Bone strength is an essential component of lifelong health. Peak bone mass achieved in early adulthood as a result of accumulation of bone mass during skeletal growth and development is indicative of long-term bone health.
Suboptimal accrual of bone mass at young age can pave the way for development of osteoporosis in older age. Besides genetics, early-life factors, including physiological and environmental elements, significantly influence bone mass build-up. Therefore, implementing specific strategies to promote accumulation of bone mass during early life has the potential to lower the risk of fractures and osteoporosis in the later stages of life. Recent compelling evidence shows positive effects of early-life exposure to green spaces and better bone health in 4 to 6-year-old children.
This study by Hanne Sleurs et al., published in the “JAMA Network Open”, demonstrated the potential association of high exposure to residential green spaces with high bone mineral density in children aged 4 to 6 years residing in an affluent society. Other studies have reported remarkable benefits of early-life green exposure on neurocognitive, social-behavioral, emotional, and mental development of children.
This ongoing prospective Belgian birth cohort (ENVIRONAGE) study involved 1,492 participants aged 4 to 6 years, with 541 mother-child pairs in the final analysis. Data on sociodemographic, lifestyle, and health factors including ethnicity, passive smoke exposure, screen time, vitamin supplementation, dairy product consumption, and maternal education were collected from a semi-structured questionnaire during the follow-up visit. Radial assessment for bone mineral density was carried out using quantitative ultrasonography. The residential addresses were geocoded, and green space percentages were calculated within various radii (100─3000 m) around the residence for high green (>3 m vegetation height), low green (≤3 m vegetation height), and total green (sum of high and low) spaces. The probability of a low bone mineral density was investigated using logistic regression.
The study results are summarized below:
- The study included children (55% girls, 45.0% boys) with a mean age of 4.6 years, mostly of European descent (95.1%) and not exposed to passive smoke at home (77.3%).
- The mean total green space ranged from 49.5% to 55.9%.
- Bone mineral density increased with the child’s age and height:
- 1-year increase: By 53.79 m/s; p <0.001
- 1-cm increase: By 3.01 m/s; p = 0.02)
- The most pronounced correlation was identified for green space within a 500-meter radius for total and high green spaces:
- Total green space – An interquartile range (IQR) increase of 21.2% in total green space was linked to a 27.38 m/s rise in bone mineral density (p = 0.003; Table).
- High green space – An IQR increase of 19.9% in high green space was linked to a 25.30 m/s rise in bone mineral density (p = 0.004; Table).
- A 25.2% IQR rise in total green space within a 1000-meter radius was linked to a 67% reduction in the risk (odds ratio 0.33; p <0.001) of having a bone mass below the sex-specific 10th percentile (3567.6 m/s for girls and 3522.8 m/s for boys).
Clinical implications
- The study underscores the significant impact of residential green space exposure on bone health in children during the critical developmental period from birth to age 4 to 6 years.
- The study suggests that promoting strategies focused on enhancing residential green spaces can potentially reduce the risk of fractures and osteoporosis in later life, leading to both individual and community-wide advantages, including financial, physical, and psychological well-being.
(Source: Sleurs H, Silva AI, Bijnens EM, Dockx Y, Peusens M, Rasking L, Plusquin M, Nawrot TS. Exposure to residential green space and bone mineral density in young children. JAMA Network Open. 2024 Jan 2;7(1):e2350214. Doi: 10.1001/jamanetworkopen.2023.50214)