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What is NK Cell?

Immune system is one of body functions that prevent viruses, bacteria, and other germs that cause human infections. It also prevents and get rids of the development of abnormal cells such as cancer cells.

1 Pages
2 Jun 2019

Immune system is one of body functions that prevent viruses, bacteria, and other germs that cause human infections. It also prevents and get rids of the development of abnormal cells such as cancer cells.

The immune system is composed of chemicals produced within a body, namely, white blood cells. These cells are produced bone marrow and released into the blood system and tissues to perform surveillance for infections.

NK Cell (Natural Killer Cell) is another type of white blood cells which are present within a body and are found only 15% out of overall lymphocytes1. They, however, play an important role in destroying virus-infected and cancer cells without antigen stimulation. Therefore, NK cells are crucial and regarded as the beginning level of innate immune system in finding and destroying cancer cells at initial stage and controls virus infections2.  

According to the studies, NK cells decline in performance as the body ages. This correlates with the fact that the incidence of cancer increases as the body ages3-7. In addition to age, there also are other factors that weaken NK cells. For example:

-Insufficient rest8, less than 8-hour sleep;

-Lack of exercise, as it is an effective way to enhance immune system functioning9;

-Unhealthy food consumption; for example, highly sugary or fatty foods and insufficient consumption of vegetables will affect immune system functioning within the body as it lacks sufficient minerals and vitamins to strengthen immune system;10

-Chronic stress: when the body suffers stress chronically, stress hormone will weaken immune system and put the body at risk of infection11.


At present, NK Cell Count and NK Activity can be detected medically by blood test to evaluate the potential to destroy viruses and cancer cells of each individual. Therefore, individuals who benefit the tests are those who are found to have abnormally low immune system – which means that they are more prone to be infected by viruses; it is more difficult for them to recover; and, it increases the cancer risks. We recommend all individuals who are at risk to undergo NK cell tests. For example:12-14
-Individual who is frequently infected with diseases, such as, Herpes simplex, shingles, hepatitis, frequent cold, influenza A or B, avian influenza, etc.;
-Individual whose family member has history of cancer;
-Individual who has chronic fatigue syndrome;
-Individual who has history of being a heavy smoker;
-Individual who has been exposed to hormone or environmental pollution for long period;
-Individual who has strong health and desires to test and track innate immune system functioning having nonspecific defense mechanism. 

Immune system is regarded as a significant level of health. Therefore, for a stronger health there should be more focuses on immune system. For better immune system we can start with ourselves. NK cell activity can increase by consumption of nutritious foods the Five Food Groups, supplemented with blueberries, Maitake mushroom, Reishi mushroom, garlic, or supplementary food such as Cordyceps, MGN-3 (Biobran), Resveratrol, Reishi extract, AHCC, Quercetin, and probiotics.15-17

          Moreover, regular exercise, sufficient rest, and 8-hour sleep are recommended. Relieve stress and observe your body. If something abnormal happens, such as, more frequent infection, you should see a doctor for diagnosis, ignoring it may result in the illness becoming worsened.







1.Cheent K, Khakoo SI. Natural killer cells: integrating diversity with function. Immunology. 2009 Apr;126(4):449-57.

2.Janeway Jr CA, Medzhitov R. Innate immune recognition. Annual review of immunology. 2002 Apr;20(1):197-216.

3.Pawelec G. Immunosenescence: impact in the young as well as the old? Mech Ageing Dev 1999;108:1–7.

4.Hirokawa K. Immunity and aging. In: Pathy MSJ, ed. Principles and practice of geriatric medicine. 3d ed. New York: John Wiley and Sons, 1998:35–47.

5.Ogata K, Yokose N, Tamura H, et al. Natural killer cells in the late decades of human life. Clin Immunol Immunopathol 1997;84:269–75.

6.Castle SC. Clinical Relevance of Age-Related Immune Dysfunction. CID 2000;31:578–85.

7.Camous X, Pera A, Solana R, Larbi A. NK Cells in Healthy Aging and Age-Associated Diseases. Journal of Biomedicine and Biotechnology [Internet]. 2012;2012:1–8. 

8.Fondell E, Axelsson J, Franck K, Ploner A, Lekander M, Bälter K, et al. Short natural sleep is associated with higher T cell and lower NK cell activities. Brain, Behavior, and Immunity [Internet]. 2011 Oct;25(7):1367–75.

9.Pedersen BK, Ullum H. NK cell response to physical activity: possible mechanisms of action. Med Sci Sports Exerc. 1994 Feb;26(2):140-6.

10.Maggini S, Pierre A, Calder P. Immune Function and Micronutrient Requirements Change over the Life Course. Nutrients. 2018 Oct;10(10):1531.

11.Pike JL, Smith TL, Hauger RL, et al. Chronic Life Stress Alters Sympathetic, Neuroendocrine, and Immune Responsivity to an Acute Psychological Stressor in Humans. Psychosomatic Medicine. 1997. 59:447-457.

12.Cancer Prevention Overview. National Cancer Institute [Internet]. Available :

13.Parkin DM: The global health burden of infection-associated cancers in the year 2002. Int J Cancer 118 (12): 3030-44, 2006.

14.Nelson DE, Kirkendall RS, Lawton RL, et al.: Surveillance for smoking-attributable mortality and years of potential life lost, by stateUnited States, 1990. Mor Mortal Wkly Rep CDC Surveill Summ 43 (1): 1-8, 1994.

15.McAnulty LS, Nieman DC, Dumke CL, Shooter LA, Henson DA, Utter AC, et al. Effect of blueberry ingestion on natural killer cell counts, oxidative stress, and inflammation prior to and after 2.5 h of running. Applied Physiology, Nutrition, and Metabolism. 2011;36(6):976-84.

16.Ishikawa H, Saeki T, Otani T, Suzuki T, Shimozuma K, Nishino H, et al. Aged Garlic Extract Prevents a Decline of NK Cell Number and Activity in Patients with Advanced Cancer. The Journal of Nutrition. 2006;136(3):816S-20S.

17.Aziz N, Bonavida B. Activation of Natural Killer Cells by Probiotics. Forum on immunopathological diseases and therapeutics. 2016;7(1-2):41-55.

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