IIDA MÄKELÄ
Uute Scientific Oy, Helsinki, Finland

Abstract

Our understanding of the natural microbiome and its importance to our immune system has increased during the last few decades as the urbanization-rate has grown and people are spending less time in physical contact with biodiversity-rich nature. The prevalence of many immune-mediated diseases, such as many allergies and asthma, within urban population has increased significantly compared to people living in rural areas with close contact with nature. Further understanding how these two seemingly different topics of natural biodiversity and immune-mediated diseases are related, can provide us tools to intervene the increased prevalence of immune mediated diseases within urban population.

ENVIRONMENTAL MICROBIOME, URBANIZATION AND HUMAN HEALTH
People living in their natural habitats are constantly exposed to wide diversity of microbes throughout their lives. We are colonized by microbes, and they affect every part of our body - whether we wanted it or not. This has led to mutualism of humans and natural microbiota on and in our bodies, where the healthy functioning of our physiological processes, such as functions of our immune system, is interconnected with environmental and internal microbial diversity (1,2). This natural level of microbial diversity in our surroundings and continuous exposure to them has existed throughout our history as a species, thus our immune system recognizes this level of stimuli as normal (3).

Over the past decades, people have moved into the cities in ever-growing numbers, as the need for self-sufficiency of food and other commodities is not necessarily due to industrialization. Over 50% of global population is currently living inside city borders and increasingly in highly urbanized megacities (4). Although COVID-19 pandemic has created some movement back to less densely populated and ru ...