Kids living near green spaces have higher BMD

Early exposure to green spaces may positively influence children’s bone health during crucial periods of growth and development, according to a new study.

There are data showing that looking at nature and greenery alone through a window can lower blood pressure and anxiety levels. In children, the benefits of early exposure to green spaces extend to neurocognitive, social, behavioural, and mental development. [Rev Environ Health 2020; 35:189-200;  Front Psychol 2020; 11:859; Health Place 2016; 40:44-50] It is also linked to lower BMI, increased physical activity, and reduced risks of obesity and hypertension. However, there is a dearth of data focusing on “greenness” and bone mineral density (BMD) benefits.

In the current study, researchers followed 327 children (from birth to 4–6 years) and examined correlations between bone health and their exposure to green spaces. Data were collected from October 2014 to July 2021 and analysed between January and February 2022. [JAMA Netw Open 2024;7:e2350214]

Green spaces were categorized as high (vegetation height >3 m), low (vegetation height ≤3 m), and mixed (combination of both). The distances of green spaces from participants’ residences ranged from a radius of 100 m to 3 km. Radial BMD were assessed using quantitative ultrasound during follow-up consultations.

The closer the green spaces to homes the better

After adjusting for covariates including age, weight, height, ethnicity, and maternal education level, children frequently exposed to high and mixed vegetation areas within a 500-m radius of their homes had significantly higher BMD than those at other distances, or those frequenting spaces with different vegetation.

BMD is commonly used as a proxy measure of overall bone strength. Decreased BMD is a major risk factor for osteoporotic fractures.

Interestingly, an interquartile range (IQR) of increment in total green (21.2 percent) and high green (19.9 percent) space within 500 m was associated with an increase of 27.38 m/s (95 percent confidence interval [CI], 9.63–45.13 m/s) and 25.30 m/s (95 percent CI, 7.93-42.68 m/s) in BMD, respectively.

Additionally, access to larger green spaces with mixed and high vegetation within 1-km radius was significantly associated with a reduced likelihood of having low bone density in children. An IQR increase in total (25.2 percent) and high (23.2 percent) green space within 1,000 m was associated with a 67 percent (odds ratio [OR], 0.33, 95 percent CI, 0.17-0.61 (OR, 0.39, 95 percent CI, 0.18–0.75) lower risk of having a bone density lower than the sex-specific 10^th percentile (3,567.6 m/s for girls and 3,522.8 m/s for boys).

Public health implications

“What we know is that this is the first study to assess the association between residential green space exposure and bone health in children,” said the researchers. “The findings highlight the positive impact on bone health of early childhood exposure to green areas near their homes during growth and development periods, with long-term implications.”

The results are crucial for public health because they emphasize the need for urban investments in accessible green spaces as a strategy for fracture and osteoporosis prevention, they added. Such initiatives could translate to reduced public health expenses, with physical and emotional gains in communities adopting environmental strategies, in the long term.