Health Benefits of Nature

How nature nurtures: Amygdala activity decreases as the result of a one-hour walk in nature

This study suggests that going for a walk in nature can have health promoting effects on stress-related brain regions, and consequently, it may act as a preventive measure against mental strain and potentially disease. Living in cities is associated with increased mental health risks. This study is causal in design and is an intervention study that investigates changes in the brain. This is the first study that we know to demonstrate the causal effects of acute exposure to natural vs. urban environment on stress-related brain regions, disentangling positive effects of nature from negative effects of city.

Convergence of Ecohealth and One Health

Interest and participation in EcoHealth and One Health approaches have grown considerably over the past decade. We present our deliberations and insights on two questions: Where and how can the two concepts converge? What is their common ground and where can they live happily apart?

An expanded One Health model: Integrating social science and One Health to inform study of the human-animal interface

Zoonotic disease emergence is not a purely biological process mediated only by ecologic factors; opportunities for transmission of zoonoses from animals to humans also depend on how people interact with animals. This paper proposes an expanded “One Health” conceptual model for human-animal exposure that accounts for social as well as epidemiologic factors.

Impact of climate change on biodiversity and associated key ecosystem services in Africa: a systematic review

Biodiversity and biodiversity-based ecosystems services are intrinsically dependent on the climate. As biodiversity underlies all goods and services provided by ecosystems that are crucial for human survival and well-being, this paper synthesizes and discusses observed and anticipated impacts of climate change on biodiversity and biodiversity-based ecosystem service provision and livelihoods, and what strategies might be employed to decrease current and future risks on the well-being of human in Africa.

Understanding Nature and Its Cognitive Benefits

Many people have the intuition that interacting with natural environments benefits their psychological health. This article describes empirical research on the cognitive benefits of interacting with natural environments and several theories that have been proposed to explain these effects.

Biodiversity, the Human Microbiome and Mental Health: Moving toward a New Clinical Ecology for the 21st Century?

Advances in research concerning the brain-related influences of the microbiome have been paradigm shifting, although at an early stage, clinical research involving beneficial microbes lends credence to the notion that the microbiome may be an important target in supporting mental health (defined here along the continuum between quality of life and the criteria for specific disorders).

EcoHealth and One Health: A theory-focused review in response to calls for convergence

EcoHealth and One Health are two major approaches broadly aimed at understanding the links between human, animal, and environment health. We aimed to gain a more in-depth understanding of the ontological, epistemological and methodological underpinnings of EcoHealth and One Health in order to identify areas of difference and overlap, and consider the extent to which closer convergence between the two may be possible.

The great outdoors: how a green exercise environment can benefit all

The studies of human and environment interactions usually consider the extremes of environment on individuals or how humans affect the environment. This review considers the declining levels of physical activity, particularly in the Western world, and how the environment may help motivate and facilitate physical activity.

Green Infrastructure, Ecosystem Services, and Human Health

Contemporary ecological models of health prominently feature the natural environment as fundamental to the ecosystem services that support human life, health, and well-being. This survey of the literature aims to provide a more comprehensive picture—in the form of a primer—of the many simultaneously acting health co-benefits of green infrastructure.

The Role of One Health in Wild- Life Conservation: A Challenge and Opportunity

Numerous emerging infectious diseases (EIDs) have arisen from or been identified in wildlife, with health implications for both humans and wildlife. Here, we focus on a little-studied and seldom discussed concern: how real and perceived risks of wildlife-associated diseases for human and companion animal health might erode public support for wildlife conservation.

Biodiversity and human health: mechanisms and evidence of the positive health effects of diversity in nature and green spaces

Natural environments and green spaces provide ecosystem services that enhance human health and well-being. This review describes mechanisms and evidence of effects of biodiversity in nature and green spaces on human health.

