Current Hypothesis for the Relationship between Dietary Rice Bran Intake, the Intestinal Microbiota and Colorectal Cancer Prevention

Role of Dietary Defatted Rice Bran in the Modulation of Gut Microbiota in AOM/DSS-Induced Colitis-Associated Colorectal Cancer Rat Model

Defatted rice bran (DRB) is a by-product of rice bran derived after the oil extraction. DRB contains several bioactive compounds, including dietary fiber and phytochemicals. The supplementation with DRB manifests chemopreventive effects in terms of anti-chronic inflammation, anti-cell proliferation, and anti-tumorigenesis in the azoxymethane (AOM) and dextran sodium sulfate (DSS)-induced colitis-associated colorectal cancer (CRC) model in rats. However, little is known about its effect on gut microbiota. Herein, we investigated the effect of DRB on gut microbiota and short chain fatty acid (SCFA) production, colonic goblet cell loss, and mucus layer thickness in the AOM/DSS-induced colitis-associated CRC rat model. The results suggested that DRB enhanced the production of beneficial bacteria (Alloprevotella, Prevotellaceae UCG-001, Ruminococcus, Roseburia, Butyricicoccus) and lessened the production of harmful bacteria (Turicibacter, Clostridium sensu stricto 1, Escherichia-Shigella, Citrobacter) present in colonic feces, mucosa, and tumors. In addition, DRB also assisted the cecal SCFAs (acetate, propionate, butyrate) production. Furthermore, DRB restored goblet cell loss and improved the thickness of the mucus layer in colonic tissue. These findings suggested that DRB could be used as a prebiotic supplement to modulate gut microbiota dysbiosis, which decreases the risks of CRC, therefore encouraging further research on the utilization of DRB in various nutritional health products to promote the health-beneficial bacteria in the colon.

Plasma, urine, and stool metabolites in response to dietary rice bran and navy bean supplementation in adults at high-risk for colorectal cancer

Introduction

Dietary intake of whole grains and legumes and adequate physical activity (PA) have been associated with reduced colorectal cancer (CRC) risk. A single-blinded, two-arm, randomized, placebo-controlled pilot trial was implemented to evaluate the impact of a 12-week dietary intervention of rice bran + navy bean supplementation and PA education on metabolite profiles and the gut microbiome among individuals at high risk of CRC.

Methods

Adults (n=20) were randomized 1:1 to dietary intervention or control. All participants received PA education at baseline. Sixteen study foods were prepared with either heat-stabilized rice bran + navy bean powder or Fibersol®-2 as a placebo. Intervention participants consumed 30 g rice bran + 30 g navy bean powder daily; those in the control group consumed 10 g placebo daily. Non-targeted metabolite profiling was performed by UPLC-MS/MS to evaluate plasma, urine, and stool at 0, 6, and 12 weeks. Stool was also analyzed for primary and secondary bile acids (BAs) and short chain fatty acids (SCFAs) by UPLC-MS/MS and microbial community structure via 16S amplicon sequencing. Two-way ANOVA was used to compare differences between groups for metabolites, and mixed models were used to compare differences between groups for BAs, SCFAs, and alpha and beta diversity measures of microbial community structure.

Results

Across biological matrices, the intervention resulted in changes to several amino acid and lipid metabolites, compared to control. There was a 2.33-fold difference in plasma (p<0.001) and a 3.33-fold difference in urine (p=0.008) for the amino acid S-methylcysteine at 12 weeks. Fold-differences to 4-methoxyphenol sulfate in plasma and urine after 6 and 12 weeks (p<0.001) was a novel result from this combined rice bran and navy bean intervention in people. A 2.98-fold difference in plasma (p=0.002) and a 17.74-fold difference in stool (p=0.026) was observed for the lipid octadecenedioylcarnitine at 12 weeks. For stool BAs, 3-oxocholic acid was increased at 12 weeks compared to control within a subset of individuals (mean difference 16.2 ug/uL, p=0.022). No significant differences were observed between groups for stool SCFAs or microbial community structure.

Discussion

Dietary intake of rice bran + navy beans demonstrates beneficial modulation of host and gut microbial metabolism and represents a practical and affordable means of increasing adherence to national guidelines for CRC control and prevention in a high-risk population.

