Gut bacteria play key role in body's self-defense

Scientists have found that human gut bacteria regulate the levels of the body's main antioxidant, glutathione, which fights a host of diseases.
The study could lead to new probiotic-delivering foods, and a better understanding of the metabolic processes behind diseases such as type 2 diabetes, said Adil Mardinoglu, a systems biology researcher at Stockholm's KTH Royal Institute of Technology.
The research helps complete our understanding of how nonessential amino acids are synthesised to equip the body's cells with detoxifying agents and antioxidants, Mardinoglu said.
"Gut microbiota regulate your glutathione and amino acid metabolism - not only in the small intestine but also in the liver and the colon," he said.

The small intestine is host to more than 1,000 known different species of bacteria. Some of these microbiota were found to be consuming glycine, which is one of the three amino acids required for the synthesis of the body's main antioxidant, glutathione.
In a test with bacteria-free mice, the researchers measured the level of the amino acids in the portal vein, the main vessel that drains blood from the gastrointestinal tract and spleen to the liver.

They found a lower level of glycine in the liver and colon tissues, which indicated that the gut bacteria regulates glutathione metabolism in those organs, too.

Mardinoglu said that since decreased levels of glycine and other amino acids have been linked to type 2 diabetes, non-alcoholic fatty liver disease and other metabolism-related disorders, further study of microbial amino acids in the human gastrointestinal tract could shed light on the development of these diseases.
"The link between gut bacteria and glutathione metabolism could lead to the development of food products that can deliver beneficial bacteria, or probiotics, to the gut," Mardinoglu said.
The study was published in the journal Molecular Systems Biology.