A Breath of Fresh Air: Perspectives on Inhaled Nutrients and Bacteria to Improve Human Health.

We propose that the human respiratory system and olfactory pathways sequester airborne nutrients (vitamins, fatty acids, and trace minerals) that are beneficial for health, which we term "aeronutrients." In addition, airborne bacteria, termed "aeromicrobes," have the potential for positive health effects by improving species diversity in the microbiotas of the respiratory and gastrointestinal tracts. These concepts have implications for people living in urban areas or those who have limited access to nature, such as astronauts exposed for long periods to highly filtered air that may be depleted of aeronutrients and aeromicrobes. The possibility that fresh air contributes to human nutrition and health may stimulate a re-evaluation of guidelines pertaining to nutrition and access to natural environments, and will open new avenues of scientific enquiry.