Gut bacteria predictive of body mass index (BMI), waist circumference, and fat mass are different in men and women, and therefore, interventions to prevent obesity may need to be different, as well, new research suggested.
Metagenomic analyses of fecal samples and metabolomic analyses of serum samples from 361 volunteers in Spain showed that an imbalance in specific bacterial strains likely play an important role in the onset and development of obesity, and that there are “considerable differences” between the sexes, said lead study author Paula Aranaz, MD, Centre for Nutrition Research, at the University of Navarra, Pamplona, Spain.
“We are still far from knowing the magnitude of the effect that the microbiota [bacteria, viruses, fungi, and protozoa] has on our metabolic health and, therefore, on the greater or lesser risk of suffering from obesity,” Dr. Aranaz told this news organization.
“However,” she said, “what does seem clear is that the microorganisms of our intestine perform a crucial role in the way we metabolize nutrients and, therefore, influence the compounds and molecules that circulate through our body, affecting different organs and tissues, and our general metabolic health.”
The study will be presented at the European Congress on Obesity (ECO) 2024, to be held in Venice, Italy, from May 12 to 15. The abstract is now available online.
Variation in Bacteria Species, Abundance
The researchers examined the fecal metabolome of 361 adult volunteers (median age, 44; 70%, women) from the Spanish Obekit randomized trial, which investigated the relationship between genetic variants and how participants responded to a low-calorie diet.
A total of 65 participants were normal weight, 110 with overweight, and 186 with obesity. They were matched for sex and age and classified according to an obesity (OB) index as LOW or HIGH.
LOW included those with a BMI ≤ 30 kg/m2, fat mass percentage ≤ 25% (women) or ≤ 32% (men), and waist circumference ≤ 88 cm (women) or ≤ 102 cm (men). HIGH included those with a BMI > 30 kg/m2, fat mass > 25% (women) or > 32% (men), and waist circumference > 88 cm (women) or > 102 cm (men).
In men, a greater abundance of Parabacteroides helcogenes and Campylobacter canadensis species was associated with higher BMI, fat mass, and waist circumference.
By contrast, in women, a greater abundance of Prevotella micans, P brevis, and P sacharolitica was predictive of higher BMI, fat mass, and waist circumference.
Untargeted metabolomic analyses revealed variation in the abundance of certain metabolites in participants with a HIGH OB index — notably, higher levels of phospholipids (implicated in the development of metabolic disease and modulators of insulin sensitivity) and sphingolipids, which play a role in the development of diabetes and the emergence of vascular complications.
“We can reduce the risk of metabolic diseases by modulating the gut microbiome through nutritional and lifestyle factors, including dietary patterns, foods, exercise, probiotics, and postbiotics,” Dr. Aranaz said. Which modifications can and should be made “depend on many factors, including the host genetics, endocrine system, sex, and age.”
The researchers currently are working to try to relate the identified metabolites to the bacterial species that could be producing them and to characterize the biological effect that these species and their metabolites exert on the organism, Dr. Aranaz added.
Ultimately, she said, “we would like to [design] a microbiota/metabolomic test that can be used in clinical practice to identify human enterotypes and to personalize the dietary strategies to minimize the health risks related to gut dysbiosis.”
No funding was reported. Dr. Aranaz declared no conflicts of interest.
A version of this article appeared on Medscape.com .