Gender-based effect of absence of gut microbiota on the protective efficacy of Bifidobacterium longum-fermented rice bran diet against inflammation-associated colon tumorigenesis

Dietary rice bran (RB) has shown capacity to influence metabolism by modulation of gut microbiota in individuals at risk for colorectal cancer (CRC), which warranted attention for delineating mechanisms for bidirectional influences and cross-feeding between the host and RB-modified gut microbiota to reduce CRC. Accordingly, in the present study, fermented rice bran (FRB, fermented with a RB responsive microbe Bifidobacterium longum), and non-fermented RB were fed as 10% w/w (diet) to gut microbiota-intactspf or germ-free micegf to investigate comparative efficacy against inflammation-associated azoxymethane/dextran sodium sulfate (AOM/DSS)-induced CRC. Results indicated both microbiota-dependent and independent mechanisms for RB meditated protective efficacy against CRC that was associated with reduced neoplastic lesion size and local-mucosal/systemic inflammation, and restoration of colonic epithelial integrity. Enrichment of beneficial commensals (such as, Clostridiales, Blautia, Roseburia), phenolic metabolites (benzoate and catechol metabolism), and dietary components (ferulic acid-4 sulfate, trigonelline, and salicylate) were correlated with anti-CRC efficacy. Germ-free studies revealed gender-specific physiological variables could differentially impact CRC growth and progression. In the germ-free females, the RB dietary treatment showed a ∼72% reduction in the incidence of colonic epithelial erosion when compared to the ∼40% reduction in FRB-fed micegf . Ex vivo fermentation of RB did not parallel the localized-protective benefits of gut microbial metabolism by RB in damaged colonic tissues. Findings from this study suggest potential needs for safety considerations of fermented fiber rich foods as dietary strategies against severe inflammation-associated colon tumorigenesis (particularly with severe damage to the colonic epithelium).

Enriched Riceberry Bran Oil Exerts Chemopreventive Properties through Anti-Inflammation and Alteration of Gut Microbiota in Carcinogen-Induced Liver and Colon Carcinogenesis in Rats

Riceberry has recently been acknowledged for its beneficial pharmacological effects. Riceberry bran oil (RBBO) exhibited anti-proliferation activity in various cancer cell lines. However, animal studies of RBBO on anti-carcinogenicity and its molecular inhibitory mechanism have been limited. This study purposed to investigate the chemopreventive effects of RBBO on the carcinogen-induced liver and colorectal carcinogenesis in rats. Rats were injected with diethylnitrosamine (DEN) and 1,2-dimethylhydrazine (DMH) and further orally administered with RBBO equivalent to 100 mg/kg body weight of γ-oryzanol 5 days/week for 10 weeks. RBBO administration suppressed preneoplastic lesions including hepatic glutathione S-transferase placental form positive foci and colorectal aberrant crypt foci. Accordingly, RBBO induced hepatocellular and colorectal cell apoptosis and reduced pro-inflammatory cytokine expression. Interestingly, RBBO effectively promoted the alteration of gut microbiota in DEN- and DMH-induced rats, as has been shown in the elevated Firmicutes/Bacteroidetes ratio. This outcome was consistent with an increase in butyrate in the feces of carcinogen-induced rats. The increase in butyrate reflects the chemopreventive properties of RBBO through the mechanisms of its anti-inflammatory properties and cell apoptosis induction in preneoplastic cells. This would indicate that RBBO containing γ-oryzanol, phytosterols, and tocols holds significant potential in the prevention of cancer.

A Review: Cereals on Modulating the Microbiota/Metabolome for Metabolic Health

PURPOSE OF REVIEW

Diet can modulate both the composition and functionality of the human gut microbiota. Cereals are rich in specific macro and functional elements that are considered important dietary components for maintaining human health; therefore, it is important to examine precise nutritional mechanism involved in exerting the health benefits via modulating gut microbiota. The purpose of this review is to summarize recent research on how different cereals in the diet can regulate the microbiota for health and disease.

RECENT FINDINGS

There is an increased interest in targeting the gut microbiome for the treatment of chronic diseases. Cereals can alter the gut microbiome and may improve energy and glucose homeostasis, interfere with host energy homeostasis, appetite, blood glucose regulation, insulin sensitivity, and regulation of host metabolism. However, more human research is necessary to confirm the beneficial health outcomes of cereals via modulating gut microbiota. Cereals play an essential role in shaping the intestinal microbiota that contributes to exerting health effects on various diseases.

