Is dietary fibre truly protective against colon cancer? A systematic review and meta-analysis

Short-Chain Fatty Acids and Human Health: From Metabolic Pathways to Current Therapeutic Implications

The gastrointestinal tract is home to trillions of diverse microorganisms collectively known as the gut microbiota, which play a pivotal role in breaking down undigested foods, such as dietary fibers. Through the fermentation of these food components, short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate are produced, offering numerous health benefits to the host. The production and absorption of these SCFAs occur through various mechanisms within the human intestine, contingent upon the types of dietary fibers reaching the gut and the specific microorganisms engaged in fermentation. Medical literature extensively documents the supplementation of SCFAs, particularly butyrate, in the treatment of gastrointestinal, metabolic, cardiovascular, and gut-brain-related disorders. This review seeks to provide an overview of the dynamics involved in the production and absorption of acetate, propionate, and butyrate within the human gut. Additionally, it will focus on the pivotal roles these SCFAs play in promoting gastrointestinal and metabolic health, as well as their current therapeutic implications.

Indole-3-carboxyaldehyde does not reverse the intestinal effects of fiber-free diet in mice

Objective

Fiber-free diet impairs intestinal and colonic health in mice, in parallel with a reduction in glucagon like peptide-1 (GLP-1) levels. Endogenous GLP-1 is important for intestinal growth and maintenance of the intestinal integrity. We aimed to investigate whether fiber-free diet reduces luminal content of metabolites which, upon supplementation, could increase GLP-1 secretion and restore the adverse effects of fiber-free diet.

Methods

Untargeted metabolomics (LC-MS) was performed on colonic content of mice fed a fiber-free diet, identifying a metabolite of particular interest: indole-3-carboxyaldehyde (I3A). We exposed cultured GLUTag cells to I3A, and measured cumulative GLP-1 secretion. Isolated colon perfusions were performed in male C57BL/6JRj mice and Wistar rats. I3A was administered luminally or vascularly, and GLP-1 was measured in portal vein effluent. Finally, female C57BL/6JRJ mice were fed chow or fiber-free diet, with I3A or vehicle by oral gavage. After 10 days, plasma GLP-1 (ELISA) and intestinal permeability (FITC-dextran) were measured, animals were sacrificed and organs removed for histology.

Results

Mice fed a fiber-free diet had significantly lower I3A in their colonic content compared to a control diet (7883 ± 3375 AU, p=0.04). GLP-1 secretion from GLUTag cells was unchanged after five minutes of exposure to I3A. However, GLP-1 levels increased after 120 minutes of exposure to 1 mM (60% increase, p=0.016) and 5 mM (89% increase, p=0.0025) I3A. In contrast, 48 h exposure to 1 mM decreased GLP-1 secretion (51% decrease, p<0.001) and viability. In isolated perfused mouse and rat colon, I3A applied into the luminal or vascular side did not affect GLP-1 secretion. Mice fed a fiber-free diet tended to weigh less compared to chow fed mice; and the small intestine and colon were significantly smaller. No differences were seen in crypt depth, villus length, mucosal area, and intestinal permeability. Supplementing I3A did not affect body weight, morphology or plasma GLP-1 levels.

Conclusions

Fiber-free diet lowered colonic content of I3A in mice. I3A stimulates GLP-1 secretion in vitro, but not in animal studies. Moreover, it has no evident beneficial effect on intestinal health when administered in vivo.

Analysis of 1999-2017 NHANES Data: Minimal Increase and Racial Disparities in U.S. Fiber Consumption Over 18 Years

Low dietary fiber consumption is associated with an increased risk of colorectal cancer, a leading cause of cancer-related mortality in the United States. The average daily fiber intake has declined over recent decades. Notably, Black Americans exhibit lower fiber consumption than other racial/ethnic groups, possibly influencing their elevated colorectal cancer rates. We hypothesize that there has been a significant increase in dietary fiber consumption in the United States from 1999 to 2017. The study encompassed 59,204 adult NHANES participants and observed variations in caloric intake over survey years. Although there was a slight overall increase in dietary fiber intake compared to 1999, the most substantial increment occurred among individuals classified as Hispanic (AD: +2.86 g, P < 0.001), followed by non-Hispanic Black (AD: +1.64 g, P < 0.001), and finally non-Hispanic White showed a decrease in fiber intake (AD: -0.86 g, P < 0.001). The findings suggest a modest rise in fiber consumption from 1999 to 2017, but disparities persist, particularly with non-Hispanic Black individuals consuming the least fiber. This emphasizes the need for interventions to promote fiber intake and address racial/ethnic inequalities in dietary habits.

