A team of scientists analyzed how microbes in the gut process the plant-based, sulfur-containing sugar sulfokinovoses. Their study discovered that specialized bacteria cooperate in the use of sulfosugar, which produces hydrogen sulfide. This gas has a divergent effect on human health: at low concentrations it has an anti-inflammatory effect, while increased amounts of hydrogen sulfide in the gut are again linked to diseases such as cancer.
Diet and the intestinal microbiome
With the consumption of a single vegetable such as spinach, hundreds of chemical components enter our digestive tract. There, they are further metabolized by the intestinal microbiome, a unique collection of hundreds of microbial species. The intestinal microbiome therefore plays an important role in determining how nutrition affects our health. “So far, however, the metabolic abilities of many of these microorganisms in the microbiome are still unknown. This means that we do not know what substances they feed on and how they process them,” explains Buck Hanson, lead author of the study and a microbiologist. at the Center for Microbiology and Environmental Systems Science (CMESS) at the University of Vienna. “By examining the microbial metabolism of the sulfosugar sulfokinovose in the gut for the first time, we shed some light in this black box,” he adds. The study therefore generates knowledge needed to therapeutically target the interactions between nutrition and the microbiome in the future.
Sulphosaccharides of green plants and algae
Sulfokinovose is a sulfonic acid derivative of glucose and is found mainly in green vegetables such as spinach, lettuce and algae as a chemical building block. From previous studies by the research group led by the microbiologist David Schleheck at the University of Konstanz, it was known that other microorganisms can use the sulfo sugar in principle as a nutrient. In their current study, researchers from the universities of Konstanz and Vienna used analyzes of stool samples to determine how these processes take place specifically in the human gut. “We have now been able to show that sulfoquinovosis, unlike glucose, for example, which carries a large number of microorganisms in the intestines, stimulates the growth of very specific key organisms in the intestinal microbiome,” says David Schleheck. These key organisms include the bacterium of the species Eubacterium rectale, which is one of the ten most common intestinal microbes in healthy people. “The E. rectal bacteria ferment sulfokinovose via a metabolic pathway we have just deciphered, which produces a sulfur compound, dihydroxypropane sulfonate or DHPS for short, which in turn serves as an energy source for other intestinal bacteria such as Bilophila wadsworthia. Bilophila wadsworthia eventually produces water. DHPS via a metabolic pathway that has also only recently been discovered, ‘explains the microbiologist.
A question about dosage: hydrogen sulfide in the intestine
Hydrogen sulfide is produced in the gut by our own body cells as well as by specialized microorganisms and has a variety of effects on our body. “This gas is a metabolic product with a Janus face,” explains Alexander Loy, head of the research group at the University of Vienna. “According to current knowledge, it can have a positive but also negative effect on intestinal health.” According to him, a decisive factor is the dose: in low amounts, hydrogen sulphide can, among other things, have an anti-inflammatory effect on the intestinal mucosa. In contrast, increased hydrogen sulfide production by intestinal microbes is associated with chronic inflammatory diseases and cancer. Hitherto, mainly sulphate and taurine, which occur in increased amounts in the intestine as a result of a diet rich in meat or fat, have been sources of hydrogen sulphide for microorganisms. The discovery that sulfokinovoses from green foods such as spinach and algae also contribute to the production of gas in the intestines therefore comes as a surprise.
“We have shown that we can use sulfokinovosis to promote the growth of very specific intestinal bacteria, which is an important component of our intestinal microbiome. We now also know that these bacteria in turn produce the contradictory hydrogen sulfide from it,” Loy concludes. Further studies by the scientists of Konstanz and Vienna will now clarify whether and how the intake of the plant-based sulfo sugar can have a health-promoting effect. “It is also possible that sulfokinovose could be used as a so-called prebiotic,” Schleheck adds. Prebiotics are food ingredients or additives that are metabolized by specific microorganisms and used to explicitly support the intestinal microbiome.
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