Nature-based therapy: Forest bathing for women with breast cancer

On , In Soul
Lush green forest trail with mountains in background and sun peeking through trees, highlighting the benefits of forest bathing and breast cancer

Breast cancer is the most common form of cancer in women and the second highest cause of female cancer mortality.1 Nature-based therapies (NBT) such as forest bathing (aka forest therapy or FT) shows promising research in its ability to upregulate the immune system in women with breast cancer.

While most of us intuitively feel better when we spend time in nature, grounding ourselves to the earth and immersing ourselves in natural environments – the Japanese have a term for this, and it is called ShinRin Yoku. Several years of research support forest bathing by demonstrating psychological improvements in mood, anxiety and quality of life, as well as measurable improvements in heart rate, heart rate variability, lung capacity and salivary cortisol levels. These studies ranged with forest therapy duration from as little as 15 minutes a day to 3 full days.2-5

“The enjoyment of natural scenery employs the mind without fatigue and yet exercises it; tranquilizes it and yet enlivens it; and thus, through the influence of the mind over the body gives the effect of refreshing rest and reinvigoration to the whole system.”              – Frederick Law Olmstead (19th century Landscape Architect)1

Enhancing Natural Killer Cells, Perforin & Granzyme

One well-known study reviewed the health impacts of just a few hours in a forest environment with noticeable increases in serum natural killer cells. Natural killer (NK) cells are immune cells in the human body well-known for their ability to identify and reduce the size of cancerous tumors.6 NK cells and their associated “cytotoxic entourage” of perforin and granzyme enzymes,7 remained elevated in the bloodstream greater than 30 days after this single forest therapy exposure.

In 2015, a Korean study published a small trial of 11 women with stage 1-3 breast cancer. This was a two-week forest therapy immersion program.8 where these women lived in a forest cabin and engaged in two-hour daily forest walks every morning. The afternoons involved free-time activities and group discussions surrounding their cancer diagnosis and other personal details. Meals were standardized to the Korean Nutritional Health guidelines and blood samples were drawn three times: at the start (Day 1) of the trial, at the end of the forest therapy experience (Day 14), and one week after returning home and back to regular life (Day 21). This clinical trial showed impressive results. Serum NK cells were increased by 39% at the two-week mark and remained elevated 13% above the baseline one week upon returning home. Likewise, the NK cells cancer-fighting enzymes increased throughout the study and continued to increase in perforin and granzyme B levels, rising 59% and 155%, respectively, from Day 1 to Day 14, and continued to double to 114% and 359%, respectively, above baseline and after returning home on Day 21. These findings support forest therapy’s substantial upregulation in tumor-fighting capacity of the immune system in women coping with breast cancer. While this subject pool was very small and lacked a control group, the results are promising as an adjunctive nature-based therapy, warranting more research.

Cognitive Function, Mental Health & Stress

Imagine being told you have cancer… or perhaps, this has already happened. The ability to comprehend this new reality, to focus your attention, to simply listen – such a diagnosis greatly affects your mental acuity. For women with breast cancer, there is not just physical pain, but social stigma, emotional irritability and fear of the unknown – all while managing doctors’ appointments and maintaining family and work responsibilities. Before long, these stressors impact one’s cognitive ability to focus, concentrate, and retain information. And this all sets in even before the damaging cognitive effects of chemotherapy that many recognize as “Chemo Brain.”9

With respect to memory, focus and concentration, a Michigan study looked at natural restorative experiences (NRE) in breast cancer patients with significant improvements in standard measures of these 3 areas.10 The study involved 157 women with newly-diagnosed breast cancer who participated in home-based natural restorative experiences for a minimum of 120 minutes per week for an average of 36 days. The time frame for these patients began shortly after their diagnosis and up to a time after their surgery but ended before beginning any adjuvant therapy such as chemotherapy or radiation therapy.

According to the University of Michigan’s professor Stephen Kaplan’s Classic Attention Restoration Therapy, NRE is defined as any experience in nature fulfilling these four criteria:11

  1. Fascination: the NRE should easily capture a person interest
  2. Being Away: the NRE should mentally and/or physically remove one from typical daily routines, concerns and or locations
  3. Extent: The NRE should not be boring or become tedious
  4. Compatibility: The NRE should be personally enjoyable and/or pleasant

While not limited to the following activities, the participants stated their activities as: “taking care of my garden,” walking along the river,” “watching a beautiful sunrise,” and “spending an hour with my plants.” This study demonstrated (via multiple regressional analysis) that women who engaged in NRE had significant improvements in memory, focus and concentration when compared to no changes in the wait-listed control group (b+-0.872 (0.345), b= -0.158, p<0.01).