High and low dietary fiber consumption and cancer risk: a comprehensive umbrella review with meta-meta-analysis involving meta-analyses of observational epidemiological studies

It is a well-known fact that dietary fiber is recognized as one of the essential components of a healthy diet. The aim of this paper was to investigate the impact of dietary fiber on the incidence and mortality of various types of cancer, the current evidence in this field, and the biases of this evidence using the meta-meta-analysis method. We identified meta-analyses that particularly focused on the association between dietary fiber consumption and the risk/mortality of cancer. A structured and comprehensive computer literature search was undertaken in the electronic databases PubMed/Medline, Web of Science (WoS), and Scopus. The search yielded a total of 25 papers and 28 reports. In the pooled analysis, higher dietary fiber consumption was associated with a 22% lower cancer risk (OR = 0.78, 95% CI: 0.74-0.83, p < 0.001) and a 17% lower mortality (RR = 0.83, 95% CI: 0.78-0.90, p < 0.001). In the secondary meta-meta-analysis, it was observed that there was an inverse association between dietary fiber intake and digestive tract cancers (OR = 0.68, 95% CI: 0.62-0.76) and breast cancer (OR = 0.92, 95% CI: 0.90-0.94). Taken together, this paper suggests that promoting a high-fiber diet may be an effective strategy for the prevention and management of cancer.

Curcumin-loaded porous particles functionalized with pH-responsive cell-penetrating peptide for colorectal cancer targeted drug delivery

The anticancer properties of curcumin have been broadly examined in several shapes, such as nanoparticles and nanocomposite structures. Despite its benefits, curcumin also has some disadvantages, including rapid metabolism, poor absorption, and rapid systemic excretion. Therefore, numerous strategies have been used to increase curcumin's bioavailability. One of these approaches is the use of porous particles like aerogels as drug carriers. Aerogels are special due to their peculiar physical structure. They have a high specific surface area, a significant amount of porosity, and a solid composition, which make them a good choice for drug delivery systems. In the present study, a pH-sensitive aerogel was constructed and evaluated for targeted drug delivery of curcumin to colon cancer. To control the release of curcumin, trehalose was used as a coating agent, and PLP (poly(l-lysine isophthalamide)) was used as a targeted drug delivery agent. PLP is a pseudo-peptidic polymer that increases the cell permeability. In order to investigate and compare the synthesized aerogel before and after loading curcumin and coating with trehalose, physicochemical characterization analyses were performed. Finally, the efficacy of the final formulation was evaluated on HT29 colon cells using the cell bioavailability test. The results indicated the successful synthesis of the aerogel with porous structure with solitary cavities. The trehalose coating performed well, preventing drug release at lower pH but allowing the drug to be released at its intended site. The designed curcumin-loaded porous particles functionalized with PLP showed significant efficacy due to increasing penetration of curcumin into cells, and has potential for use as a new drug carrier with dual effectivity in cancer therapy.

Fibres and Colorectal Cancer: Clinical and Molecular Evidence

Colorectal cancer (CRC) is one of the leading causes of mortality for cancer in industrialized countries. The link between diet and CRC is well-known, and presumably CRC is the type of cancer which is most influenced by dietary habits. In Western countries, an inadequate dietary intake of fibers is endemic, and this could be a driving factor in the increase of CRC incidence. Indeed, several epidemiologic studies have elucidated an inverse relationship between daily fiber intake and risk of CRC. Long-term prognosis in CRC survivors is also dependent on dietary fibers. Several pathogenetic mechanisms may be hypothesized. Fibers may interfere with the metabolism of bile acids, which may promote colon carcinogenesis. Further, fibers are often contained in vegetables which, in turn, contain large amounts of antioxidant agents like resveratrol, polyphenols, or phytoestrogens. Moreover, fibers can be digested by commensal flora, thus producing compounds such as butyrate, which exerts an antiproliferative effect. Finally, fibers may modulate gut microbiota, whose composition has shown to be associated with CRC onset. In this regard, dietary interventions based on high-fiber-containing diets are ongoing to prevent CRC development, especially in patients with high potential for this type of tumor. Despite the fact that outcomes are preliminary, encouraging results have been observed.

