By Tim Arnott M.D. — Natural Killer (NK) cells are a type of white blood cell with packets filled with enzymes that can kill cancer cells or cells infected with a virus, including the SARs-CoV-2 virus. Preliminary studies in COVID-19 patients with severe disease suggest a decrease in natural killer cell numbers, resulting in decreased removal of virus-infected cells, and unchecked increase of tissue-damaging inflammation.[1]

Severe complications of COVID-19 are more common in elderly patients and patients with heart and blood vessel diseases and diabetes. NK cell functions are blunted in all these patient groups.  Also, the dangerous cytokine storm is more common in these patients, as their unhealthy NK cells cannot modulate the immune response properly.[2]

Cytokine storm involves an abnormal exaggerated immune response that causes collateral damage greater than the immediate benefit of the immune response.[3] Healthy NK cells are needed to prevent the cytokine storm. NK cells working properly clear the COVID virus-infected cells more quickly and efficiently, helping to prevent the cytokine storm.[4]

The good news is that there are things we can do to improve NK cell function and increase their numbers. “Pure air, sunlight, temperance, rest, exercise, proper diet, the use of water, trust in Divine power are the true remedies.”[5]  Amazingly, science is demonstrating these remedies improve NK cell function and number.

Consider pure air. We understood as early as 1905 “there are life-giving properties in the balsam of the pine, in the fragrance of the cedar and the fir.”[6]  Recently, scientists have discovered that pine trees release chemicals, called Phytoncides, which increase NK cell activity. For example, alpha-pinene, released by the pine tree, more than doubled NK cell activity against leukemia cells.[7]

Thus, to improve NK cell activity, spend more time outside. Phytoncides from Cypress, White Cedar, and Eucalyptus trees had the same effect on NK cell activity.[8]  Truly, there’s life in a tree.[9] God wants to feed our bodies in the air we breathe as well as the food we eat! So, take a walk outside every day. Open the windows at night. Air out the house first thing in the morning. You’ll be better prepared to fight COVID.

Sunlight also improves NK cell function. Sunlight “dramatically stimulates the expression of potent bacteria and virus-fighting proteins, which exist in … natural killer cells”.[10] Additionally, “(vitamin D) acts as an immune system modulator”, preventing the cytokine storm.[11] So, again, be outside in the sunlight and take a daily vitamin D supplement (at least 1000 IU daily) to help protect against viral infections, including COIVD.

Temperance likewise improves your ability to clear COVID. Research shows chronic alcohol consumption decreases NK cell number and function.[12]

Another way to boost NK cell function is to get your rest. Sleeping less than 7 hours a night was associated with 30% lower natural killer cell activity compared to those sleeping 7 to 9 hours a night.[13]  Thus, proper rest may likewise improve your ability to clear a COVID infection.

Get some exercise. Interestingly enough, prolonged intensive exercise (i.e., marathon) impairs NK-cell function and blunts the immune response.[14] On the other hand, moderate-intensity exercise (i.e., walking) “has a large and positive effect on the level of NK cell cytolytic activity.”[15] So, walk, walk, walk. Gradually increase your walking time up to 30 to 60 minutes a day. Check with your doctor before starting an exercise program.

And, of course, diet greatly affects our health. Can the food we eat improve NK cell numbers or function? Most definitely. We have about 2 billion NK cells circulating in our blood.[16] To test the affect of diet on NK cells, athletes ate 1 ½ cups of blueberries for six weeks. Then, they ran for 2.5 hours. NK cell counts “were almost doubled

(~4 billion) in the blueberry group prior to exercise, and this increase was maintained throughout the exercise.”[17]  Similarly, NK cytotoxic activity was twice as high in vegetarians than omnivore control subjects.[18]  Additionally, consuming the spice cardamom dramatically increased NK cell cytotoxicity against lymphoma cells. Thus, it makes sense, in the fight against COVID, to choose a diet of “(whole) grains, fruits, nuts, and vegetables … the diet chosen for us by our Creator.”[19]

