by Dr. Bill Rawls
Posted 6/30/17

Natural killer cells (NK cells) are specialized white blood cells. Though they only make up a small percentage of your total white blood cells, NK cells are some of the most important.

You can think of them as the elite, special forces of your immune system. It’s their job to take out stressed cells that have been infected with viruses or stealth microbes and cells that have become cancerous.

When your cells are infected with microbes or become cancerous, they lose surface markers identifying them as “self.” NK cells earned the name “natural killer” because they do not need to be activated by other parts of the immune system to attack and kill cells that have lost self-identifying surface markers.

It was once thought that NK cells always acted independently as part of the innate or “first response” part of the immune system, but it is now known that they also work in close conjunction with all other parts of the immune system.

NK cells are present in all tissues throughout the body, ready and waiting to deal with any threats. They are your best protection against chronic illness.

Natural Ways to Promote Natural Killer Cells

Anything that depletes NK cells — a processed food diet, chronic stress, an overload of toxins in the body, too much alcohol too often, smoking cigarettes — puts you at higher risk of chronic illness.

As such, a healthful diet, managing stress, detoxing, and avoiding cigarettes and excessive alcohol go a long way toward maintaining an active supply of NK cells and preventing chronic illness.
You can’t get away from stress completely, but regular practice of yoga, Qigong, meditation, or anything that promotes a calm state enhances immune function and boosts your NK cells.

Regular exercise is also important, but how much you exercise does matter. A sedentary lifestyle is associated with low levels of NK cells, but excessive strenuous exercise can be just as bad. Chronic immune suppression is a big concern of elite athletes.


Low-intensity continuous exercise, such as walking several miles a day, promotes healthy NK cell populations. In fact, it is one of the best ways of staying healthy, in general.

Where you walk may matter. A study from Japan found that walking in a pine forest is better for promoting NK cells than walking in a city. They postulated with, chemical substances present in forest air were the factors that promoted NK cells.

Of course, if you do take regular walks in the forest, take measures to protect yourself from ticks and other biting insects.

Ticks are notorious vectors for stealth microbes commonly associated with chronic Lyme disease and other chronic illnesses. NK cells are arch rivals of stealth microbes — these types of microbes are masters at manipulating the immune system to suppress NK cells.

Coming Back Into Balance With Natural Supplements

If you are suffering from any sort of chronic illness, boosting NK cells back to normal is essential for getting well. Good health habits and regular walking will go a long way toward that goal, but you may need extra help.
Fortunately, there are plenty of natural supplements known to boost NK cells.

Top of the list is herbal supplements. Many herbs boost NK cells, but a few that stand out include andrographis, cat’s claw, ashwagandha, amla, resveratrol from Japanese knotweed, echinacea, turmeric, garlic, and ginseng.

Medicinal mushrooms are an especially good choice because they are immunomodulators. This means they not only stimulate NK cells and other key white blood cells, but they also reduce damaging inflammation associated with chronic immune dysfunction. There is a long list of beneficial medicinal mushrooms, but reishi and cordyceps are the best studied.

Vitamin C, about a 1000 mg a day, has been found to boost NK cells. Maintaining optimal vitamin D levels by getting adequate sunshine also promotes healthy immune function.

Glutathione, an essential antioxidant found in all cells, optimizes killing power of NK cells. Glutathione levels are depressed in states of chronic illness. Supplementing with glutathione may help normalize glutathione levels. In addition, vitamin C, vitamin E, N-acetyl cysteine (NAC), and alpha lipoic acid promote normal levels of glutathione.

Taking a probiotic with the favorable yeast, Saccharomyces boulardii, has also been found to promote healthy levels of NK cells.

All you need to fight illness is within your grasp. Boosting your natural killer cells is just one way to bring your life back to balance. Take a look at your bigger picture. What actions can you add to your life to boost your natural killer cells today?
 

Dr. Rawls is a physician who overcame Lyme disease through natural herbal therapy. You can learn more about Lyme disease and recovery in Dr. Rawls’ new best selling book, Unlocking Lyme.

You can also learn about Dr. Rawls’ personal journey in overcoming Lyme disease and fibromyalgia in his popular blog post, My Chronic Lyme Journey.