Potential use of ground brown rice for weanling pigs

The purpose of the current study was to assess the effects of substituting corn with ground brown rice on growth performance, immune status, and gut microbiota in weanling pigs. Seventy-two weanling pigs (28 d old with 6.78 ± 0.94 kg body weight [BW]) were randomly allotted to two dietary treatments with six pens and six pigs (three barrows and gilts) per pen within a randomized complete block design. The control pigs were fed a typical diet for weanling pigs based on corn and soybean meal diet (control diet: CON), and the other pigs were fed a formulated diet with 100% replacement of corn with ground brown rice for 35d (treatment diet: GBR). Growth performance, immune status, and gut microbiota of weanling pigs were measured. The substitution of corn with GBR did not affect growth performance or diarrhea frequency. Additionally, there were no differences in white blood cell number, hematocrit, cortisol, C-reactive protein, and serum tumor necrosis factor-alpha levels between pigs fed CON or GBR for the first 2 wk after weaning. However, weanling pigs fed GBR had lower (P < 0.05) serum transforming growth factor-beta 1 level than those fed CON. Furthermore, weanling pigs fed GBR had increased (P < 0.05) relative abundance of phylum Firmicutes and genus Lactobacillus and Streptococcus and decreased (P < 0.05) relative abundance of phylum Bacteroidetes and genus Clostridium and Prevotella in the gut microbiota compared with those fed CON. In conclusion, there was no significant difference in growth performance when corn was replaced with ground brown rice in diets for weanling pigs. Furthermore, the substitution of corn with ground brown rice in weaning diet modulated immune status and gut microbiota of pigs by increasing beneficial microbial communities and reducing harmful microbial communities. Overall, ground brown rice-based diet is a potential alternative to corn-based diet without negative effects on growth performance, immune status, and gut microbiota changes of weanling pigs.

Effects of a Rice Bran Dietary Intervention on the Composition of the Intestinal Microbiota of Adults with a High Risk of Colorectal Cancer: A Pilot Randomised-Controlled Trial

Rice bran exhibits chemopreventive properties that may help to prevent colorectal cancer (CRC), and a short-term rice bran dietary intervention may promote intestinal health via modification of the intestinal microbiota. We conducted a pilot, double-blind, randomised placebo-controlled trial to assess the feasibility of implementing a long-term (24-week) rice bran dietary intervention in Chinese subjects with a high risk of CRC, and to examine its effects on the composition of their intestinal microbiota. Forty subjects were randomised into the intervention group (n = 19) or the control group (n = 20). The intervention participants consumed 30 g of rice bran over 24-h intervals for 24 weeks, whilst the control participants consumed 30 g of rice powder on the same schedule. High rates of retention (97.5%) and compliance (≥91.3%) were observed. No adverse effects were reported. The intervention significantly enhanced the intestinal abundance of Firmicutes and Lactobacillus, and tended to increase the Firmicutes/Bacteroidetes ratio and the intestinal abundance of Prevotella_9 and the health-promoting Lactobacillales and Bifidobacteria, but had no effect on bacterial diversity. Overall, a 24-week rice bran dietary intervention was feasible, and may increase intestinal health by inducing health-promoting modification of the intestinal microbiota. Further larger-scale studies involving a longer intervention duration and multiple follow-up outcome assessments are recommended.

Recent trends in cancer therapy: A review on the current state of gene delivery

Cancer treatment has been always considered one of the most critical and vital themes of clinical issues. Many approaches have been developed, depending on the type and the stage of tumor. Gene therapy has the potential to revolutionize different cancer therapy. With the advent of recent bioinformatics technologies and genetic science, it become possible to identify, diagnose and determine the potential treatment using the technology of gene delivery. Several approaches have been developed and experimented in vitro and vivo for cancer therapy including: naked nucleic acids based therapy, targeting micro RNAs, oncolytic virotherapy, suicide gene based therapy, targeting telomerase, cell mediated gene therapy, and CRISPR/Cas9 based therapy. In this review, we present a straightforward introduction to cancer biology and occurrence, highlighting different viral and non-viral gene delivery systems for gene therapy and critically discussed the current and various strategies for cancer gene therapy.

Storage characteristics of infrared radiation stabilized rice bran and its shelf-life evaluation by prediction modeling

BACKGROUND

Rice bran is a nutrient-dense and resource-rich byproduct produced from the rice milling. The limitation of rice bran utilization is mainly caused by oxidative deterioration. Improvement of stability to prolong rice bran shelf-life has thus become an urgent requirement.

