According to a small study published in Gut, an abundance of A. muciniphila is linked with lower glucose, blood fats, and healthier body fat distribution in overweight and obese people.
The research backs up previous studies that suggested A. muciniphila is associated with healthier glucose metabolism and leanness in mice. However, it had not been clear whether this also applies to people until now.
In healthy people A. muciniphila makes up around 3% to 5% of the gut's bacterial ecosystem and is associated with a diet rich in insoluble fibre, said the team – led by senior author Professor Karine Clément from the Institute of Cardiometabolism and Nutrition (ICAN) at Institut E3M, Paris.
"A. muciniphila produces a variety of fermentation products," wrote Clément and her team. "These may serve as energy sources for other bacteria and the host. It is possible that through this cross-feeding, A. muciniphila may contribute to the expansion of other beneficial species, while it may itself have a direct effect on host metabolism, consistent with rodent studies.”
“Our results shed new light on the relationship between A. muciniphila, the gut ecosystem and host health,” they added – noting that the healthiest metabolic status was seen in subjects with higher A. muciniphila abundance in the context of greater bacterial gene richness.
Indeed, the French researchers noted that higher A. muciniphila abundance is particularly associated with a healthier metabolic status and higher insulin sensitivity at baseline, in addition to an improvement after calorie restriction (CR) and weight stabilisation (WS).
“Subjects with higher A. muciniphila and gene richness are metabolically healthier before and after the dietary intervention, thus demonstrating an interaction between gut bacterial richness and A. muciniphila abundance,” concluded the team.
Clément and her colleagues assessed levels of gut A. muciniphila and other bacteria, as well as fasting blood glucose and blood fats, and indicators of body fat distribution including waist:hip ratio and the amount of fat beneath the skin, in 49 obese or overweight adults.
These assessments were made before and after a dietary intervention which involved six weeks of a low calorie diet with extra protein and fibre followed by six weeks of a stabilisation diet.
Calorie restriction is known to alter the composition of gut bacteria, noted the team.
The team found that at the start of the dietary intervention, those with evidence of abundant A. muciniphila in their guts had lower fasting blood glucose and insulin levels, a smaller waist:hip ratio, and a smaller fat cell volume beneath their skin than those with low levels of the microbe.
Those who had abundant A. muciniphila as well as a greater diversity of microbes in their gut to start with, had the healthiest metabolic profile – particularly for fasting blood glucose, triglycerides (blood fats), and body fat distribution.
After 6 weeks of calorie restriction, those with a greater abundance of A. muciniphila to start with showed stronger improvement in their metabolic profile and body fat distribution than those with lower levels, Clément and her team revealed.
The calorie restriction intervention was associated with a reduction in the abundance of A. muciniphila across the board, but these levels still remained 100 times higher in people in whom the microbe was more abundant to start with, they added.
Discussing a possible mechanism of action, the French team suggested that the by-products of A. muciniphila may act as a fuel for other beneficial gut bacteria.
Indeed, the team noted that A. muciniphila produces a variety of fermentation products, including short chain fatty acids, through mucin degradation.
“These substrates may serve as energy sources for other bacteria and the host. It is possible that through this cross-feeding A. muciniphila may contribute to the expansion of other beneficial species, while it may itself have a direct effect on host metabolism, consistent with rodent studies,” said the team.
They concluded that the gut bacteria strain warrants further investigation to see whether it could have some potential as a probiotic or medical treatment, and whether it might be used as an indicator of the likely success of dietary interventions.
Published online ahead of print, doi: 10.1136/gutjnl-2014-308778
“Akkermansia muciniphila and improved metabolic health during a dietary intervention in obesity: relationship with gut microbiome richness and ecology”
Authors: Maria Carlota Dao, et al