Danish research suggests that the balance of bacteria in a person’s gut affects how much energy they obtain from food, potentially paving the way towards personalized nutrition and weight-loss strategies.
People in the study with a lower diversity of gut bacteria weighed significantly more than others, in ways could not be explained by differences in diet.
They also had less residual energy left in their fecal stools, despite food passing through their digestive tracts more quickly.
This was surprising, the researchers report in the journal Microbiome, and counters the idea that slower transit times allow more energy to be extracted.
Senior author Henrik Roager, an associate professor at the University of Copenhagen’s department of nutrition, exercise and sports, said the findings may help explain why some people gain more weight than others without eating any more.
He told Inside Precision Medicine: “If these differences in microbiota-dependent energy extraction turn out to be of clinical significance, in other words if we can demonstrate it has implications for weight gain, then we would be able to stratify people according to their gut microbiota composition and tailor diets more to the individual having this in mind.”
The team studied 85 overweight Danish men and women, examining residual energy density in stools, intestinal food transit time and variations in gut microbial diversity.
Participants were divided into three enterotypes depending on whether their gut bacterial signatures had a marked abundance of Prevotella (P-type), Bacteroides (B-type) or Ruminococcaceae (R-type).
The 35 (41.2%) B-type individuals had lower gut bacterial diversity than the 34 (40%) R-type participants, as well as significantly less residual energy in fecal stools and shorter intestinal transit times.
Results for the 16 (18.8%) P-type adults fell in between these two groups.
Differences in stool energy density were not explained by differences in habitual diet, intake of dietary fibre or fecal bacterial cell counts.
The R-type group did, however, have higher urinary and fecal levels of microbial-derived proteolytic metabolites than B-types, indicating increased colonic proteolysis in the former.
This could indicate that colonic energy extraction is less effective in R-type individuals than B-types, the researchers suggest.
Of note, B-type participants had significantly greater body weight than R types, at 89.3 versus 80.2 kg.
“The study offers some of the first evidence to suggest that differences in human gut microbial community structures as reflected by enterotypes affect the gut microbiota’s ability to extract energy from food,” the researchers conclude.
“While the causalities remain to be established, the observations are intriguing and could be pivotal for predicting personalised dietary responses in body weight management.”