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How Does the Immune System Work?

Key Takeaways:

  • The innate immune system acts quickly and is the first line of defense against germs entering the body. The adaptive immune system provides a more targeted response and reinforces immune intelligence.
  • The main parts of the immune system include white blood cells, bone marrow, thymus, lymph nodes, spleen, tonsils, skin, and more.
  • Taking vitamin C, D, and zinc supplements can help support a healthy immune system.*

Your immune system is your body’s defense mechanism that helps you function at your very best. But how much do you really know about how the immune system works?

Let’s take a closer look at the parts of the immune system, how they function, and of course — how to support a healthy immune system.


What is the immune system?

The immune system is a large and complex network of organs, white blood cells, proteins (antibodies), and chemicals that work together to help maintain a healthy state from foreign invaders. These foreign invaders could include bacteria, viruses, parasites, and fungi.

The main tasks of the immune system are to fight potential pathogens and recognize and neutralize harmful substances from the environment.


Innate vs. adaptive immune systems

There are two subsystems within the immune system: the innate (nonspecific) immune system and the adaptive (specific) immune system. These systems are important for keeping you healthy and work together closely whenever a foreign invader triggers an immune response.

What is the innate immune system?

The innate immune system is the immune system you are born with and is active from the moment you’re born. It is the body’s first line of defense against germs entering your body. The innate immune system responds the same way to all foreign substances, which is why it is sometimes referred to as the “nonspecific immune system.”

It acts very quickly. If perhaps, you were to get a small cut on your finger, your innate immune system would work quickly to make sure that bacteria that have entered through the wound are detected and destroyed within a few hours.

The innate immune system consists of two main types of immune barriers: the skin and mucous membranes, and by immune system cells and proteins.

Your skin is actually one of the most important parts of the innate immune system. The skin’s closed surface and mucous membranes already form a physical barrier against foreign invaders, protecting them from entering. Tear fluid, sweat, and urine also stop these invaders from settling in the body.

If any invader gets past the skin and mucous membranes and enter the body, the innate immune system activates special cells and enzymes that contribute to the immune response.

However, the innate immune system has only limited power in stopping the spread of germs, which is why it needs help from its partner: the adaptive immune system.1

What is the adaptive immune system?

If the innate immune system cannot destroy these foreign invaders, the adaptive immune system takes over. The innate immune system specifically targets the type of invader, but first, it needs to identify what it is. That means that it does not respond as quickly as the innate immune system, but it is more accurate (hence why it is sometimes referred to as the “specific” immune system).

The adaptive immune system can also “remember” invaders, so the next time a known invader is encountered, the adaptive immune system can respond faster.


Main parts of the immune system

White blood cells (leukocytes)

White blood cells play an important role in the immune system. White blood cells serve as an army against unwanted invaders, and search for, attack, and destroy them to help keep you healthy.

There are two main types of white blood cells, phagocytes, and lymphocytes. Remember innate and adaptive immune systems? Phagocytes are the tools of the innate immune system, while lymphocytes are the tools of the adaptive immune system.

Two types of lymphocytes are B lymphocytes and T lymphocytes. B cells are sometimes compared to the body’s military intelligence system — they find the targets and send in defenses — while T cells are the soldiers — they destroy the invaders the intelligence system (B cells) find.

Bone marrow

The bone marrow is where all the cells of the immune system begin their development from stem cells. Your bone marrow makes billions of new blood cells every day.


The thymus is an organ located in the upper chest. Immature lymphocytes travel from the bone marrow to the thymus where they “learn” how to become mature T-lymphocytes.2

Lymph nodes

Lymph nodes are collections of T and B cells, which congregate to communicate with each other. These small glands filter and destroy invaders so they can’t spread to other parts of your body and make you sick. You have hundreds of lymph nodes all over your body, including in your neck, armpits, and groin. Swollen, tender lymph nodes are a sign that your body is fighting an infection.


The spleen stores white blood cells and filters your blood, destroying old and damaged red blood cells.


