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What Is Immunity - Immune System Facts

It is common knowledge that a strong immune system offers protection against viruses and diseases, while a weak one makes you more susceptible to catching a cold or worse. But what is immunity and how does it work? Let’s take an in-depth look at the most interesting immune system facts!

The definition of immunity

Simply put, the immune system is a way of protecting the body against an infectious disease. The three types of immunity are innate, adaptive, and passive.1 Think of it as a protection system – this is how your body defends itself. If it wasn’t for the immune system, various bacteria, viruses and even fungi could attack or infect your body at wellness. Thanks to immunity, that’s not the case.

Different types of immunity

There are 3 types of immunity:

  • Innate immunity – is the protection that you are born with. It is your body's first line of defense. It includes barriers such as the skin and mucous membranes. They keep harmful substances from entering the body. It also includes some cells and chemicals which can attack foreign substances.2
  • Active immunity – also called adaptive immunity, develops when you are infected with or vaccinated against a foreign substance. Active immunity is usually long-lasting. For many diseases, it can last your entire life.3
  • Passive immunity – when the antibodies are acquired and not produced by your own immune system. For example, newborn babies have antibodies from their mothers. People can also get passive immunity through blood products that contain antibodies. This kind of immunity gives you protection right away. But it only lasts a few weeks or months.

The purpose and functions of the immune system

The immune system’s role is to protect you from harmful microorganisms that may cause infections.4 However, it doesn’t stop at prevention – if you do get sick, it is your immune system that is your body’s first line of defence. It will fight the infection and act to minimize the damage done to your body. A healthy immune system will be able to fight off most infections. A weakened immune system means your illness can last longer, and symptoms may be more severe.5

Woman playing with her daughter and throwing her into the air

How to bolster your immune system

One of the most well known immune system facts is that a healthy lifestyle is the best immune booster.6It’s always a good idea to ensure you look after your immune system on a daily basis. Below you will find a few tips on how to keep your immune system healthy and strong through everyday activities. Remember that if you think your immunity might be weakened, you should always consult your doctor.

  • Eat a balanced diet, including lots of fresh fruit and vegetables. A healthy diet will provide essential vitamins and minerals your immune system needs to function properly.7 8 9
  • If you are not sure you are getting enough vitamins in your diet, consider adding a supplement like Redoxon® that can help strengthen your immune system.10 11 12
  • Get regular exercise. Acute exercise (moderate-to-vigorous intensity, less than 60 min) is now viewed as an important immune system adjuvant to stimulate the ongoing exchange of distinct and highly active immune cell subtypes between the circulation and tissues.13
  • Take steps to reduce stress. If you find you are under persistent stress, you can try meditation techniques or yoga.14
  • Get quality sleep. Rest allows your body to regenerate and helps your immune system to work adequately.15 16
  • Maintain a healthy weight. People who are overweight have weakened immune function, which can make them more at risk of catching illnesses.17
  • Get proactive to avoid infection. Wash your hands thoroughly  and regularly, and make sure any meat you eat is properly cooked.18
  • Don’t smoke. Smoking tobacco is harmful to your immune system and can make it less effective at fighting diseases.19



1. How to prevent infections. Harvard Medical School, 2016. (Accessed 10/02/2020, at https://www.health.harvard.edu/staying-healthy/how-to-prevent-infections.)
2. Gombart AF, Pierre A, Maggini S. A Review of Micronutrients and the Immune System-Working in Harmony to Reduce the Risk of Infection. Nutrients 2020;12.
3. Nieman DC, Wentz LM, The Compelling Link Between Physical Activity and the Body’s Defense System, Journal of Sport and Health Science, vol 8, issue 3, May 2019, p 201-217
Andersen CJ, Murphy KE, Fernandez ML, Impact of Obesity and Metabolic Syndrome on Immunity, ADVANCES IN NUTRITION, Volume 7, Issue 1, January 2016, Pages 66–75, https://doi.org/10.3945/an.115.010207

How Redoxon®
helps support your
immune system



Your body is equipped with powerful natural defences and your immune system has many ways of dealing with threats from bacteria and viruses.20 The Immune system is made up of three main defense mechanisms; Physical barriers (skin and mucosa), cellular barriers (white blood cells) and antibodies.21 Nutrients such as vitamins are essential to the health and function of this complex network.22

In our fast-paced world of fast food and pre-cooked meals, it may be challenging to consume adequate amounts of fruits and vegetables delivering all the vitamins we need to fully support our body functions. An inadequate intake of vitamins can negatively affect the immune system and overall health.23 That’s where Redoxon® comes in. Our Vitamin C product is designed to help support your immune system.24

Learn more


Redoxon® for a healthier immune system

You need to look after your immune system. Even though it may not feel like it, your immune system works 24 hours a day.25 Just as a plant needs water and sunlight, your immune system needs regular nourishment to support the body’s defence systems.26 

Together with a healthy lifestyle including physical exercise and good nutrition, supplements like Redoxon® provide the foundation for a strong immune system all year round.27






80 years of vitamin C expertise

In 1934, we pioneered the world’s first Vitamin C supplement, and we’ve been helping people keep their natural defenses in top shape for over 80 years. Today our range of innovative supplements helps to support your immunity every day.28 29


Build your immunity

Looking for ways to strengthen your immune system? Check out helpful articles on immune support.


