Green Space and Heart Health: What’s the connection?

March 7, 2022|Elizabeth Moxley

Prescribing Green Space to Promote Heart Health

While cardiovascular professionals across the globe are well-versed in applying guidelines-based care to help their patients prevent, or manage, cardiovascular disease, one important therapy may come not from a prescription bottle, but from just outside the front (or back) door. According to recent research, the key to improved cardiovascular health may be as simple as spending more time in nature. In fact, the health benefits from green space exposure are significant enough for practitioners and policymakers to recommend spending more time in nature.1-8 It is becoming more common for health care providers in the U.S., Canada, and beyond to ‘prescribe’ time in the out of doors; licensed health care providers in four provinces of Canada, for example, can now prescribe a free pass to Canada’s national parks.9

Halifax, Nova Scotia / Canada – People enjoying greenspace in the Halifax Commons Public Park

Grounded in Science

There is a growing appreciation that social determinants of health – those areas where individuals are born, live, work, play, and age – collectively have a considerable impact on health outcomes, starting in childhood. 3, 4, 5 Healthy People 2030 has specified the goal: “Create neighborhoods and environments that promote health and safety,” to acknowledge the inextricable link between the environment and health. While creating safe outdoor spaces often requires collaborative efforts among members of the community along with city/regional representatives, the end result can significantly impact the health and well-being of individuals in the area.

Natural environments are often referred to as green spaces – areas with vegetation associated with natural elements. 10 In addition to the physical elements of natural spaces, there is also a benefit from greenspace interventions (GSI), which are nature-based activities providing positive therapeutic associations with health. GSIs include a range of activities from those that individuals can do on their own to those facilitated by professionals. Examples include, but are not limited to:

  • Horticulture therapy, using plants and gardening in a professional practice to improve mental and physical health
  • Gardening (such as in the backyard or community garden)
  • Forest bathing (also known as Shinrin-yoku), is an experience in the forest atmosphere and a type of preventive medicine.6

Determining the amount of access that individuals have to green spaces includes mapping and other quantitative data. Measuring greenspace exposure includes a normalized difference vegetation index (an indicator for greenspace that estimates the density of vegetation using the difference in reflected light intensities in the red and near-infrared range divided by the sum of these intensities,11 tree canopy cover (the leaves, branches, and stems that provide the tree coverage of the ground when viewed from above), or distance to nature (which quantifies the anthropogenic influence on a landscape by considering the degree of habitat change caused by anthropogenic land use and the spatial distance to the nearest natural habitat). 12

For individuals living in urban environments (the majority of the world’s population and a sector that continues to grow 13), urban vegetation provides important ecosystem services to residents. Along with stormwater management and support for biodiversity, green views (as we’ll explore more in the next section) can reduce stress, improve psychological well-being, and aid in lowering CVD risk. Despite the clear positive influence of green space, the distribution of urban vegetation is not equitable in all cities and may contribute to health inequalities for those unable to access these spaces.14

Greenspace Mitigates the Etiology of Cardiovascular Disease

It is well established that cardiovascular disease results from the complex interplay between genetic predisposition and environmental influences. Environment and lifestyle are considered the primary influence; thus, all personal, social, and natural domains affect cardiovascular disease risk.1 Yeager et al. 2 recently found cardiovascular disease risk was associated with residential greenness, specifically lower levels of sympathetic activation, reduced oxidative stress, and higher angiogenic capacity, and these findings were independent of age, sex, race, smoking status, neighborhood deprivation, and roadway exposure.

Maintaining normal blood pressure begins in childhood4 and is enhanced from exposure to natural environments; several key features of the natural environment have been linked to cardiovascular disease risk.1-2 Elevated blood pressure during childhood contributes to hypertension and cardiovascular disease in adulthood,4 but even the presence of greenness or vegetation is thought to promote health, especially in older individuals residing in poor neighborhoods.15

Beneficial associations were found between greenspace and all-cause and stroke-specific mortality, cardiovascular disease morbidity, cardiometabolic factors, low birth weight, physical activity, sleep quality, and urban crime in Yang et al.’s16 recent umbrella review examining the effect of exposure to greenness. Furthermore, green space exposure has been associated with other cardiovascular benefits, including a decrease in heart rate, systolic and diastolic blood pressure, low-frequency heart rate variability (HRV), type 2 diabetes, stroke incidence, dyslipidemia, and all-cause mortality, and improved HDL cholesterol levels.8

The cardiovascular benefits from exposure to greenspace may be related to increased time spent outdoors and proximity to areas conducive to physical activity which likely decrease stress levels.1, 15 Lowering stress improves quality of life and prognosis in those with cardiovascular disease.17 Greenspace interventions (GSI) reduce the physiologic burden of stress across the lifespan by reducing cortisol production. In a recent scoping review involving an analysis of the findings from twenty trials and 732 participants who engaged in forest bathing, blood pressure significantly decreased compared to those who experienced a non-forest environment.18

Strategies to Promote Exposure to Greenspace

Cardiovascular nurses should recommend and prescribe greenspace exposure for patients whenever possible. To identify key areas for activity and exposure to greenspace, Geographical Information System (GIS) data preparations and calculations are beneficial, although it may be necessary to consult with a forest guide or naturalist, especially in more challenging locations or urban areas. Depending on the neighborhood, greenspace. access may be limited.

