the immune system – your body’s defense against illness

There is no way to avoid it – the world is covered in germs. Bacteria and viruses are all around us in the air and on most surfaces. So why aren’t you sick all the time?

The reason is that your immune system protects you.

What is the immune system?

“Your immune system is made up of your body’s natural defenses against illness, creating antibodies that break down invaders and help the body function,” said Tina White, APRN, who specializes in rheumatology for OSF HealthCare. “It’s a complicated system that involves your organs, cells and proteins and how they respond to invaders, like allergens, cancer, viruses or bacteria.”

Your skin, the corneas of your eyes and mucus membranes lining your organs are all parts of your immune system that provide physical barriers to prevent invaders from getting into your body.

And when invaders succeed in breaching these defensive walls, your body creates special proteins called antibodies to break down these unwanted visitors. These antibodies are basically your body’s attack dogs for when intruders breach your security fence.

Your immune system is so complex. It learns to make more of the antibodies that are most effective at defeating whichever foe it comes across – at least, that is the goal of a healthy and strong immune system.

Building a strong immune system

There are a lot of myths and false life hacks about boosting your immune system. But if you really want to build up a strong immune system, you have to pay attention to what Tina calls “the pillars of health.” That means:

Don’t smoke.

Smoking not only harms your immune system, it can also contribute to disorders where your immune system attacks healthy cells and tissues.

Eat a well-balanced diet.

Sugar has been shown to seriously decrease the ability of your white blood cells to fight infections. However, there are even foods that help improve your immune response.

Discover healthy recipes from our dietitians.

Recipe Library | OSF HealthCare

Using vitamin supplements can help if you are not getting the nutrients you need from your diet, but there can be drawbacks, especially if you overdo it. For example, vitamin C helps build your immune system, but if you take too much of it, it can cause diarrhea, and the excess vitamin C does you no good. It’s best to get your vitamin C from fruits and vegetables.

“Mega doses of anything is not good,” Tina said. “At some point, you’re just paying money without getting any health benefit in return.”


“I like to say movement is medicine,” Tina said.

It helps your general health, and a body that is healthy in general is more likely to have the tools to build up its defenses against infection.

Get a healthy amount of sleep.

Getting seven hours or more of sleep at night helps your body stay healthy and maintain its defense system.

Two people doing stretches outside

Reduce your stress.

There is a strong connection between the mind and body. High stress levels can impact your body’s ability to fight off infection.

Tina, who has a psychiatric mental health practitioner certification, as well as a family nurse practitioner certification, said people often underestimate the strength of the connection between a healthy mind and healthy body. Evidence shows that if you are exposed to multiple life stressors, you also might not be as responsive to medications.

Last Updated: August 6, 2021

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About Author: Ken Harris

Ken Harris is the proudest father and was a writing coordinator for the Marketing & Communications division of OSF HealthCare.

He has a bachelor's in journalism from the University of Wisconsin-Madison and worked as a daily newspaper reporter for four years before leaving the field and eventually finding his way to OSF HealthCare.

In his free time, Ken likes reading, fly fishing, hanging out with his dog and generally pestering his lovely, patient wife.

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Categories: General, Preventive Health