When adopting a whole food plant-based diet, remember to take vitamin B12 daily, and chew it. Methyl-cobalamin is preferred. Why?  Because “suppressed NK cell activity was noted in patients (B12 deficient) compared with control subjects”, but improved after methyl-B12 treatment.[20]

Drinking mineral water also improved natural killer cell activities compared to tap water.[21] Clearly, minerals are important for optimal NK cell function, but minerals can also be obtained from seeds, beans, greens, and nuts. Thus, enjoy six to eight glasses of purified water daily between meals. Check with your physician first if you have heart failure or kidney disease.

Finally, NK cell activity is impaired in those who have suffered a major loss, for example, in recently widowed women with clinical depression, compared with those without major depression.[22]  Thus, we would encourage all to seek rest, hope, and comfort in Christ.  He has promised, “For your Maker is your husband, The Lord of hosts is His name; And your Redeemer is the Holy One of Israel.”[23] Thus, take time to come into His presence each morning and “pour out your heart before Him. God is a refuge for us.”[24] Remember, “in His presence is fullness of joy…”[25]  Consider reading a chapter from one of the four gospels each morning with a prayer for the blessing of the Holy Spirit.

As you can see, there are many simple steps we can take to improve NK cell function and number, increasing our ability to successfully fight the SARs-CoV-2 virus and help avoid devastating tissue damage caused by cytokine storm.

–Tim Arnott M.D. is the Rocky Mountain Lifestyle Center physician; photo by UnSplash

This material is intended for informational purposes only and is not a substitute for examination, diagnosis and medical care provided by a licensed and qualified health professional. Please consult your physician before undertaking any form of medical treatment and/or adopting any exercise program or dietary guidelines. If you think you may have a medical emergency, call 911 immediately.

[1] Int J Mol Sci. 2020 Sep 1;21(17):6351.
[2] ibid
[3] N Engl J Med 2020; 383:2255-2273.
[4] Market M, (2020) Flattening the COVID-19 Curve With Natural Killer Cell Based Immunotherapies. Front. Immunol. 11:1512.
[5] White E.G. Ministry of Healing. Pacific Press Pub Assn:  Mountain View, CA, ©1905, p. 127.
[6] White E.G. Ministry of Healing. Pacific Press Pub Assn: Mountainview, CA, © 1905, p. 264.
[7] Immunopharmacol Immunotoxicol. 2006;28(2):319-33.
[8] ibid
[9] Deuteronomy 20:19. The Holy Bible. New King James Version. © 1982 Thomas Nelson.
[10] Epidemiol Infect. 2006 Dec;134(6):1129-40.
[11] ibid
[12] J Leukoc Biol. 2017 Apr;101(4):1015-1027.
[13] Brain Behav Immun. 2011 Oct;25(7):1367-75.
[14] Prog Mol Biol Transl Sci. 2015;135:355-80.
[15] Sports Med. 2021; 51(3): 519–530.
[16] Blood. (2008) 112: 461-469.
[17] Appl Physiol Nutr Metab Vol 36, 2011.
[18] Nutr Cancer. 1989;12(3):271-8.
[19] White E.G. Ministry of Healing. Pacific Press Pub Assn:  Mountain View, CA, ©1905, p. 296
[20] Clin Exp Immunol. 1999 Apr;116(1):28-32.
[21] Biochem Biophys Res Commun. 2011 May 27;409(1):40-5.
[22] Psychiatry Res. 1994 Apr;52(1):1-10.
[23] Isaiah 54:5. The Holy Bible. New King James Version®. © 1982 by Thomas Nelson.
[24] Psalm 62:8. The Holy Bible. New King James Version®. © 1982 by Thomas Nelson.
[25] Psalm 16:11. The Holy Bible. New King James Version®. © 1982 by Thomas Nelson.