It’s often said that good health begins in the gut, an aphorism that is well supported by two studies published in the August 29 issue of Nature (2013; 500, 541-46). In short, individuals with low bacterial richness in their gut have more obesity and inflammation—and weight loss can improve the richness of their bacterial genes.
Emmanuelle Le Chatelier, from the Institut National de la Recherche Agronomique in Jouy en Josas, France, and colleagues examined the microbial composition of the human gut in 123 nonobese and 169 obese Danish individuals. The researchers found that the groups differed with respect to the number of microbial genes in the gut. Twenty-three percent of the population were individuals with low bacterial richness and were characterized by more marked overall adiposity, insulin resistance and dyslipidemia (abnormal amount of fat in the blood), and by a more marked inflammatory phenotype, compared with those whose bacterial richness was high. Within the group with low bacterial richness, obese individuals also gained more weight over time. A few bacterial species were able to differentiate between lean and obese participants.
Aurélie Cotillard, from the Centre de Recherches des Cordeliers in Paris, and colleagues examined the temporal relationship between food intake, gut microbiota, and metabolic and inflammatory phenotypes during a diet-induced weight loss and weight stabilization intervention conducted in 38 obese and 11 overweight individuals. The researchers found that more pronounced dysmetabolism and low-grade inflammation were present in those with reduced microbial-gene richness (40%). Low gene richness and clinical phenotypes improved with dietary intervention, but the intervention was less efficient for inflammation variables in those with lower gene richness.
“This finding, although exploratory in nature and requiring replication, supports a recently reported link between long-term dietary habits and the structure of gut microbiota, and suggests that a permanent change of microbiota may be achieved by appropriate diet,” Cotillard and colleagues wrote.