forest bathing Archives - Amazing Health Advances

Forest Bathing to Boost Anticancer Immunity

The AHA! Team — Wed, 30 Jul 2025 06:38:14 +0000

Michael Greger M.D. FACLM via Nutrition Facts – Spending time in a forest, or even anticipating it, significantly lowers levels of cortisol (a stress hormone), more so than being in an urban area. Natural killer cells are one of the ways our body fights off cancer, and visiting a forest can induce a significant increase in both their numbers and their activity. I’ve previously shown how exposure to nature can have self-reported psychological benefits, but there was a dearth of data on changes in objective measurements, so I was excited to see this paper on the effects of forest bathing, “a traditional practice characterized by visiting a forest and breathing its air,” on levels of the stress hormone cortisol in the participants’ saliva. The level of cortisol in our saliva is considered an indicator of our stress level, and study participants’ salivary cortisol levels were significantly lower after walking in a forest or even just hanging out in one (“forest watching”), compared to walking or just being in a city, as you can see at 0:49 in my video Boosting Anticancer Immunity with Forest Bathing. However, the same effect was found before they went to the forest, too. Indeed, “forest bathing, in particular forest watching, was associated with significantly lower cortisol levels both before and after this practice if compared with visiting an urban area.” Therefore, it appears that just the thought of spending time in a forest relieves stress. So, “when comparing the effects of forest bathing versus urban visiting, the anticipated placebo effect…may play a more important role in influencing cortisol [stress] levels than the actual experience” of being in the forest. I was ready to dismiss this as just another nebulous psychological effect until I read this: “Studies on the effects of ‘Shinrin-yoku’ [forest bathing] on the immune function showed that visiting a forest can induce a significant increase in the number and activity of natural killer (NK) cells,” one of the ways our body fights off cancer. That got my attention. It all started with this study: Twelve men were taken on a long weekend trip to walk in the forest, and nearly all of them (11 out of 12) showed higher natural killer cell activity afterward. It wasn’t just a little increase either; they had about a 50 percent increase in NK cell activity after the trip compared to before they went to the forest, as you can see at 2:00 in my video. Now, exercise alone can affect immune function, but “there were no significant differences in walking steps before and during the trip.” The study participants were just walking in a forest instead. However, they were taken on a trip somewhere, which introduced other variables, so what about randomizing them to go on a city trip versus a forest trip? If there were some special forest effect, how long would it last? Do you have to walk in the forest every day? Before jumping into all that, let’s first see if it works in women, too. This study had the same kind of set-up, and the same kind of results: a significant boost in natural killer cell activity from walking in the woods. What’s more, this time, the participants were retested a week later, and their natural killer cell activity was still up. When they were retested a month after the trip their levels were back to baseline, as you can see at 2:45 in my video. So, walking in the woods once a week should do it, but the study involved a multi-day trip. Who can go to the forest all weekend, every weekend? How about just a day trip? The title gives it all away: “A Day Trip to a Forest Park Increases Human Natural Killer Activity and the Expression of Anti-Cancer Proteins in Male Subjects.” The same results and the same big jump measured the day after the trip compared to before and with the same staying power, as you can see at 3:08 in my video. And, natural killer cell activity was still boosted a week later. “This suggests that if people visit a suburban forest park once a week on a day trip, they may be able to maintain increased NK activity” and a boost in anticancer immune function. I’m still not convinced, though. How can you attribute the benefit to the forest itself, when all you have are before and after data? To make the case that nature had anything to do with it, you’d need a control group of study participants who took the same kind of trip but went somewhere else instead. And here we go. Again, the study title says it all: “Visiting a Forest, but Not a City, Increases Human Natural Killer Activity and Expression of Anti-Cancer Proteins.” By the end of the forest trip, the participants experienced a boost of 80 percent in NK activity after forest bathing, compared to only a 10 percent bump for the city walkers, as shown below and at 3:58 in my video. Both trips were matched for physical activity, alcohol, and sleep, too— other factors and behaviors that can affect immune function. So, we’ve got confirmation of boosted immunity, but only on the forest trip, “indicating that forest bathing does indeed enhance human NK activity.” Moreover, the researchers found that “the increased NK activity and numbers of NK cells induced by a forest bathing trip lasted more than 7 days, even 30 days, after the trip.” As you can see below and at 4:26 in my video, NK activity was still up a week later and even a bit up a month later. “This suggests that if people visit a forest once a month, they may be able to maintain increased NK activity. This may be important in health promotion and preventive medicine.” Now that we know that forest bathing induces a real effect, the next question is, Why? What is it about forests that give us the boost? (You can imagine Big Pharma wondering if it can be made into a pill.) We’ll find out next. The video I mentioned at the start is Are There Health Benefits of Spending Time in Nature?. Stay tuned for the follow-up post: Why Does Forest Bathing Boost Natural Killer Cell Function?. For other ways to improve immune function, check out related posts below. Key Takeaways Spending time in a forest, or even anticipating it, significantly lowers levels of cortisol (a stress hormone), more so than being in an urban area. Forest exposure is associated with a notable increase (around 50 percent) in NK cell activity, which plays a role in fighting off cancer. After a single forest trip, NK cell activity remains elevated for up to a week, and, in some cases, positive effects last up to a month. A day trip to the forest can be enough to maintain elevated NK cell activity if done weekly or monthly. Studies comparing forest versus city exposure confirm that forest environments uniquely boost immune function, independent of other factors like exercise and sleep. To read the original article click here.

