NK Cells – Natural Kills Cells Quantity and Activity Improves with Forest Walk

What are NK Cells and What Do They Do

Natural Killer (NK) cells are a specialized type of white blood cells that act as the immune system’s first line of defense, targeting and destroying virus-infected cells and cancer cells. 

Natural killer (NK) cells are a subset of lymphocytes / white blood cells – with a distinct morphology and the ability to directly kill certain target cells via one or more cytolytic mechanisms.

Natural Killer (NK) Cells are particularly important in the human endocrine and immune systems to induce tumor or virus-infected targeted cell death.

Natural Killer (NK) cells are especially critical for immune surveillance of cancerous tumors. Various studies have shown that immunosuppression is common after standard anti-cancer treatments and that NK cells are particularly suppressed after anti-cancer treatments.

Human immune system is highly diverse and not completely understood at present, but recent studies indicate that environmental and non-heritable / non-genetoc factors can make much larger contributions than genetic factors on human immune system.

Forest Bathing / Walk in Forest BOOSTS Natural Killer (NK) Cells

Considerable evidence and published studies indicates that forest environments can enhance the percentage and function of NK cells and intracellular anti-cancer proteins in lymphocytes.

Thus, exposure to a forest environment can have health-promoting effects.

Forest environments may have some positive health effects on physiological and psychological activities. In particular, the beneficial health effects of a forest environment involve an enhancement in immune functions, including human quantity and activity of Natural Killer (NK) cells, decrease in sympathetic nerve activity, enhanced parasympathetic nerve activity and lower blood pressure, pulse rate, heart rate variability and cholesterol concentration.

Forest environments are more greatly associated with positive health effects on subclinical cardiovascular disease and health-related quality of life compared with urban environments, who didn’t knew this :-).

Where is Evidence – Forest Bathing BOOSTS Natural Killer (NK) Cells

Following are the links to 3 important publications, highlighting the quantified benefits of “Walk in the Park/Forest”:

1. https://pmc.ncbi.nlm.nih.gov/articles/PMC2793341/
2. https://pmc.ncbi.nlm.nih.gov/articles/PMC5893257/
3. https://www.researchgate.net/publication/44616251_A_day_trip_to_a_forest_park_increases_human_natural_killer_activity_and_the_expression_of_anti-cancer_proteins_in_male_subjects

1. Inhaling Phytoncides: Trees release airborne antimicrobial compounds called phytoncides to protect themselves from insects and germs. When humans inhale these fragrant essential oils, they cross into the bloodstream and directly stimulate NK cell performance and cytotoxic activity of NK Cells
2. Stress Reduction: Walking in a forest lowers the stress hormone cortisol. Because high cortisol levels suppress immune function, reducing cortisol allows your body’s defenses to function optimally

• Day trip: Spending a few hours in a forest can elevate Natural Killer (NK) cell activity by up to 40%, with the effect lasting for about a week
• Multi-day trip: A 2 to 3-day weekend excursion in the woods can boost Natural Killer (NK) Cells activity by 50% or more and that this boost can last for up to 30 days