Growing edible plants at home is associated with a significant increase in bacterial diversity on the skin after just one month. In addition, the level of anti-inflammatory molecules in the blood improves and the risk of immune-mediated diseases decreases.
A new study involving experts from the University of Helsinki examined the health effects of growing edible plants indoors. The results have been published in the journal Environment International.
Changes in the immune system
When we come into contact with natural microbial materials, it can alter our microbiota and lead to long-term changes in immune system function, the team explains.
However, urban life, among other things, leads to a reduction in microbial load, which brings about changes in the human microbiota and an increased risk of immune-mediated diseases.
The researchers now tested whether “indoor gardening” can also strengthen the immune system through contact with microbiological materials in people who used either a microbially diverse nutrient medium (intervention group) or a visually similar but microbially poor peat-based medium (control group) for indoor gardening during the winter months.
At the beginning of the study, the skin microbiota and seven additional immune markers were examined, which was repeated after one month, the team explains.
Increased bacterial diversity on the skin
It was found that the diversity of five bacterial strains (Bacteroidetes, Planctomycetes, Proteobacteria, Cyanobacteria and Verrucomicrobia) on the skin of participants in the intervention group increased significantly, as did a class of gram-negative bacteria (Bacteroidia). No such change occurred in the control group.
“One month of urban gardening indoors increased the bacterial diversity on the skin of the subjects and was associated with higher levels of anti-inflammatory cytokines in the blood,” reports study author Mika Saarenpää. The nutrient medium used was modeled on forest soil with its high microbial diversity.
“The results are significant because urbanization has led to a significant increase in immune-mediated diseases such as allergies, asthma and autoimmune diseases, which causes high healthcare costs. We live too 'clean' in the cities,” adds Saarenpää in a press release.
Ideally, microbially mediated immune regulation could reduce the risk of immune-mediated diseases or even their symptoms. Such health-promoting microbial exposure at the population level could reduce healthcare costs and improve the quality of life of people with immune-mediated diseases, the expert emphasizes.
It is still unclear how long the changes in the skin microbiota and anti-inflammatory cytokines last, but researchers assume that with regular gardening, the regulation of the immune system becomes more and more continuous.
Start in childhood
Since the development of the immune system is most active in childhood, it is important to ensure that children come into contact with nature and with beneficial microbes. For example, plant boxes with microbially diverse soil could be set up in kindergartens and schools, especially in densely built-up urban areas, explains Saarenpää.
However, care should be taken to ensure that the soil does not come into contact with skin injuries on the hands, and inhaling dusty potting soil should be avoided as much as possible in order to avoid any risks, say the experts.
Easy way to promote health
Overall, urban gardening offers a simple way to safely increase microbial loads all year round. The space required and the costs for urban gardening are very low; peas, beans, mustard and lettuce were grown in the study, for example, the team reports.
“Research underlines the dependence of our health on the diversity of nature and especially on that of the soil. We are one species among others and our health depends on the diversity of other species,” Saarenpää concludes. (as)