1 https://www.cancer.gov/publications/dictionaries/cancer-terms/def/immunity#NCI-glossary-app-root:~:text=In%20medicine%2C%20the%20immune%20system%E2%80%99s%20way%20of%20protecting%20the%20body%20against%20an%20infectious%20disease
2 https://medlineplus.gov/immunesystemanddisorders.html#anch_54:~:text=Innate%20immunity%20is%20the%20protection%20that,chemicals%20which%20can%20attack%20foreign%20substances
3 https://medlineplus.gov/immunesystemanddisorders.html#anch_54:~:text=Innate%20immunity%20is%20the%20protection%20that,chemicals%20which%20can%20attack%20foreign%20substances
4 https://medlineplus.gov/immunesystemanddisorders.html#topic-summary:~:text=When%20germs%20such%20as%20bacteria%20or,disease%20by%20fighting%20off%20the%20germs
5 https://www.foodsafety.gov/people-at-risk/people-with-weakened-immune-systems#anch_41:~:text=People%20with%20weakened%20immune%20systems%20are%20more%20likely%20to%20have%20a%20lengthier%20illness
6 https://www.hsph.harvard.edu/nutritionsource/nutrition-and-immunity/#post-16756:~:text=combined%20with%20healthy%20lifestyle%20factors%20like,body%20to%20fight%20infection%20and%20disease
7 https://academic.oup.com/advances/article/7/1/66/4524061#jumplink-b2:~:text=obesity%20negatively%20affects%20immunity%2C%20as%20evidenced,for%20other%20infectious%20and%20chronic%20diseases
8 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7019735/#__p1:~:text=Immune%20support%20by%20micronutrients%20is%20historically,of%20physical%20barriers%20and%20immune%20cells
9 A Review of Micronutrients and the Immune System–Working in Harmony to Reduce the Risk of Infection PDF
10 Vitamins C, D and Zinc: Synergistic Roles in Immune Function and Infections PDF
11 https://www.health.harvard.edu/staying-healthy/should-you-get-your-nutrients-from-food-or-from-supplements#main:~:text=If%20you%20are%20unable%20to%20make,that%20a%20supplement%20may%20be%20helpful
12 https://www.nia.nih.gov/health/dietary-supplements#what:~:text=Dietary%20supplements%20are%20substances%20you%20might,health%20problems%2C%20like%20osteoporosis%20or%20arthritis
13 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6523821/#para0042:~:text=Each%20exercise%20bout%20causes%20transient%20increases%20in%20total%20white%20blood%20cells
14 https://www.health.harvard.edu/mind-and-mood/yoga-for-anxiety-and-depression#main:~:text=Available%20reviews%20of%20a%20wide%20range,exercise%2C%20or%20even%20socializing%20with%20friends
15 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7019735/#__p28:~:text=A%20stressful%20lifestyle%2C%20often%20accompanied%20by,such%20as%20vitamins%20C%20and%20E
16 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3256323/#__p49:~:text=Sleep%20and%20the%20circadian%20system%20are%20strong,the%20circadian%20system%20on%20these%20parameters
17 https://academic.oup.com/advances/article/7/1/66/4524061#110894319:~:text=Obesity%20is%20associated%20with%20metabolic%20disturbances,liver%2C%20pancreas%2C%20and%20the%20vasculature.%20However
18 https://www.health.harvard.edu/staying-healthy/how-to-prevent-infections#main:~:text=Wash%20your%20hands%20with%20soap%20and,Cook%20fish%20until%20it%20is%20opaque
19 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5352117/#__p1:~:text=Cigarette%20smoking%20is%20associated%20with%20numerous,responses%20or%20attenuation%20of%20defensive%20immunity
20 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5091071
21 https://www.news-medical.net/health/What-are-the-Three-Lines-of-Defense.aspx#ctl00_cphBody_divText:~:text=The%20immune%20system%E2%80%99s%20three%20lines%20of,innate%20responses%2C%20and%20specific%20adaptive%20responses
22 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7019735/#:~:text=It%20has%20since%20been%20established,stage%20of%20the%20immune%20response
23 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7019735/#__p1:~:text=Immune%20support%20by%20micronutrients%20is%20historically,stage%20of%20the%20immune%20response
24 Vitamins C, D and Zinc: Synergistic Roles in Immune Function and Infections PDF
25 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5091071
26 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7019735/#:~:text=It%20has%20since%20been%20established,stage%20of%20the%20immune%20response
27 Vitamins C, D and Zinc: Synergistic Roles in Immune Function and Infections PDF
28 Redoxon Product Information Leaflet
29 Vitamins C, D and Zinc: Synergistic Roles in Immune Function and Infections PDF