HealthDay News – Individuals with a lower level of intestinal flora diversity tend to be heavier and have more inflammation and metabolic dysfunction than those with more robust gut bacteria, researchers have found.

About a quarter of Danish patients from the European consortium MetaHIT had low bacterial gut richness, which was associated with greater adiposity, insulin resistance and dyslipidemia compared with those with greater bacterial diversity, Oluf Pedersen, MD, of the University of Copenhagen and colleagues reported in Nature.

“The present report provides evidence that studies of alterations in our other genome — the microbial gut metagenome — may define subsets of adult individuals with different metabolic risk profiles,” they wrote.

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The researchers performed a DNA analysis to examine gut microbial composition in 292 Danish patients, 169 of whom were obese and 123 who were not and found that the groups differed.

They found that 23% of their population had low bacterial richness, with an average of 380,000 microbial genes compared with an average of 640,000 genes in the remaining population.

Patients with lower gene counts were characterized by more marked overall adiposity, insulin resistance, dyslipidemia, and a more pronounced inflammatory phenotype compared to those with high bacterial richness.

Within the low bacterial richness group, obese individuals also gained significantly more weight during the previous nine years.

Certain bacterial species were associated with the two groups. Anti-inflammatory species such as Faecalibacterium, Bifidobacterium, and Lactobacillus were more common in patients with high microbiotic diversity whereas inflammatory species including Bacteroides and Ruminococcus were associated with low diversity.

In a second study published in the same journal, researchers found that diet can influence the gut micrbiome.

Aurélie Cotillard of 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.

A six-week, energy-restricted, high-protein diet plus six weeks of weight maintenance improved the number and diversity of microbial species.

The researchers found that more pronounced dys-metabolism and low-grade inflammation was present in individuals with reduced microbial gene richness (40%).

A six-week, energy-restricted, high-protein diet plus six weeks of weight maintenance improved the number and diversity of microbial species. However, the intervention was less efficient at improving inflammation variables in those with lower baseline 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 write.

In an accompanying editorial, Sungsoon Fang, PhD, and Ronald Evans, PhD, of the Gene Expression Laboratory at the Salk Institute in La Jolla, Calif., suggest that gut microbial diversity may function as a new biomarker for to screen for and treat metabolic disorder.

“Such a concept is promising for clinical research and pharmaceutical drug development, because it opens potential avenues for customizing drugs and reprogramming microbial ecology in individual patients,” they wrote.


  1. Le Chatelier E et al. Nature. 2013; 500: 541-549. 
  2. Cotillard A et al. Nature. 2013; 500: 585-590. 
  3. Fang S, Evans RM. Nature. 2013; 500: 538-539.