What Are Phytoncides? How The Scent Of The Forest Can Boost Your Immune System

Forest bathing has more than peace and quiet to offer–it’s also full of nature’s aromatherapy immune boosters, phytoncides.

Although forest walks have been considered therapeutic for centuries, recent studies such as those conducted by Dr. Qing Li in Japan have shed light on a plethora of healthful forest medicine, including phytoncides. These compounds, released in the aromas of plants and trees, are breathed in and build the immune system of forest bathers around the world.

Beneficial aromatic phytoncide compounds are released by specific tree species, including cedar, oak, locust, and pine. These powerful, sensory-absorbed compounds are available to forest bathers around the world as tangible benefits of mindful self-care.

What Are Phytoncides and How Do They Work?

Phytoncides are airborne chemical compounds that protect trees and other plants from bacterial, fungal, and insect attacks. As they are absorbed through our olfactory glands, these same compounds that protect trees from disease can also boost our human immune system, keeping it strong for days after a single outing.

There are at least a half-dozen types of phytoncides with documented health benefits. Some of these compounds produce a chemical reaction with specialized immune system cells in the human body, causing them to reproduce more prolifically over a period of time.

Other responses of the human body to phytoncides include:

  • Increased skin health
  • Lowered cortisol (stress hormone) levels, anti-depressant
  • Better sleep
  • Lowered blood glucose levels
  • Lessened inflammation

How do Trees Help Strengthen Our Immune System?

Many scientists consider phytoncides’ greatest impact on the human immune system to be the increase in the production of powerful NK cells. NK (Natural Killer) cells are white blood cells programmed to attack a wide list of undesirable infectious substances, tumors, and cancers.

Forest bathing trips of just a couple of hours weekly can significantly impact NK cell production. Breathing in these natural chemicals can help our bodies continue to fight off unfriendly microbes we encounter at home, work, or in crowded areas each day.

How Long Do The Positive Effects Of Forest Bathing Last?

In a 2005 study, Dr. Qing Li wrote a paper on the effect forest bathing has on the immune function. The study analyzed the effect a 3-day forest bathing trip had on the immune system. Blood and urine samples were taken on days 2 and 3 during the trip. Then also at 7 and 30 days following the trip.

The findings were very encouraging.

The increased NK activity lasted for more than 30 days after the trip, suggesting that a forest bathing trip once a month would enable individuals to maintain a higher level of NK activity.

Dr. Qing Li – Nippon Medical School

It should be noted that a similar test was performed on subjects after a sightseeing visit to the city and no increased activity was found.

girl with a bike quietly observing the trees

Do Essential Oils Have Phytoncides?

For those who do not have access to a forest bathing environment, at least some of the health benefits are not beyond reach. Essential oils that are naturally derived from trees known to contain phytoncides. Studies show these essential oils can supply many health benefits in an indoor setting.

Hinoki Cypress is one of the more potent coniferous essential oils on the market. The oil is derived from the needles, roots, and wood of the Japanese Cypress. The oil’s fragrance is soothing as an aromatherapy medium. And the oil can also be used topically or ingested in small amounts.

Japanese cedar is also a good source of phytoncide aromatherapy, along with pine and Idaho balsam fir. Look for high-quality sources of these essential oils. But remember, they’re no substitute for the total-sensory benefits of forest medicine in the midst of the trees themselves.

Women forest bathing in Nara, Japan in a forest of Hinoki Cypress
Women forest bathing in Nara, Japan in a forest of Hinoki Cypress


Among the many benefits of forest bathing highlighted in recent studies, the effects of phytoncides are one of the most compelling. The ongoing work of Dr. Qing Li and others has added a new impetus for many to seek out forested areas for their mental, emotional, and physical health.

The surprising impact of breathing in nature’s aromatic compounds can be a pleasant supplement to other medical treatments for ill patients and a strong preventative for the healthy. Wherever you may live, you can enjoy a more healthful life by seeking out places to relax and breathe in nature’s incredible forest medicine.

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