Prescriptions encouraging people to spend more time in nature are linked to reduced blood pressure and improvements in anxiety and depression symptoms, according to new analysis. Doctors sometimes use nature-based social prescription programs – sometimes described as “green prescriptions” or “blue prescriptions” – to advise patients to spend time in green spaces or near bodies of water. Australian academics reviewed existing research into the impacts and effectiveness of nature prescribing in different countries, looking at 92 studies in which participants spent time engaging with nature in various capacities. The most frequently recommended activities were walking in nature (46% of all programs), farming or gardening (29%) and mindfulness exercises (29%). Common settings were forests and nature reserves (35% of prescriptions), parks (28%) and community or home gardens (16%). A meta-analysis of data in 28 of the studies that measured similar outcomes found that nature prescriptions were associated with better blood pressure control, improvements in anxiety and depression symptoms, and an increase in average daily step counts among participants. Prof Thomas Astell-Burt, a population health expert at the University of Wollongong who co-led the research, said the improvements were interlinked. “You go out for a walk out in a green space which helps with fitness – that also helps to improve your mental health, reduces loneliness, improves sleep, and can also help to reduce one’s blood pressure. These outcomes aren’t independent of each other. “It’s good for mental health, good for physical health [and] good for keeping active.” One-fifth of all the programs reviewed were administered in South Korea, followed by the US (17%) and Japan (11%). The researchers found the analysed research had a “moderate to high risk of bias” due to challenges in designing blinded studies in the area. “It’s very difficult to hide from a person whether they’re in the intervention or the control group if the intervention is ‘spend more time outdoors in a park’ and the control is ‘don’t’,” Astell-Burt said. Co-lead researcher Prof Xiaoqi Feng of the University of New South Wales School of Population Health said more randomised controlled trials were required to “reveal how effective and cost-effective nature prescriptions can be over a sustained period of time, and also what kinds of nature prescriptions work for whom”. Astell-Burt and Feng last month secured $1.5m in funding through the Medical Research Future Fund for a trial testing the effectiveness of nature prescriptions in Australians over 45 years old. Feng said the research team was designing the trial in combination with consumers, healthcare providers and nature professional so that “when we have the … results, we are well-positioned to roll [programs] out nationwide”. In Australia, nature prescriptions are not commonplace. However, research in nearly 47,000 Australians has previously found that in urban areas, 30% green space or tree canopy cover was beneficial to health, lowering the odds of experiencing diabetes and psychological distress. The study was published in the Lancet Planetary Health.