Because they are located in your throat and nasal passage, tonsils can trap foreign invaders as soon as they enter the body. Tonsils have immune cells that produce antibodies to help protect you from invaders that cause throat and lung infections.

Skin & mucous membranes

Skin produces oils and secretes other protective immune system cells. Mucous membranes line the respiratory, digestive, urinary, and reproductive tracts and help support the immune system.3


How to support your immune system

The immune system is complex, but thankfully supporting immune system health doesn’t have to be. Let’s go over a few ways you can support your immune system every day.

1. Get lots of vitamin C

While supplements cannot help the body cure, treat, or prevent disease or symptoms of disease, adding supplements — such as vitamin C — to your routine can help support a healthy immune system.*

Vitamin C is one of the leading vitamins for immune support.* This nutrient is important for the function of white blood cells, vital components of the immune system. It also acts as an antioxidant, helping to fight free radicals in the body.*

However, the body cannot store vitamin C, so it needs to be replenished daily. Your body can’t make vitamin C on its own, so it needs to acquire it from external sources – such as your diet or supplements.

Citrus fruits such as oranges or grapefruits are rich in vitamin C. Red bell peppers are also a great source of vitamin C for people trying to get their daily dose of vitamin C while avoiding the sugar in fruit.

Vitamin C supplements:

Solgar® Ester-C® Plus Immune Complex gives you the ultimate combination of immune-supporting ingredients.* Ester-C® is the only vitamin C with 24-hour immune support.* Ester-C® is also less acidic than regular vitamin C and more gentle on the stomach compared to regular vitamin C. Ester-C® Plus Immune Complex supports upper respiratory health and gives you*:

  • 1000 mg of clinically studied Ester-C®
  • Vitamins A, D3, and zinc for additional immune support*
  • Elderberry, astragalus, and echinacea
  • Magnesium and a range of B-vitamins

Solgar® U-Cubes™ Children’s Vitamin C Gummies offer great-tasting vitamin C in gummies that are made with naturally sourced colors and flavors.

2. Get your daily dose of vitamin D and zinc

Vitamin D is an important nutrient that helps support healthy bones, teeth, and the immune system.* Vitamin D is involved in all three layers of immune support:*

  • Skin and barrier function
  • Function and movement of immune cells
  • Normal functioning of T-cells and B-cells

The sun is your main source of Vitamin D, but if you’re spending a lot of time indoors or live in a northern climate, a supplement is a great idea.

Vitamin D supplements:

Solgar® Vitamin D3 is a great way to support immune health as well as healthy bones and teeth.*

Solgar® Chewable Vitamin D3 is perfect for kids or adults alike, with a great-tasting strawberry banana swirl flavor.

Zinc is a trace mineral that is important for immune function.* Zinc plays a role in over 300 enzymes in the body and is a key player in supporting your health.*

Zinc supplements:

Solgar® Zinc Picolinate is a highly absorbable, chelated form of zinc that helps support immune health, healthy skin and eyes, normal taste and vision, and normal skeletal, endocrine, and reproductive system functions.*

Solgar® Chelated Zinc helps support immune health, healthy skin and eyes, normal taste and vision, and normal skeletal, endocrine, and reproductive system functions.*

3. Exercise regularly

During and after exercise, pro- and anti-inflammatory cytokines are released, and immune-cell circulation improves, increasing immune support.

4. Get adequate sleep

Skipping out on sleep does more than make you feel groggy the next day, it can also prevent your immune system from working optimally. Getting seven to nine hours of sleep each night can help promote overall health.

Learn more about how sleep affects the immune system.


The bottom line

The immune system has one of the most important jobs in the body: to help keep you healthy. It is a complex system, made of a variety of parts, from your skin to your white blood cells. Supporting your immune system by taking supplements, exercising, and sleeping is essential to helping it run optimally so that you can continue to live your best life every day!

*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure or prevent any disease.

The information provided on this site is intended for your general knowledge only and is not a substitute for professional medical advice or treatment for specific medical conditions. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition. The information on this website is not intended to diagnose, treat, cure or prevent any disease. Never disregard medical advice or delay in seeking it because of something you have read on the Solgar® site.