Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Meta-Analysis
. 2019 Oct 18;11(10):2512.
doi: 10.3390/nu11102512.

Short Chain Fatty Acids and Fecal Microbiota Abundance in Humans with Obesity: A Systematic Review and Meta-Analysis

Affiliations
Meta-Analysis

Short Chain Fatty Acids and Fecal Microbiota Abundance in Humans with Obesity: A Systematic Review and Meta-Analysis

Kyu Nam Kim et al. Nutrients. .

Abstract

There have been mixed results regarding the relationship among short chain fatty acids (SCFAs), microbiota, and obesity in human studies. We selected studies that provided data on SCFA levels or fecal microbiota abundance in obese and nonobese individuals and then combined the published estimates using a random-effects meta-analysis. Obese individuals had significantly higher fecal concentrations of acetate (SMD (standardized mean differences) = 0.87, 95% CI (confidence interva) = 0.24-1.50, I2 (I-squared) = 88.5), propionate (SMD = 0.86, 95% CI = 0.35-1.36, I2 = 82.3%), and butyrate (SMD = 0.78, 95% CI = 0.29-1.27, I2 = 81.7%) than nonobese controls. The subgroup analyses showed no evidence of heterogeneity among obese individuals with a BMI >30 kg/m2 (I2 = 0.0%). At the phylum level, the abundance of fecal microbiota was reduced in obese compared to nonobese individuals, but the difference was not statistically significant (Bacteroidetes phylum, SMD = -0.36, 95% CI = -0.73-0.01; Firmicutes phylum, SMD = -0.10, 95% CI = -0.31-0.10). The currently available human case-control studies show that obesity is associated with high levels of SCFA but not gut microbiota richness at the phylum level. Additional well-designed studies with a considerable sample size are needed to clarify whether this association is causal, but it is also necessary to identify additional contributors to SCFA production, absorption, and excretion in humans.

Keywords: colon; feces; humans; microbiome; obesity; systematic review.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Flow diagram of the search strategy and study selection process.
Figure 2
Figure 2
Forest plots of studies of short-chain fatty acid (SCFA) levels in obese and non-obese individuals. The combined standardized mean differences (SMD) and 95% confidence intervals (CIs) were calculated using random-effects models.
Figure 3
Figure 3
Begg’s funnel plots with 95% confidence intervals for the meta-analysis of SCFAs and obesity. (a) total SCFA; (b) acetate; (c) propionate; (d) butyrate; (e) iso-butyrate; (f) valerate; (g) iso-valerate.
Figure 4
Figure 4
Subgroup analyses of the fecal short-chain fatty acid (SCFA) levels in obese and nonobese individuals. a. Forest plots of 20 data sets of SCFA levels in obese cases (BMI >25kg/m2) and nonobese controls (BMI <25kg/m2); b. Forest plots of 17 datasets of SCFA levels in obese cases (BMI >30kg/m2) and nonobese controls (BMI <25kg/m2). The combined standardized mean differences (SMDs) and 95% confidence intervals (CIs) were calculated using random effects models.
Figure 5
Figure 5
Forest plots of studies of fecal microbiota abundance at the phylum level in obese and nonobese individuals. The combined standardized mean differences (SMD) and 95% confidence intervals (CIs) were calculated using random effects models.
Figure 6
Figure 6
Association between age and the fecal microbiota abundance in obese and nonobese individuals. The participants’ mean ages were modeled using separate random-effects meta-regression models. The fecal microbiota ((a) Bacteroidetes; (b) Firmicutes) abundance levels were compared between obese and nonobese individuals. The Y axes indicate a standardized mean difference (SMD). Each circle represents a study and the size of the circle reflects the influence of that study on the model. The circle size is inversely proportional to the standard error of that study. The solid lines represent the weighted regression lines based on variance-weighted least squares.

References

    1. Upadhyay J., Farr O., Perakakis N., Ghaly W., Mantzoros C. Obesity as a Disease. Med. Clin. N. Am. 2018;102:13–33. doi: 10.1016/j.mcna.2017.08.004. - DOI - PubMed
    1. Blaut M. Gut microbiota and energy balance: Role in obesity. Proc. Nutr. Soc. 2015;74:227–234. doi: 10.1017/S0029665114001700. - DOI - PubMed
    1. Brusaferro A., Cozzali R., Orabona C., Biscarini A., Farinelli E., Cavalli E., Grohmann U., Principi N., Esposito S. Is It Time to Use Probiotics to Prevent or Treat Obesity? Nutrients. 2018;10:1613. doi: 10.3390/nu10111613. - DOI - PMC - PubMed
    1. Morrison D.J., Preston T. Formation of short chain fatty acids by the gut microbiota and their impact on human metabolism. Gut Microbes. 2016;7:189–200. doi: 10.1080/19490976.2015.1134082. - DOI - PMC - PubMed
    1. den Besten G., Lange K., Havinga R., van Dijk T.H., Gerding A., van Eunen K., Muller M., Groen A.K., Hooiveld G.J., Bakker B.M., et al. Gut-derived short-chain fatty acids are vividly assimilated into host carbohydrates and lipids. Am. J. Physiol. 2013;305:G900–G910. doi: 10.1152/ajpgi.00265.2013. - DOI - PubMed