To escape to nature, nurses should emphasize the following strategies for their patients at risk for, or with, cardiovascular disease:

  • Taking a walk in the woods or on a nearby path in the neighborhood
  • Planting native flowers to attract butterflies or bees by grouping according to color
  • Starting a small garden and spending time in it
  • Leaving technology behind
  • Touching nature: tree bark, water, or leaves and breathing in the scent of flowers and air
  • Noticing the beauty of nature as it is experienced
  • Consulting with a forest guide or naturalist to identify ideal settings in unfamiliar areas

Nurses can also advocate for environmental justice where everyone has the opportunity to experience the health benefits of green space. Whether from exposure to an urban park or a national forest, nature has a nurturing effect for individuals of all ages and persistent exposure to greenness improves heart health.

References

  1. Bhatnagar A. Environmental determinants of cardiovascular disease. Circ Res. 2017;121(2):162-180. doi:10.1161/CIRCRESAHA.117.306458
  2. Yeager R, Riggs DW, DeJarnett N, et al. Association Between Residential Greenness and Cardiovascular Disease Risk. J Am Heart Assoc. 2018;7(24):e009117. doi:10.1161/JAHA.118.009117
  3. Dzhambov AM et al. Natural and built environments and blood pressure of Alpine schoolchildren. Environmental Research. 2022;204(Pt A):111925. doi:10.1016/j.envres.2021.111925
  4. Yang BY, Zhao T, Hu LX, et al. Greenspace and human health: An umbrella review. Innovation (N Y). 2021;2(4):100164. doi:10.1016/j.xinn.2021.100164
  5. Warembourg, C., Nieuwenhuijsen, M., Ballester, F., et al.. Urban environment during early-life and blood pressure in young children. Environ. Int. 2021;146:106174. doi.org/10.1016/j.envint.2020.106174.
  6. Jones, Reo et al. Greenspace interventions, stress and cortisol: a scoping review. Int J Environ Res Public Health. 2021;18(6):2802. doi:10.3390/ijerph18062802
  7. Kondo MC, Fluehr JM, McKeon T, Branas CC. Urban green space and its impact on human health. Int J Environ Res Public Health. 2018;15(3):445. doi:10.3390/ijerph15030445
  8. Twohig-Bennett C and Jones A. The health benefits of the great outdoors: A systematic review and meta-analysis of greenspace exposure and health outcomes.. Environmental research 2018;166:628-637. doi:10.1016/j.envres.2018.06.030
  9. Root T. Doctors in Canada can now prescribe national parks passes to patients. The Washington Post. February 7, 2022. Accessed February 28, 2022.
  10. Taylor L., Hochuli DF. Defining greenspace: multiple uses across multiple disciplines. Landscape and Urban Planning. 2017;158:25-38. doi.org/10.1016/j.landurbplan.2016.09.024.
  11. Rhew IC, Vander Stoep KA, Smith N., Dunbar MD. Validation of the normalized difference vegetation index as a measure of neighborhood greenness. Ann. Epidemiol. 2011;21:946–952. doi.org/10.1016/j.annepidem.2011.09.001.
  12. Rüdisser J, Tasser E, Tappeiner U. Distance to nature—a new biodiversity relevant environmental indicator set at the landscape level. Ecol. Indicat. 2012;15:208–216.
  13. Ritchie H, Roser M. Urbanization. OurWorldInData.org. 2018. Accessed 02 March 2022.
  14. Nesbitt L, Meitner, MJ, Girling C, Sheppard SRJ, Lu Y. Who has access to urban vegetation? A spatial analysis of distributional green equity in 10 US cities. Landscape and Urban Planning. 2019; 181: 51-79, doi.org/10.1016/j.landurbplan.2018.08.007.
  15. Brown SC, Lombard J, Wang K, et al. Neighborhood Greenness and Chronic Health Conditions in Medicare Beneficiaries. Am J Prev Med. 2016;51(1):78-89. doi:10.1016/j.amepre.2016.02.008
  16. Yang L, Magnussen CG, Yang L, Bovet P, Xi B.. Elevated blood pressure in childhood or adolescence and cardiovascular outcomes in adulthood: a systematic review. Hypertension 2020;75(4):948–955. doi.org/10.1161/ HYPERTENSIONAHA.119.14168.
  17. Arnold SV, Smolderen KG, Buchanan DM, Li Y, Spertus JA. Perceived stress in myocardial
    infarction: long-term mortality and health status outcomes    . Journal of the American College of
    Cardiology. 2012;60:1756–63.
  18. Ideno Y, Hayashi K, Abe Y, et al. Blood pressure-lowering effect of Shinrin-yoku (forest bathing): a systematic review and meta-analysis. BMC Complement Altern Med. 2017;17(1):409. doi:10.1186/s12906-017-1912-z

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