Evaluating the relative impact of multiple healthy food choice interventions on choice process variables and choices

Fiscal tools-taxes and/or subsidies-are increasingly used to address diet-related health problems. However, some studies have found that these tools are markedly more effective if attention is drawn to the tax or subsidy, suggesting that the price change alone may go unnoticed in the complex food environments that consumers face. Interventions that prompt individuals to consider health during choice show promise for promoting healthy food choices in both simple laboratory settings and complex, real-world markets. In this pre-registered study, I examine the impact of dietary fiber health prompts and/or dietary fiber subsidies on the per-serving fiber content of foods chosen, the documented set of products considered, and (self-reported) nutrition information use by participants in an online supermarket setting. Participants were randomized to one of four conditions: 1) control, 2) subsidy, 3) fiber prompt, and 4) fiber prompt + subsidy. Results show that both the prompt and prompt + subsidy conditions significantly increase fiber content of foods chosen (with the latter having a larger effect). While all three interventions influence the probability of using nutrition information during food choice and affect the set of products that respondents consider relative to the control condition, the effects were larger for the prompt and prompt + subsidy conditions. A multiple mediation analysis illustrates that both direct and indirect (through the set of products considered and the use of fiber information during choice) pathways lead to the significant overall increase in fiber content of selected foods.

The effects of FTO gene rs9939609 polymorphism on the association between colorectal cancer and dietary intake

Background

FTO gene is associated with obesity, dietary intake, and the risk of colorectal cancer (CRC). In this study, patients with colorectal cancer were assessed for the interactions between FTO gene polymorphisms and dietary intake.

Methods

This case-control study was carried out on 450 participants aged 35-70 years including 150 patients with colorectal cancer and 300 healthy controls. Blood samples were collected in order to extract DNA and genotyping of FTO gene for rs9939609 polymorphism. A validated 168-item food frequency questionnaire (FFQ) and the Nutritionist-IV software were used to assess dietary intake.

Results

In the participants with the TT genotype of FTO rs9939609 polymorphism, CRC risk was significantly associated with higher intake of dietary fat (OR:1.87 CI95%:1.76-1.99, p = 0.04), vitamin B3 (OR:1.20 CI95%:1.08-1.65, p = 0.04), and vitamin C (OR:1.06 CI95%:1.03-1.15, p = 0.04) and lower intake of β-carotene (OR:0.98 CI95%:0.97-0.99, p = 0.03), vitamin E (OR:0.77 CI95%:0.62-0.95, p = 0.02), vitamin B1 (OR:0.15 CI95%:0.04-0.50, p < 0.01), and biotin (OR:0.72 CI95%:0.0.57-0.92, p = 0.01). No significant association was found between CRC and dietary intake in carriers of AA/AT genotypes after adjustments for the confounders.

Conclusion

CRC risk may be decreased by β-carotene, vitamins E, B1, and biotin only in those without the risk allele of the FTO gene. The association of CRC and diet may be influenced by FTO genotype. Further studies are warranted.

Publication trends and hotspots of colorectal adenoma during 2002-2022: a bibliometric and visualized analysis

Background

Prevention and treatment of colorectal adenoma (CRA) are great significant to reduce morbidity and mortality of colorectal cancer. Although there have been numerous studies on CRA recently, few publications utilized the bibliometrics to evaluate this field. The objective of current study was to provide a comprehensive analysis of the current state and frontier progress of CRA over the past 20 years.

Methods

The Web of Science Core Collection was utilized to extracted all studies of CRA during 2002-2022. Bibliometric tools including CiteSpace, VOSviewer, and the Online Analysis Platform of Literature Metrology were used for statistical analysis. CiteSpace and the Online Analysis Platform were used to evaluate the contributions of various countries/regions, institutions, authors, and journals in this field. Research hotspots and trends were identified through keywords and references analysis by VOSviewer and CiteSpace.

