The association of gut microbiota with body weight and body mass index in preschool children of Estonia.

Background: The gut microbiota has been shown to affect both fat storage and energy harvesting, suggesting that it plays a direct role in the development of obesity. The aim of this study was to investigate whether intestinal colonization by particular species/groups of the intestinal microbiota is related to body weight values in Estonian preschool children born in different years during the entire 1990s.

Methods: Body weight, height, body mass index (BMI), and quantitative composition of cultivable gut microbiota (staphylococci, enterococci, streptococci, enterobacteria, lactobacilli, anaerobic gram-positive cocci, bifidobacteria, eubacteria, bacteroides, clostridia, and candida) were studied in 51 healthy 5-year-old children (40 were born between 1993 and 94 and 11 were born between 1996 and 97).

Results: At the age of 5 years, median weight was 19.5 kg and median BMI was 15.3 kg/m(2). Significantly higher BMI (p=0.006) was found in 5-year-old children born in late versus early 1990s during the development of socioeconomic situation of Estonia (2% rise in gross domestic product). The counts of the different gut bacteria did not show any association with weight and BMI in the 5-year-old children. However, the BMI values were in positive correlation with a relative share of anaerobic gram-positive bacteria, for example, bifidobacteria when adjusted for sex and year of birth (adj R(2)=0.459, p=0.026) and eubacteria (adj R(2)=0.484, p=0.014) in the community of cultured intestinal microbiota. The relative share of bacteroides showed a negative correlation with the childrens' weight (adj R(2)=- 0.481, p=0.015).

Conclusion: The body weight indices of preschool children of the general population are associated with the proportion of anaerobic intestinal microbiota and can be predicted by sex and particular socioeconomic situation from birth to 5 years of age.