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The Diet - Gut microbiome - Breath Axis

The Diet - Gut microbiome - Breath Axis


S. Cristescu, E. Aarts - Radboud University


31 August 2020


From the time of Hippocrates, physicians used the body odours as effective means of identifying health issues and diagnosing some diseases. Nowadays, the modern breath analysis has connected these odours with specific volatile metabolites (some established as biomarkers) or profile of several metabolites. For example, the fruity scent as nail polish remover may indicate high levels of ketones (i.e. acetone) in your blood. This could become a problem for type 1 diabetes, but also for type 2 (e.g. ketoacidosis). Other examples of molecules in exhaled breath and their role in health status are listed in the table below. In addition, other organisms, such as the gut microbiome produces a wide variety of volatile organic and inorganic compounds as part of its metabolism. Yet, little progress has been made to reveal the origin of the metabolites present in exhaled breath.


Molecules in exhaled breath


acetaldehyde, ethanol

alcoholic fermentation induced by intestinal bacteria (e.g. excessive carbohydrates uptake)


by-product of intestinal flora, energy balance, diabetes, nutrition-related behaviour (e.g. starvation and ketogenic diet)


lipid peroxidation

hydrogen cyanide

bacterial infections

methane, hydrogen

colonic fermentation, indicators of malabsorption of carbohydrates and bacterial (over)growth, indigestion, intestinal upset                                                                                    

methanethiol, dimethyl sulfide

incomplete metabolism of the sulfur-containing amino acid methionine by gastrointestinal bacteria



An abundance of information is nowadays available for helping the clinicians to know that an individual is healthy or diseased. However, it is up to our wisdom to know how to manage our health. Genes are important when it comes to heart disease or diabetes, but statistics shows that no more than 25 percent of the variation in human life span is determined by genetics. A lot has to do with our lifestyle. The sooner we take on healthy habits, the better chance we have for a long and healthy life. Childhood Obesity - one of the most serious public health challenges of the 21st century - is highly associated with dietary quality.


In Nutrishield we investigate how breath and microbiome link to each other and to diet (via nutritional status measures) in the development of young children. A technological platform is developed in parallel for detection of some of these metabolites (see blog contributions “ Novel laser technology and Novel Analyzer Based On Photonics).


NUTRISHIELD aims at creating a personalised platform for the young. The platform will consist of novel methods & techniques, which analyse a wide range of biomarkers related to nutrition and health disorders.