Abstract
Obesity is an increasing public health concern worldwide. According to the latest Organization for Economic Co-operation and Development (OECD) report (2014), the incidence of child obesity in Korea has exceeded the OECD average. To better understand and control this condition, the present study examined the composition of the gut microbial community in normal and obese adolescents. Fecal samples were collected from 67 obese (body mass index [BMI] ≥ 30 kg/m2, or ≥ 99th BMI percentile) and 67 normal (BMI < 25 kg/m2 or < 85th BMI percentile) Korean adolescents aged 13–16 years and subjected to 16S rRNA gene sequencing. Analysis of bacterial composition according to taxonomic rank (genus, family, and phylum) revealed marked differences in the Bacteroides and Prevotella populations in normal and obese samples (p < 0.005) at the genus and family levels; however, there was no difference in the Firmicutes-to-Bacteroidetes (F/B) ratio between normal and obese adolescents samples at the phylum level (F/B normal = 0.50 ± 0.53; F/B obese = 0.56 ± 0.86; p = 0.384). Statistical analysis revealed a significant association between the compositions of several bacterial taxa and child obesity. Among these, Bacteroides and Prevotella showed the most significant association with BMI (p < 0.0001 and 0.0001, respectively). We also found that the composition of Bacteroides was negatively associated with triglycerides (TG), total cholesterol, and high-sensitive C-reactive protein (hs-crp) (p = 0.0049, 0.0023, and 0.0038, respectively) levels, whereas that of Prevotella was positively associated with TG and hs-crp levels (p = 0.0394 and 0.0150, respectively). We then applied the association rule mining algorithm to generate “rules” to identify the association between the populations of multiple bacterial taxa and obesity; these rules were able to discriminate obese from normal states. Therefore, the present study describes a systemic approach to identify the association between bacterial populations in the gut and childhood obesity.
Highlights
Obesity is a public health issue worldwide and tops the public health agenda in both industrialized and developing countries
A total of 134 adolescents aged 13 to 16 years were recruited from Seoul and Kyunggi province as part of the Korean Children and Adolescent Study (KoCAS) in 2012, which has monitored this cohort on an annual basis since they entered elementary school in 2005 aged 7 years
We found no significant differences between the Bacteroidetes, Firmicutes, and Proteobacteria populations in normal and obese adolescents (Fig 3A)
Summary
Obesity is a public health issue worldwide and tops the public health agenda in both industrialized and developing countries. The recently emerged field of metagenomics has allowed researchers to examine the microorganisms that inhabit the human gut, known as the microbiota, as a novel environmental factor associated with obesity [7,8,9,10,11,12]. These studies identified marked changes in the composition of the gut microbiota and its metabolic function in obese subjects. A metagenomic analysis of samples from European populations indicated that the number of gut microbial genes, and the “richness” of gut bacterial population, differed between obese and lean groups [20]
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