Background: The effect of nature-based interventions on self-reported mental well-being in patients with physical disease is gaining increasing attention. However, there is a lack of randomized controlled trials investigating this area. Due to the massive costs in health care systems, there is a need for new strategies to address these issues and an urgent need for attention to this field. Nature-based interventions are low cost, easy to implement, and should get attention within the health care field. Therefore, the objective was to find the impact of nature interventions on mental well-being in humans with a physical disease.

Methods: In four major databases (PubMed, Cinahl, PsycINFO, and Cochrane Library), a systematic review of quantitative studies of nature’s impact on self-reported mental health in patients with physical disease was performed. A total of 1909 articles were retrieved but only five met the inclusion criteria and were summarized.

Results: All five studies were quantitative, with a control group and a nature-based intervention. A source of heterogeneity was identified: the patients in one of the five studies were psychosomatic. In the four studies with somatic patients, significant benefit of nature on self-reported mental health outcomes was found; the only study that failed to show a significant benefit was the one with psychosomatic patients.

Conclusion: A significant effect of nature on mental well-being of patients with somatic disease was found. The result in patients with psychosomatic disease is inconclusive, and more studies in this category are needed. Further research on the effect of nature on mental health is merited, with special attention to standardizing intervention type and dose as well as outcome measures within each medical discipline.