Why your immune system needs a forest
For millions of years, the immune system of our ancestors co-evolved with its environment. There are gazillions of viruses, bacteria and other micro organisms out and about to which living beings are being exposed to on a daily basis. Some are beneficial and some harmful, so life learned to collaborate with the benign ones ( there are more non-human cells in your body than human cells ) and to defend itself to the harmful ones ( the immune system of healthy living organisms is still the most sophisticated security system in the world ). Because of the process of co-evolution, life learned to immunize itself to infectious diseases and the immune system of the forest dwellers evolved in concert with the immune system of the forest. For instance, studies with students and elderly show that spending time in nature significantly reduces inflammation. Additionally, research from the Nippon Medical School in Japan shows that time spent in forests increases the number of natural killer cells, ...