“An Apple-a-day Keeps the Doctor Away”- Immune System Health, what really keeps the “bugs” at bay?

“An Apple-a-day Keeps the Doctor Away”- Immune System Health, what really keeps the “bugs” at bay?

At this time of the year it's common to worry about the strength of your immune system. Is it strong enough? Is it protecting you from common illnesses? Can you do anything to strengthen your immune system?

The immune system is a hugely complicated defence mechanism of the body, it’s an evolutionary development that aims to keep us protected from harmful invaders and most importantly keep us thriving!

What is the Immune System? What is it made up of? 

The Immune system is made up of numerous cell types, chemicals, molecules and systems, which are sub-dived into the innate and the adaptive immune systems.

Innate Immunity

The innate immune system is present from birth. This is what we would classify as the initial lines of defence, e.g. skin, nose hairs, mucous, stomach acid and so on. This is the immune system our body relies on to keep us safe from all pathogens, new and old ones we have already encountered. It triggers a non-specific response to anything it deems to be “foreign”. This can be a pathogen, a virus or even food particles. It is then the job of the immune system to determine whether these foreign bodies are safe [1].

Adaptive Immune System

This is sometimes also known as “Acquired Immunity”, this refers to the immune system developed throughout your years. It develops as you encounter new pathogens and new strains of diseases. This is a specific form of immune system, that attacks, remembers and stores a “plan of action” for the next invasion. The benefit of immune cell memory is that the body is able to fight a disease faster by producing a mass of specific immune cells. An example of this is Chicken pox, you rarely get chickenpox twice if you do the 2nd bout is never as severe.

The cells most frequently used in the immune system are the white blood cells, of which there are many types, e.g neutrophils, basophils, mast cells, macrophages, T and B lymphocytes etc. These white blood cells communicate via cytokines, which are chemical messengers. Cytokines are used to create interactions that lead to a reduction in infectious molecules [1].

The History of Illness

Throughout history many peculiar ideas about disease have been founded starting with the Ancient Greeks (4th Century). The Ancient Greeks were founders of modern medicine, based upon their idea of the Four Humors. These consisted of: Blood, Phlegm, Yellow and Black Bile. It was of these 4 that the Ancient Greeks pinned their entire medical founding upon. They believed as long as there was balance of all humors you would remain healthy. Any upset of this balance could cause illness. In some respects they were correct, too little or too much of any of the 4 could indicate illness, but they weren’t correct for the root of the illness [2]. A little further along in history and it would appear we took a step back, because in the medieval era (5th-15th century) it was believed that we brought illness upon ourselves. Illness was thought to depend on our actions, if we sinned, we became ill [3] Then, it wasn’t until the 19th century that scientists Andral and Addison discovered “White globules” we now know as White Blood cells (Leukocytes) [4].

What weakens the immune system? Who is most at risk of disease?

The immune system is highly complicated, thus incredibly delicate. It can be affected by the following:

  • Poor living standards, with poor ventilation and hygiene.
  • Stress
  • Poor nights sleep. REM sleep is restorative so is essential for the body.
  • Dietary inadequacies. Exclusive diets and low Fruit/Vegetable intake.

Those most at risk of poor immune systems include the following groups:

  • Pregnant women
  • Elderly People
  • Malnourished people: Overweight or underweight.
  • Immuno-suppressant diseases, HIV/AIDS or Cancer
  • Infants and Children

What can you do to strengthen your immune system?

Diet plays a massive role in the immune system, many of the essential Vitamins and Minerals are used as part of the messaging system between cells. Without them the immune system is weakened.

Vitamin A and the Immune System

Vitamin A is known for its ability to act as a barrier against infections. This is how it earned its colloquial name “anti-infective vitamin”[5]. The most common outbreak of disease thought to be caused by a deficiency in Vitamin A is measles [6]. Vitamin A can be found in its purest form in liver, dairy products and egg yolks. In its precursor form, it can be found in red peppers, mangoes and carrots [5]. It’s often advised to take supplementation for this Vitamin.

