What the breath carries
The breath is a readout of the whole body.
The blood passes through the lungs in full, every minute. Volatile molecules made all over the body cross from blood into air and leave on the breath — so a single exhaled stream carries a trace of metabolism from far beyond the lungs. Researchers call this the volatilome: the volatile fraction of the body’s metabolism, hundreds of compounds reflecting how the body is actually running. Outside of acute care, almost none of it is read.
It already works
One breath test is routine medicine.
This is not a hope — it is a clinic. Exhaled nitric oxide (FeNO) is measured every day to gauge airway inflammation and steer asthma treatment: a health signal read straight from the breath. And it is not alone — single molecules already map to systemic states.
- Acetone rises with ketosis and tracks glycaemic state.
- Ammonia rises when the kidneys clear less, and falls sharply after dialysis.
- Pentane and aldehydes mark oxidative stress — a body-wide strain signal.
The body announces itself
Some conditions arrive with a scent.
Clinicians are still taught the sweet acetone of a diabetic crisis, the maple-sugar urine of one inherited disorder, the fishy note of another. Newer instruments reach further: Parkinson’s leaves a faint signature in the skin’s oils; malaria reshapes a host’s odour to draw mosquitoes; trained dogs and rats pick cancer and tuberculosis out of breath. And the sense itself reports: losing one’s sense of smell predicts mortality.
Reading the whole pattern — our lane
Not one molecule, but the chord.
Single markers are only the start. The richer signal is the pattern — the shifting blend of a whole exhaled stream. Electronic noses paired with machine learning can already read those patterns to classify disease in research settings, and prospective validation is beginning. SHEMIM’s work sits here: to turn that pattern into an index of well-being a person can read over time, and reshape by how they live.
Honest limit: only FeNO is in routine clinical use today; broader breath-VOC reading is emerging and not yet standardized, and a real share of breath molecules come from diet and environment, not the body. We keep the deployed apart from the promising, and say which is which.
Why it matters
Read early, and you prevent.
A signal that is continuous, non-invasive, and one a person can read themselves is a signal that can speak before the clinic would. That is the quiet promise of the breath: not a new drug, but an earlier sentence — and a measure a person owns rather than waits to be told.
How sure are we?
Every claim, tagged for how settled it is.
- Exhaled nitric oxide (FeNO) is a standardized clinical breath test, read directly from breath to gauge airway inflammation and guide treatment (American Thoracic Society, 2021).
- The volatilome — the volatile fraction of the body’s metabolism — sends hundreds of compounds out on each exhale, reflecting pathways such as oxidative stress (Ratiu et al., 2023).
- Breath acetone tracks ketosis and glycaemic state; breath ammonia tracks renal function — specific molecules mapping to systemic conditions (Qiao et al., 2014; Narasimhan et al., 2001).
- Several conditions announce themselves by smell — acetone in diabetic crisis, maple-syrup urine, the fishy note of trimethylaminuria — recognised clinically for decades.
- Parkinson’s disease leaves a distinct volatile signature in skin sebum — found because one woman could smell it, later confirmed by mass spectrometry (Trivedi et al., 2019).
- Malaria infection changes a person’s body odour in ways that make them measurably more attractive to mosquitoes (Robinson et al., 2018).
- Loss of the sense of smell predicts five-year mortality — the sense itself behaves like a vital sign (Pinto et al., 2014).
- Trained dogs and rats detect cancer and tuberculosis from breath and sputum VOCs (Guest et al., 2021; Mahoney et al., 2012).
- Machine-learning analysis of breath-VOC patterns can classify cancers in research settings, with prospective external validation beginning (de Vries et al., Annals of Oncology, 2025).
- Electronic-nose and GC-MS breath panels are under active validation for multiple diseases — though beyond FeNO, none is yet deployed.
Common questions
Frequently asked.
- What can exhaled breath reveal about health?
- Exhaled breath carries hundreds of volatile organic compounds (VOCs) produced by the body’s metabolism — collectively the "volatilome," the volatile fraction of the metabolome (Ratiu et al., 2023). These reflect systemic processes such as oxidative stress, and specific molecules map to specific states: acetone to ketosis, ammonia to renal function. One breath biomarker, exhaled nitric oxide (FeNO), is already in routine clinical use (American Thoracic Society, 2021).
- Is there a breath test used in medicine today?
- Yes. Fractional exhaled nitric oxide (FeNO) is a standardized, guideline-endorsed breath test that measures type-2 airway inflammation and helps guide asthma treatment — a health signal read directly from the breath (American Thoracic Society, 2021).
- Can breath detect cancer?
- It is an active research frontier, not yet a deployed screen. Tumour metabolism alters breath VOCs; trained dogs and electronic-nose plus machine-learning systems can classify cancer from breath patterns, and prospective external validation is beginning (de Vries et al., Annals of Oncology, 2025). These are promising research-grade results, not a validated clinical test.
- What is the volatilome?
- The volatilome is the complete set of volatile organic compounds an organism emits — the volatile fraction of the metabolome. In humans it is carried in breath, skin emanations, and other fluids, and it reflects underlying metabolic pathways, which is why it can act as a non-invasive readout of physiological state (Ratiu et al., 2023; de Lacy Costello et al., 2014).
Selected sources
- American Thoracic Society (2021) — FeNO clinical practice guideline.
- Ratiu et al. (2023), Frontiers in Molecular Biosciences — the volatilome as metabolic readout.
- de Lacy Costello et al. (2014), Journal of Breath Research — catalogue of human VOCs.
- Qiao et al. (2014), BioMed Research International — breath acetone and ketosis.
- Narasimhan, Goodman & Patel (2001), PNAS — breath ammonia and renal function.
- Trivedi et al. (2019), ACS Central Science — Parkinson’s sebum volatilome.
- Robinson et al. (2018), PNAS — malaria alters host odour and mosquito attraction.
- Pinto et al. (2014), PLOS One — olfactory loss predicts 5-year mortality.
- Guest et al. (2021), BMC Cancer — canine VOC cancer detection.
- de Vries et al. (2025), Annals of Oncology — eNose breath classification, external validation.
The same chemistry, read two ways.
The breath is the signal; the receptors are the levers. SHEMIM studies both, and keeps clear which is evidence, which is inference, and which is hypothesis.