Forest Bathing Enhances Human Natural Killer Activity And Expression Of Anti-Cancer Proteins

In order to explore the effect of forest bathing on human immune function, we investigated natural killer (NK) activity; the number of NK cells, and perforin, granzymes and granulysin-expression in peripheral blood lymphocytes (PBL) during a visit to forest fields. Twelve healthy male subjects, age 37-55 years, were selected with informed consent from three large companies in Tokyo, Japan. The subjects experienced a three-day/two-night trip in three different forest fields. On the first day, subjects walked for two hours in the afternoon in a forest field; and on the second day, they walked for two hours in the morning and afternoon, respectively, in two different forest fields. Blood was sampled on the second and third days, and NK activity; proportions of NK, T cells, granulysin, perforin, and granzymes AlB-expressing cells in PBL were measured. Similar measurements were made before the trip on a normal working day as the control. Almost all of the subjects (11/12) showed higher NK activity after the trip (about 50% increased) compared with before. There are significant differences both before and after the trip and between days 1 and 2 in NK activity. The forest bathing trip also significantly increased the numbers of NK, perforin, granulysin, and granzymes AlB-expressing cells. Taken together, these findings indicate that a forest bathing trip can increase NK activity, and that this effect at least partially mediated by increasing the number of NK cells and by the induction of intracellular anti-cancer proteins.

Almost all of the subjects (11/12) showed higher NK activity after the trip (about 50% increased) compared with before. There are significant differences both before and after the trip and between days 1 and 2 in NK activity. The forest bathing trip also significantly increased the numbers of NK, perforin, granulysin, and granzymes AlB-expressing cells. Taken together, these findings indicate that a forest bathing trip can increase NK activity, and that this effect at least partially mediated by increasing the number of NK cells and by the induction of intracellular anti-cancer proteins.

Creativity in the Wild: Improving Creative Reasoning through Immersion in Natural Settings

Adults and children are spending more time interacting with media and technology and less time participating in activities in nature. This life-style change clearly has ramifications for our physical well-being, but what impact does this change have on cognition? Higher order cognitive functions including selective attention, problem solving, inhibition, and multi-tasking are all heavily utilized in our modern technology-rich society. Attention Restoration Theory (ART) suggests that exposure to nature can restore prefrontal cortex-mediated executive processes such as these. Consistent with ART, research indicates that exposure to natural settings seems to replenish some, lower-level modules of the executive attentional system. However, the impact of nature on higher-level tasks such as creative problem solving has not been explored. Here we show that four days of immersion in nature, and the corresponding disconnection from multi-media and technology, increases performance on a creativity, problem-solving task by a full 50% in a group of naive hikers. Our results demonstrate that there is a cognitive advantage to be realized if we spend time immersed in a natural setting. We anticipate that this advantage comes from an increase in exposure to natural stimuli that are both emotionally positive and low-arousing and a corresponding decrease in exposure to attention demanding technology, which regularly requires that we attend to sudden events, switch amongst tasks, maintain task goals, and inhibit irrelevant actions or cognitions. A limitation of the current research is the inability to determine if the effects are due to an increased exposure to nature, a decreased exposure to technology, or to other factors associated with spending three days immersed in nature.

Here we show that four days of immersion in nature, and the corresponding disconnection from multi-media and technology, increases performance on a creativity, problem-solving task by a full 50% in a group of naïve hikers.

The physiological effects of Shinrin-yoku (taking in the forest atmosphere or forest bathing): evidence from field experiments in 24 forests across Japan

This paper reviews previous research on the physiological effects of Shinrin-yoku (taking in the forest atmosphere or forest bathing), and presents new results from field experiments conducted in 24 forests across Japan. The term Shinrin-yoku was coined by the Japanese Ministry of Agriculture, Forestry, and Fisheries in 1982, and can be defined as making contact with and taking in the atmosphere of the forest. In order to clarify the physiological effects of Shinrin-yoku, we conducted field experiments in 24 forests across Japan. In each experiment, 12 subjects (280 total; ages 21.7 ± 1.5 year) walked in and viewed a forest or city area. On the first day, six subjects were sent to a forest area, and the others to a city area. On the second day, each group was sent to the other area as a cross-check. Salivary cortisol, blood pressure, pulse rate, and heart rate variability were used as indices. These indices were measured in the morning at the accommodation facility before breakfast and also both before and after the walking (for 16 ± 5 min) and viewing (for 14 ± 2 min). The R–R interval was also measured during the walking and viewing periods. The results show that forest environments promote lower concentrations of cortisol, lower pulse rate, lower blood pressure, greater parasympathetic nerve activity, and lower sympathetic nerve activity than do city environments. These results will contribute to the development of a research field dedicated to forest medicine, which may be used as a strategy for preventive medicine.

• The results show that forest environments promote lower concentrations of cortisol, lower pulse rate, lower blood pressure, greater parasympathetic nerve activity, and lower sympathetic nerve activity than do city environments.

Therapeutic effect of forest bathing on human hypertension in the elderly

Objective

To provide scientific evidence supporting the efficacy of forest bathing as a natural therapy for human hypertension.