RESULTS

The present study aimed to determine the characteristics of infrared radiation heat treatment of rice bran (IRRB) and raw rice bran stored under different temperatures. The effects of heating and storage time on physicochemical, microbial, storage stability and structural properties were investigated. Additionally, the prediction model for the shelf-life of rice bran was established based on free fatty acids and the peroxide value by fitting the curve of bran lipid oxidation. The results obtained demonstrated that infrared radiation heating at 300 °C for 210 s resulted in decreased lipase activity and peroxidase activity of 73.05% and 81.50%, respectively. The free fatty acids and peroxide value of IRRB stored at 4 and 25 °C for 8 weeks were only reached at 2.35% and 3.17% and 2.53 and 3.64 meq kg^-1 , respectively. The shelf-life prediction model showed the the shelf-life of infrared radiation-treated samples increased to 71.6 and 25.8 weeks under storage at 4 and 25 °C, respectively.

CONCLUSION

The stabilizing process could effectively suppress microbial growth and had no prominent effect on the physicochemical and microstructure properties of rice bran and, simultaneously, storage life was greatly extended. © 2020 Society of Chemical Industry.

Rice bran attenuated obesity via alleviating dyslipidemia, browning of white adipocytes and modulating gut microbiota in high-fat diet-induced obese mice

Obesity has become an international public health problem. In this study, an obese mice diet was supplemented with raw rice bran (RRB) or infrared radiation-stabilized rice bran (IRRB) to investigate the attenuation of obesity induced by a high-fat diet. Mice were fed a normal diet or a high-fat diet with and without rice bran supplementation (300 mg per kg body weight per day) by oral gavage for 39 days to investigate the obesity preventive effect. The results indicate that different rice bran supplements reduced body weight, relative adipose tissue weight, inflammation, and serum parameters, and relieve liver steatosis to varying degrees. The data of real-time qPCR and western blots (WB) showed that rice bran activated brown adipose tissue (BAT) and increased white adipose tissue (WAT) browning. Rice bran also reduced the ratio of Firmicutes/Bacteroidetes and enhanced the relative abundance of Akkermansia. In summary, our findings suggest that rice bran intervention played a significant role in reducing dyslipidemia, alleviating inflammation, enhancing thermogenesis and modulating gut microbiota for the prevention and control of obesity.

Phytochemicals and Gastrointestinal Cancer: Cellular Mechanisms and Effects to Change Cancer Progression

Gastrointestinal (GI) cancer is a prevailing global health disease with a high incidence rate which varies by region. It is a huge economic burden on health care providers. GI cancer affects different organs in the body such as the gastric organs, colon, esophagus, intestine, and pancreas. Internal and external factors like smoking, obesity, urbanization, genetic mutations, and prevalence of Helicobacter pylori and Hepatitis B and Hepatitis C viral infections could increase the risk of GI cancer. Phytochemicals are non-nutritive bioactive secondary compounds abundantly found in fruits, grains, and vegetables. Consumption of phytochemicals may protect against chronic diseases like cardiovascular disease, neurodegenerative disease, and cancer. Multiple studies have assessed the chemoprotective effect of selected phytochemicals in GI cancer, offering support to their potential towards reducing the pathogenesis of the disease. The aim of this review was to summarize the current knowledge addressing the anti-cancerous effects of selected dietary phytochemicals on GI cancer and their molecular activities on selected mechanisms, i.e., nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), detoxification enzymes, adenosine monophosphate activated protein kinase (AMPK), wingless-related integration site/β-catenin (wingless-related integration site (Wnt) β-catenin, cell apoptosis, phosphoinositide 3-kinases (PI3K)/ protein kinase B AKT/ mammalian target of rapamycin (mTOR), and mitogen-activated protein kinase (MAPK). In this review phytochemicals were classified into four main categories: (i) carotenoids, including lutein, lycopene, and β-carotene; (ii) proanthocyanidins, including quercetin and ellagic acid; (iii) organosulfur compounds, including allicin, allyl propyl disulphide, asparagusic acid, and sulforaphane; and (iv) other phytochemicals including pectin, curcumins, p-coumaric acid and ferulic acid. Overall, phytochemicals improve cancer prognosis through the downregulation of β-catenin phosphorylation, therefore enhancing apoptosis, and upregulation of the AMPK pathway, which supports cellular homeostasis. Nevertheless, more studies are needed to provide a better understanding of the mechanism of cancer treatment using phytochemicals and possible side effects associated with this approach.

