Doctors in Scotland made headlines a few years ago when they began “prescribing nature” for their patients with a range of afflictions. That new practice was based on research that suggested that people who spent two or more hours per week in nature improved their health and well-being.
Recently, however, scientists have taken those findings one step further: they investigated how nature relatedness—simply feeling connected with the natural world—benefits our dietary diversity and fruit and vegetable intake. Their results proved to be highly positive.
And, speaking of vegetables, a recent U.S. nationwide study found that increasing green vegetation in large, metropolitan areas could have prevented thousands of deaths. Happily, that study also showed that overall greenness in metro areas has increased in the past 20 years.
“Happily,” I say, because yet another recent survey revealed that as a city becomes more economically developed, its citizens’ levels of happiness become more directly related to the urban green spaces available.
Nature and nutrition
In a study recently published in the American Journal of Health Promotion, a research team from Pennsylvania’s Drexel University College of Nursing and Health Professions surveyed more than 300 adults living in Philadelphia to measure their self-reported connection to nature, their experience with it and their perspective on it. They also asked the participants about the beverages and foods they had consumed the previous day to assess their dietary diversity and estimate their daily fruit and vegetable consumption. The respondents to the survey mirrored demographic characteristics (education, gender, income and race) of Philadelphia, as of the 2010 census.
Results showed that participants with a stronger connection to nature reported a more varied diet and ate more fruits and vegetables. This work can now aid health care practitioners in two ways: first, integrating nature- and park-prescription programs into health care practices (like the Scotland model) may increase nature relatedness across a person’s life span and potentially improve his or her dietary intake. And second, augmenting dietary interventions with nature-based activities may lead to greater improvements in dietary quality.
These new findings add to the potential for leveraging nature-based experiences or interventions in other ways, too—such as incorporating green spaces into city planning and promoting nature-based experiences in classroom settings.
However, improving dietary intake through exposure to nature will be a complex challenge. Every community is a unique intersection of culture, environment, history (including a feeling of connection to the land), race, social cohesion and other social and economic factors. Future research will need to explore the ways in which different communities experience and value nature.
Leaves and longevity
One of the ways that a city can promote more experience with nature is by having urban green spaces readily available. Doing so may also substantially reduce mortality due to all causes, according to a new study led by Boston University School of Public Health researchers and published in the journal Frontiers in Public Health.
While we’ve known for a while that living in greener areas can have a positive impact on our mental and physical health, there had been a lack of data on how changes in greenness distribution can affect death rates across the country. The Boston University study quantifies the impact of greenness expansion in urban areas and shows how increasing green vegetation could potentially add to a person’s life expectancy.
For the study, researchers used publicly available population data from the U.S. Census Bureau, mortality data from the Centers for Disease Control and Prevention and greenness data from NASA’s Landsat satellites to estimate the impact of increased green vegetation on all-cause mortality among adults 65 and older in 35, large U.S. metropolitan areas. The study period focused on three years across a 20-year span: 2000, 2010 and 2019. Using the Normalized Difference Vegetation Index (NDVI), a widely used metric that estimates the quantity of green vegetation, the researchers calculated that the deaths of 34,080 to 38,187 elderly people—or about 15 to 20 deaths per 10,000 seniors—could have been prevented between 2000 and 2019 with a 0.1 increase in NDVI across all 35 metropolitan areas.
Fortunately, overall greenness in metro areas has increased in the past 20 years, by 2.86 percent between 2000 and 2010, and 11.11 percent from 2010 to 2019, with the largest regional increase observed in the South (from .40 percent in 2000 to .47 percent in 2019).
Greening may not be feasible in all cities, however, due to differences in climate, landscape, urbanization and water sources. For example, increasing greenness in an arid area in the Southwest is different from increasing greenness in a hydrated region in the Pacific Northwest. But if an area’s climate makes it difficult to plant lush trees, urban planners can use this greenness data as a starting point and consider other types of vegetation that may be more realistic for their local climate.
They can also use the study’s findings to examine local changes in greenness over time and develop an appropriate and effective climate action plan in their cities. The authors of the study say that urban planners frequently ask them where they should implement greening and if they can quantify the impact of greening initiatives because of the costs of tree and shrubbery planting. Being able to target which areas would have the highest reduction in mortality can justify such campaigns, not only as a mitigation measure, but to directly improve health.
Greens and gladness
Incorporating green spaces or urban greening into city planning turns out to have another bonus benefit: happiness.
Urban green spaces, including gardens, parks and riversides, not only provide aesthetic pleasure, but also positively affect our health by promoting physical activity and social interactions. Previously, most of the research attempting to verify the correlation between urban green spaces and citizen happiness was based on a few developed countries. Therefore, it was difficult to identify whether the positive effects of green spaces were global, or merely phenomena that depended on the economic state of a country. There had also been limitations in collecting data, as it’s difficult to visit each location in every country or carry out investigations on a large scale based just on aerial photographs.
But by using data obtained from high-resolution satellites to investigate 90 green spaces from 60 different countries around the world and cross-referencing them with data from the World Happiness Report and GDP (gross domestic product) by country reported by the United Nations in 2018, the relationships between green spaces, the economy and citizen happiness could be analyzed.
The results of such an analysis, published in the journal EPJ Data Science in 2021, showed that in all cities, the levels of happiness residents reported were positively correlated with the area of urban green spaces regardless of the country’s economic state. However, out of the 60 countries studied, the happiness index of the bottom 30 by GDP showed a stronger correlation with economic growth. In countries whose gross national income (GDP per capita) was higher than $38,000, the amount of green spaces acted as a more important factor affecting happiness than economic growth.
This research has several policy-level implications. First, public green spaces should be made accessible to urban dwellers to enhance social support. But if public safety in urban parks is not guaranteed, its positive role in social support and happiness may diminish. Second, urban planning for public green spaces is needed for both developed and developing countries. Since it’s challenging or nearly impossible to secure land for green spaces after an area is developed, planning for parks and green spaces should be considered in developing economies where new cities and suburban areas are rapidly expanding. Third, climate change can present substantial difficulties in sustaining urban green spaces. Extreme events, such as cold waves, droughts, floods and wildfires could endanger urban forests, while global warming could accelerate tree growth (and make trees die sooner) in cities due to the urban heat island effect. Thus, more attention must be paid to predicting climate changes and discovering their impacts on green space maintenance.
Surroundings and soundness
Nature relatedness has been associated with better cognitive, physical and psychological health and greater levels of environmental stewardship. The findings from the new Drexel University study extend this list of benefits to include healthier dietary intake, including greater variety and higher fruit and vegetable consumption. The recent Boston University study tells us that having access to green spaces can decrease our mortality rates.
As always, in the end, it seems, our happiness depends on the quality of our connection to nature and the greenness that surrounds us.
Here’s to finding your true places and natural habitats,