Metabolic syndrome (MetS) is a common condition worldwide that has been related not only to biochemical abnormalities and inflammation, but also to imbalances in the gut microbiota.
Researchers from the National Institute of Medical Sciences and Nutrition Salvador Zubirán and the National Autonomous University of Mexico in Mexico City have found that the gut microbiota may explain the benefits of a lifestyle intervention for the hallmarks of metabolic syndrome.
In an initial step, using a sample of 1065 subjects from Mexico City, the authors found that 72% of participants with MetS had a sedentary lifestyle and 22% suffered from irritable bowel syndrome. Such findings prompted the researchers to explore associations between metabolic alterations and gut microbiota composition.
The gut microbiota of subjects with MetS was different to that of normal weight subjects. Specifically, subjects with MetS—whether they showed class III obesity (BMI equal or higher than 40) or not—showed a rise in the relative abundance of Prevotella, a drop in Bacteroides and an increase in serum lipopolysaccharides (LPS). In addition, LPS were positively correlated with the presence of P. copri, which may be involved in metabolic endotoxemia in subjects with MetS.
In a sample consisting of 146 subjects with MetS, Guevera-Cruz and colleagues studied the impact on biochemical parameters of a 2.5-month lifestyle intervention with a diet low in saturated fat, reduced-energy intake, functional foods and physical activity.
A reduction of certain parameters such as serum triglycerides was detected 15 days after the beginning of the intervention. Such changes were even more apparent after a 75-day lifestyle intervention and they included a reduction in low-density lipoprotein cholesterol, small low-density lipoprotein particles, glucose intolerance, lipopolysaccharide, and branched-chain amino acid (BCAA).
The gut microbiota may partly explain some of these results, as certain gut commensals can modulate the body’s pool of BCAA. As such, the researchers wanted to explore this in further detail.
Subjects with normal weight, MetS and MetS with class III obesity were selected for a randomized control-placebo study to assess the gut microbiota following the dietary intervention. Alpha diversity and richness were higher in normal weight participants and increased after the 2-week intervention in subjects with MetS, when compared with the placebo groups. Furthermore, the lifestyle intervention led to a reduction in the Prevotella/Bacteroides ratio—considered by the authors to be an indicator of gut microbiota dysbiosis—and an increase in the abundance of Akkermansia muciniphila and Faecalibacterium prausnitzii.
Although the reported benefits of a lifestyle intervention combining diet and physical exercise on MetS are not new, this intervention study highlights the impact of a lifestyle intervention on reducing the risk of MetS by modifying gut microbiota composition.
The involvement of gut microbiota in MetS, as reported here through 16S ribosomal DNA sequencing, is the starting point for investigation into the microbiome’s role in cardiovascular health. As sequencing studies do not provide an understanding of the functional interactions between members of the gut microbiota, human research exploring this functional ecology in more detail is needed.
Guevara-Cruz M, Flores-López AG, Aguilar-López M, et al. Improvement of lipoprotein profile and metabolic endotoxemia by a lifestyle intervention that modifies the gut microbiota in subjects with metabolic syndrome. J Am Heart Assoc. 2019; 8(17):e012401. doi: 10.1161/JAHA.119.012401.
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