Residential Greenness Alters Serum 25(OH)D Concentrations: A Longitudinal Cohort of Chinese Older Adults.
Anna Zhu, Yi Zeng, John S Ji
PMID 32605814WHAT IT FOUND
Living in greener areas was associated with higher vitamin D status in older Chinese adults.
Residents were more likely to not be deficient and to improve over time, especially men and those without disability in daily tasks.
Key findings
01Each 0.1-unit increase in annual average residential greenness was associated with 13% higher odds of vitamin D nondeficiency.
02Living in greener areas was associated with improved vitamin D status rather than stable or deteriorated vitamin D status (OR: 1.94).
03The association was stronger among men than women and stronger among participants free of baseline ADL disability than those with ADL disability.
STILL TO COME
How it was doneWhat they foundWhat it means for RNs
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What it does not show
This was an observational cohort, not a randomised trial, so it cannot show that greenness caused higher vitamin D. The study did not measure vitamin D supplement intake, oily fish consumption, or time spent outdoors. Blood samples were collected in different seasons, and season was adjusted for but may still influence vitamin D. Participants lost to follow-up were older and had lower serum 25(OH)D, which may bias results. The sample was very old, mostly rural, and from Chinese longevity areas, so it may not apply to younger or other populations. Definitions of education, financial support, and physical activity were broad, so residual confounding remains.
The easy way to misread this
Do not conclude that increasing residential greenness raises vitamin D or improves health. This was an observational cohort, not an intervention study. It did not measure time spent outdoors, sun exposure, vitamin D supplements, or oily fish intake.