 

REFERENCES
Walking in a forest
1. Li Q et al. Visiting a forest, but not a city, increases human natural killer activity and expression of anti-cancer proteins. Int J Immunopathol Pharmacol. 2008 Jan-Mar;21(1):117-27.
2. Li Q et al. A forest bathing trip increases human natural killer activity and expression of anti-cancer proteins in female subjects. J Biol Regul Homeost Agents. 2008 Jan-Mar;22(1):45-55.
3. Li Q et al. A day trip to a forest park increases human natural killer activity and the expression of anti-cancer proteins in male subjects. J Biol Regul Homeost Agents. 2010 Apr-Jun;24(2):157-65.
Vitamin C
1. Huijskens MJ et al. Ascorbic acid promotes proliferation of natural killer cell populations in culture systems applicable for natural killer cell therapy. Cytotherapy. 2015 May;17(5):613-20.
2. Shaik-Dasthagirisaheb YB et al. Role of vitamins D, E and C in immunity and inflammation. J Biol Regul Homeost Agents. 2013 Apr-Jun;27(2):291-5.
3. Wintergerst ESet al. Immune-enhancing role of vitamin C and zinc and effect on clinical conditions. Ann Nutr Metab. 2006;50(2):85-94. Epub 2005 Dec 21.
4. Heuser G, Vojdani A. Enhancement of natural killer cell activity and T and B cell function by buffered vitamin C in patients exposed to toxic chemicals: the role of protein kinase-C. Immunopharmacol Immunotoxicol. 1997 Aug;19(3):291-312.
5. NAC, vitamin C, glutathione, vitamin E
Ferrández MD et al. Effects in vitro of several antioxidants on the natural killer function of aging mice. Exp Gerontol. 1999 Aug;34(5):675-85.
6. Allen M et al. Mechanisms of Control of Mycobacterium tuberculosis by NK Cells: Role of Glutathione. Front Immunol. 2015 Oct 5;6:508.
Herbs
1. Suresh K et al. Augmentation of murine natural killer cell and antibody dependent cellular cytotoxicity activities by Phyllanthus emblica, a new immunomodulator. J Ethnopharmacol. 1994 Aug;44(1):55-60.
2. Groom SN, Johns T, Oldfield PR. The potency of immunomodulatory herbs may be primarily dependent upon macrophage activation. J Med Food. 2007 Mar;10(1):73-9.
3. Sheeja K, Kuttan G. Andrographis paniculata downregulates proinflammatory cytokine production and augments cell mediated immune response in metastatic tumor-bearing mice. Asian Pac J Cancer Prev. 2010;11(3):723-9.
4. Sheeja K, Kuttan G. Modulation of natural killer cell activity, antibody-dependent cellular cytotoxicity, and antibody-dependent complement-mediated cytotoxicity by andrographolide in normal and Ehrlich ascites carcinoma-bearing mice. Integr Cancer Ther. 2007 Mar;6(1):66-73.
5. Gupta S, Mishra KP, Ganju L. Broad-spectrum antiviral properties of andrographolide. Arch Virol. 2017 Mar;162(3):611-623.
6. Naito Y et al. Gut-targeted immunonutrition boosting natural killer cell activity using Saccharomyces boulardii lysates in immuno-compromised healthy elderly subjects. Rejuvenation Res. 2014 Apr;17(2):184-7.
7. Percival SS. Aged Garlic Extract Modifies Human Immunity. J Nutr. 2016 Feb;146(2):433S-436S.
Meditation
1. Fang CY et al. Enhanced psychosocial well-being following participation in a mindfulness-based stress reduction program is associated with increased natural killer cell activity. J Altern Complement Med. 2010 May;16(5):531-8.
2. Infante JR et al. Levels of immune cells in transcendental meditation practitioners. Int J Yoga. 2014 Jul;7(2):147-51.
3. Vera FM et al. Acute Effects on the Counts of Innate and Adaptive Immune Response Cells After 1 Month of Taoist Qigong Practice. Int J Behav Med. 2016 Apr;23(2):198-203.
NK cells
1. Erick TK, Brossay L. Phenotype and functions of conventional and non-conventional NK cells. Curr Opin Immunol. 2016 Feb;38:67-74.
2. Engel I et al. Innate-like functions of natural killer T cell subsets result from highly divergent gene programs. Nat Immunol. 2016 Jun;17(6):728-39.
3. Human Natural Killer Cell | Credit: NIAID, https://www.flickr.com/photos/niaid/29228845335 https://www.flickr.com/photos/niaid/29120480442/in/photostream/