Methods

Twenty-four elderly patients with essential hypertension were randomly divided into two groups of 12. One group was sent to a broad-leaved evergreen forest to experience a 7-day/7-night trip, and the other was sent to a city area in Hangzhou for control. Blood pressure indicators, cardiovascular disease-related pathological factors including endothelin-1, homocysteine, renin, angiotensinogen, angiotensin II, angiotensin II type 1 receptor, angiotensin II type 2 receptor as well as inflammatory cytokines interleukin-6 and tumor necrosis factor α were detected. Meanwhile, profile of mood states (POMS) evaluation was used to assess the change of mood state of subjects. In addition, the air quality in the two experimental sites was monitored during the 7-day duration, simultaneously.

Results

The baselines of the indicators of the subjects were not significantly different. Little alteration in the detected indicators in the city group was observed after the experiment. While subjects exposed to the forest environment showed a significant reduction in blood pressure in comparison to that of the city group. The values for the bio-indicators in subjects exposed to the forest environment were also lower than those in the urban control group and the baseline levels of themselves. POMS evaluation showed that the scores in the negative subscales were lowered after exposure to the forest environment. Besides, the air quality in the forest environment was much better than that of the urban area evidenced by the quantitative detection of negative ions and PM10 (particulate matter <10 μm in aerodynamic diameter).

Conclusion

Our results provided direct evidence that forest bathing has therapeutic effects on human hypertension and induces inhibition of the renin–angiotensin system and inflammation, and thus inspiring its preventive efficacy against cardiovascular disorders.

• The baselines of the indicators of the subjects were not significantly different. Little alteration in the detected indicators in the city group was observed after the experiment. While subjects exposed to the forest environment showed a significant reduction in blood pressure in comparison to that of the city group. The values for the bio-indicators in subjects exposed to the forest environment were also lower than those in the urban control group and the baseline levels of themselves. POMS evaluation showed that the scores in the negative subscales were lowered after exposure to the forest environment. Besides, the air quality in the forest environment was much better than that of the urban area evidenced by the quantitative detection of negative ions and PM10 (particulate matter <10um in aerodynamic diameter).
• It has been reported that an elevated level of Hcy, known as hyperhomocysteinemia (HHcy), is associated with the increment of vascular thickness, elastin fragmentation, and arterial BP [15,28]. Consistently, a significant association between SBP (systolic BP) and Hcy (p < 0.01) was observed in our study (Table 1). A mild decline in Hcy level was found in the forest group which indicated its beneficial effect on human health.

Effects of Short-Term Forest Bathing on Human Health in a Broad-Leaved Evergreen Forest in Zhejiang Province, China

Objective To investigate the effects of short-term forest bathing on human health.Methods Twenty healthy male university students participated as subjects and were randomly divided into two groups of 10.One group was sent on a two-night trip to a broad-leaved evergreen forest,and the other was sent to a city area.Serum cytokine levels reflecting inflammatory and stress response,indicators reflecting oxidative stress,the distribution of leukocyte subsets,and plasma endothelin-1 (ET-1) concentrations were measured before and after the experiment to evaluate the positive health effects of forest environments.A profile of mood states (POMS) evaluation was used to assess changes in mood states.Results No significant differences in the baseline values of the indicators were observed between the two groups before the experiment.Subjects exposed to the forest environment showed reduced oxidative stress and pro-inflammatory level,as evidenced by decreased malondialdehyde,interleukin-6,and tumor necrosis factor α levels compared with the urban group.Serum cortisol levels were also lower than in the urban group.Notably,the concentration of plasma ET-1 was much lower in subjects exposed to the forest environment.The POMS evaluation showed that after exposure to the forest environment,subjects had lower scores in the negative subscales,and the score for vigor was increased.Conclusion Forest bathing is beneficial to human health,perhaps through preventive effects related to several pathological factors.

No significant differences in the baseline values of the indicators were observed between the two groups before the experiment. Subjects exposed to the forest environment showed reduced oxidative stress and pro‐inflammatory level, as evidenced by decreased malondialdehyde, interleukin‐6, and tumor necrosis factor α levels compared with the urban group. Serum cortisol levels were also lower than in the urban group. Notably, the concentration of plasma ET‐1 was much lower in subjects exposed to the forest environment. The POMS evaluation showed that after exposure to the forest environment, subjects had lower scores in the negative subscales [decrease in negative mood], and the score for vigor was increased.

