The use of breath analysis in research is a rapidly advancing field, and 2022 brought with it some exciting papers. Now that we’ve reached the end of the year and are into 2023, we’ve curated a list to highlight some of the most important papers published last year that significantly advanced our knowledge of breath testing.
Visualization of exhaled breath metabolites reveals distinct diagnostic signatures for acute cardiorespiratory breathlessness. Ibrahim et al. (2022), Science Translational Medicine.
Several compounds, known as volatile organic compounds (VOCs) show promise as breath biomarkers, and the true expanse of conditions, drug treatments, and microbiome changes that could result in specific molecular traces in breath composition is not known. On behalf of the EMBER consortium, Ibrahim et al. published their results aimed at discovering and validating the effectiveness of VOC biomarkers for cardiorespiratory conditions in the breath (1).
The breath samples in this study were collected using Owlstone Medical’s ReCIVA device and a machine learning tool was utilized to identify predictive biomarkers in the breath between healthy volunteers and those accessing emergency care services suffering from conditions causing acute breathlessness (such as COPD, acute heart failure, asthma, and pneumonia). The composition of breath was found to be significantly different in cardiorespiratory patients compared to healthy volunteers (P = < 0.0001). Several classes of exhaled VOCs were highly correlated with disease groups, as well as subgroups. This included a cluster of highly similar carbonyls and hydrocarbons to heart disease, which are promising for follow-up studies to investigate further.
This is an exciting demonstration of the potential of breath biomarkers and highlights the need to characterize the origin of these VOCs in the body. VOCs could in the future be used to optimally triage patients to ensure they receive rapid, and targeted care, as well as to stratify patients into disease subgroups and monitor whether treatment is successful.
Performance and Interpretation of Hydrogen and Methane Breath Testing Impact of North American Consensus Guidelines. Pitcher et al. (2022), Digestive Diseases and Sciences.
The North American Consensus (NAC) was first published in June 2017 to provide standardized criteria for the use of hydrogen and methane breath tests for the diagnosis of small intestinal bacterial overgrowth (SIBO) and carbohydrate malabsorption (CMs) (2). The standardization of testing protocols and criteria for positive results have been a challenge of HMBTs, implementation, and therefore the guidelines are important to keep evaluating and developing to ensure their use is up to clinical standards.
Pitcher et al. provided a further evaluation of the guidelines, comparing the diagnosis of these conditions using the NAC criteria versus previous criteria (3). The findings of this study support the NAC criteria for the diagnosis of SIBO as there were significantly fewer positives (42% vs. 53%, P = 0.04), which the authors attributed to decreasing false positive results. There was an increase in positive CMs tests (36 vs. 22%, p = 0.04), which were considered as an increase in true positives, therefore showing increased diagnostic sensitivity using the NAC criteria.
If you are suffering from gastrointestinal symptoms that are affecting your quality of life and think a HMBT and longitudinal monitoring might be useful to help you gain some answers, we have recently launched OMED Health. Alongside a traditional HMBT, we have developed a device suitable for at home-use and that can be used alongside our OMED Health app to monitor your own food responses and microbiome. We are partnered with clinicians who will review the data, and help you take control of your gut health through a personalized treatment plan. Join the waitlist here.
Breath biomarkers of insulin resistance in pre-diabetic Hispanic adolescents with obesity. Khan et al. (2022), Scientific Reports.
Exhaled breath contains VOCs that are produced from metabolism systemically throughout the body, and therefore has the enormous potential to provide measurable reporter molecules about specific pathways, and disease states in a non-invasive manner. This can be used not only for diagnostic and screening purposes but also to provide non-invasive surrogate markers of organ function overall, with the particular benefit of non-invasiveness allowing longitudinal sampling to be conducted at ease. Khan et al have published important data on linking Insulin Resistance (IR), a precursor condition to type II diabetes associated with the development of cardio-metabolic disease, to specific compounds exhaled on the breath (4).
