Researchers propose coastal and rural air may carry 'aeronutrients' that could supplement diets

Scientists are advancing the idea that air in coastal and rural areas can contain trace nutrients and microbes — dubbed “aeronutrients” — that may modestly supplement dietary intake and help relieve symptoms linked to deficiencies, such as fatigue, headaches and dry skin.

The proposal, set out by researchers including Dr. Flavia Fayet-Moore of the University of Newcastle in Australia in a paper published last year in the journal Advances in Nutrition, argues that aerosolised vitamins and beneficial airborne microbes could be absorbed through the mouth and nasal cavity and enter the bloodstream. Humans inhale roughly 10,000 litres of air each day, and the researchers argue that small amounts of vitamins and minerals in that air could make up shortfalls caused by diet or limited sun exposure.

The researchers point to several lines of evidence and mechanisms that could explain airborne nutrient transfer. Some vitamins, such as B12 and D, are already delivered via aerosol sprays that are absorbed rapidly through mucous membranes in the mouth and nasal passages. Airborne molecules may arise from sea spray, decaying vegetation, soil, cooking and other environmental sources. The team also highlights research suggesting that helpful airborne bacteria, sometimes called “aeromicrobes,” could broaden exposure to microbes that influence the gut microbiome and immune function.

One often-cited study, conducted by the National University of Ireland in Galway in 2011, compared iodine levels in schoolchildren living near beaches with abundant seaweed, near beaches without seaweed, and inland. The study found higher iodine levels among children near seaweed-bearing beaches and the Newcastle researchers say that breathing iodine released from seaweed could account for a substantial portion of intake. Dr. Fayet-Moore has said air may account for up to 40% of iodine intake in such settings.

Other recent research has examined airborne microbial diversity. A 2023 study by researchers at the University of North Carolina, published in Science of the Total Environment, found that air samples from vegetated areas carried a broader range of airborne bacteria than those from heavily urbanised locations. The UNC team suggested that exposure to a more diverse airborne microbiome in greener areas might support immune function and be associated with lower morbidity.

Proponents of the aeronutrient concept say the idea complements established public-health advice rather than replaces it. For example, the National Health Service in the U.K. estimates around one in five adults have inadequate vitamin D and recommends most people take a 10 microgram supplement, particularly in autumn and winter when sunlight is limited. Vegetarians and vegans are known to be at higher risk of vitamin B12 deficiency because the vitamin is found predominantly in animal products, and an iodine shortfall can produce symptoms such as fatigue, dry skin, weight gain and hair loss.

Not all nutrition scientists are persuaded. Tom Sanders, a professor of nutrition and dietetics at King’s College London, described the aeronutrient idea as “daft,” arguing that dietary intake and soil iodine levels are the primary determinants of nutrient status and that airborne contributions are likely negligible. Mike Lean, a professor at the University of Glasgow, said it is well established that some substances are absorbed through the nose and lungs, but added that the quantities of nutrients in the air are usually far too small to prevent deficiencies.

Critics also note alternative explanations for observational findings. The 2011 Irish study’s authors and others have warned that higher iodine levels in coastal children might reflect dietary sources — for example, meat from animals that grazed on seaweed — rather than inhalation of iodine gas.

Researchers advancing the aeronutrient hypothesis acknowledge uncertainty about how many nutrients circulate in the air, their concentrations in different environments, and how much they contribute to overall intake. They call for more controlled measurement studies to quantify airborne nutrient levels, identify sources, and test absorption pathways in people.

Public-health authorities continue to emphasise established prevention measures for nutrient deficiencies: balanced diets that include fortified foods or supplements where appropriate, and exposure to sunlight for vitamin D when safe. While the aeronutrient theory suggests an additional, environment-based factor that could have modest effects, the evidence to date does not replace current dietary guidance.

In the meantime, doctors and public-health experts note that walks by the sea or in green spaces offer well-documented benefits such as physical activity, exposure to cleaner air than dense urban centres, and mental-health advantages. Whether those walks also deliver measurable quantities of vitamins or beneficial microbes through inhalation remains an open question for further study.