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Infection & Immunity [Part Two - The Immune System and Immunity Boosters]

Updated: Nov 26, 2021

In the previous article, we discussed infection and infectious diseases. Now the question is, how do we protect ourselves from getting sick?

Disclaimer: I am not a trained medical professional, hence all the information below it’s gathered from different sources (look: References). In case of an existing, or suspected illness I strongly recommend talking to a professional health worker and getting a proper diagnosis and more precise information regarding the condition.

The Immune System - What It Is and Why Do We Need It

Let’s start by explaining what the Immune System is.

In simple words, the human immune system is an extremely complex and powerful defense mechanism, made of a network of interacting tissues, cells, and proteins. Its primary function is to defend the body from disease-causing pathogens, such as viruses and bacteria.

The immune system uses a range of specially adapted cells and molecules to attack those pathogens, which get past the physical and chemical barriers (your body’s natural defense system).

We live in a world that heavily threatens normal human body homeostasis (the ability to maintain a relatively stable internal state). Our environment contains a huge range of pathogenic microbes and toxic substances that challenge our bodies every day. It is not surprising, therefore, that the immune system uses a complex array of protective mechanisms to control and usually eliminate these organisms and toxins.


Natural barriers against pathogens

Physical Barriers:

  • The most comprehensive barrier is the layer of skin that covers the body’s surface. Human skin keeps most pathogens out as long as it remains intact. The speed with which a cut or graze can become infected is a reminder of the protection we normally get from our skin.

  • The inner surface of the respiratory system (nose, throat, airways, and lungs), stomach, intestines, bladder, and reproductive tract are lined with membranes that secrete jelly-like mucus, presenting a barrier against pathogens entering our tissues via these routes. Microscopic hair (cilia) that line the respiratory system shunt mucus containing trapped pathogens towards the nose and mouth, where they can be expelled by coughing and sneezing or swallowed into the stomach where acid destroys them.

  • Commensal bacteria are non-pathogenic inhabitants of the gut and the reproductive system. They occupy space that could otherwise be colonized by pathogenic species, and they use nutrients for their own growth, thereby reducing the resources available for pathogens to multiply and cause disease.

Chemical Barriers:

  • Enzymes in tears, saliva, and mucus break down the surface of bacteria.

  • The acid in sweat and in the stomach kills cellular pathogens.

  • There also are anti-bacterial proteins in semen.

The more complex mechanisms of the immune system are only needed if pathogens breach these physical and chemical barriers.


How Immunity Works

If any of the pathogens get past the barriers mentioned above, the immune system uses a range of specially adapted cells and molecules to attack them. One of these cell types is known as a B cell (So-called because they're found in the bone marrow.) and it plays a vital role in producing antibodies to fight infection. Antibodies are vital in our fight against infectious diseases because they're created by the body to recognize the presence of a pathogen invader. Antibodies themselves cannot kill pathogens. So strictly speaking, they cannot fight infection. They're simply a signaling mechanism that says to other cells of the immune system, here is a pathogen. Come and get it. Their signaling, however, is vital for immunity, since once the B cells have developed antibodies specific to an antigen, they can do so again but much faster. And this means that the recognition of a pathogen invader is much more efficient and the body cells can kill this pathogen invader before it replicates extensively and takes hold.

The immune response to infection occurs in overlapping stages:

  • When tissues are injured, the damaged cells release chemicals that trigger the sequence of events described as inflammation. It occurs in response to any type of injury, such as a blow or a cut, an insect bite, or damage caused by pathogens multiplying in body tissues. Inflammation has four characteristic effects at the site of an injury: swelling, redness, heat, pain.

  • The inflamed area shows these signs because the local blood vessels dilate (get wider), increasing blood flow into the injury site, so it looks red as well as feeling warmer than the surrounding tissue. The walls of the blood vessels near the injury become leaky, allowing fluid, defensive proteins, and immune system cells to flood into the area, which becomes swollen as a result. One of the proteins released during the inflammatory response also makes the area more sensitive to painful stimuli, so inflamed tissue is sore to touch.

  • Sites of tissue injury are vulnerable to invasion by pathogens so the benefits of inflammation generally outweigh the discomfort it causes. Flooding the area with fluid dilutes any pathogens that are already present, and the local concentration of immune system cells and defensive proteins enables an immune response to begin more quickly.


Innate and Adaptive Immunity

In basic terms, the immune system has two lines of defense: innate immunity and adaptive immunity. The innate immunity (‘innate’ means ‘inborn’), can be also found in some texts under the term ‘natural’ immunity. It is a rapid immune response, occurring within minutes or hours after aggression.

Adaptive immunity, on the other hand, is antigen-dependent and antigen-specific. It is said to be adaptive because, after the first encounter with a pathogen, it can develop a much faster response to repeated infection with the same pathogen.

Thanks to scientific experimentation, we now know that it's possible to deliberately administer a pathogen to generate an immunological memory by the production of memory B cells. This adaptive response is important for vaccination and immunization.

