For generations, mankind has struggled to find a cure for cancer. We’ve spent billions on research and development as thousands of therapies have been used to treat different forms of the disease.
Once the pharmaceutical industry got involved, those therapies quickly narrowed to expensive drugs and harmful treatments that have become the standard of care in Western medicine.
In Japan, they have a different approach that’s been scientifically proven to increase the body’s anti-cancer ability: forest bathing.
Did you know that by 2050, nearly 2/3 of the world’s population is projected to live in urban centers? Or that the EPA estimates that the average American spends 87% of their time indoors, and another 6% in their vehicles?1,2
We’re becoming an increasingly sedentary culture, and there are many benefits to exercise and time spent outside. But as it turns out, time in nature is substantially more beneficial than outdoor time in the city.
What is Forest Bathing?
Forest bathing, or shinrinyoku as it’s known in Japan, has been around for thousands of years.
Contrary to what you may think, forest bathing has nothing to do with water. In essence, forest bathing is a short, leisurely trip to the forest used for relaxation and recreation. It is NOT strenuous exercise like jogging, climbing, or hiking. It’s been used for centuries to help with mood, stress, and energy.
The aromatic benefits alone have been recognized by the Forest Agency of Japan for nearly 40 years now, and researchers using the Profile of Mood States test successfully showed that forest bathing significantly decreased anxiety, depression, and anger.3
And while these positive effects are great, it may offer a significantly more substantial benefit: Forest bathing has been shown to boost the immune system and prevent cancer. You read that correctly. Several published studies have found that forest bathing trips – in addition to improving mood and energy, decreasing stress and anxiety, fighting inflammation, regulating blood sugar, and reducing hypertension – may have a preventative effect on cancer generation and development.
Natural Killer Cells, Cancer, and the Immune System
In order to explain how this works, we’ll first need to talk about natural killer cells. The immune system is our best defense against disease and plays an important role in combating cancer. But tumor cells have a unique ability to escape immune surveillance by mutating and disguising themselves as other cells. That’s where natural killer cells come in.
Natural killer (NK) cells are white blood cells found in our lymphatic system. These cells are specifically designed to hunt cancerous cells and destroy them, hence the name “natural killer”. When it comes to the immune system, these cells are our first and best defense against cancer. Healthy NK cells are absolutely vital in your body’s battle with disease.4
What’s especially interesting is that NK cells identify and destroy diseased or damaged cells without any conditioning or prior exposure. Unlike the rest of the immune system, which learns through exposure to new bacteria or viruses, NK cells can identify cancerous cells immediately. This means that the more NK cells we have working in our bodies, the better protected we are from chronic diseases like cancer.5
And this is where forest bathing comes in. Many studies over the past 15 years have examined the effects of forest bathing on immune function, all concluding that the result is an increase in both the number of NK cells and their activity level.
This means that time in nature equips the immune system with more of these “cancer assassins” AND keeps these cells functioning at the highest levels.3,5-8
This is HUGE news.
The absolute best way to treat and beat cancer is to stop it from developing in the first place. And it turns out that keeping our immune system strong may be as simple as getting out into nature. The researchers found that the benefits to the immune system and NK cells only occurred with forest bathing trips – not with trips in an urban setting. They also evaluated the impact on men and women in two separate studies.
Both groups experienced increased NK activity for more than 7 days after a trip. For women, the effects could last up to 30 days.3,6,8
5 Additional Forest Bathing Benefits
In addition to preventing cancer, forest bathing has been shown to have many other benefits. Here are our top 5 benefits of forest bathing.