Results

2,268 publications from 2002 to 2022 in total were identified. The number of global publications in this field has increased annually. The USA was the most productive country, contributing nearly 30% of global publications. But in recent years, China's publications grew rapidly and had the highest citation strength. The most productive institutions was the National Cancer Institute. Baron JA from the USA was the most productive and the one of most co-cited authors. Cancer Epidemiology Biomarkers & Prevention had the highest number of publications and Gastroenterology was the most co-cited journals. Analysis of keywords clusters showed that "mechanism/pathophysiology", "risk factors and prevention", "colonoscopy screening and treatment", "metabolism", and "microbiota" were the major frontier topics and the main research directions.

Conclusions

CRA publications have shown a gradual upward trend in recent years, most of which have been published by developed countries. Developing countries should further focus on CRA research and transnational cooperation with developed countries in the future, in order to better improve the situation of the increasing morbidity and mortality of CRC. Baron JA was the most outstanding researcher in this field. More attention should be devoted to "pathogenesis of CRA", "less invasive diagnostic methods", "chemoprevention", and "screening and risk prediction of CRA including gut microbiome and metabolism", which will be frontiers in the future.

Molecular Mechanisms of Western Diet-Induced Obesity and Obesity-Related Carcinogenesis-A Narrative Review

The present study aims to provide a narrative review of the molecular mechanisms of Western diet-induced obesity and obesity-related carcinogenesis. A literature search of the Cochrane Library, Embase and Pubmed databases, Google Scholar and the grey literature was conducted. Most of the molecular mechanisms that induce obesity are also involved in the twelve Hallmarks of Cancer, with the fundamental process being the consumption of a highly processed, energy-dense diet and the deposition of fat in white adipose tissue and the liver. The generation of crown-like structures, with macrophages surrounding senescent or necrotic adipocytes or hepatocytes, leads to a perpetual state of chronic inflammation, oxidative stress, hyperinsulinaemia, aromatase activity, activation of oncogenic pathways and loss of normal homeostasis. Metabolic reprogramming, epithelial mesenchymal transition, HIF-1α signalling, angiogenesis and loss of normal host immune-surveillance are particularly important. Obesity-associated carcinogenesis is closely related to metabolic syndrome, hypoxia, visceral adipose tissue dysfunction, oestrogen synthesis and detrimental cytokine, adipokine and exosomal miRNA release. This is particularly important in the pathogenesis of oestrogen-sensitive cancers, including breast, endometrial, ovarian and thyroid cancer, but also 'non-hormonal' obesity-associated cancers such as cardio-oesophageal, colorectal, renal, pancreatic, gallbladder and hepatocellular adenocarcinoma. Effective weight loss interventions may improve the future incidence of overall and obesity-associated cancer.

Colorectal Cancer Chemoprevention: A Dream Coming True?

Colorectal cancer (CRC) is one of the deadliest forms of cancer worldwide. CRC development occurs mainly through the adenoma-carcinoma sequence, which can last decades, giving the opportunity for primary prevention and early detection. CRC prevention involves different approaches, ranging from fecal occult blood testing and colonoscopy screening to chemoprevention. In this review, we discuss the main findings gathered in the field of CRC chemoprevention, focusing on different target populations and on various precancerous lesions that can be used as efficacy evaluation endpoints for chemoprevention. The ideal chemopreventive agent should be well tolerated and easy to administer, with low side effects. Moreover, it should be readily available at a low cost. These properties are crucial because these compounds are meant to be used for a long time in populations with different CRC risk profiles. Several agents have been investigated so far, some of which are currently used in clinical practice. However, further investigation is needed to devise a comprehensive and effective chemoprevention strategy for CRC.

