88 million adults in the US have prediabetes, 34 million develop diabetes, and about 90% of that number have type 2 diabetes. Staggering numbers, but very real. Type 2 diabetes individuals do not produce enough insulin, or their cells do not respond to it correctly. This results in the cells not absorbing sugar efficiently, and blood sugar levels rise. Given time, this can lead to damage to internal organs.
Westerners usually have a diet high in saturated fats and refined sugars. Many tend to be obese or overweight, and are more at risk of developing type 2 diabetes. But, scientists recently set out to identify which specific gut bacteria may play a role in the relationship between diet and diabetes.
There are hundreds of species of gut bacteria. Research has shown that an imbalance in the microbiome, or dysbiosis, may have adverse health effects. One 2019 study suggested a disturbance in the gut microbiome may play a role in developing type 2 diabetes. A recent paper also suggests that a small number of specific bacteria may be of crucial importance.
The research was carried out by scientists from the University of Vienna in Austria, Oregon State University in Corvallis, OR, the National Cancer Institute, and the National Institutes of Health in Bethesda, MD. The paper’s importance is that it shows specific bacteria that are not key influencers of the whole microbiome may still have an essential impact on health.
Study co-leader Andrey Morgun said, “the analysis pointed to specific microbes that potentially would affect the way a person metabolizes glucose and lipids. Even more importantly, it allowed us to make inferences about whether those effects are harmful or beneficial to the host. And we found links between those microbes and obesity.”
Combined experiments on mice, with the analysis of large quantities of data from previous research on mice and humans, were done by the research team. The scientists gave the mice either a regular diet, or food equivalent to the Western diet. As expected, mice fed a Western diet developed glucose intolerance and insulin resistance. These 2 contribute to developing type 2 diabetes.
Also noted was a significant change in the composition of the gut microbiome. A “Transkingdom Network” analysis was applied, which is a data-driven approach that models interactions between the body and the microbes, to identify which bacteria contributed most to the changes in metabolism. The list was narrowed down to four bacteria that seemed to play a key role in reducing the harmful effects of a Western diet: Lactobacillus johnsonii, Lactobacillus gasseri, Ruminococcus gnavus, and Romboutsia ilealis.
The study’s other co-leader, Natalia Shulzhenko, an associate professor of biomedical sciences in OSU’s College of Veterinary Medicine, said, “The first two microbes are considered potential ‘improvers’ to glucose metabolism, the other two potential ‘worseners.’ The overall indication is that individual types of microbes and/or their interactions, and not community level dysbiosis, are key players in type 2 diabetes.”
Data analysis from human research also showed that the four bacteria identified in mice also correlates with the Body Mass Index (BMI) of people on a Western diet. People with higher levels of ‘improvers’ had a lower BMI; those with more ‘worseners’ were more likely to have a higher BMI. it was also found that R.ilealis was present in more than 80% of obese people. This suggests that this microbe may contribute to obesity.
The researchers now wanted to know what happens to the mice’s metabolism when treated with ‘improvers’ and ‘worseners’ to see if the bacteria could improve the metabolism of individuals with type 2 diabetes.
Certain dairy products, like yogurt, contain different strains of Lactobacillus, which occur in many fermented products. Mice on a diet that contained R. ilealis showed a reduced glucose tolerance level as well as insulin production, suggesting a diabetes-like condition. What is interesting, was that R. ilealis did not affect the amount of body fat, but L. johnsonii and L. gasseri helped reduce it.
As expected, L. gasseri and L. johnsonii improved glucose tolerance in mice fed on a Western diet. In addition, L. gasseri improved established glucose tolerance in the mice. They also noted that “minimal alterations in microbiota induced by L. gasseri and L. johnsonii supplementation did not explain the restoration of glucose metabolism promoted by these bacteria.”
The next step was to look at target organs like the gut and liver, which the Lactobacilli may affect. Scientists previously have shown that reducing fat in the liver is essential for recovery from type 2 diabetes. The recent study found that genes that controlled liver cell mitochondrial function, were upregulated. They have links to lipid metabolism and overall glucose control.
The mice that received L. gasseri and L. johnsonii had improved mitochondrial health in their livers. This means bad lipids were reduced. The authors of the study firmly believe that these findings may develop treatments for type 2 diabetes.
“Our study reveals potential probiotic strains for treatment of type 2 diabetes and obesity as well as insights into the mechanisms of their action. That means an opportunity to develop targeted therapies rather than attempting to restore ‘healthy’ microbiota in general,” Morgun explained.
Looks like good news for those with type 2 diabetes. Many will argue that the Western diet should not be the culprit, all you have to remember is that everything in moderation. Have your diet checked, and if a lifestyle change is needed, well, it should not pose to be much of a problem.