In this study, 28 obese adolescent participants were tested using breath sampling collected using Owlstone Medical’s ReCIVA device, as well through as well-established clinical blood tests. Ten important metabolites were identified as predictors of IR, interestingly one of which was limonene, which we have also identified as an important marker of liver function. Crucially, the breath-based IR markers correlated with the blood-based metrics, as well as with all glycemic clinical measurements, and the breath-IR model can accurately identify the separate categories of IR presence. This is promising evidence to support the potential use of breath-based biomarkers to diagnose and monitor IR as well as liver function overall.
Breast cancer detection using volatile compound profiles in exhaled breath via selected ion-flow tube mass spectrometry. Nakayama et al. (2022), Journal of Breath Research.
Breast cancer is one of the most common cancers for women, and early detection is a major research focus. Screening techniques such as mammographs are effective but false positives are common – with approximately 12% of patients called for further investigations which are not necessary (5), resulting in patient anxiety and unnecessary costs for the healthcare system. Breath offers a unique alternative method to screen for cancer metabolic biomarkers.
Nakayama et al. investigated VOCs on the breath of 45 breast cancer patients and compared the composition to 51 volunteers without breast cancer (6). A total of 672 peaks were identified, of which 65 showed significant differences between healthy controls and breast cancer patients (P = <0.05). From the VOC profiles, glycerophospholipid metabolism was indicated as a major affected pathway in breast cancer, and so it was suggested that cancer-related metabolic changes in glucose metabolism were likely behind the differences in VOC levels. This study provided evidence that biomarkers indicative of breast cancer-specific metabolism could be detected on the breath, which could potentially be utilized as specific biomarkers in many clinical contexts in the future, including non-invasive screening methods.
Volatile compounds in human breath: critical review and meta-analysis. Issitt et al. (2022), Journal of Breath Research.
Translation of breath biomarkers into clinical practice has previously proved to be tricky. This may in part be due to the historical lack of standardization across the literature in collecting breath samples, but also due to confounding variables caused by differences between, and within individuals. A meta-analysis and review by Issitt et al. aimed to compare published outcomes of breath research across the literature, and thereby suggest new frameworks to inform future studies (8).
From this analysis, common networks of VOCs were identified in the breath of patients across several different disease groups, as well as the differences between them. Using commonly identified networks of VOCs in disease groups, rather than focusing on individual VOC potential biomarkers, improved explanatory capacity from 19.1% to 38% in a principal component analysis. Some examples include hydrocarbons, aldehydes, and more that separate lung cancer from other diseases, ketones, and acetone being associated with diabetes, IBD with hydrocarbons, nitrogen and sulfur compounds, and liver disease with monoterpenes such as limonene and pinene. This is validated by data that we have generated in-house including a catalog of breath VOCs in a heterogenous population of healthy volunteers, their associated metabolic pathways as well as potential disease states that can be accessed through our VOC Atlas. Overall, this work demonstrates a movement in the field towards a greater incorporation of complexity, and identifying functional groups of biomarker VOCs as opposed to single VOCs to improve the accuracy of breath biomarkers for clinical purposes.
Non-invasive breath collection in murine models using a newly developed sampling device. Hintzen et al. (2022), Journal of Breath Research.
Animal studies form an important part of the evidence base of clinical science and serve as proof of concept that can indicate that VOCs are useful biomarkers. However, most previously published studies use anesthetized mice, and tracheal cannulation or tracheostomy to collect exhaled breath. This is a significantly different approach to how breath is collected in humans, and so a better, standardized procedure to collect exhaled VOC on the breath of animal models is needed. This paper published by Hintzen et al. demonstrates a custom-made breath sampling device from the noses of awake mice (7).
The device developed has several beneficial traits, five mice can be sampled simultaneously, and a filtered and fresh air supply reduces background compounds, therefore, minimizing contaminating sources of VOCs. Using the device various compounds that are commonly associated with exhaled breath were able to be detected, including ethanol, limonene, and butanal, supporting that this device is capable of collecting biologically meaningful breath VOCs.