Trimethylamine-N-oxide as One Hypothetical Link for the Relationship between Intestinal Microbiota and Cancer - Where We Are and Where Shall We Go?

Previous epidemiological studies had provided evidence for a link between the microbial dysbiosis and cancer, particularly colorectal cancer (CRC), yet the molecular basis of this link remains elusive. Recently, the association between plasma levels of trimethylamine-N-oxide (TMAO), an oxidised form of trimethylamine (TMA), and risks of various cancers was demonstrated. The discovery could potentially provide an alternative explanation for the aforementioned link, as TMA production is attributed to intestinal bacteria. Current evidence suggests that inflammation could be a potential molecular mechanism to explain the link between TMAO and cancer, although other mechanisms such as oxidative stress, DNA damage and disruption in protein folding might also play a role. This mini-review article first provides an overview of the current evidence for the association between TMAO and certain cancer types, and the potential mechanisms that could explain their association. Thereafter, the direction of further research on the connection between the intestinal microbiota, TMAO and cancer is suggested.

Bifidobacterium longum-fermented rice bran and rice bran supplementation affects the gut microbiome and metabolome

This study investigated gut microbiota composition along with food, host, and microbial derived metabolites in the colon and systemic circulation of healthy mice following dietary rice bran and fermented rice bran intake. Adult male BALB/c mice were fed a control diet or one of two experimental diets containing 10% w/w rice bran fermented by Bifidobacterium longum or 10% w/w non-fermented rice bran for 15 weeks. Metabolomics was performed on the study diets (food), the murine colon and whole blood. These were analysed in concert with 16S rRNA amplicon sequencing of faeces, caecum, and colon microbiomes. Principal components analysis of murine microbiota composition displayed marked separation between control and experimental diets, and between faecal and tissue (caecum and colon) microbiomes. Colon and caecal microbiomes in both experimental diet groups showed enrichment of Roseburia, Lachnospiraceae, and Clostridiales related amplicon sequence variants compared to control. Bacterial composition was largely similar between experimental diets. Metabolite profiling revealed 530 small molecules comprising of 39% amino acids and 21% lipids that had differential abundances across food, colon, and blood matrices, and statistically significant between the control, rice bran, and fermented rice bran groups. The amino acid metabolite, N-delta-acetylornithine, was notably increased by B. longum rice bran fermentation when compared to non-fermented rice bran in food, colon, and blood. These findings support that dietary intake of rice bran fermented with B. longum modulates multiple metabolic pathways important to the gut and overall health.

Rice bran supplementation modulates growth, microbiota and metabolome in weaning infants: a clinical trial in Nicaragua and Mali

Rice bran supplementation provides nutrients, prebiotics and phytochemicals that enhance gut immunity, reduce enteric pathogens and diarrhea, and warrants attention for improvement of environmental enteric dysfunction (EED) in children. EED is a subclinical condition associated with stunting due to impaired nutrient absorption. This study investigated the effects of rice bran supplementation on weight for age and length for age z-scores (WAZ, LAZ), EED stool biomarkers, as well as microbiota and metabolome signatures in weaning infants from 6 to 12 months old that reside in Nicaragua and Mali. Healthy infants were randomized to a control (no intervention) or a rice bran group that received daily supplementation with increasing doses at each month (1–5 g/day). Stool microbiota were characterized using 16S rDNA amplicon sequencing. Stool metabolomes were analyzed using ultra-high-performance liquid-chromatography tandem mass-spectrometry. Statistical comparisons were completed at 6, 8, and 12 months of age. Daily consumption of rice bran was safe and feasible to support changes in LAZ from 6–8 and 8–12 months of age in Nicaragua and Mali infants when compared to control. WAZ was significantly improved only for Mali infants at 8 and 12 months. Mali and Nicaraguan infants showed major differences in the overall gut microbiota and metabolome composition and structure at baseline, and thus each country cohort demonstrated distinct microbial and metabolite profile responses to rice bran supplementation when compared to control. Rice bran is a practical dietary intervention strategy that merits development in rice-growing regions that have a high prevalence of growth stunting due to malnutrition and diarrheal diseases. Rice is grown as a staple food, and the bran is used as animal feed or wasted in many low- and middle-income countries where EED and stunting is prevalent.

