Let's say, when you walk in a forest, you bathe in the forest's natural immunity. You're immersed in the forest's phytochemical immune system.
Professor Qing Li, of the Department of Hygiene and Public Health at Nippon Medical School in Tokyo, gave this story to American Scientist writer Anna Lena Phillips. There's more specific info in the article about effects on specific hormones as well, including noradrenaline and DHEA that affect stress response, and adiponectin, lower levels of which is associated with Type 2 Diabetes and obesity. The study appeared in the European Journal of Applied Physiology.
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