Different Levels of Urinary Short-chain Fatty Acids in Overweight and Normal-weight Children

Background: Obesity may bring about various co-morbidities, which commonly not only include cardiometabolic disorders but also mood and cognitive disorders. Gut microbiota which attracts researchers’ much attention recently plays an important role in maintaining human health. As the major metabolites of gut microbiota, short-chain fatty acids (SCFAs) detected in faces have been found to be associated with childhood obesity. But it has been unclear whether SCFAs in urines have the same association. This study focuses on the comparison of urinary SCFAs concentrations from overweight and normal children, trying to find certain interplay between urinary SCFAs and childhood obesity.

Methods: We analyzed the data from 23 overweight children and 23 normal weight children aged 5-6 years. The concentrations of eight urinary short-chain fatty acids -- acetic acid, propionic acid, isobutyric acid, butyric acid, isovaleric acid, valeric acid, hexanoic acid, heptanoic acid, were measured using gas chromatography-mass spectrometer (GC-MS).

Results: Overweight children showed significantly higher levels of acetic acid (P<.001), propionic acid (P<.001), isobutyric acid (P=.003), isovaleric acid (P<.001), hexanoic acid (P<.001) and heptanoic acid (P<.001) than normal-weight children. Positive correlations were found between BMI and acetic acid (r=.460, P=.001), and propionic acid (r=.452, P=.002), and isovaleric acid (r=.366, P=.012), and hexanoic acid (r=.648, P<.001).

Conclusion: Urinary SCFAs are related to childhood obesity as well, compared to fecal ones. Overweight/obese children might have higher levels of SCFAs than normal ones. Our results suggest that detecting short-chain fatty acids in urine samples is a feasible method in studying multiple obesity-associated health consequences.