183 trials tested wellbeing. Four tested nature.
The best review in this field found 183 randomised trials of ways to improve wellbeing. Four tested nature. The trial that would settle this has not been run.
Top of the evidence hierarchy, independently funded. how we score evidence
Caveat on this rating: Read this as absence of evidence, not evidence of absence - the body says so and the authors insist on it: "Contrary to expectations, nature-based interventions did not significantly outperform controls. However, this finding should be interpreted cautiously... studies in this group were small, at moderate-to-high risk of bias and conceptually diverse... This conceptual heterogeneity probably diluted the pooled effect estimate and limits interpretability." The abstract adds that the evidence "was limited by conceptual and methodological heterogeneity". Across the 183 trials risk of bias was "frequently moderate to high" and funnel asymmetry suggested publication bias, though sensitivity analyses held. Separately: the field's most-cited experiment, Bratman et al. 2015 PNAS (38 people), did not hold exercise constant - its nature route climbed 155m and its urban route 4m over the same 5.3km - and its brain finding has never been replicated.
The best evidence review in this field found 183 randomised trials of ways to improve wellbeing. Four of them tested nature.
Significant findings
Published in 2026, planned in advance, covering 22,811 adults. Exercise showed a clear and reliable benefit. So did mindfulness and yoga.
Four. Out of 183.
With four small studies, the review could not detect a benefit. It also could not rule one out.
That is not a finding that nature does nothing. It means the study that would settle it has never been run.
The reviewers say the same. Those studies were "small, at moderate-to-high risk of bias and conceptually diverse."
Worth asking
Weak evidence is not evidence against. It is a gap.
When someone quotes research on nature and mental health, ask how many trials they are standing on.
Source
A systematic review and network meta-analysis of randomized controlled trials of well-being-focused interventions — Wilkie L, Fisher Z, Geidel A, Goodall I, Kamil S, Davies E, Kemp AH (2026)
Top-tier peer-reviewed journal
Read the source: https://doi.org/10.1038/s41562-025-02369-1
DOI: 10.1038/s41562-025-02369-1
How this was scored
- Study design
- Meta-analysis of randomised trials
- Funding
- No external funding
- Published in
- Top-tier peer-reviewed journal
- Sample size
- 22,811
- Preregistered
- Yes
- Conflicts disclosed
- Yes
- Independent of proponent
- not recorded
- Retracted
- No
Read the full scoring rubric, including what it can't tell you.
Published August 31, 2026.
Questions
How strong is the evidence behind this?
Resolv rates this source "gold standard". Top of the evidence hierarchy, independently funded. It scores 95 out of 100 on our published rubric. One caveat travels with that badge: Read this as absence of evidence, not evidence of absence - the body says so and the authors insist on it: "Contrary to expectations, nature-based interventions did not significantly outperform controls. However, this finding should be interpreted cautiously... studies in this group were small, at moderate-to-high risk of bias and conceptually diverse... This conceptual heterogeneity probably diluted the pooled effect estimate and limits interpretability." The abstract adds that the evidence "was limited by conceptual and methodological heterogeneity". Across the 183 trials risk of bias was "frequently moderate to high" and funnel asymmetry suggested publication bias, though sensitivity analyses held. Separately: the field's most-cited experiment, Bratman et al. 2015 PNAS (38 people), did not hold exercise constant - its nature route climbed 155m and its urban route 4m over the same 5.3km - and its brain finding has never been replicated. The score is calculated from recorded facts about the source — study design, funding, publication venue, sample size, preregistration — not typed in by an editor.
What is the source for this?
A systematic review and network meta-analysis of randomized controlled trials of well-being-focused interventions — Wilkie L, Fisher Z, Geidel A, Goodall I, Kamil S, Davies E, Kemp AH (2026). Published in: Top-tier peer-reviewed journal. DOI: 10.1038/s41562-025-02369-1. The full source is linked on this page so you can read it yourself.
Who paid for this research, and does that matter?
Study design: Meta-analysis of randomised trials. Funding: No external funding. Independence from the proponent is not recorded. Industry sponsorship is one of the most reliably measured biases in medicine, which is why funding carries real weight in the score rather than sitting in a footnote.
Is this medical advice?
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.