However, no significant impact was observed for body mass index (BMI) or waist-to-hip (W/H) ratio, Dr Harriët Schellekens and her co-workers wrote in EBioMedicine.
The data represents a partial translation of results from mice to humans: The mouse data indicated that supplementing a high-fat diet with B. longum APC1472 led to decreased bodyweight, less build-up of fat, and increased glucose tolerance, compared to control animals.
“Noteworthy, stratification and analysis of the obese human subpopulation revealed that B. longum APC1472 was able to normalize active ghrelin levels and the cortisol awakening response, which are both dysregulated in obesity,” wrote Dr Schellekens and her co-workers.
“This highlights the translational value of this novel Bifidobacterium longum species, B. longum APC1472, from a preclinical mouse model to a human intervention study where this probiotic positively impacts markers of obesity, which may be linked to the ghrelinergic effects previously demonstrated,” they wrote.
Gut microbiota and obesity
The link between the gut microbiota and obesity was first reported in 2006 by Jeffrey Gordon and his group at Washington University in St. Louis, who found that microbial populations in the gut are different between obese and lean people, and that when the obese people lost weight their microflora reverted back to that observed in a lean person. This suggested that obesity has a microbial component (Nature, Vol. 444, pp. 1022-1023, 1027-1031).
A 2013 paper in Science (Vol. 341, Issue 6150), also led by Prof Gordon, found that transplanting gut bacteria from obese humans into germ-free mice leads to greater weight gain and fat accumulation than mice that were given bacteria from the guts of lean humans.
The findings showed that weight and fat gain is influenced by communities of microbes in the gut and their effect on the physical and metabolic traits of the host, leading to metabolic changes in the rodents that are associated with obesity in humans.
This has led many research groups to explore if probiotics may help manage weight. A probiotic is defined as a “live microorganisms which when administered in adequate amounts confer a health benefit on the host” – FAO/WHO.
The APC study sought to build on the group’s earlier pre-clinical data, which found that B. longum APC1472 modulated ghrelin signaling. Ghrelin is often referred to as the hunger hormone because it is involved in regulating hunger and food intake.
The new study involved two parts: An intervention trial in lab mice fed a high fat diet with or without APC1472 supplementation, and then a 12-week placebo-controlled human intervention trial.
Data from the 16-week animal study found that mice receiving the probiotic supplements displayed lower bodyweight, less fat accumulation, and increased glucose tolerance.
Data from the human study indicated that, while no significant differences between the groups were observed for BMI and waist-to-hip ratio, improvements in blood glucose levels were observed in the probiotic group.
“… the decrease in fasting plasma glucose induced by B. longum APC1472 may have clinically significant health implications for prediabetic and type 2 diabetes mellitus populations in particular,” wrote Dr Schellekens and her co-workers.
In addition, “while the modulation of ghrelin receptor signalling by B. longum APC1472 strain may have contributed to an improved metabolic profile, we cannot rule out other beneficial anti-obesity effects,” they wrote.
“As such, future studies are warranted further investigating the mechanisms and metabolites through which B. longum APC1472 modulates host glucose homeostasis, with a focus on the ghrelinergic system.”
The research was funded by Science Foundation Ireland and by Cremo S.A.
2021, Volume 63, 103176, doi: 10.1016/j.ebiom.2020.103176
“Bifidobacterium longum counters the effects of obesity: Partial successful translation from rodent to human”
Authors: H. Schellekens et al.