Volatile organic compounds: A proinflammatory activator in autoimmune diseases. Ogbodo et al. (2022), Frontiers in Immunology.
Finally, we would like to draw your attention to an important review that focussed on discussing the impact of exogenous VOCs on the development of autoimmune conditions. The mechanisms through which VOCs are produced and interact with the environment is a key fundamental area to understand to advance breath science, and the multitude of ways that VOC levels can be influenced in the breath relies on a deeper mechanistic understanding of their presence in the body.
This review by Ogbodo et al. (9) mostly focuses on the impact of exogenous VOCs and environmental exposure on the body, and details important background information of many VOC chemical classes and their regulatory link with the immune system.
Incorporating breath analysis into your research
Analysis of breath VOCs is an ever-advancing and important monitoring method that all scientists interested in using biomarkers to investigate health and disease need to be aware of. Owlstone Medical is a world leader in breath analysis and has successfully partnered with academic researchers and pharmaceutical companies to heighten clinical research in many ways. If you would like to incorporate analysis of breath in your research, please reach out to us and we would be happy to discuss how our Breath Biopsy technology could help you to achieve your research goals.
- Ibrahim W, Wilde MJ, Cordell RL, Richardson M, Salman D, Free RC, et al. Visualization of exhaled breath metabolites reveals distinct diagnostic signatures for acute cardiorespiratory breathlessness. Science Translational Medicine. 2022 Nov 16;14(671):eabl5849. DOI: 10.1126/scitranslmed.abl5849
- Rezaie A, Buresi M, Lembo A, Lin H, McCallum R, Rao S, et al. Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus. Am J Gastroenterol. 2017 May;112(5):775–84. DOI: 10.1038/ajg.2017.46
- Pitcher CK, Farmer AD, Haworth JJ, Treadway S, Hobson AR. Performance and Interpretation of Hydrogen and Methane Breath Testing Impact of North American Consensus Guidelines. Dig Dis Sci. 2022;67(12):5571–9. DOI: 10.1007/s10620-022-07487-8
- Khan MS, Cuda S, Karere GM, Cox LA, Bishop AC. Breath biomarkers of insulin resistance in pre-diabetic Hispanic adolescents with obesity. Sci Rep. 2022 Jan 10;12(1):339. DOI: 10.1038/s41598-021-04072-3
- Lehman CD, Arao RF, Sprague BL, Lee JM, Buist DSM, Kerlikowske K, et al. National Performance Benchmarks for Modern Screening Digital Mammography: Update from the Breast Cancer Surveillance Consortium. Radiology. 2017 Apr;283(1):49–58. DOI: 10.1148/radiol.2016161174
- Nakayama Y, Hanada M, Koda H, Sugimoto M, Takada M, Toi M. Breast cancer detection using volatile compound profiles in exhaled breath via selected ion-flow tube mass spectrometry. J Breath Res. 2022 Dec;17(1):016006. DOI: 10.1088/1752-7163/aca696
- Hintzen KFH, Smolinska A, Mommers AGR, Bouvy ND, Schooten FJ van, Lubbers T. Non-invasive breath collection in murine models using a newly developed sampling device*. J Breath Res. 2022 Feb;16(2):027102. DOI: 10.1088/1752-7163/ac4fae
- Issitt T, Wiggins L, Veysey M, Sweeney ST, Brackenbury WJ, Redeker K. Volatile compounds in human breath: critical review and meta-analysis. J Breath Res. 2022 Feb;16(2):024001. DOI: 10.1088/1752-7163/ac5230
- Ogbodo JO, Arazu AV, Iguh TC, Onwodi NJ, Ezike TC. Volatile organic compounds: A proinflammatory activator in autoimmune diseases. Front Immunol. 2022 Jul 29;13:928379. DOI: 10.3389/fimmu.2022.928379