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How trees boost our immune system

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Gym membership can be a good thing for achieving a good indoor workout when the weather is too hot or cold or wet for outdoor activities but research shows that spending time outside among trees and plants has its own advantages. If you dress appropriately and head to the park, you can enjoy the benefits of substances emitted from plants called phytoncides. These chemicals protect plants from rotting and from insects and when humans breathe them in, they experience lower blood pressure, lower stress hormone levels and a boost in their immune system as well.

Nippon Medical School in Japan explored the factors in a forest environment that activated human natural killer cells by investigating the effect of essential oils from trees on human immune function. Japanese researchers found that phytoncide exposure and decreased stress hormone levels may partially contribute to increased natural killer cell activity and that the increased NK activity lasted for more than 7 days after trips to forests.

Other studies have shown up to a 50% increase in NK cells as well as an increase in white blood cells that lasted for up to a week after forest exposure. These cells are the body's defense against disease and illness, including cancer.

In Japan, where it is called “Shinrin-yoku," forest bathing has become popular for its therapeutic value.

Getting the most benefit from forest walking can sometimes mean coping with allergies or avoiding city air pollution but the boost in the body's immune system may be well worth a trip to the park or countryside.

Check out the video above for a tour of the relaxing Houston Arboretum and Nature Center, open 365 days a year and free of charge.

Effect of phytoncide from trees on human natural killer cell function

Recommended reading:
Chronic stress may be the most reliable indicator of heart attack risk
Studies show free time is good for kids
Asthmatics may have lower risk of certain cancers
How stress causes heart disease and cancer



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