Effects of Anthocyanin on Intestinal Health: A Systematic Review

Abstract

Intestinal health relies on the association between the mucosal immune system, intestinal barrier and gut microbiota. Bioactive components that affect the gut microbiota composition, epithelial physical barrier and intestinal morphology were previously studied. The current systematic review evaluated evidence of anthocyanin effects and the ability to improve gut microbiota composition, their metabolites and parameters of the physical barrier; this was conducted in order to answer the question: "Does food source or extract of anthocyanin promote changes on intestinal parameters?". The data analysis was conducted following the PRISMA guidelines with the search performed at PubMed, Cochrane and Scopus databases for experimental studies, and the risk of bias was assessed by the SYRCLE tool. Twenty-seven studies performed in animal models were included, and evaluated for limitations in heterogeneity, methodologies, absence of information regarding allocation process and investigators' blinding. The data were analyzed, and the anthocyanin supplementation demonstrated positive effects on intestinal health. The main results identified were an increase of Bacteroidetes and a decrease of Firmicutes, an increase of short chain fatty acids production, a decrease of intestinal pH and intestinal permeability, an increase of the number of goblet cells and tight junction proteins and villi improvement in length or height. Thus, the anthocyanin supplementation has a potential effect to improve the intestinal health. PROSPERO (CRD42020204835).

Keywords: intestinal barrier; microbiota; polyphenols; short chain fatty acids.

Figure 1

Flowchart of the search for articles included in the systematic review, according to PRISMA (2020) recommendation.

Figure 2

Risk of bias of animal studies.

Figure 3

Proposed mechanisms of action of anthocianins on intestinal health. Abbreviations: ZO-1: zonula occludentes–1; SCFA: short chain fatty acids; LPS: lipopolysaccharides; TLR-4: Toll like receptor 4; IP: intestinal permeability; mTOR: mammaliam target of rapamycin; STAT3: signal transducers and activator of transcription 3; NF-ĸB: factor nuclear kappa B; MyD88: Myeloid differentiation primary response 88; IkBα: I-Kappa-B-alpha; NLRP6: inflammasome nucleotide-oligomerization domain-like receptor 6; GRP43: G protein-coupled receptor; TNF-α: tumor necrosis factor alpha IL1β:interleukin 1 beta; Nrf2: erythroid-2-related factor.