Have you ever contemplated the connection between tuberculosis and cancer? Of course, you haven’t. Why would you? Well, as it turns out the discovery of an ancient forest treatment to boost immune function was used successfully to treat tuberculosis and has now been discovered to be a powerful tool in eradicating cancer and other chronic diseases.
More than three million years ago, a bacteria called mycobacterium tuberculosis appeared in humans with devastating effects [1], and by the 1800’s, one out of seven people living in the United States and Europe were impacted by tuberculosis (TB). Since antibiotics would not come to the fore until the 1950s, a forest cure took hold across the world with surprising effects. Sanatoriums began popping up near forests across the globe and physicians Hermann Brehmer and TB sufferer Peter Detweiler were credited with opening the first in Germany. However, the records show Dr. John Cockley led the way with his facility in England built in 1791. Soon after, sanatoriums in Sweden recorded excellent success healing TB patients by strengthening their immune system through fresh forest air and nutritious food. Photos from the archives of the Swedish Heart and Lung Foundation depict patients resting in the ‘fresh air’ year round. [2]
By 1875, Joseph Gleitsmann broke ground in Asheville, North Carolina, bringing sanatoriums to America. On the whole, doctors using exposure to forest air also reported that other medical treatment methods were magnified with the “unseen airborne healer” secreted by the trees. Today, we know these unseen healers to be phytoncides, more commonly referred to as essential oils, which are part of a tree’s powerful defense mechanism as well as its communication pathway with other trees.
Is the science behind shinrin-yoku real?
Today, despite a multitude of medications available to treat a variety of illnesses, the use of nature is still alive and well. The term most widely used is forest bathing, which came from the Japanese words shinrin-yoku, meaning to be in nature and connect all of your senses to it in a mindful way. The first studies into the science behind shinrin-yoku were conducted in the 1980’s by Physician Qing Li, Chairman of the Japanese Society for Forest Medicine, in Japan’s Akasawa National Recreational Forest, which was designated a forest therapy base in 2006. In a 2007 study conducted by Dr. Qing Li [3], men taking two-hour walks in the woods over a two-day period exhibited a 50% increase in anti-cancer proteins and natural killer cells (NK). That’s significant since NK cells are a type of white blood cell that attacks and kills unhealthy cells, including tumor cells by using the anti-cancer proteins in your body. The more natural killer cells and anti-cancer proteins a person has the lower their risk of disease.
Today, forest bathing is a world-wide wellness phenomenon done alone, in groups or offered by certified guides in wilderness and urban centers alike. In fact, forest medicine has become an interdisciplinary science recognized by the National Institutes of Health (NIH) under the categories of alternative medicine, environmental medicine and preventive medicine[4], for its human health benefits.
Benefits of forest environments as identified by the NIH include:
· Increase anti-cancer protein production.
· Increase natural killer cells that prevent and help fight cancer and other diseases.
· Increase immune system function.
· Exposure to anti-inflammatory Terpenes.
· Decrease inflammation.
· Decrease risk of heart attack.
· Improve cardiovascular and metabolic health.
· Lower blood-sugar levels.
· Reduce blood pressure.
· Protection against obesity and diabetes.
· Mood-boosting effects.
· Anti-depressant effects.
· Improve focus even with ADHD challenges.
· Improve memory.
· Quicker recovery from surgery or illness.
· Improve sleep patterns.*
· Lower stress by lowering cortisol and adrenaline.
· Increase levels of serum adiponectin and dehydroepiandrosterone sulfate.
· Suppress the sympathetic system (fight or flight).
· Enhance the parasympathetic system (rest and digest).
· Improve pain thresholds.
· Increase energy.
· Improve skin conditions.
· Relieve muscle soreness.
· Support weight loss.
· Improve intuition.
· Increase overall sense of happiness.
*Quality sleep is vital to helping brain function, balance hormones and strengthen the immune system. Sleep deficiency is linked to risk of heart disease, kidney disease, high blood pressure, diabetes and stroke.
How does it work?
The phytoncides washing over your body as you walk through a wooded area provide a variety of health benefits, and boosting NK cells that strengthen your immune system to fight diseases such as cancer [5] [6] [7] is just one way. Forest bathing also increases the levels of anti-inflammatory cytokines, which are the proteins that tell the immune system to work harder, something no medication has been able to replicate thus far. It appears the magic is found in the terpenes, but how they work has yet to be discovered. The NIH [8] published a review that categorized various terpenes according to their anti-inflammatory, anti-tumorigenic, and neuroprotective properties, and found evergreens to be more effective, particularly pine, cedar, spruce and conifers than other types of trees.
Dr. Mary O’Brien, oncologist at the Royal Marsden Hospital in London discovered that walking in the woods provided another powerful benefit derived from a common bacteria living in the forest soil called mycobacterium vaccae. When breathed in, it activated the neurons associated with immune function while also acting as an anti-depressant [9] [10].
Even a small amount of time in nature can have huge impacts on your health [11] [12]. The NIH reported that a 50-minute walk in a wooded area improved short-term memory by 20%, while walking along a city street did not [13]. Another study from the University of Exeter (UK) [14], found that people who lived where there were trees and green spaces were less anxious and depressed. Remarkably, it was also found that people living on tree-lined streets used fewer prescription medications. A Canadian study looked at tree density and public health in Toronto [15] and found that having 10 or more trees on a city block could make a person feel as good as if they had been given a $10,000 pay raise, while having 11 or more trees resulted in lowering blood pressure and decreasing diabetes and obesity risks. Trees can even affect mortality rates. The U.S. Forest Service found that the death of trees [16] is somehow tied to human mortality. In places where ash trees had been affected by emerald ash borer disease, human mortality rates were higher, specifically death from cardiovascular and respiratory tract disease.
