The study of the gut microbiome is becoming increasingly relevant in managing metabolic-related conditions such as obesity. Although initial findings in mice revealed the gut microbiome’s role as an important environmental factor that affects how energy is harvested from diet and stored in the host, gut microbial signatures of obesity in humans are inconsistent.
The involvement of the gut microbiome in obesity has led scientists to explore the role of probiotics in its prevention and treatment. Indeed, some clinical trials show the anti-obesogenic effects of probiotics not only in people with obesity but in healthy individuals as well.
Of the probiotics that have anti-obesity effects, Bifidobacterium longum APC1472 has been shown to have preclinical benefits for attenuating signalling on the ghrelin receptor involved in regulating hunger and food intake.
This probiotic was identified using a screening approach using bacteria from the APC Microbiome Ireland’s “culture-to-product” platform, which is a well catalogued and quality controlled collection of bacteria with potential biofunctional activities, explained the first author Harriët Schellekens to GMFH editors via email.
Based on those preliminary findings, researchers at APC Microbiome Ireland have explored whether this probiotic could improve markers of obesity in healthy overweight/obese adults.
First, the authors showed the anti-obesity effects of B. longum APC1472 in mice with obesity induced by a high-fat diet. Those effects were evidenced by decreased body weight gain, fat depots accumulation, circulating leptin levels and increased glucose tolerance. The probiotic also reduced the gene expression levels of cocaine- and amphetamine-regulated transcripts, which are hypothalamic neuropeptides involved in appetite modulation in mice.
On translating findings from mice to humans, researchers found that the administration of B. longum APC1472 at a daily dose of 1 x 1010 colony forming units in healthy overweight/obese adults for 12 weeks led to greater reductions in fasting blood glucose levels compared to placebo.
More interestingly, the effect size of reducing glucose in the obese subpopulation was greater than the effect size in the overall study population. In addition, in the subgroup of participants with obesity, the probiotic also normalized cortisol awakening responses in saliva and ghrelin in blood—two variables that are altered in obesity. Those changes were mediated by an increase in the abundance of Bifidobacterium in the gut microbiota.
However, the probiotic did not change body mass index and waist-to-hip ratio, showing the partial translation from mice to humans in one component of metabolic syndrome. The most reported adverse event was constipation.
Altogether, the findings show the benefits of the probiotic B. longum APC1472 in improving glucose and ghrelin levels, which are biomarkers associated not only with obesity but also with other metabolic-related conditions such as type 2 diabetes.
The connection between stress and obesity has been known for a long time. Regarding how these findings might impact on clinical practice of dietitians and endocrinologists in the foreseeable future, Schellekens explained that “the findings from this study highlight the promising potential of B. longum APC1472 to be developed as a valuable probiotic supplement to reduce blood glucose, which is important in the development of conditions such as type 2 diabetes, and as a potential probiotic in conditions of stress”.
It should be acknowledged that, in the light of all the available evidence, it is too early to recommend the use of probiotics for preventing or managing obesity. This is explained by several factors, including the small sample sizes of studies, the heterogeneity of the studied populations, the absence of long-term follow-up and the use of different probiotic strains with mechanisms of action that are not always clinically relevant.
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