There is a great deal of synergy between the adaptive immune system and its innate counterpart, and defects in either system can provoke illness or disease, such as autoimmune diseases, immunodeficiency disorders, and hypersensitivity reactions.

Children who have suffered from chickenpox and recovered are unlikely ever to develop it again because they have circulating memory cells specifically programmed to recognize chickenpox viruses. These memory cells are unable to recognize any other pathogens, but they react swiftly and effectively if the chickenpox virus gets into the body again.

The secondary adaptive immune response is usually so effective that the person doesn’t become ill and may never know that they have been infected by chickenpox viruses for a second time. When the secondary response subsides, even more, memory cells that recognize chickenpox viruses as their specific target are left in circulation, providing lifelong protection against this pathogen to almost everyone who suffered this disease as a child.


What Does it Mean to “Boost Immunity”?

According to the immunologist, and Functional Medicine Doctor in Philadelphia, Dr. Heather Moday, boosting the immune system means balancing it, which also makes it very complex. Therefore, a one-size-fits-all approach isn’t the case here.

Creating a healthy and sustainable lifestyle is the real best immune booster. That involves sleep, stress management, physical activity, and proper nutrition.

Here are some simple tips on how to strengthen your immune system:

1. Nutrition Tips:

  • Stay hydrated.

  • Drink tea - certain teas (green tea, black tea) have antioxidant polyphenols, which have been known to support the immune system by fighting free radicals.

  • Limit inflammatory foods - limiting (or eliminating) inflammatory foods, like sugar, helps your body recover faster and it also helps the immune system be more resilient and dynamic.

  • Get your pre-and probiotics - prebiotics help nourish your gut's healthy bacteria, and probiotics help feed those good bacteria and support gut health. Getting enough of both is helpful for immunity since a healthy gut makes the rest of you less vulnerable to bacterial and viral invaders.

  • Reduce alcohol intake - alcoholic beverages and drugs affect both our sleep and hydration, so avoiding them is one of the most important ways to strengthen our immunity.

  • Get creative with your recipes - we live in times where finding new recipes couldn’t be easier. Buy a new cookbook, or search your favorite foods in Google, and increase the diversity in your kitchen. Opting for a healthy meal will only add bonus points to your immune system.

2. Sleep Tips:

  • Limit exposure to light, especially so-called blue light. Bright lights are known to suppress melatonin and interfere with sleep, so opt for a small night lamp or candles before sleep.

  • Read more books - following on the previous point, reading more before sleep will help you avoid looking at your phone, tv or laptop, which exposes you to the unwanted blue light. Make sure the book you’re reading is something relaxing. Avoid reading news or work-related publications.

  • Listen to music.

  • Take a warm bath.

  • Try aromatherapy - in particular, lavender oil.

  • Stretching, relaxation techniques or breathing exercises before sleep can help you to enter the "downtime" before going to sleep.

  • The whole evening routine is very important in getting an adequate amount of restful sleep.

3. Stress Management Tips:

  • Try breathing exercises - many Pilates or Yoga practices incorporate breathing techniques too.

  • Practice meditation - but don’t get anxious if you’re not able to do so, it’s not easy for everyone.

  • Take a walk in the sun - boost your vitamin D in a natural way, improve your mood and overall health.

  • Call a friend or a family member.

4. Sports and Exercise Tips:

According to David C. and Laurel M.Wentz in The compelling link between physical activity and the body's defense system (Journal of Sport and Health Science, Volume 8, Issue 3, May 2019, Pages 201-217):

  • Acute exercise is an immune system adjuvant that improves defense activity and metabolic health.

  • Data support a clear inverse relationship between moderate exercise training and illness risk.

  • Exercise training has an anti-inflammatory influence mediated through multiple pathways.

  • Illness risk is increased in athletes during periods of intensified training and competition.

  • Increased carbohydrate and polyphenol intake is an effective nutritional strategy for immune support.

  • Habitual exercise improves immune regulation, delaying the onset of age-related dysfunction.


The Bottom Line

To sum it all up there’s no magic pill to boost your immune system. And if someone is selling you one, run! Eating more minimally processed food, getting all the necessary nutrients, being physically active, and getting adequate sleep to recover and manage your stress. All of these areas should be taken care of if you’d like to bulletproof your immune system. So skip the heavily marketed “immune boosters”, and learn how to maintain a healthy lifestyle, on a daily basis, not just once a year. As we all know prevention is better than cure, so protect yourself and prepare your body for exposure to unwanted pathogens.



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Turvey, Broide, Bonilla, Oettgen, Travers, P., Walport, M., … Rra. (1970, January 1). An introduction to immunology and immunopathology. Retrieved from

Chaplin, D. D. (2010, February). Overview of the immune response. Retrieved from

Thompson, A. E. (2015, April 28). The Immune System. Retrieved from Barreto, M. L., Teixeira, M. G., & Carmo, E. H. (2006, March). Infectious diseases epidemiology. Retrieved from

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Moore, A. (2020, March 12). What Does It Really Mean To "Boost" Your Immunity? An MD Weighs In. Retrieved from


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