Lower gut flora diversity associated with three risk factors for metabolic syndrome

Researchers from the University Medical Centre of Groningen in the Netherlands have found that decreased gut microbial diversity is strongly associated with three risk factors for metabolic syndromen, and therefore diabetes.
These risk factors are high body mass index (BMI) and triglyceride levels, as well as a low level of high-density lipoproteins (HDL).
The study, published in the online journal Circulation Research, is the first large human population research to shed light on how the gut microbiome relates to body weight and blood lipids.
The findings link 34 intestinal bacteria with BMI and lipids, and the composition of gut microbiota was found to explain up to six per cent of the variation in lipid levels, independently of age, gender and genetics.
The lead investigator of the study, Jingyuan Fu, and her colleagues knew from previous research that the bacterial community in our gut is associated with an individual’s susceptibility to many diseases, including cardiovascular diseases and, other studies have suggested, obesity.
But very little was known until now about the extent to which the gut microbiome contributes to the risk associated with blood lipids or BMI, and which bacteria are involved.
This lack of data stems from the fact that less than 30% of bacteria in the human gut can be cultured. It has only recently been made possible to use sequencing technology to identify the bacteria and determine their effects on markers like blood lipid levels.
In this study, researchers examined the gut microbiomen, BMI, and blood lipids in 893 human subjects from the project Dutch LifeLines-DEEP, which aims to investigate universal risk factors contributing to chronic diseases.
The participants had a wide range of BMIs (between 16.9 and 44.9) and lipid levels. Patients on lipid-lowering or antibiotic medication were excluded from the experiment to prevent bias.
The results revealed that healthy lipid levels tend to be associated with increased microbial diversity with 34 novel microbial species especially associated with BMI and blood lipids.
The researchers also investigated how much of the variation in blood lipids or BMI could be explained by the gut microbiome. They found that up to 25.9 per cent of HDL variance was due to differences in gut microbiome.
In addition to that, 4.5 per cent of the variance in BMI as well as 6 per cent of the variation in triglycerides levels were explained by the microbiota.
In terms of the bacteria identified within the microbiomen, at least three low-BMI-associated bacteria are also associated with lower levels of triglycerides and higher levels of protective HDL, which tend to suggest that certain gut bacteria play an important role in human metabolism.