Culture-independent studies on bacterial dysbiosis in oral and oropharyngeal squamous cell carcinoma: A systematic review

Imbalance within the resident bacterial community (dysbiosis), rather than the presence and activity of a single organism, has been proposed to be associated with, and to influence, the development and progression of various diseases; however, the existence and significance of dysbiosis in oral/oropharyngeal cancer is yet to be clearly established. A systematic search (conducted on 25/01/2018 and updated on 25/05/2018) was performed on three databases (Pubmed, Web of Science & Scopus) to identify studies employing culture-independent methods which investigated the bacterial community in oral/oropharyngeal cancer patients compared to control subjects. Of the 1546 texts screened, only fifteen publications met the pre-determined selection criteria. Data extracted from 731 cases and 809 controls overall, could not identify consistent enrichment of any particular taxon in oral/oropharyngeal cancers, although common taxa could be identified between studies. Six studies reported the enrichment of Fusobacteria in cancer at different taxonomic levels whereas four studies reported an increase in Parvimonas. Changes in microbial diversity remained inconclusive, with four studies showing a higher diversity in controls, three studies showing a higher diversity in tumors and three additional studies showing no difference between tumors and controls. Even though most studies identified a component of dysbiosis in oral/oropharyngeal cancer, methodological and analytical variations prevented a standardized summary, which highlights the necessity for studies of superior quality and magnitude employing standardized methodology and reporting. Indeed an holistic metagenomic approach is likely to be more meaningful, as is understanding of the overall metabolome, rather than a mere enumeration of the organisms present.

Association of whole grain, refined grain, and cereal consumption with gastric cancer risk: A meta-analysis of observational studies

Many studies have analyzed the relationship between cereal, whole, or refined grain and the risk of gastric cancer (GC) and have yielded mixed results. Therefore, we performed a meta-analysis of observational studies to summarize the available evidence on this topic. Databases such as PubMed, EMBASE, Web of Science, MEDLINE, and the Cochrane Library were searched for studies focusing on these associations from inception to October 2017. Summary odd ratios (OR) and 95% confidence intervals (CI) were calculated by using either a random- or fixed-effect model according to the between-studies heterogeneity. Subgroup analysis was also performed. In total, eleven studies that included 530,176 participants were identified. In a pooled analysis of all studies, cereal exposure was not associated with GC risk (OR, 1.11, 95%CI, 0.85-1.36). Specific analyses indicated that whole grain consumption was associated with decreased GC risk (OR, 0.61, 95%CI, 0.40-0.83) and that refined grain consumption was associated with increased GC risk (OR, 1.65, 95%CI, 1.36-1.94). Higher whole grain and lower refined grain intake but not cereal consumption reduces GC risk. This study has been registered at ClinicalTrials.gov (ID: NCT03419663).

Germinated brown rice combined with Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis inhibits colorectal carcinogenesis in rats

Colorectal cancer is a common cancer strongly associated with diet. Certain probiotics and prebiotics possess an inhibitory activity against colorectal cancer, while synbiotics may be more effective in preventing this cancer than either prebiotics or probiotics alone. Germinated brown rice (GBR) is considered as a candidate prebiotics with anticancer potential. However, the effect of GBR combined with probiotics on colorectal cancer is not clear. The present study investigated the preventive effect of combination of GBR and Lactobacillus acidophilus, Bifidobacterium animalis subsp. lactis, or both on colorectal carcinogenesis and the possible mechanism in rats treated with 1,2-dimethylhydrazine (DMH) and dextran sulfate sodium (DSS). DMH/DSS treatment induced preneoplastic aberrant crypt foci (ACF) and mucin-depleted foci (MDF), reduced superoxide dismutase (SOD) activity, increased anti-apoptotic Bcl-2 expression, and decreased the expression of pro-apoptotic p53, Bax, and caspase-3 in the colon. Germinated brown rice alone or combined with probiotics inhibited the formation of MDF in the middle colon, enhanced the colonic expression of p53 and Bax, and increased the ratio of Bax/Bcl-2. Combined treatment of GBR and probiotics inhibited the formation of ACF-producing sialomucin (SIM-ACF) and recovered the activity of SOD in the colon. Combination of GBR and L. acidophilus further increased caspase-3 expression and decreased Bcl-2 expression. These findings suggest that GBR combined with L. acidophilus and/or B. animalis subsp. lactis may inhibit colorectal carcinogenesis by enhancing antioxidative capacity and inducing apoptosis. This synbiotics may be a potential functional food or chemopreventive agent for controlling colorectal cancer.

