Japanese population: 23 BMI < 20 kg/m2 and 33 BMI ≥ 25 kg/m2 Subsample: 4 nonobese and 6 obese subjects
Bacterial diversity was significantly greater in obese subjects compared with nonobese subjects. Reduced numbers of Bacteroidetes and a higher F/B ratio in obese subjects compared with nonobese subjects.
L. reuteri was associated with obesity. M. smithii was depleted in obese subjects. Some Bifidobacterium or Lactobacillus species were associated with normal weight (B. animalis).
39 men and 36 women with CVD within CORDIOPREV study 3 groups according to BMI: BMI < 30, 30 < BMI < 33, and BMI > 33
F/B ratio changed with the BMI and between genders. Men had higher F/B ratio under a BMI of 33. By contrast, men had a significantly lower F/B ratio than women in the BMI > 33 group. At genera level, BMI > 33: higher Bacteroides genus in women, but decrease in men.
Firmicutes and Actinobacteria were the most predominant phyla of the bacterial composition of the duodenal microbiota in both groups. The obese group presented a higher proportion of anaerobic genera and a lesser proportion of aerobic genera, mostly associated with the presence of Veillonella, Bulleidia, and Oribacterium.
The interstudy variability in the taxonomic composition of stool microbiomes far exceeds differences between lean and obese individuals within studies. No quantitative association between the continuous BMI variable and the ratio of B/F. Variation in the relative abundance of F and B is much larger among studies than between lean and obese individuals within any study. MetaHIT and HMP go in the opposite direction [11].
Twin population: 416 twin pairs, mostly females, mean age 60.6 ± 0.3 years : BMI < 25 : BMI 25–30 : BMI > 30
The family Christensenellaceae was significantly enriched in subjects with a BMI < 25 compared to those with BMI > 30. Overall, a majority () of the OTUs with highest heritability scores were enriched in the lean subjects. A subset of OTUs classified as Oscillospira were enriched in lean subjects, and M. smithii, though not significantly heritable, was positively associated with a lean BMI.
16 healthy monozygotic twin pairs discordant for weight (BMI difference > 3 kg/m2) Control pairs: nine concordant monozygotic pairs
No differences in fecal bacterial diversity were detected when comparing cotwins discordant for weight. We found that within-pair similarity is a dominant factor in the metabolic postprandial response, independent of acquired obesity.
Fecal samples
Diversity of the major bacterial groups by using 5 different validated bacterial group-specific DGGE methods
30 obese, 24 overweight, and 30 lean children (3–11 years old)
B. fragilis group and Lactobacillus spp. were found at high concentrations in obese and overweight children when compared with the lean ones and positively correlated with BMI. Bifidobacterium spp. were found in higher numbers in the lean group than the overweight and obese ones. Furthermore, a negative correlation between BMI and Bifidobacterium spp. copy number was observed.
Cross-sectional study fecal samples from 67 obese (BMI > 30 kg/m2) and 67 normal (BMI < 25 kg/m2) individuals
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Korean adolescents aged 13–16 years
No significant differences in the Bacteroidetes, Firmicutes, and Proteobacteria populations in samples from normal and obese adolescents at the phylum level, although the proportion of Bacteroides was highest in normal children (45%), whereas that in obese was 25%. Conversely, the proportion of Prevotella in BMI < 25 was 16%; obese adolescents (35%).
T-RFLP reference human fecal microbiota profiling; qPCR: quantitative PCR; CVD: cardiovascular disease; DGGE: denaturing gradient gel electrophoresis.
