1. Patients with higher levels of gut Akkermansia muciniphila may have had more improvement in metabolic health with calorie restriction despite lack of a difference in waist circumference.
Evidence Rating Level: 3 (Average)
Study Rundown: Increasing evidence finds that predominance of certain bacteria in the gastrointestinal tract can have significant effects on health. In particular, Akkermansia muciniphila has been implicated as having a role in metabolic health and insulin sensitivity, though the results from past studies have been varied. This study tracked A. muciniphila abundance in overweight patients undergoing calorie restriction and measured various markers of health during the study. When separating these patients into two groups, high abundance and low abundance of A. muciniphila groups, they found that those with in the high abundance group had slightly better waist-hip-ratios, adipocyte diameter and insulin sensitivity. Those with both high abundance of A. muciniphila and more varied microbiome had the best metabolic health overall. During calorie restriction, those with high abundances of A. muciniphila may have had better successes in certain areas of metabolic health, such as lowering LDL and waist circumference, though these differences were not necessarily statistically significant when the total time of calorie restriction and weight stabilization was considered.
This study tenuously associates overall metabolic health and improvement after calorie restriction with pre-existing microbiome make-up. However, there were many experimental inconsistencies or oversights that make the results difficult to interpret. The study population was mostly women but a few men were included, which could have added variation to the results. The high abundance group was significantly younger which may account for some of the better findings in metabolic health. Some of the statistical approaches, such as using a paired t-test to compare results over three time points, were not optimal. Finally, while effect sizes were small the results provide stimulus for further studies into the mechanisms of metabolic mediation by A. muciniphila.
Relevant Reading: The role of the gut microbiome in metabolic health
In-Depth [prospective cohort]: A total of 41 women and 8 men who were overweight but otherwise healthy were selected for this French study and put on a calorie restriction program for weight loss. Multiple endpoints of overall and metabolic health were taken at baseline, 6 weeks, and 12 weeks after calorie restriction. At baseline, the fecal abundance of A. muciniphila was determined and patients were separated into high- and low-abundance groups for further analysis. At baseline, the high abundance group was younger (p = 0.02) and had a smaller waist-to-hip ratio, adipocyte diameter, peripheral glucose, insulin, insulin resistance (HOMA-IR and Disse Index), AST and GGT, and leptin (Wilcoxin Rank Sum; p < 0.05). As calorie restriction was undertaken during a 6-week period, the high abundance group had a decrease in A. muciniphila while the low abundance group had an increase (p < 0.05). A trend towards more loss of waist circumference and lower cholesterol may have occurred in the high abundance group, but this was not statistically significant. Although effect sizes were small, decreased android fat, glucose, and triglycerides were found in patients with high-abundance of A. muciniphila and high microbiome diversity (p < 0.05).
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