Nature-based therapies have the ability to ease mental fatigue and reduce the substantial impacts of stress that comes with a cancer diagnosis. The field of “Psycho-oncology has been well-established with the focus on reducing the mental health burden of cancer, including its effects on mood, concentration and quality of life.12-14 Navigating life with breast cancer is more than just lab values, CT scans, immune markers and quality of life scores. Living with a breast cancer diagnosis becomes a challenging, scary, and heartbreaking journey. Spending time in nature can provide a place of sanctuary, allow time for introspection and reflection and provide a sense of safety and connection.

There are many more evidence-based research articles supporting the health benefits of a natural environment. A large scale study in Japan looked at 126 million people and revealed a highly significant inverse correlation between residential proximity to a forest and a woman’s risk of having diagnosed breast cancer (r=-0.530, p<0.0001).15

Ultimately, while more research is always helpful, Nature-based therapies health benefits are impressive, supportive and low cost. Forest Bathing is easily accessible to many of us here in the Okanagan. Most people have experienced some form of contentment, relaxation and peace of mind, whilst walking on a forest trail or taking a stroll through the park.

Some of our favorite places to visit in the greater Kelowna area include:

  1. Scenic Canyon Regional Park
  2. Hiking Trails up at Predator Ridge
  3. Hardy Falls Regional Park
  4. Glen Canyon Regional Park

Where will you go today to immerse yourself in nature? 


Courtesy of Dr. Emina Jasarevic, ND

References: Credit and Excerpts from this review go to Kurt Beil, Lac, MPH from Townsend Newsletter

  1. Olmsted FL. Nature , Health & Well-being Health & Environment. 1865
  2. Song C, et al. Effects of Walking in a Forest on Young Women. Int J Environ Res Public Health. 2019;16(2).
  3. Yu YM, et al. Effects of forest therapy camp on quality of life and stress in postmenopausal women. Forest Sci Technol. 2016;12(3):125-129.
  4. Lanki T, et al. Acute effects of visits to urban green environments on cardiovascular physiology in women: A field experiment. Environ Res. 2017;159(June):176-185.
  5. Lee JY, Lee DC. Cardiac and pulmonary benefits of forest walking versus city walking in elderly women: A randomised, controlled, open-label trial. Eur J Integr Med. 2014;6(1):5-11.
  6. Miller JS, Lanier LL. Natural Killer Cells in Cancer Immunotherapy. Annu Rev Cancer Biol. 2019;3(1):77-103.
  7. 7. Backes CS, et al. Natural killer cells induce distinct modes of cancer cell death: Discrimination, quantification, and modulation of apoptosis, necrosis, and mixed forms. J Biol Chem. 2018;293(42):16348-16363.
  8. Kim BJ, et al. Forest adjuvant anti-cancer therapy to enhance natural cytotoxicity in urban women with breast cancer: A preliminary prospective interventional study. Eur J Integr Med. 2015;7(5):474-478.
  9. Hermelink K. Chemotherapy and Cognitive Function in Breast Cancer Patients: The So-Called Chemo Brain. JNCI Monogr. 2015;2015(51):67-69.
  10. Cimprich B, Ronis DL. An Environmental Intervention to Restore Attention in Women With Newly Diagnosed Breast Cancer. Cancer Nurs. 2003;26(4):284-292.
  11. Kaplan S. The restorative benefits of nature: Toward an integrative framework. J Environ Psychol. 1995;15(3):169-182.
  12. Holland JC. Psycho-oncology: Overview, obstacles and opportunities. Psychooncology. 2018;27(5):1364-1376.
  13. Pérez S, et al. Acute stress trajectories 1 year after a breast cancer diagnosis. Support Care Cancer. 2016;24(4):1671-1678.
  14. Kang D-H, Park N-J, McArdle T. Cancer-Specific Stress and Mood Disturbance: Implications for Symptom Perception, Quality of Life, and Immune Response in Women Shortly after Diagnosis of Breast Cancer. ISRN Nurs. 2012;2012:1-7.
  15. Li Q, Kobayashi M, Kawada T. Relationships Between Percentage of Forest Coverage and

Other References:

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