Dietary intervention impact on gut microbial gene richness | Nature

In obese and overweight individuals, diet-induced weight loss and weight-stabilization interventions improve the low microbiota gene richness and clinical phenotypes seen before intervention, but have less of an effect on inflammatory phenotypes. Obesity is a risk factor for cardiovascular disease, diabetes, osteoporosis and other conditions including some cancers. Other influences must be at work to determine which, if any, metabolic diseases obese individuals will suffer, and two papers in this issue of Nature look at the role one of these factors, the richness of the gut microbiome. Le Chatelier et al. analysed the gut microbial gene composition in non-obese and obese individuals and found marked differences in gene and species richness. Individuals with low richness exhibited increased adiposity, insulin resistance, dyslipidaemia and inflammation. Obese individuals with low microbial richness tended to gain more body weight than those with high microbial richness. The authors also demonstrate that analysis of just a few bacterial marker species was sufficient to distinguish between high and low bacterial richness. Cotillard et al. monitored gut microbe profiles during diet-induced weight loss and weight stabilization interventions in obese or overweight individuals. They report that increased consumption of high-fibre foods, such as fruit and vegetables, leads to an increase in bacterial richness and improves some clinical symptoms associated with obesity. This finding supports previous work linking diet to the composition of gut microbe populations, and suggests that a permanent change might be achieved by appropriate diet. Complex gene–environment interactions are considered important in the development of obesity1. The composition of the gut microbiota can determine the efficacy of energy harvest from food2,3,4 and changes in dietary composition have been associated with changes in the composition of gut microbial populations5,6. The capacity to explore microbiota composition was markedly improved by the development of metagenomic approaches7,8, which have already allowed production of the first human gut microbial gene catalogue9 and stratifying individuals by their gut genomic profile into different enterotypes10, but the analyses were carried out mainly in non-intervention settings. To investigate the temporal relationships between food intake, gut microbiota and metabolic and inflammatory phenotypes, we conducted diet-induced weight-loss and weight-stabilization interventions in a study sample of 38 obese and 11 overweight individuals. Here we report that individuals with reduced microbial gene richness (40%) present more pronounced dys-metabolism and low-grade inflammation, as observed concomitantly in the accompanying paper11. Dietary intervention improves low gene richness and clinical phenotypes, but seems to be less efficient for inflammation variables in individuals with lower gene richness. Low gene richness may therefore have predictive potential for the efficacy of intervention....