Stool energy density is positively correlated to intestinal transit time and related to microbial enterotypes
Boekhorst et al. 2022
It has been hypothesised that the gut microbiota causally affects obesity via its capacity to extract energy from the diet. Yet, evidence elucidating the role of particular human microbial community structures and determinants of microbiota-dependent energy harvest is lacking. Here, we investigated whether energy extraction from the diet in 85 overweight adults, estimated by dry stool energy density, was associated with intestinal transit time and variations in microbial community diversity and overall structure stratified as enterotypes. We hypothesised that a slower intestinal transit would allow for more energy extraction. However, opposite of what we expected, the stool energy density was positively associated with intestinal transit time. Stratifications into enterotypes showed that individuals with a Bacteroides enterotype (B-type) had significantly lower stool energy density, shorter intestinal transit times, and lower alpha-diversity compared to individuals with a Ruminococcaceae enterotype (R-type).
DOI: https://doi.org/10.1186/s40168-022-01418-5 12 December 2022
Advancing human gut microbiota research by considering gut transit time
Procházková et al. 2022
Accumulating evidence indicates that gut transit time is a key factor in shaping the gut microbiota composition and activity, which are linked to human health. Both population-wide and small-scale studies have identified transit time as a top covariate contributing to the large interindividual variation in the faecal microbiota composition. Despite this, transit time is still rarely being considered in the field of the human gut microbiome. Here, we review the latest research describing how and why whole gut and segmental transit times vary substantially between and within individuals, and how variations in gut transit time impact the gut microbiota composition, diversity and metabolism. Furthermore, we discuss the mechanisms by which the gut microbiota may causally affect gut motility.
DOI: 10.1136/gutjnl-2022-328166 10 September 2022
Prevotella abundance and salivary amylase gene copy number predict fat loss in response to wholegrain diets
Christensen et al. 2022
Salivary amylase (AMY1) gene copy number (CN) and Prevotella abundance in the gut are involved in carbohydrate digestion in the upper and lower gastrointestinal tract, respectively; and have been suggested as prognostic biomarkers for weight loss among overweight individuals consuming diets rich in fiber and wholegrains.
In both studies, individuals with low AMY1 CN exhibited a positive correlation between baseline Prevotella abundance and fat loss after consuming the wholegrain diet (r > 0.5, P < 0.05), but no correlation among participants with high AMY1 CN (P ≥ 0.6). Following consumption of the refined wheat control diets, there were no associations between baseline Prevotella abundance and changes in body fat in any of the AMY1 groups.
DOI: https://doi.org/10.3389/fnut.2022.947349 22 August 2022
Safety and efficacy of liraglutide versus colesevelam for the treatment of bile acid diarrhoea: a randomised, double-blind, active-comparator, non-inferiority clinical trial
Kårhus et al. 2022
Bile acid diarrhoea is an underdiagnosed disease estimated to affect 1–2% of the general population. Case reports indicate that the glucagon-like peptide 1 receptor agonist liraglutide might be an effective treatment for bile acid diarrhoea. We aimed to investigate the safety and efficacy of liraglutide for the treatment of bile acid diarrhoea.
DOI: https://doi.org/10.1016/S2468-1253(22)00198-4 20 July 2022
Personal diet-microbiota interactions and weight loss
Roager et al. 2022
The aim of this review is to provide an overview of how person-specific interactions between diet and the gut microbiota could play a role in affecting diet-induced weight loss responses. The highly person-specific gut microbiota, which is shaped by our diet, secretes digestive enzymes and molecules that affect digestion in the colon. Therefore, weight loss responses could in part depend on personal colonic fermentation responses, which affect energy extraction of food and production of microbial metabolites, such as short-chain fatty acids (SCFAs), which exert various effects on host metabolism. Colonic fermentation is the net result of the complex interplay between availability of dietary substrates, the functional capacity of the gut microbiome and environmental (abiotic) factors in the gut such as pH and transit time.
DOI: https://doi.org/10.1017/S0029665122000805 17 February 2022
The Gut Microbiome and Abiotic
Factors as Potential Determinants of
Postprandial Glucose Responses: A
Single-Arm Meal Study
Nestel et al. 2021
The gut microbiome has combined with other person-specific information, such as
blood parameters, dietary habits, anthropometrics, and physical activity been found to
predict personalized postprandial glucose responses (PPGRs) to various foods. Yet, the
contributions of specific microbiome taxa, measures of fermentation, and abiotic factors
in the colon to glycemic control remain elusive. We tested whether PPGRs 60min after a
standardized breakfast was associated with gut microbial a-diversity (primary outcome)
and explored whether postprandial responses of glucose and insulin were associated
with specific microbiome taxa, colonic fermentation as reflected by fecal short-chain
fatty acids (SCFAs), and breath hydrogen and methane exhalation, as well as abiotic
factors including fecal pH, fecal water content, fecal energy density, intestinal transit
time (ITT), and stool consistency.
DOI https://doi.org/10.3389/fnut.2020.594850 14 January 2021
Settlers of our inner surface – factors shaping the gut
microbiota from birth to toddlerhood
Laursen et al. 2021
During the first 3 years of life, the microbial ecosystem within the human gut undergoes a process that is unlike what
happens in this ecosystem at any other time of our life. This period in time is considered a highly important developmental
window, where the gut microbiota is much less resilient and much more responsive to external and environmental factors
than seen in the adult gut. While advanced bioinformatics and clinical correlation studies have received extensive focus
within studies of the human microbiome, basic microbial growth physiology has attracted much less attention, although it
plays a pivotal role to understand the developing gut microbiota during early life. In this review, we will thus take a
microbial ecology perspective on the analysis of factors that influence the temporal development of the infant gut
microbiota. Such factors include sources of microbes that seed the intestinal environment, physico-chemical (abiotic)
conditions influencing microbial growth and the availability of nutrients needed by the intestinal microbes.
DOI: https://doi.org/10.1093/femsre/fuab001 11 January 2021
In vitro ecology: a discovery engine for microbiome therapies
Hernandez-Sanabria et al. 2020
To therapeutically modulate gut microbial ecosystems, a better understanding of gut ecology is key. High-throughput in vitro ecology provides a tool with the necessary power to address these needs and interpersonal treatment response variation.
DOI https://doi.org/10.1038/s41575-020-00364-7 15 September 2020
The metabolic nature of individuality
Lars O. Dragsted, 2020
A diet-controlled study indicates that metabolic flexibility is an important driver of inter-individual difference in the response to dietary change, and a high flexibility score is a likely health asset.
DOI https://doi.org/10.1038/s43016-020-0104-z 17 June 2020