Scientists propose 'aeronutrients' in coastal and rural air could supplement diets and ease common symptoms

Researchers are exploring whether tiny amounts of nutrients and beneficial microbes in the air — dubbed “aeronutrients” — can help supplement dietary intake and reduce symptoms such as fatigue, headaches and dry skin. Investigators say exposure to coastal and rural air, and simple activities such as regular seaside or countryside walks, could increase inhalation of those airborne compounds and influence nutritional status.

The concept, advanced in a paper published in the journal Advances in Nutrition, proposes that inhaled aerosolised particles and organisms may deliver measurable quantities of vitamins, minerals or microbes to the body. Proponents argue this route of exposure could be a fast and reliable complement to food, particularly for people at risk of specific nutrient shortfalls.

Public-health interest in non-dietary sources of nutrients comes amid persistent deficiencies in several populations. In the United Kingdom, for example, about one in five adults does not meet recommended intakes of vitamin D, which is primarily produced in the skin after sun exposure; the NHS advises most people to take a daily 10 microgram supplement in autumn and winter. Vegetarians and vegans are known to be at risk of vitamin B12 deficiency, which can cause breathlessness, headaches and heart palpitations, because B12 is concentrated in animal-based foods. Iodine, essential for thyroid function, can be low in those who avoid seafood and dairy; deficiency symptoms include fatigue, dry skin, weight gain and hair loss.

Proponents point to laboratory and field studies suggesting airborne nutrients and microbes exist in varying concentrations across environments. A 2011 study by researchers at the National University of Ireland in Galway compared iodine levels in schoolchildren who lived near beaches with abundant seaweed, beaches without seaweed and inland areas. The researchers reported that children living nearest seaweed-laden shores had higher iodine levels, which the Newcastle, Australia, investigators and other authors interpret as possibly reflecting inhalation of iodine released from seaweed into the air.

Dr. Flavia Fayet-Moore, a nutritional scientist and co-author of the Advances in Nutrition paper, said in an interview that while ingestion remains the predominant source of nutrients, aeronutrients may provide an additional pathway. "This might come from greater exposure to the natural environment and ‘fresh air,’" she said, adding that aerosols from soil, decaying plants, sea spray and even cooking emissions could carry micronutrients. Some vitamins and minerals are already formulated as oral or nasal sprays, which are absorbed rapidly through the vascular tissues in the mouth and nasal cavity; inhalation would follow a similar mucosal route, the researchers note.

Other researchers have drawn attention to airborne microbial diversity. A 2023 study in Science of the Total Environment by investigators at the University of North Carolina found that air sampled in vegetated areas contained a broader range of airborne bacteria than samples from urban zones with little greenery. The authors suggested that exposure to diverse aerobiomes might support immune function and be linked to reduced morbidity in greener environments, though they cautioned that causal links remain to be demonstrated.

Not all experts are convinced the amounts of nutrients present in air are clinically meaningful. Tom Sanders, professor of nutrition and dietetics at King’s College London, described the aeronutrient hypothesis as "daft" and noted that dietary supply of minerals like iodine depends primarily on soil and food-chain factors. "For example, iodine in our diet normally comes from food and that’s dependent on the level of iodine in the soil," he said, and raised the possibility that coastal children’s higher iodine could result from dietary differences, including meat from animals that grazed on seaweed.

Mike Lean, a professor at the University of Glasgow, agreed that nutrients can be absorbed through the nose and lungs but added that "the amount of nutrients in the air is usually far too small to prevent deficiencies." Both critics and proponents call for rigorously controlled studies that quantify concentrations of specific airborne nutrients, measure intake via inhalation, and determine physiological effects.

Researchers behind the aeronutrient concept acknowledge uncertainties. They say the number and concentration of nutrients that circulate in air, and how much is absorbed by the human body, remain poorly characterised. They also emphasise that inhalation would not replace conventional dietary sources or clinically recommended supplementation, but could be a supplementary vector that warrants further study.

Public-health guidance currently remains unchanged. Health authorities continue to recommend dietary sources and supplements where indicated: for instance, routine vitamin D supplementation during periods of low sunlight and tailored advice for groups at risk of B12 or iodine deficiency. While the aeronutrient hypothesis may prompt additional research on environmental contributions to nutrition, experts caution that confirmed clinical benefits will require robust evidence from environmental sampling, exposure assessment and human clinical studies.

In the meantime, clinicians and public-health bodies say that walking in green or coastal spaces provides well-established benefits for mental health, physical activity and general well-being, even as the significance of inhaled nutrients and microbes is investigated further.