Vitamin C and the Immune System

Vitamin C is a water-soluble vitamin, predominantly known for its work in Scurvy treatment. It’s a common wives tale that Vitamin C cures a cold, this is both wrong and right. It does not cure it, however, Vitamin C has been shown to stimulate T-cell Lymphocyte proliferation (A form of white blood cell), this helps to attack and destroy specific pathogens[7]. Although, one study did show an 85% reduction in cold and flu symptoms after being treated with a large dose of Vitamin C [8]. Vitamin C can be found in kale, red peppers, oranges or supplements.

Zinc and the Immune System

Zinc is an essential mineral in nutrition. Recent studies have shown that Zinc may be the most effective supplement to take during cold and flu season. It showed that taking zinc lozenges reduced the duration of the cold by one day. Also, it was proven to reduce the number of colds encountered per year [9]. Zinc can be found in very few rich and natural forms (Oysters, red meat, liver and nuts), and so supplementation is almost always recommended.

Selenium and the Immune System

Selenium is a trace mineral rarely spoken of, but very important to health. Selenium is responsible for the creation of Glutathione reductases and thioredoxin enzymes which are essential in combating viral and bacterial infections [10]. Selenium is an antioxidant which reduces oxidative stress, DNA, protein and lipid damage [11].

Omegas oils and the Immune System

The T and B cells previously mentioned are affected by Omegas. It has been shown that Omega oils increase the number of T-cells that roam the body which increases the chances of fighting disease [12,13].

Concentrating on nutrition, taking the time to unwind, and putting yourself first can reduce those annoying sniffles. Fight illness all year around and prepare yourself for this cold and flu season!

  1. Escott-Stump.S. (2015). 15: HIV-AIDs and Immunology,Burns, Sepsis and Trauma. In: Joyce, J and Malakoff-Klein, E Nutrition and Diagnosis-Related Care. 8th ed. Philadelphia: Walters-Kluwer. pg. 841-883.
  2. David.K, and Osborn.L. (2015). THE FOUR HUMORS. Available: http://www.greekmedicine.net/b_p/Four_Humors.html.
  3. Trueman,C.N. (2016). Health and Medicine in Medieval England.Available: http://www.historylearningsite.co.uk/medieval-england/health-and-medicine-in-medieval-england/.
  4. Hajdu, S. (2003). The Discovery of Blood Cells. The Annals of Laboratory and Clinical Science. 33 (2), Pg. 237-238.
  5. Thurnham.D. (2012). 12: Vitamin A and Carotenoids. In: Mann,J. Truswell,S. Essentials of Human Nutrition. Oxford: Oxford University Press. Pg. 197-215.
  6. Hussey,G.D. (1990). A randomized, controlled trial of vitamin A in children with severe measles.. The New England Journal of Medicine . 323 (3), Pg 160-164.
  7. Jacob,R.A and Sotoudeh,G. (2002). Vitamin C function and status in Chronic Disease. Nutrition in Clinical Care. 5 (2), Pg. 66-74.
  8. Gorton, HC. (1999). The effectiveness of vitamin C in preventing and relieving the symptoms of virus-induced respiratory infections.. Journal of manipulative and physiological therapeutics. 22 (8), pg. 530-533.
  9. Bauer,B. (2015). Will taking zinc for colds make my colds go away faster?. Available: http://www.mayoclinic.org/diseases-conditions/common-cold/expert-answers/zinc-for-colds/faq-20057769.
  10. Thomson, C. (2012). 11.4 : Selenium. In: Mann,J. Truswell,S.Essentials of Human Nutrition. 4th ed. Oxford: Oxford University Press. Pg. 184-192.
  11. NCBI Gene. (2016). TXNRD1 thioredoxin reductase 1 [ Homo sapiens (human) ]. Available: https://www.ncbi.nlm.nih.gov/gene/7296
  12. Brawn.A. (2016). Omega 3 To Boost Immune Health. Available: http://www.myvitamins.com/articles/abcs-of-good-health/omega-3-to-boost-immune-health/.
  13. Fenton.J, et-al. (2013). Immunomodulation by dietary long chain omega-3 fatty acids and the potential for adverse health outcomes..Prostaglandins, Leukotrienes and Essential Fatty Acids. 89 (6), Pg.379-390.
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