If you haven’t yet heard the term “microbiome” in the news, it probably won’t be long before you do. Although researchers haven’t yet settled on an agreed definition, the term refers to the trillions of microorganisms such as bacteria, fungi, and viruses (and their genes) that live in the human gastrointestinal tract, or gut. Some of these microorganisms can be harmful, and many experts believe that autoimmune diseases, such as type 1 diabetes, are related to dysfunction in the microbiome. But scientists are especially interested in the beneficial gut bacteria that help us fight disease and digest food. Researchers say that these bacteria can even affect our mood. Now a new study in JAMA Network Open from researchers in Rotterdam, the Netherlands, indicates that a diverse microbiome in the gut might help ward off type 2 diabetes.
The researchers retrieved data on 2,166 individuals from two Dutch studies — the Rotterdam Study and the LifeLines-DEEP Study. A little more than half (58%) were men; the averages ages were 62 (Rotterdam Study) and 45 (LifeLines-DEEP Study). The gut microbiome information was obtained through stool samples and analyzed by what’s known as the 16S rRNA method, a standard means of identifying, enumerating, and classifying the microbes within biological entities, such as sea water and the human microbiome.
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Certain bacteria identified as possibly playing a role in type 2
The researchers identified 12 specific types of gut bacteria that stood out as apparently playing a role in type 2 diabetes. A high abundance of five types (Clostridiaceae, Peptostreptococcaceae, C sensu stricto 1, Intestinibacter, and Romboutsia) were associated with a lower prevalence of type 2 diabetes, while seven types were associated with lower insulin resistance (high insulin resistance causes insulin to be less effective). These seven bacteria were Christensenellaceae, Christensenellaceae R7 group, Marvinbryantia, Ruminococcaceae UCG005, Ruminococcaceae UCG008, Ruminococcaceae UCG010, and Ruminococcaceae NK4A214 group.
A reason that these bacteria seem to play a role in reducing diabetes risk, the researchers said, is that they are all known to produce butyrate. Butyrate is what’s called a four-carbon short-chain fatty acid, and it’s produced by means of microbial fermentation of dietary fiber in the lower intestinal tract. Previous studies have linked butyrate-producing bacteria to lower insulin resistance, but the researchers in this study made new identifications that further made the case for the bacteria’s role in lowering the risk of diabetes. As they put it, “Of interest, some of these newly identified bacteria associated with type 2 diabetes have been previously reported in relation to obesity, which is closely associated with insulin resistance and development of type 2 diabetes.” They also commented, “Several studies have indicated that, compared with healthy participants, patients with type 2 diabetes have a lower overall … diversity of gut microbiome composition. More specifically, lower abundance of certain butyrate-producing bacteria, such as class Clostridia and genus Faecalibacterium, have been observed in patients with type 2 diabetes.”
Scientists are a long way from being able to introduce specific butyrate-producing bacteria into the human gut, but, as the authors explain, the research is encouraging: “These findings suggest that gut microbiome composition may influence the development of type 2 diabetes. An increased gut microbial diversity, along with specifically more butyrate-producing bacteria, may benefit insulin resistance and risk of rype 2 diabetes. These findings may help provide new insight into causes, mechanisms, and prevention of, as well as therapy for, type 2 diabetes.”
An Italian study from January of this year reviewed the possible use of butyrate in combating obesity and obesity-related conditions such as diabetes. The research, it said, is promising, but the authors were a long way from recommending that particular fatty acid as a therapy. One of the drawbacks, they pointed out, is that butyrate supplements taste terrible.
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