How residential green spaces impact bone health and osteoporosis risk

By Dr. Chinta SidharthanReviewed by Benedette Cuffari, M.Sc.Mar 6 2024

In a recent study published in the Annals of the Rheumatic Diseases, scientists investigate whether green spaces in residential areas were associated with a lower risk of incident osteoporosis and changes in bone mineral density.

Study: Associations of residential greenness with bone mineral density and osteoporosis: the modifying effect of genetic susceptibility. Image Credit: Roschetzky Photography / Shutterstock.com

The prevalence and health effects of osteoporosis

Osteoporosis is a highly prevalent metabolic disorder in which the bone microarchitecture deteriorates and bone density decreases. Since the incidence of osteoporosis is often higher with progressing age, it is rapidly becoming a global problem due to rising life expectancy rates throughout the world. Changes in lifestyles due to modernization and the spread of urban spaces also contribute to the increasing risk of osteoporosis.

Health problems associated with reduced bone density include chronic pain, increased probability of fractures, decreased mobility, and an overall reduction in quality of life, which impose significant economic and social burdens on patients and their families. Previous studies have found that environmental factors can play an important role in the development of osteoporosis, with high air pollution levels strongly associated with a higher risk of developing osteoporosis.

Green spaces in urban landscapes have been shown to reduce the risk of serious health concerns such as cardiovascular disease and improve mental health by lowering air pollution levels, providing open spaces for exercise, and reducing psychological stress.

About the study

The present study analyzed whether long-term exposure to green spaces was associated with a reduced risk of osteoporosis and improved bone mineral density. The scientists also examined whether genetic susceptibility and exposure to green spaces affected the risk of incident osteoporosis.

A prospective study using data from the United Kingdom Biobank was conducted, which included information on physical examination findings, demographic characteristics, lifestyle factors, and socioeconomic status of the participants. Green spaces in residential areas were characterized using the normalized difference vegetation index, which is based on the spectral reflectance difference between visible and near-infrared reads in a specified region.

An ultrasound device was used to estimate the mineral density of the bone. Additionally, T-scores were calculated based on the body mass index (BMI) of the participant and BMI of a healthy adult of matching age and gender. A T-score value of less than -2.5 was set as the cut-off to define prevalent osteoporosis.

Follow-up information such as medical records, registry data for primary care or death, and self-reports were used to confirm incident osteoporosis. Polygenic risk scores for osteoporosis from the U.K. Biobank, which were calculated using data from genome-wide association studies that were conducted to examine genetic predisposition to osteoporosis, were also included in the analysis.

The postal codes of the participants’ areas of residence were used to determine whether they resided in rural or urban areas. Other covariates such as sex, age, education levels, annual income, ethnicity, and lifestyle factors such as smoking behavior, consumption of alcohol, and intake of healthy foods were also included as potential confounding factors in the analysis.

Study findings

Exposure to green spaces in residential areas was independently associated with a lower risk of developing osteoporosis and higher mineral density in the bones. The incidence of osteoporosis was also consistently lower in areas with a higher percentage of green spaces, natural environments, and domestic gardens.

Air pollution, specifically involving nitrogen dioxide (NO₂) and particulate matter smaller than 2.5 microns (PM_2.5), had a significant role in mediating the association between exposure to green spaces and the risk of osteoporosis. Psychological stress and physical activity levels also influenced the impact of green spaces on osteoporosis risk.

Genetic susceptibility and exposure to green residential spaces together exhibited a dose-response association with the risk of osteoporosis. Exposure to green residential spaces had a stronger impact in reducing the risk of osteoporosis among individuals with low genetic susceptibility as compared to those who were genetically more susceptible to the disease.

Conclusions

The study findings reinforce the positive impact of urban green spaces on human health and elucidate possible mechanisms through which air pollution and exercise impact the risk of osteoporosis.

More green spaces in urban residential areas were found to lower the risk of osteoporosis by decreasing air pollution, providing residents with green, open spaces to exercise, and lowering psychological stress. The impact of green spaces on osteoporosis risk was also associated with genetic susceptibility to the disease, with individuals who were genetically less susceptible and had more exposure to green spaces having the lowest risk of osteoporosis.