Health Benefits of Plants and Green Space: Establishing the Evidence Base

Among the many benefits provided by plants, “health” stands out as a benefit that is especially highly valued. Over the past decades, people-plant studies have increasingly focused on empirically demonstrating relationships between plants and health. However, there are as yet no consensual standards in the field as to which research findings qualify as evidence for health benefits of plants. In this paper, we first argue that only studies that directly relate exposure to plants and green spaces to health outcomes should be admitted into the evidence base. We then discuss several studies that meet this requirement. An important conclusion is that the experimental evidence base for health benefits of plants seems to be less strong than the evidence provided by observational population studies linking green spaces to public health. Consequently, observational studies deserve more attention from horticultural professionals and other audiences who share an interest in health benefits of plants. However, as living in green areas is often accompanied by certain conditions and lifestyles that promote health, there is still an urgent need for more rigorous studies that allow for a causal interpretation of health effects of plants and green spaces. INTRODUCTION Plants provide a myriad of benefits to people, from the provision of food, fibers and building materials to more intangible benefits such aesthetic pleasure and improvement of health (Lohr, 2011). These benefits may occur not only with individual plants, but also with natural environments or “green spaces” such as gardens, parks, forests and other natural settings. Among the benefits provided by plants, “health” stands out as a benefit that is especially highly valued in modern society. Health is generally considered the most valuable asset in life (Schwartz, 1992). Unfortunately, in many parts of the world, this asset is threatened by developments related to aging populations and unhealthy lifestyles. To relieve the healthcare burden that derives from these developments, governments and other health authorities are actively seeking new ways to prevent disease and promote health. Plants have long since been associated with healing powers, and there is a long tradition of the use of plants for medical purposes. Plants therefore provide a potentially powerful means to relieve the healthcare burden of an aging and increasingly unfit population in nations worldwide.