Markers for assessment, consumption and health
The Junior Research Group "Sugars and Sugar Profiling in Foods and Biofluids" focuses on sugars in foods and biofluids and their analysis. Different questions regarding sugars in our diet as to food, health, and physiology are addressed in four work packages (WP), including the intake of sugars and sugary foods (food markers), the relationship between the presence of different sugars in saliva and diet, oral microbiota, as well as taste perception and preference, and the use of allulose as a possible new low-calorie substitute sugar in food. A semi-targeted sugar profiling method has already been established at the Department of Safety and Quality of Fruit and Vegetables for the analysis of a variety of sugar compounds. This method is being further developed into a quantitative sugar profiling method, which will be used in the various work packages.
Sugar, what does that actually mean?
Sugar is commonly understood to be household sugar (sucrose), fruit sugar (fructose), grape sugar/blood sugar (glucose) or milk sugar (lactose). Chemically speaking, sugars are carbohydrates or saccharides, i.e. compounds composed of the elements carbon, oxygen and hydrogen. The term sugar therefore covers a huge number of different substances, from mono-, di- and polysaccharides to sugar alcohols, sugar acids, deoxy sugars, but also amino sugars, thio sugars and other compounds.
Nevertheless, when analyzing body fluids and foods, only a small selection of particularly common sugars such as sucrose, glucose, fructose and lactose are usually considered. These only represent a small fraction of the sugars found in our food and our bodies, as shown by the Department of Safety and Quality of Fruit and Vegetables with the above-mentioned sugar profiling method: More than 80 different sugar compounds have been detected in urine (see figure) as well as in blood. Some of these sugars have already been linked to the consumption of certain foods, to gender, to health status (especially type 2 diabetes mellitus) or to age.
AP1 Quantitative sugar profiling
The method established so far only allows a "relative quantitative comparison" of the detected sugars. This means that the signal of a sugar in an investigated group is evaluated in relation to the signal of the same sugar in the control group. Compared to this, "absolute quantitative values", i.e. the concentrations of sugars in blood, urine or food, are higher as to their information content and significance. Therefore, the first main objective of the Junior Research Group is to further develop the existing sugar profiling method into a quantitative method.
This quantitative method will then be used to answer different biological questions:
AP2 Sugars in the diet (markers of food intake).
Markers of food intake are compounds quantified in urine or blood and associated with the consumption of a specific food or food group. This work package will evaluate whether the sugar profile in urine, in combination with the quantification of selected sugars, can be used to calculate total sugar intake and, at the same time, test whether the additional information provided by the sugar profile can also differentiate the source of sugar intake (e.g., fruit, vegetable vs. soda).
AP3 Sugars in saliva, oral microbiota and taste perception
The mouth is the entry point of food into the gastrointestinal tract; here food is mechanically broken down by chewing and mixed with saliva. Saliva has a very complex composition and contains a variety of metabolites derived from human metabolism, from the oral microbiota present in the mouth (i.e., the bacteria that colonize the mouth), as well as from food components or contaminants. However, the composition of the sugar profile in human saliva has not yet been described. Therefore, within this work package, the Junior Research Group will determine for the first time the sugar profile in saliva of a healthy person .
AP4 Evaluation of allulose as a substitute sugar in foods
Various alternatives are currently being tested for the necessary reduction of free sugars in the diet. One alternative could be the comparatively rare sugar allulose. A safety assessment by EFSA (European Food Safety Authority) is still pending, partly because basic data are lacking. Therefore, the Junior Research Group will work on various topics related to allulose in close collaboration with cooperation partners at MRI.