There is no shortage of research on how critical trees are to our overall health, and Dr. Philip Barr, an integrative medicine physician at Duke Integration Medicine[17], noted that he prescribes forest bathing to his patients because it’s a self-nurturing technique they can do anywhere and at any time and only requires a pair of comfortable shoes. He also asserted that the overall effects are similar to meditation.
"We prescribe drugs to accomplish some of these things, to lower blood pressure and enhance our oxygen levels in the body and relax muscles. If people can get out anywhere from once a week to once a month, they can get ongoing benefits,” Barr said. "If we can accomplish these ends through a beautiful walk in nature and re-engaging with nature that brings us the sounds and scents and the vision of the woods and sun coming through the trees, that's very healing. There is something about the walking meditation that makes this process very healing."
Stanford University [18] also found that forest bathing alleviates negative emotions, increases positive thoughts, and boosts immune function. Based on countless studies replicated in a variety of cultures, there is a measurable physical and mental advantage to spending time immersed in nature, including it’s ability to increase creativity. A study on participants of Outward Bound programs [19] found they performed 50% better on creative problem-solving tasks after just three days of wilderness backpacking.
Other studies have compared the psychological effects of urban walking vs. nature walking and have found that nature walks tend to correlate with greater mood improvements. One small study found that regular walks in a forest or park significantly reduced blood pressure and increased dopamine levels compared to walks in a city [20]. Another small study found that forest bathing significantly reduced pulse rate, increased energy, and decreased depression, fatigue, anxiety, and confusion [21]. It’s even possible to reduce the release of cortisol just by gazing at a forest scene.
Why is cortisol so important?
Higher cortisol levels will increase your risk of anxiety, depression, memory and concentration loss, heart disease, and weight gain. While there’s a long list of factors that increase your risk of developing a chronic illness such as cancer, one major factor is chronic stress. When your mind is chronically stressed, your body reacts by releasing cortisol, which increases inflammation and depresses your immune system. The unhealthy growth of blood vessels called angiogenesis is then triggered, opening the door for chronic disease to develop. Anyone with a chronic illness can tell you it can squash your spirit and lead to depression, more inflammation, more disease and so on.
When you’re under stress, your sympathetic nervous system jumps into gear, and your parasympathetic nervous system backs off. Let’s say a bear starts to chase you setting off your fight or flight response. When that happens, your heart beats faster, blood pressure increases, cortisol levels spike, digestion slows and inflammation grows. It’s an acute reaction to stress that subsides quickly and doesn’t have the long-term health impact chronic stress ushers in. According to the World Health Organization (WHO), 60% of the world population suffers from chronic disease much of which is caused by the insidious stressors we experience every day. Learning to decrease daily stress will allow your parasympathetic nervous system to become more active, which will prompt rest, conserve energy and slow your heart rate while lowering cortisol levels and reducing overall inflammation to heal your body.
What if you can’t walk among the trees today?
If you’re not able to walk among the trees today, don’t fret. You can bring the forest to you by using essential oils in your work or living space to improve immune function and decrease stress. You can also bring specific types of plants into your indoor space that help remove toxins released by carpets, printers, and upholstery, for example. The NASA Clean Air Study [22] developed a list of the top ten air-purifying plants, which include peace lilly, aloe vera, English ivy, chrysanthemum, Boston fern, mother-in-law’s tongue, bamboo palm, weeping fig, rubber plant and spider plant. However, indoor forest bathing will not be as effective as a long rejuvenating walk through the woods.
Since 2009, the National ParkRx initiative in the United States has encouraged the use of forests, parks and trails to reverse the growing rates of chronic illness. There are more than 150 park-prescription programs across the U.S., including in my home state of Wisconsin that help improve human health with forest medicine.
What else do trees give us?
Forests are key players in helping us eradicate chronic stress and reduce disease but that’s not all they do for us. There are myriad benefits to forests, including oxygen production, particulate removal from the air, water purification, flood water mitigation, and protection against soil erosion. Of course, forests also provide clothing, food, shelter, and building materials, but perhaps the most critical role trees play across the globe is that they store more than one trillion tons of carbon (twice the amount found in the atmosphere), which helps to slow global warming.
According to the World Health Organization (WHO), air pollutants and fine particulate matter have the greatest impact on human health, contributing to asthma, lung disease, heart attacks, cancer and strokes. Air pollution has been estimated to kill 4.6 million people [23] each year, and that number is expected to reach 6.2 million by in the next 30 years. In London’s largest tree survey [24], eight million trees were valued at an estimated $6.1 billion due to their extensive environmental and health benefits. Interestingly, some trees do this job better than others, for example the silver birch can remove up to 50% of the particulate matter expelled by cars.
What can you do to ensure trees continue to work for you?
WHO and the Environmental Protection Agency (EPA) noted by 2050, 66% of the world’s population is projected to live in cities, and the EPA found that the average American spends 93% of their time indoors [25]. These are stunning revelations and have prompted efforts to raise awareness of our need for trees. The United Nations has declared March 21 International Forest Day, encouraging each of us to plant more trees as one effective way to help mitigate climate change and improve human health. Another great way to be a part of the solution is to organize or take part in community celebrations that promote the critical role trees play in helping us heal while protecting our planet for future generations. And speaking of future generations, teach your kids to “speak for the trees…” with my favorite childhood classic The Lorax.
Forest bathing is simple, attainable and sustainable, so give it a try!
1. Choose a forest or natural area.
2. Leave your electronics behind.
3. Take some deep breaths in and blow them out slowly as you become mindful.
4. Let nature come into view then connect with the sights, sounds, smells, feel and taste.
5. Walk slowly or sit in one place and listen to the birds sing and the wind move through the trees, notice the different shades of green, and breathe in the natural essential oils all around you.
6. Feel the healing happen.