Can Your Body Odor Diagnose Disease? Scientists Are Building a Medical Nose

Can Your Body Odor Diagnose Disease? Scientists Are Building a Medical Nose

Nurses in Norway smelled infections first

The story starts with the human nose. Reporting published on November 1 by The Washington Post describes interviews with nurses at a Norwegian cancer ward: many said they routinely relied on smell at work. One nurse said a urinary tract infection has a distinctive odor, recognizable "in the corridor." Another claimed to pick out digestive bleeding and cell necrosis. A third said she would not know what to do without her sense of smell. Anecdotes like these point to a serious scientific question: do diseases change how we smell, and can that smell become a diagnostic signal?

The scent comes from volatile organic compounds

The answer hides in molecules called volatile organic compounds, or VOCs. Mostly gaseous at room temperature, they leave the body in breath, sweat, urine, blood and fecal matter. When disease rewires metabolism, the mix of emitted molecules changes too. In one study of patients before and after surgery to remove lung tumors, researchers identified 16 candidate lung-cancer breath biomarkers, including pentanal, foul-smelling butyric acid, woody hexanal and decanal, which smells like orange peel. Smelling disease, in other words, has a molecular basis.

A laser spectrometer sniffs three body sites

Researchers at Fraunhofer IIS and Dresden University of Technology in Germany have turned the idea into hardware. Using laser-based photoacoustic spectroscopy, they analyzed VOCs captured on simple cotton swabs taken from the anterior nasal cavity, the navel and the outer ear — three spots that rarely carry soap or perfume, so the sample is mostly the person. The first trial was small: 24 participants, six healthy controls and six each with Parkinson's disease, COVID-19 and other conditions including mild cognitive impairment. The samples from healthy people and patients showed distinguishable differences, and the work was published in Scientific Reports. The institute frames the potential carefully: faster preliminary screening in the future, not a diagnosis on the spot.

Dogs detect Parkinson's with striking accuracy

While instruments catch up, dogs are already on the job. In a double-blind trial, trained dogs identified skin swabs from people with Parkinson's disease with sensitivity of up to 80 percent and specificity of 98 percent, even when other health conditions were present. In Britain, the charity Medical Detection Dogs has applied canine noses to prostate cancer: dogs first distinguished cancerous samples among 500 urine samples provided by patients from Milton Keynes Hospital, and those results now train an electronic nose. Perfume founder Jo Malone donated 100,000 pounds to the project. As the BBC reported, the device built by RealNose.ai uses protein odorant receptors to capture scent molecules from urine, then uses artificial intelligence to recognize patterns in receptor activation, aiming at an in vitro diagnostic device for the National Health Service.

Blood tests are the Alzheimer's screening bet

One disease odor-based screening most wants to crack is Alzheimer's. Bill Gates recently wrote that artificial intelligence plus simple blood tests could detect Alzheimer's much earlier. The current state of play: the US Food and Drug Administration approved two amyloid-clearing antibody drugs: Leqembi in 2023 and Kisunla in 2024, which slow decline in people with mild cognitive impairment and mild dementia but do not cure the disease. Blood testing centers on p-tau217, a marker that rises as amyloid accumulates; Roche's Elecsys pTau217 and C2N's PrecivityAD2 are leading examples. Two trials, AHEAD 3-45 and TRAILBLAZER-ALZ 3, are testing whether treating healthy people with early brain changes can delay decline, with some results possibly published in 2027.

Reversal therapies enter controlled trials

The further horizon is reversal. According to BBC Science Focus, medicines that target and clear amyloid-beta proteins can slow progression and manage symptoms, but there is no known cure; controlled trials of newer reversal approaches are now getting underway in China, the United States and South Korea, adding the comparison groups earlier studies lacked. From smelling disease to reversing it, a long validation road remains — but the direction looks concrete for the first time.

What stands between odor screening and the clinic

The populations most affected are clear: people at risk of lung nodules, gastrointestinal cancers, Parkinson's and Alzheimer's. If a breath sample or a navel swab could triage who urgently needs a biopsy and who can safely watch and wait, clinical sorting would look very different. Yet researchers admit most current analytical methods are complex and slow, and VOC signals are noisy: resident microbes, inflammation and other physiological processes all shape the mix. A multicenter prospective study of exhaled breath after surgery in non-small-cell lung cancer found no significant change in VOC composition in the first weeks after tumor removal — a reminder that the tumor is only one voice in the chorus.

Three validations to watch next

Three things deserve attention. First, whether laser spectroscopy in the Fraunhofer style reproduces its discrimination in cohorts of hundreds or thousands. Second, whether electronic noses and canine screening complete the medical-device approval path. Third, the early-intervention Alzheimer's trial readouts expected around 2027. Only if all three deliver could "sniff first, test second" enter real clinics. Until then, body odor's most practical message may be personal: if your bodily smell changes markedly and stays changed, don't just blame the shower — get it checked.