Prescribed nature activities cut loneliness 17% in a year-long trial of 320 lonely adults

Loneliness scores among 320 lonely adults in Barcelona fell 17% over one year after they were prescribed nature-based social activities, according to a randomized trial published in The Lancet Regional Health. The reductions were 11% at three months, 12% at six months and 17% at one year. The trial, known as RECETAS-BCN, was observer-blinded and drew participants from 12 low-income neighborhoods.

The result needs careful reading, because both groups in the trial received a nature-based prescription. The 17% figure is the fall across the whole study population, not a gain of group outings over doing nothing, and the researchers themselves did not find a significant difference between the groups at three months.

Two ways to be prescribed nature

A University of Colorado Boulder release distributed through EurekAlert describes the design. Half of the participants joined groups of eight to ten people that met for two hours a week for nine weeks, led by two trained facilitators, doing activities such as gardening, birdwatching and nature-based art. The other half received the same menu of free nature activities to pursue on their own. The release describes the sample as lonely older adults; the Barcelona Institute for Global Health, whose researchers worked on the trial, ISGlobal, describes adults aged 18 and over with a median age of about 63, and says 80% were women.

ISGlobal gives more detail on the comparison arm. Its participants received a 30-minute motivational interview and information about nature-based activities in their neighborhood, which they could pursue independently. The group intervention, called Friends in Nature, combined group dynamics and peer support with outdoor activities in the local area.

Two prescription arms with similar results

Loneliness fell by an average of 10.5% after three months and 16.8% after one year across the whole study population, according to ISGlobal, and at three months there was no significant difference in loneliness between the two groups. No significant changes in health-related quality of life were found. Because there was no arm that received nothing, the trial cannot say how much of the decline came from the nature activities and how much from the passage of time, the attention of the research team or the motivational interview that both arms received.

Where the groups did diverge was among the loneliest. Participants who started with higher loneliness and poorer emotional wellbeing benefited more from the facilitated groups, while among people with less loneliness the lighter-touch approach produced comparable reductions. The release adds that the group format worked better for participants who began with lower emotional wellbeing. That subgroup pattern is the main evidence for matching the intensity of a prescription to the person.

ISGlobal researchers on social prescribing

Jill Litt, a professor of environmental health at the University of Colorado Boulder, principal investigator of the RECETAS project, corresponding author and researcher at the Barcelona Institute for Global Health, said that “There has been a lot of passion about nature-based prescriptions, but not a lot of evidence.” She said randomized controlled trials now show that the approach works and that the impacts last. Litt defines loneliness as a “subjective disconnect between one’s expectations of their social relationships and one’s reality.”

Louise Chawla, an environmental psychologist and professor emerita at Colorado Boulder who co-wrote a separate paper with Litt on nature and social connection, said time outdoors builds a reservoir of calm that people can draw on later in life during stressful periods. Laura Coll-Planas of the University of Vic, first author of the trial paper per ISGlobal, said the group program “combines strategies by building groups with peer support.” Litt said that a mechanism is now needed to connect these resources with health systems, and ISGlobal quotes her as saying the findings provide novel insights that will advance nature-based social prescribing as a strategy. Her call for a bridge implies that a routine referral pathway is not yet in place, though the sources do not say how far any health system has gone.

RECETAS and the wider evidence

RECETAS stands for Re-imagining Environments for Connection and Engagement: Testing Actions for Social Prescribing in Natural Spaces. The project brings together 13 institutions from nine countries and tests the idea in Barcelona, Marseille, Prague, Helsinki, Cuenca in Ecuador and Melbourne, through three randomized controlled trials and three observational studies. It began in March 2021 with a grant from the European Union’s Horizon 2020 programme. The release says only the Barcelona trial is reported in detail, while the Prague and Helsinki trials and the Marseille, Cuenca and Melbourne studies are mentioned without results.

The trial’s registration is on ClinicalTrials.gov, and the paper is in The Lancet Regional Health, published Aug. 18, 2026 and included in the October issue. The release gives percentages rather than absolute scores or effect sizes, and it does not discuss limitations, so the size of the change on the loneliness scale remains unclear from the sources available here. The participants, who lived in low-income urban neighborhoods and were mostly women, also limit how far the findings travel.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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