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Science-Backed Benefits of Forest Walking That Will Surprise You

AHA Publisher — Tue, 06 Apr 2021 07:00:04 +0000

Karen Sanders via NaturalHealth365 – There is strong scientific evidence coming out of Japan about the anticancer effects of shinrin-yoku or forest bathing. In fact, according to Dr. Qing Li – one of the world’s foremost experts on shinrin-yoku, forest walking may prevent chronic illnesses like cancer, reduce blood pressure, heart rate, and stress hormones. Chronic stress slowly kills. Environmental toxins like car fumes and industrial wastes, processed foods, and EMF pollution increase our cortisol levels and the risk for disease. Bottom line, most people in modern society are stressed out and need to relax – much more. A Growing Body of Evidence Supports the Idea of Getting Out in Nature May Just Be What You Need There’s simply no debate – forest bathing provides a natural environment of grass, trees, and fresh air – which can literally bring you back to life. Thankfully, there is mounting scientific data to prove that being in contact with nature is good for us physically, emotionally, and mentally. Naturally, it is widely thought that leaving the noise and stress of everyday life and spending more time in nature is good for us. Researchers have now been putting this understanding to the test. Unfortunately, only until recently, the practice of walking in the woods was never really investigated using laboratory equipment. Medical Studies Prove Forest Walking Offers Multiple Health Benefits The studies which began in Japan sought to find the physiological impact of forest bathing. Dr. Li, an associate professor at Nippon Medical School in Tokyo and current president of the Japanese Society of Forest Medicine, has conducted experiments to test forest bathing on human health. The studies found favorable effects on mood, stress level, and immune function. The scientists in Japan back up the work done by Boris Tokin, a Russian researcher, who discovered trees and other plants actually release chemicals called phytoncides. This chemical protects plants from harmful pathogens and can offer significant health benefits to humans. How Does Forest Walking Reduce Cancer Risk? The profile of the Mood States test showed that forest bathing trips significantly increased vigor in test subjects – while decreasing anxiety, depression, and anger. This factor alone was shown to decrease the risk of stress-related diseases like heart disease and cancer. The studies on immune system function showed an increase in the activity of natural killer (NK) cells – a component of the immune system in charge of preventing cancer. Wouldn’t it be nice if every (conventionally-trained) oncologist talked to their patients about this? Here Is One of the Best Studies to Date In one particular study, subjects experienced a 3-day/2-night trip to three different Japanese forests. Prior to the forest visit, the same subjects participated in a city tourist visit – consisting of a 3-day/2-night trip to Nagoya city, which had very few trees. The class of hotel and the lifestyle of the subjects during the stays in the hotels were the same for the city and forest trips. The walking courses of both trips were 2.5 km. Interestingly, the city tourist visit did not increase participants’ natural killer cell activity or the expression of selected intracellular perforin (more about this in a moment). These findings showed that forest bathing trips did increase natural killer cell activity, the number of NK cells, and the levels of perforin. You may be wondering – what is perforin? It’s actually a protein, known for breaking into cells that have been taken over by a virus or turned into a cancerous cell and allowing toxic enzymes in. This process destroys the cell from within. But, without this protein, the immune system can’t destroy rogue cells. Breathing in This Unique Chemical Compound May Be Responsible for Anticancer Effect Dr. Li attributes the increase in NK activity partly to breathing in air containing phytoncide – an essential oil from the wood – like α-pinene and limonene, which are antimicrobial volatile organic compounds emitted from trees to protect them from rotting and insects. By the way, phytoncides are natural preservatives and fungicides, classified as antimicrobial volatile organic compounds, and can also be used as essential oils in aromatherapy. These phytoncides induce NK cell activity, which kills tumor cells by releasing anticancer proteins. In fact, it’s been shown that ‘forest bathers’ have increased this activity by 50%. So, it makes sense, living in heavily forested areas is associated with a decreased risk of early mortality and cancer. For example, researchers compiled data from several major cities in Japan and found that populations that lived in areas with more trees had a decreased rate of several different types of cancer. Forest Walking Offers Immediate POSITIVE Results Walking in a forest or park strengthens your white blood cells, lowers your heart rate, reduces blood pressure and decreases the stress hormone – cortisol. By breathing in the aroma of the plants – we are saturating our body with chemicals known for their ability to prevent infections, viruses, and cancer. So, remember, the next time you’re in the forest – hug a tree and take a deep breath, because it may just save your life. Sources for this article: NIH.gov ScienceDaily.com hphpcentral.com smh.com.au To read the original article click here. For more articles from NaturalHealth365 click here.

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