A meta-analysis of 140 studies from 20 countries found that exposure to greenspace reduces the risk of type II diabetes, cardiovascular disease, premature death, preterm birth, stress, and high blood pressure.
Living close to nature and spending time outside has significant and wide-ranging health benefits – according to research from the University of East Anglia.
Populations with higher levels of greenspace exposure are also more likely to report good overall health – according to global data involving more than 290m people. Lead author Caoimhe Twohig-Bennett, from UEA's Norwich Medical School, said: "Spending time in nature certainly makes us feel healthier, but until now the impact on our long-term wellbeing hasn't been fully understood.
"We gathered evidence from over 140 studies involving more than 290m people to see whether nature really does provide a health boost."
The research team studied data from 20 countries including the UK, the US, Spain, France, Germany, Australia and Japan – where Shinrin yoku or “forest bathing” is already a popular practice.
“Green space” was defined as open, undeveloped land with natural vegetation as well as urban greenspaces, which included urban parks and street greenery.
The team analysed how the health of people with little access to green spaces compared to that of people with the highest amounts of exposure. "We found that spending time in, or living close to, natural green spaces is associated with diverse and significant health benefits. It reduces the risk of type II diabetes, cardiovascular disease, premature death, and preterm birth, and increases sleep duration.
"People living closer to nature also had reduced diastolic blood pressure, heart rate and stress. In fact, one of the really interesting things we found is that exposure to greenspace significantly reduces people's levels of salivary cortisol – a physiological marker of stress.
"This is really important because in the UK, 11.7m working days are lost annually due to stress, depression or anxiety."
"Forest bathing is already really popular as a therapy in Japan – with participants spending time in the forest either sitting or lying down, or just walking around. Our study shows that perhaps they have the right idea!
"Although we have looked at a large body of research on the relationship between greenspace and health, we don't know exactly what it is that causes this relationship.
"People living near greenspace likely have more opportunities for physical activity and socialising. Meanwhile, exposure to a diverse variety of bacteria present in natural areas may also have benefits for the immune system and reduce inflammation.
"Much of the research from Japan suggests that phytoncides – organic compounds with antibacterial properties – released by trees could explain the health-boosting properties of forest bathing."
Study co-author Professor Andy Jones, also from UEA, said: "We often reach for medication when we're unwell but exposure to health-promoting environments is increasingly recognised as both preventing and helping treat disease. Our study shows that the size of these benefits can be enough to have a meaningful clinical impact."
The research team hope that their findings will prompt doctors and other healthcare professionals to recommend that patients spend more time in greenspace and natural areas.
Twohig-Bennett said: "We hope that this research will inspire people to get outside more and feel the health benefits for themselves. Hopefully our results will encourage policymakers and town planners to invest in the creation, regeneration, and maintenance of parks and greenspaces, particularly in urban residential areas and deprived communities that could benefit the most."
Background: The health benefits of greenspaces have demanded the attention of policymakers since the 1800s. Although much evidence suggests greenspace exposure is beneficial for health, there exists no systematic review and meta-analysis to synthesise and quantify the impact of greenspace on a wide range of health outcomes.
Objective: To quantify evidence of the impact of greenspace on a wide range of health outcomes.
Methods: We searched five online databases and reference lists up to January 2017. Studies satisfying a priori eligibility criteria were evaluated independently by two authors.
Results: We included 103 observational and 40 interventional studies investigating ~100 health outcomes. Meta-analysis results showed increased greenspace exposure was associated with decreased salivary cortisol −0.05 (95% CI −0.07, −0.04), heart rate−2.57 (95% CI −4.30, −0.83), diastolic blood pressure −1.97 (95% CI −3.45, −0.19), HDL cholesterol −0.03 (95% CI −0.05, <-0.01), low frequency heart rate variability (HRV) −0.06 (95% CI −0.08, −0.03) and increased high frequency HRV 91.87 (95% CI 50.92, 132.82), as well as decreased risk of preterm birth 0.87 (95% CI 0.80, 0.94), type II diabetes 0.72 (95% CI 0.61, 0.85), all-cause mortality 0.69 (95% CI 0.55, 0.87), small size for gestational age 0.81 (95% CI 0.76, 0.86), cardiovascular mortality 0.84 (95% CI 0.76, 0.93), and an increased incidence of good self-reported health 1.12 (95% CI 1.05, 1.19). Incidence of stroke, hypertension, dyslipidaemia, asthma, and coronary heart disease were reduced. For several non-pooled health outcomes, between 66.7% and 100% of studies showed health-denoting associations with increased greenspace exposure including neurological and cancer-related outcomes, and respiratory mortality.
Conclusions: Greenspace exposure is associated with numerous health benefits in intervention and observational studies. These results are indicative of a beneficial influence of greenspace on a wide range of health outcomes. However several meta-analyses results are limited by poor study quality and high levels of heterogeneity. Green prescriptions involving greenspace use may have substantial benefits. Our findings should encourage practitioners and policymakers to give due regard to how they can create, maintain, and improve existing accessible greenspaces in deprived areas. Furthermore, the development of strategies and interventions for the utilisation of such greenspaces by those who stand to benefit the most.
Caoimhe Twohig-Bennett, Andy Jones