Rethinking health: Will air be a new source of essential nutrients and microbes?

Experts are challenging the long-held belief that our gastrointestinal system is the only route for nutrient absorption, proposing that the air we breathe might also provide essential nutrients and beneficial microbes.

Research in the Journal Advances in Nutrition coined the term “aeronutrients” to describe airborne nutrients inhaled through the respiratory system and olfactory pathways, with the same for “aeromicrobes.”

The authors believe that fresh air can contribute to human nutrition and health, potentially meriting a “re-evaluation of guidelines pertaining to nutrition and access to natural environments…opening new avenues of scientific enquiry.” 

They highlight evidence of bacterial cross-talk and transfer between the gastrointestinal tract and the lungs. “These microbiotas may share essential nutrients and contribute to overall health…airborne bacteria improve species diversity in the airways and gut.”

The authors note fresh air may also contain peptides and proteins, which have not traditionally been considered nutritional components but can be transported to the bloodstream via the lungs.

“We note that when inhaled, airborne bacteria can replenish the populations of commensal bacteria living in the airways. Some of these bacteria enter the gastrointestinal tract where they also replenish the gut microbiome and aid digestion,” reads the paper.

“Further research is needed to quantify their contributions to human health and improve public health policies.”

Researchers believe fresh air can contribute to human nutrition and health, which can stimulate a re-evaluation of guidelines.A postdoctoral fellow at the Center for Alimentary and Metabolic Science, University of California Davis, US, Jean Debédat, PharmD-PhD, discusses with Nutrition Insight how breathing in substances like vitamins, trace minerals, and even bacteria creates a new way to investigate how it might affect local and systemic health. 

Although there is currently little data, there may be opportunities for air to improve diets and promote health. He suggests the need for urban air quality improvements and green spaces could restore beneficial aeromicrobes that benefit public health, especially in marginalized communities.

How much evidence do we have that people absorb nutrients through the air? What kind of studies would be needed to prove this idea?
Debédat: Short answer — not that much. Some small evidence exists, particularly for iodine, manganese, and vitamin B12. The study by Smyth et al. (2011) is probably the most convincing study we have so far, showing that inhaled iodine contributes roughly 7% of daily needs. The field definitely needs studies measuring air nutrient levels, tracking absorption, and comparing populations with controlled diets at the top of my head. A lot more work is required.

The lungs are mainly for breathing. How do we know that inhaled nutrients or microbes can make a difference in our health?
Debédat: You are right; that is their “main” function. However, the lungs’ large surface area and vascularization enable very efficient absorption, way beyond gases. For instance, the airways are explored as a way to provide vitamin B12, vaccines, or even insulin. This area of research is expanding rapidly. 

Debédat imagines solutions targeting the airways, such as medical nebulizers for specific delivery of key nutrients or medicine.To date, we have no evidence that inhaled nutrients or microbes improve our health, but I think they will become part of our “exposome” and be linked to varying health/disease indices.

If air can provide nutrients, how much does it contribute compared to food? Could this change how we think about nutrition?
Debédat: Air’s contribution is, very likely, minimal. But very small doesn’t mean negligible. This could expand nutrition to include environmental factors, potentially integrating air quality into dietary guidelines. Still, we will need large-scale quantitative comparisons and deficiency studies to even consider that.

Air pollution is a big issue in cities. Do you think access to “healthy air” could become another inequality, like access to healthy food? What could be done about it?
Debédat: Urban air lacks beneficial aeromicrobes and nutrients (although it needs to be further demonstrated) compared to rural settings. Even more important than what might be missing and what is there, we know that urban air contains more pollutants and harmful chemicals. Unequal access to “good quality” outdoors is indeed a risk to health disparity. Solutions include urban greening, access to natural spaces, public education on air’s health role, and means to reduce pollutants.

If aeronutrients and aeromicrobes are real, could companies start selling air with added nutrients or microbes? What risks or ethical issues could that bring?
Debédat: It seems hard to imagine a way to start selling “air with added nutrients or microbes” because we do not even know if they are really that impactful. However, we could imagine solutions targeting the airways, such as medical nebulizers for specific delivery of key nutrients or medicine. Why not? But caution is needed; who will be able to access those? What is the benefit/risk balance? After all, we do not want to cause more harm than good. If a market niche is created, products will be released. We just need to make sure they are safe and useful.