Black corn (Zea mays L.) flour has the potential to improve the gut microbiota composition and goblet cell proliferation in mice fed a high-fat diet

High-fat diets are associated with intestinal dysbiosis and leaky gut leading to intestinal inflammation. Bioactive components, including phenolic compounds, isolated or in their original food matrix, have alleviated intestinal impairments promoted by a high-fat diet. Black corn (Zea mays L.) is a colored corn in which anthocyanins are the most abundant bioactive compound. Thus, we hypothesized that black corn flour may have preventive effects on poor intestinal health in mice fed a high-fat diet. To study this, 30 C57BL/6 mice were randomly divided into 3 experimental groups receiving the following diets for 8 weeks: normal control (fed a normal diet); high-fat (fed a high-fat diet: 60% of calories from fat); high-fat corn (fed a high-fat diet added with 20% of black corn whole flour). The cecal microbiota analyzed by 16S ribosomal RNA sequencing showed that black corn flour intake increased the relative abundance of Ruminococcus, Roseburia, and Prevotellaceae_UCG-001, and decreased Bacteroides and Faecalibaculum. No difference was observed in the cecal short-chain fatty acids and fecal pH among the experimental groups (P > .05). Further, the consumption of black corn flour improved cecal morphology by increasing the number of goblet cells but with no difference in the crypt depth and width. These findings suggest that black corn flour as a source of anthocyanins could have preventive effects on gut dysbiosis resulting from a high-fat diet. SCFA, short chain fatty acids.

Effect of Black Corn Anthocyanin-Rich Extract (Zea mays L.) on Cecal Microbial Populations In Vivo (Gallus gallus)

Black corn has been attracting attention to investigate its biological properties due to its anthocyanin composition, mainly cyanidin-3-glucoside. Our study evaluated the effects of black corn extract (BCE) on intestinal morphology, gene expression, and the cecal microbiome. The BCE intra-amniotic administration was evaluated by an animal model in Gallus gallus. The eggs (n = 8 per group) were divided into: (1) no injection; (2) 18 MΩ H2O; (3) 5% black corn extract (BCE); and (4) 0.38% cyanidin-3-glucoside (C3G). A total of 1 mL of each component was injected intra-amniotic on day 17 of incubation. On day 21, the animals were euthanized after hatching, and the duodenum and cecum content were collected. The cecal microbiome changes were attributed to BCE administration, increasing the population of Bifidobacterium and Clostridium, and decreasing E. coli. The BCE did not change the gene expression of intestinal inflammation and functionality. The BCE administration maintained the villi height, Paneth cell number, and goblet cell diameter (in the villi and crypt), similar to the H2O injection but smaller than the C3G. Moreover, a positive correlation was observed between Bifidobacterium, Clostridium, E. coli, and villi GC diameter. The BCE promoted positive changes in the cecum microbiome and maintained intestinal morphology and functionality.

Black corn (Zea mays L.) whole flour improved the antioxidant capacity and prevented adipogenesis in mice fed a high-fat diet

Black corn (Zea mays L.) is a source of anthocyanins, which have shown the ability to reduce metabolic disorders. This study investigated the anti-inflammatory, antioxidant, and anti-adipogenic preventive effects of black corn. C57BL/6 mice were divided into 3 groups (n = 10): normal control (NC): AIN-93 M; high-fat diet (HF); HF + corn (20%) (HFC). Black corn improved the antioxidant status, through the superoxide dismutase hepatic levels and serum total antioxidant capacity. Animals fed an HFC diet showed decreased gene expression of sterol regulatory element-binding protein-1c (SREBP-1c) and peroxisome proliferator-activated receptor-γ (PPARγ) and increased gene expression of adiponectin and lipoprotein lipase in the adipose tissue, which led to a less inflammatory infiltrate and decreased the adipocyte number and length. In the liver, black corn reduced the gene expression of SREBP-1c and acetyl CoA carboxilase 1. Therefore, black corn whole flour improved the antioxidant capacity, contributed to hepatic β-oxidation, and decreased adipogenesis in animals.

Effects of Anthocyanin on Intestinal Health: A Systematic Review

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).