In the present study, the concentration of negative air ions was also determined, and a significantly higher daytime level of negative air ions was recorded in the forest environment (1509.1±357.0 cm‐3) than in the urban area (263.3±99.3 cm‐3). Thus, our finding about the Biomed Environ Sci, 2012; 25(3): 317‐324 323 beneficial effect of forests for humans may be at least partly due to the abundance of negative air ions.

Effect of forest bathing trips on human immune function

In Japan, a forest bathing trip, called “Shinrinyoku” in Japanese, is a short, leisurely visit to a forest; it is regarded as being similar to natural aromatherapy. This review focuses on the effects of forest bathing trips on human immune function. Beginning in 2005, adult Japanese individuals, both male and female, participated in a series of studies aimed at investigating the effect of forest bathing trips on human immune function. The subjects experienced a 3-day/2-night trip to forest areas, and blood and urine were sampled on days 2 (the first sampling during each trip) and 3 (the second sampling during each trip), and on days 7 and 30 after the trips. Natural killer (NK) activity, the numbers of NK, granulysin-, perforin-, and granzymes A/B-expressing lymphocytes in the blood, and the concentration of urinary adrenaline were measured. The same measurements were made before the trips on a normal working day as a control. The mean values of NK activity and the numbers of NK, granulysin-, perforin-, and granzymes A/B-expressing cells on forest bathing days were significantly higher than those on the control days, whereas the mean values of the concentration of urinary adrenaline on forest bathing days were significantly lower than that on the control days in both male and female subjects. The increased NK activity lasted for more than 30 days after the trip, suggesting that a forest bathing trip once a month would enable individuals to maintain 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 intracellular granulysin, perforin, and granzymes A/B. These findings indicate that forest bathing trips resulted in an increase in NK activity, which was mediated by increases in the number of NK cells and the levels of intracellular granulysin, perforin, and granzymes A/B.

The mean values of NK activity and the numbers of NK, granulysin-, perforin-, and granzymes A/B-expressing cells on forest bathing days were significantly higher than those on the control days, whereas the mean values of the concentration of urinary adrenaline on forest bathing days were significantly lower than that on the control days in both male and female subjects. The increased NK activity lasted for more than 30 days after the trip, suggesting that a forest bathing trip once a month would enable individuals to maintain 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 intracellular granulysin, perforin, and granzymes A/B. These findings indicate that forest bathing trips resulted in an increase in NK activity, which was mediated by increases in the number of NK cells and the levels of intracellular granulysin, perforin, and granzymes A/B.

• NK, granulysin-, perforin-, and granzymes A/B-expressing cells: immune boosting/cancer killing cells 
• Phytoncides from trees = NK increase

Interacting with Nature Improves Cognition and Affect for Individuals with Depression

Background

This study aimed to explore whether walking in nature may be beneficial for individuals with major depressive disorder (MDD). Healthy adults demonstrate significant cognitive gains after nature walks, but it was unclear whether those same benefits would be achieved in a depressed sample as walking alone in nature might induce rumination, thereby worsening memory and mood.

Methods

Twenty individuals diagnosed with MDD participated in this study. At baseline, mood and short term memory span were assessed using the PANAS and the backwards digit span (BDS) task, respectively. Participants were then asked to think about an unresolved negative autobiographical event to prime rumination, prior to taking a 50 minute walk in either a natural or urban setting. After the walk, mood and short-term memory span were reassessed. The following week, participants returned to the lab and repeated the entire procedure, but walked in the location not visited in the first session (i.e., a counterbalanced within-subjects design).

Results

Participants exhibited significant increases in memory span after the nature walk relative to the urban walk, p < .001, ηp2= .53 (a large effect-size). Participants also showed increases in mood, but the mood effects did not correlate with the memory effects, suggesting separable mechanisms and replicating previous work.

Limitations

Sample size and participants’ motivation.

Conclusions

These findings extend earlier work demonstrating the cognitive and affective benefits of interacting with nature to individuals with MDD. Therefore, interacting with nature may be useful clinically as a supplement to existing treatments for MDD.

• Participants exhibited significant increases in memory span after the nature walk relative to the urban walk, p < .001, ηp 2= .53 (a large effect-size). Participants also showed increases in mood, but the mood effects did not correlate with the memory effects, suggesting separable mechanisms and replicating previous work.
• Effect sizes nearly 5 times in depressed (MDD) as large as the effect sizes observed in healthy.