People who suffer from gut dysbiosis are more at risk of developing metabolic dysfunction, according to data reviewed by The Journal of Clinical Endocrinology & Metabolism.
The study looked at research relating to the mechanisms involved in the contribution of gut dysbiosis to metabolic dysfunction. The areas of focus included microbiota driven increases in lipopolysaccharide (LPS) concentrations, changes in bile acid metabolism, alterations in short chain fatty acid (SCFAs) production and gut hormone secretion, as well as changes in circulating branched chain amino acids, with the aim of directing future research in this area.
Type 2 diabetes (T2DM) is a rapidly growing problem, making the development of new strategies to prevent or reverse the underlying pathophysiology of paramount importance. A number of cross-sectional studies have indicated that those with T2DM or pre-diabetes have a different composition of gut bacteria than those with normal glucose tolerance.[2-4] People at risk of developing T2DM may benefit from the transplant of faecal material from lean donors, which has been shown to increase the diversity of gut microbiota and improve insulin sensitivity.
LPS is a bacterial component of the gut cell wall that is involved in the inflammatory response. Individuals with diabetes have been found to have a decreased presence of gram-positive bacteria species that lack LPS and an increased presence of gram-negative opportunistic bacteria species that contain LPS.
The intestinal wall serves as a barrier for LPS to enter circulation; however, increased intestinal permeability (i.e. leaky gut) allows for LPS to translocate through intercellular pathways. Healthy gut bacteria play a role in maintaining the integrity of the intestinal barrier , and it is thought this mechanism helps to prevent LPS entering circulation and causing inflammation; however, more research needs to be done in this area.
The human microbial community also plays an important role in bile acid metabolism, and there is evidence to suggest that bile acids are involved in the regulation of glucose homeostasis.[7,8] The mechanism by which this occurs is still not completely understood and requires further investigation.
SCFAs – a product of the fermentation process of non-digestible carbohydrates by bacteria in the colon – may protect against the development of non-alcoholic fatty liver disease by stimulating the oxidation of fatty acids.
In addition, SCFAs are involved in the regulation of the secretion of several gut hormones that regulate energy homeostasis and glucose metabolism.
Finally, gut microbes play a role in the synthesis of amino acids, which contribute to glucose homeostasis via the stimulation of both insulin and glucagon secretion.
The role of the gut microbiome in glucose metabolism and metabolic dysfunction continues to be an exciting area of research, which may aid in the development of targeted approaches to preventing and treating type 2 diabetes and related metabolic conditions.
- Utzschneider KM, Kratz M, Damman CJ, et al. Mechanisms linking the gut microbiome and glucose metabolism. The Journal of Clinical Endocrinology & Metabolism 2016;1-11 [Full Text]
- Karlsson FH, Tremaroli V, Nookaew I, et al. Gut metagenome in European women with normal, impaired and diabetic glucose control. Nature 2013;498:99-103 [Abstract]
- Qin J, Li Y, Cai S etal. A metagenome-wide association study of gut microbiota in type 2 diabetes. Nature 2012;490;55-60 [Abstract]
- Zhang X, Shen D, Fang Z et al. Human gut microbiota changes reveal the progression of glucose intolerance. PloS One 2013;8:e71108 [Full Text]
- Vrieze A, Van Nood E, Holleman F et al. Transfer of intestinal microbiota from lean donors increases insulin sensitivity in individuals with metabolic syndrome. Gastroenterology 2012;143:913-916 [Abstract]
- Delzenne NM, Cani PD. Interaction between obesity and the gut microbiota: relevance in nutrition. Annual Review of Nutrition 2011;31:15-31 [Abstract]
- Huller MA, Burnett-Hartman AN, Lampe JW. Gut microbiomes, diet and cancer. Cancer Treatment and Research 2014;159:377-399 [Abstract]
- Ridlon JM, Kang DJ, Hylemon PB et al. Bile acids and the gut microbiome. Current Opinion in Gastroenterology 2014;30:332-338 [Abstract]
- Hullar MA, Lampe JW. Gut microbiome and obesity. Nestle Nutrition Institute Workshop Series 2012;73:67-79 [Full Text]
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