Greenery slows ageing, especially for women
Researchers at Monash University’s School of Public Health and Preventive Medicine say being surrounded by greenery could be good for our bodies, at least for women. In a world first, they’ve shown a link between how much plant life in your immediate environment and how you age biologically.
“We searched the medical literature prior to embarking on this project,” says PhD candidate and first author Rongbin Xu, “and could only find a single abstract, presented at a conference but never written up and published in a peer-reviewed journal, that touched on this subject. It focused on infants, and compared their biological gestational age with the greenness surrounding the mother during pregnancy, so it was quite a different application to our current study.”
One of the key markers of biological ageing is the change in methylation found in our DNA. This is where some sections of DNA become covered by methyl molecules, which restrict the functioning of affected genes. DNAmAge is a measure of our biological age as measured by methylation. By comparing our DNAmAge to our chronological age in years, researchers can calculate the acceleration of biological ageing (DNAmAgeAC). While some methylation changes are inevitable, we do have some influence over it. For instance, research shows changing diet and environmental factors may reverse adverse methylation changes.
“A high degree of local vegetation density — gardens, parkland, bush — can reduce mental stress, provide a space for social interaction, encourage physical activity and reduce harm from air pollution and heat,” says Rongbin. “Given these are all determinants of good health, it made sense that there may be a connection.”
The study began with female twins aged 40–70 years in Perth, Sydney and Melbourne, but was later expanded to include their non-twin sisters. Blood samples were collected, methylation levels analysed, and four DNAmAges were calculated for each of 479 women from 130 different families.
The team used infrared and visible light readings from a NASA satellite to estimate local vegetation mass in the 12 months leading up to each participant’s blood draw. Plant life absorbs visible red light for photosynthesis, but strongly reflects infrared and near-infrared light. They then used this to estimate greenness density up to two kilometres from their homes.
The study also found that greenness seems to help reverse DNA methylation changes arising from exposure to cigarette smoke; as well as boosting immune function and metabolic health; reducing fatty tissues seen in obesity; and improving kidney health.
“More research is needed to confirm our results in larger studies,” says Rongbin, “and to look at the process in men, but it’s an exciting foray into this field.”
PHOTO Brooke Cagle