Written by Erin Chamerlik, Nutrition Educator, MS, MT(ASCP)
Natural Killer Cells (NK cells). Not something we talk about everyday, or any day, but these little white blood cells are your friends because they are your front line of defense against cancer and this winter's germs, including those that cause colds, flu and pneumonia.
When cells are infected by a virus or changed into cancerous cells, NK cells attack causing the rogue cell to die (apoptosis).
Here's the bad news. Like so many things in the body, NK cells lose their functionality as we age. The good news is that we can optimize our NK cell function with a few simple improvements.
There are a few strategies that you can employ to help strengthen your immune system and increase the function of NK cells, your immune system’s front line fighters.
DHEA, (dehydroepiandrosterone), produced and metabolized in the adrenal glands, gonads, and dermis, has the abilityto improve the immune system (and many other things) when blood levels of the important hormone precursor are increased to more youthful levels. After age 25, DHEA levels decline at the rate of about 2% per year. Some unwanted signs of low DHEA include low libido, low energy, poor memory, increased belly fat, weight gain and a sub-optimal immune system.
It is important to maintain DHEA levels because DHEA has immune-enhancing effects and increases the NK cells. 1, 2
A study of men taking DHEA for five months was conducted by Dr. Omid Khorram of the University of Wisconsin. The results were described in Dr. William Regelson in his book, The Super-Hormone Promise.
Regelson wrote, "Dr. Khorram found that DHEA did indeed have a palpable, measurable rejuvenating effect on their aging immune systems." He found that DHEA geared up the immune system to fight foreign invaders and specifically DHEA "increased the number and activity of cancer-fighting NK (natural killer) cells, which keep a watchful eye on potential cancerous cells and destroy them before they can grow.” 3
DHEA helps the immune system in another way, by providing a counterbalance to stress. The body responds to stress by producing more of the adrenal hormone cortisol. When stress is not managed, large amounts of cortisol reduce the number and function of NK cells. 4
It is important to maintain youthful levels of DHEA to feel and look your best and help reduce the negative effects cortisol can have. Adults over age 25 can safely benefit from topical application of bioidentical DHEA cream, Twist 25.
NK Cell Boosting Foods and Supplements
Foods and supplements that increase beneficial NK cells will help bolster your front line defense against newly arising infected cells and malignant cells.
The following foods and supplements have been shown to have a positive impact on NK cells:
• Dark Chocolate and Cacao 5
• Panax ginseng 6
• Blueberries 7
• Aged Garlic 8
• Vitamin E 10
• Foods high in beta carotene - carrots, dark green leafy vegetables and sweet potatoes 10
Factors Known to Reduce NK Cell Activity
Just as we want to add beneficial foods and supplements to support our first line fighters, it is wise to address negative influencers too.
These factors negatively affect NK cell function:
• Micronutrient deficiencies in zinc or vitamins A, C, and D 11, 12
• Exposure to toxins 12
• Obesity 12
• Smoking 12
• Certain medications 12
• Lack of adequate sleep 13
In this article, we have only addressed factors that directly affect the NK cells of the immune system. Supporting the immune system begins with a strong foundation of healthy, unprocessed food, clean, filtered water, and adding supplements like Vitamin C, Omega-3 Fish Oil, Vitamin D3 + K2, and probiotics. Regular exercise is important year-round, but may be even more important in winter to keep your immune system strong.
1. Bovenberg SA, van Uum SH, Hermus AR. Neth J Med. 2005 Sep;63(8):300-4. Review. PubMed PMID: 16186639.
2. Khorram O, Vu L, Yen SS. Activation of immune function by dehydroepiandrosterone (DHEA) in age-advanced men. J Gerontol A Biol Sci Med Sci. 1997 Jan;52(1):M1-7. PubMed PMID: 9008662.
3. Regelson W. The Super-Hormone Promise. New York, NY: Pocket Books; 1997. 400p.
4. Andersen BL, Kiecolt-Glaser JK, Glaser R. Am Psychol. 1994 May;49(5):389-404. Review. PubMed PMID: 8024167; PubMed Central PMCID: PMC2719972.
5. Kamei M, Nishimura H, Takahashi T, Takahashi N, Inokuchi K, Mato T, Takahashi K. J Sci Food Agric. 2015 Apr 2. doi: 10.1002/jsfa.7197. [Epub ahead of print] PubMed PMID: 25847473.
6. Kang S, Min H. J Ginseng Res. 2012 Oct;36(4):354-68. doi: 10.5142/jgr.2012.36.4.354. PubMed PMID: 23717137; PubMed Central PMCID: PMC3659612.
7. McAnulty LS, Nieman DC, Dumke CL, Shooter LA, Henson DA, Utter AC, Milne G, McAnulty SR. Effect of blueberry ingestion on natural killer cell counts, oxidative stress, and inflammation prior to and after 2.5 h of running. Appl Physiol Nutr Metab. 2011 Dec;36(6):976-84. doi: 10.1139/h11-120. Epub 2011 Nov 23. PubMed PMID: 22111516.
8. Ishikawa H, Saeki T, Otani T, Suzuki T, Shimozuma K, Nishino H, Fukuda S, Morimoto K. Aged garlic extract prevents a decline of NK cell number and activity in patients with advanced cancer. J Nutr. 2006 Mar;136(3 Suppl):816S-820S. PubMed PMID: 16484572.
9. Stamets P. Turkey Tail Mushrooms Help Immune System Fight Cancer. [Internet]. HuffPost2012 June. Available from: Turkey Tail Mushrooms Help Immune System Fight Cancer.
10. Ashfaq MK, Zuberi HS, Anwar Waqar M. Int J Food Sci Nutr. 2000;51 Suppl:S13-20. PubMed PMID: 11271852.
11. Erickson KL, Medina EA, Hubbard NE. J Infect Dis. 2000 Sep;182 Suppl 1:S5-10. Review. PubMed PMID: 10944478.
12. Bush B, Mo S. Natural killer cells – Canaries in the immunological coal mine. [Internet]. https://neuroendoimmune.wordpress.com2011 May. Available from: https://neuroendoimmune.wordpress.com/2011/05/08/natural-killer-cells-canaries-in-the-immunological-coal-mine/.
13. Irwin M, McClintick J, Costlow C, Fortner M, White J, Gillin JC. Partial night sleep deprivation reduces natural killer and cellular immune responses in humans. FASEB J. 1996 Apr;10(5):643-53. PubMed PMID: 8621064.
About the Writer
Erin Chamerlik is the founder of , a wellness-focused education company located in Nashville, TN. Learn how you can reach optimal health through a whole food eating plan that integrates ancient wisdom with an innovative, science-based approach to health and wellness.
Erin extends her message through podcasts, public workshops, social media (Twitter, FaceBook, Pinterest and Instagram) and she blogs at
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