Effects of dietary tryptophan supplementation in the acetic acid-induced colitis mouse model

Inflammatory bowel disease (IBD) is characterized by chronic inflammation of the gastrointestinal tract and is strongly associated with intestinal immunity and the microbiome. Tryptophan (Trp) is an inflammatory inhibitor and modulator of the intestinal microflora. We explored the serum profile of amino acids and the effects of diet supplementation with Trp (1.0 g kg-1) on intestinal immunity and microbiota in the acetic acid-induced colitis mouse model. We analyzed the survival rate, colonic morphological parameters, profiles of serum amino acids, microbiota in colonic contents and the relative gene abundance of intestinal proinflammatory cytokines. Although the dietary Trp supplementation failed to improve the survival rate and ameliorate the morphological parameters of colon in mice with colitis, Trp modulated the general serum amino acid profile by reducing the amino acid profiles of threonine, methionine and proline, affected intestinal immunity by inhibiting the colonic expression of interleukin-22 and changed the microbiota by reducing the abundance of Candidatus, Clostridium and Coprococcus at the genus level. In conclusion, dietary Trp supplementation in a mouse model of colitis did not ameliorate the survival rate and morphological parameters of colon but did modulate the serum amino acid profiles, intestinal immunity and microbiota. These findings enhance our understanding of the roles of Trp in the metabolism of serum amino acids, intestinal immunity and microbiota.

Gamma-aminobutyric Acid Enriched Rice Bran Diet Attenuates Insulin Resistance and Balances Energy Expenditure via Modification of Gut Microbiota and Short-Chain Fatty Acids

In this study, gamma-aminobutyric acid (GABA) enriched rice bran (ERB) was supplemented to obese rats to investigate the attenuation of metabolic syndromes induced by high-fat diet. ERB-containing diet stimulated butyrate and propionate production by promoting Anaerostipes, Anaerostipes sp., and associated synthesizing enzymes. This altered short-chain fatty acid (SCFA) distribution further enhanced circulatory levels of leptin and glucagon-like peptide-1, controlling food intake by downregulating orexigenic factors. Together with the enhanced fatty acid β-oxidation highlighted by Prkaa2, Ppara, and Scd1 expression via AMPK signaling pathway and nonalcoholic fatty liver disease pathway, energy expenditure was positively modulated. Serum lipid compositions showed ERB supplement exhibited a more efficient effect on lowering serum sphingolipids, which was closely associated with the status of insulin resistance. Consistently, genes of Ppp2r3b and Prkcg, involved in the function of ceramides in blocking insulin action, were also downregulated following ERB intervention. Enriched GABA and phenolic acids were supposed to be responsible for the health-beneficial effects.

Hypotheses on the Potential of Rice Bran Intake to Prevent Gastrointestinal Cancer through the Modulation of Oxidative Stress

Previous studies have suggested the potential involvement of oxidative stress in gastrointestinal cancers. In light of this, research efforts have been focused on the potential of dietary antioxidant intake to prevent gastrointestinal cancer through the modulation of oxidative stress. Rice bran, a by-product of rice milling, has been shown to contain an abundance of phytochemicals, which are dietary antioxidants. To date, a number of studies have shown the antioxidative effect of rice bran intake, and some demonstrated that such an effect may contribute to gastrointestinal cancer prevention, largely through the antioxidative properties of rice bran phytochemicals. In addition, these phytochemicals were shown to provide protection against cancer through mechanisms linked to oxidative stress, including β-catenin-mediated cell proliferation and inflammation. The present article provides an overview of current evidence for the antioxidative properties of rice bran and its phytochemicals, and for the potential of such properties in cancer prevention through the oxidative-stress-linked mechanisms mentioned above. The article also highlights the need for an evaluation of the effectiveness of rice bran dietary interventions among cancer survivors in ameliorating oxidative stress and reducing the level of gastrointestinal cancer biomarkers, thereby establishing the potential of such interventions among these individuals in the prevention of cancer recurrence.