Additionally, CRC incidence was higher in individuals with lower levels of SCFAs (SMD = 0.45, 95% CI 0.19 to 0.72, P = 0.0009), compared to healthy individuals. ResultsĬombined analysis of acetic, propionic, and butyric acid revealed significantly lower concentrations of these SCFAs in individuals with a high-risk of CRC (SMD = 2.02, 95% CI 0.31 to 3.74, P = 0.02). Studies lacking quantitation were included in qualitative analyses.

Standardized mean differences (SMD) with 95% confidence intervals (CI) were calculated using a random-effects model. Studies were categorized for CRC risk or incidence, and RevMan 5.4 was used to perform the meta-analyses. Predefined inclusion/exclusion criteria led to the selection of 17 case-control and six cross-sectional studies for quality assessment and analyses.

Data extraction through Medline, Embase, and Web of Science was carried out from database conception to June 29, 2022. We performed a systematic review and meta-analysis to examine the associations of fecal SCFA concentrations to the incidence and risk of CRC. The beneficial role of gut microbiota and bacterial metabolites, including short-chain fatty acids (SCFAs), is well recognized, although the available literature around their role in colorectal cancer (CRC) has been inconsistent.

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