Dr Li, a medical physician and immunologist did the first peer reviewed study showing that time spent in a forested area in Japan increases immune system regulating NK cells and cancer fighting protein cells.
Dr Li researches the health effects of tree aerosols.
Li is the Japanese researcher in the Forestry Medicine, Nippon University in Japan who introduced the term “forest bathing” decades ago.
Japan is 65% forest. The boreal forest stretches into northern Japan.
The study linked here shows that forest bathing trips (or walks in the trees) may have a preventive effect on cancer starting and developing.
How They Did It
Li and his team measured the concentrations of tree aerosols in 1) city streets, 2) city parks and 3) forests. Research subjects went on timed walks in each of these areas.
Before and after these walks Dr Li et al counted and measured the activity of NK cells and cancer fighting proteins inside the cell. Anti-cancer proteins inside the cell are granulysin, perforin, and granzymes A/B. The measurements were reliable blood and urine tests.
The Experiment
In the study referenced here subjects went on a 3-day/2-night trip to forest areas. During the day the participants went on 2.5 km hikes for two hours. Blood and urine were sampled on days 2 of the trip and day 3 and on days 7 and 30 after the trips.
The Results
The increased NK activity lasted for more than 30 days after the trip.
This suggests that a forest bathing trip once a month would allow people to keep a higher level of NK activity.
In contrast, a visit to the city as a tourist did not increase NK activity, the numbers of NK cells, or the level of anti-cancer proteins: intracellular granulysin, perforin, and granzymes A/B.
This mechanism of forest bathing – induced NK activity diagram in the same research paper
NK cells can kill tumor cells by releasing anti-cancer proteins, such as perforin, GRN, and GrA/B.
Forest bathing trips increase NK activity and the intracellular level of anti-cancer proteins.
These findings the suggest that forest bathing trips may have a preventive effect on cancer starting and developing.
All the more reason for us to go outside and stay outside for as long as we can. It is April in Manitoba and still cold. So I am still wearing my light, warm Columbia jacket. My sister and I are going to buy second ones this week while they are on sale.
Wow! Amazing, lifesaving studies! Thanks for sharing!
I so believe this. I think stress is a killer and getting back to nature can relax and make us healthier.
I love that you provide evidence behind the science. We had been trying to hard to focus on our financial health that we neglected our personal health. With a Noreaster every week it’s been hard to get out, but we are working on making goals to hit the outdoors more frequently.
Verla, these studies are really amazing!
Love this article, Verla. I’ve been making an effort to get out more, although I don’t enjoy feeling like a wet dog afterwards! But if you can get out in 25 degree below, I really have no excuses! Thanks for this awesome information!
It is neat to know how much forest Japan has. I wish we had that much here!
What a very interesting concept! I love to walk in the trees. I am not really an outdoorsy person, but I take my family to the forest and the lake, just to breathe in.
Wow! Merely being in nature and out in the outdoors definitely makes me feel healthier! Thank you for sharing 🙂
Great research! Thank you for sharing it!
I can see how walking in the forest can cure pretty much everything! This should be prescribed before medicine.
Oh wow, I never thought about being in nature would prevent cancer. Great research too!
I love that you are so passionate about this topic.
I love the term ‘forest bathing’…a new one for me. Thanks for sharing another reason trees really can help mend us.
I had no idea that Japan had that much forest land. That’s amazing results!
What an encouraging article! Great news on how to keep yourself healthy. There’s also a good reminder for those who have the hiking habit to keep it going!
So scientific and smart! Love reading new things I have never heard of before, thanks for sharing!
I love the phrase “forest bathing trips.” Need to work that into my daily speak.