1| Improving Mood and Energy
A 2007 study published in Public Health found that forest bathing can be extremely effective in managing acute emotions. In the study of nearly 500 participants, hostility and depression were significantly reduced after forest bathing compared to the control groups. Additionally, forest bathing can increase energy and vigor.9
Dr. Qing Li, considered one of the foremost authorities on forest bathing and its medicinal properties, authored a study in 2016 showing that people who spend regular time in the forest have more energy throughout the day and get better quality sleep at night. Forest bathing also helps to regulate dopamine levels, which increase focus and productivity.10
2| Lowering Stress and Anxiety
Forest bathing has long been considered beneficial for mental health, and several studies utilizing the Profile of Mood States or similar tests have confirmed this. One of the ways in which this happens is a reduction in cortisol. Dr. Li and other researchers have consistently demonstrated a correlation between forest bathing and cortisol regulation.3,9,11
Cortisol, like adrenaline, is an important hormone that is released in high amounts when we are in fight or flight” mode, but also helps with several basic functions. Cortisol helps keep us alert, manages metabolic processes, helps with memory, reduces inflammation, and balances blood pressure.12
However, there is a direct and proven correlation between chronically high cortisol levels and cancer. Emotional stress is a major contributing factor to the six leading causes of death in the United States: cancer, coronary heart disease, accidental injuries, respiratory disorders, cirrhosis of the liver, and suicide.
As it turns out, a simple walk through the trees may be all it takes to reduce stress.11-13
3| Reducing Inflammation
Inflammation is the body’s natural stress response to injury, but when inflammation persists, it can be extremely harmful. Chronic inflammation can result from disease, injury, or an unhealthy lifestyle. Doctors and scientists agree that chronic inflammation is likely at the root of most chronic disease.14
The D-limonene in forest air has been shown to reduce lung inflammation. Studies have shown that those with asthma and Chronic Obstructive Pulmonary Disease (COPD) have shown symptom improvement after forest bathing. This is because oxygen intake is increased, and inflammation is lessened.
A 2016 study confirmed this, finding decreased levels of pro-inflammatory cytokines and stress hormones in those who spent time forest bathing.15
4| Regulating Blood Sugar
Forest bathing can also help reduce blood glucose levels, which is extremely important. High blood sugar and diabetes are both risk factors for heart disease and cancer – the leading causes of death in the U.S.6-7,14,16
Cancer cells feed on glucose, a byproduct of refined sugars and carbs. The best environment you can create for cancer cells is one with elevated blood sugar. In addition to diabetes and heart disease, keeping healthy blood glucose levels can increase metabolism, provide you with more energy, and help fight off chronic disease.
Because forest bathing has an effect on hormone secretion, it’s able to help our bodies regulate glucose. The importance of a healthy diet is paramount, but time in nature can assist in regulating our glucose production.16
5| Combating Hypertension
A 2017 study published in BMC Complementary and Alternative Medicine found overwhelming evidence that forest bathing can help reduce both systolic blood pressure and diastolic blood pressure. Systolic blood pressure is the pressure in your vessels when your heart beats. Diastolic blood pressure is the vascular pressure when your heart rests. Both numbers are important, though systolic pressure is considered a stronger risk factor for heart disease.17
20 trials involving over 700 participants all reached the same conclusion: forest bathing can significantly reduce blood pressure. There is a clear connection between heart disease and cancer, and risk factors include high blood pressure, obesity, and an inactive lifestyle.17
In the U.S., over 600,000 people die every year from heart disease; that’s about 1 in 4 deaths annually. Hypertension is one of the leading risk factors for heart disease and other causes of mortality, but you can lower your risk for these diseases just by taking a leisurely stroll through the woods.17,18
There are many, many ways to help prevent disease and illness; diet and exercise are chief among them.
But the science is in: forest bathing is an extremely effective way to protect your health.
Not only can you improve your mental and physical health, you can actually stop cancer in its tracks. More importantly, forest bathing is dose-dependent. The more time you spend in nature, the greater its impact on your health. So take some time away from your phone or computer, throw some shoes on, and get outside!
Editor’s note: This post was originally published in June 2019. It has been updated and republished in January 2020.
The average American spends 87% of their time indoors.
The average American spends 87% of their time indoors.
Forest bathing is a short, leisurely trip to the forest used for relaxation and recreation.
Forest bathing has been shown to boost the immune system and prevent cancer.
5 Additional Forest Bathing Benefits:
- Improving Mood and Energy
- Lowering Stress and Anxiety
- Reducing Inflammation
- Regulating Blood Sugar
- Combating Hypertension