Ferroptosis open a new door for colorectal cancer treatment

Colorectal cancer (CRC) is the third highest incidence and the second highest mortality malignant tumor in the world. The etiology and pathogenesis of CRC are complex. Due to the long course of the disease and no obvious early symptoms, most patients are diagnosed as middle and late stages. CRC is prone to metastasis, most commonly liver metastasis, which is one of the leading causes of death in CRC patients. Ferroptosis is a newly discovered cell death form with iron dependence, which is driven by excessive lipid peroxides on the cell membrane. It is different from other form of programmed cell death in morphology and mechanism, such as apoptosis, pyroptosis and necroptosis. Numerous studies have shown that ferroptosis may play an important role in the development of CRC. For advanced or metastatic CRC, ferroptosis promises to open a new door in the setting of poor response to chemotherapy and targeted therapy. This mini review focuses on the pathogenesis of CRC, the mechanism of ferroptosis and the research status of ferroptosis in CRC treatment. The potential association between ferroptosis and CRC and some challenges are discussed.

Microbial Metabolite Dysbiosis and Colorectal Cancer

The global burden of colorectal cancer (CRC) is expected to continuously increase. Through research performed in the past decades, the effects of various environmental factors on CRC development have been well identified. Diet, the gut microbiota and their metabolites are key environmental factors that profoundly affect CRC development. Major microbial metabolites with a relevance for CRC prevention and pathogenesis include dietary fiber-derived short-chain fatty acids, bile acid derivatives, indole metabolites, polyamines, trimethylamine-N-oxide, formate, and hydrogen sulfide. These metabolites regulate various cell types in the intestine, leading to an altered intestinal barrier, immunity, chronic inflammation, and tumorigenesis. The physical, chemical, and metabolic properties of these metabolites along with their distinct functions to trigger host receptors appear to largely determine their effects in regulating CRC development. In this review, we will discuss the current advances in our understanding of the major CRC-regulating microbial metabolites, focusing on their production and interactive effects on immune responses and tumorigenesis in the colon.

Adherence to Mediterranean Diet and Risk of Pancreatic Cancer: Systematic Review and Meta-Analysis

Pancreatic cancer (PC) represents the 6th cause of cancer death. Although the aetiology of PC is not completely understood, numerous risk factors have been identified in association with this cancer, among them diet. However, little is known about the association between the Mediterranean Diet (MedDiet) and the risk of PC. For this reason, we conducted a systematic review with meta-analysis according to the PRISMA guidelines, searching on three databases (PubMed/MEDLINE, Scopus, and EMBASE). The protocol was registered in PROSPERO. Both fixed and random effect models were performed. The Effect size was reported as a hazard ratio (HR) with a 95% Confidence Interval (CI). A total of eight articles were included. The methodological quality of the included meta-analyses was high. Our results show that a higher adherence to the MedDiet is associated with a lower risk of PC [HR:0.82 (0.76-0.88) p < 0.001, based on 1,301,320 subjects]. The results were also confirmed in sensitivity and subgroups analyses (avoidance of potential overlapping effects, type of tools used to assess dietary intake and the diagnosis of PC, prevalence and incidence of PC risk, country where the studies took place, sex, and cancer site). Promoting a higher adherence to the MedDiet could be an effective approach to reduce the risk of PC.

Highlights on the Role of Galectin-3 in Colorectal Cancer and the Preventive/Therapeutic Potential of Food-Derived Inhibitors

Colorectal cancer (CRC) is a leading cause of death worldwide. Despite advances in surgical and therapeutic management, tumor metastases and resistance to therapy still represent major hurdles. CRC risk is highly modifiable by lifestyle factors, including diet, which strongly influences both cancer incidence and related mortality. Galectin-3 (Gal-3) is a multifaceted protein involved in multiple pathophysiological pathways underlying chronic inflammation and cancer. Its versatility is given by the ability to participate in a wide range of tumor-promoting processes, including cell-cell/cell-matrix interactions, cell growth regulation and apoptosis, and the immunosuppressive tumor microenvironment. This review provides an updated summary of preclinical and observational human studies investigating the pathogenetic role of Gal-3 in intestinal inflammation and CRC, as well as the potential of Gal-3 activity inhibition by plant-source food-derived bioactive compounds to control CRC onset/growth. These studies highlight both direct and immuno-mediated effects of Gal-3 on tumor growth and invasiveness and its potential role as a CRC prognostic biomarker. Substantial evidence indicates natural food-derived Gal-3 inhibitors as promising candidates for CRC prevention and therapy. However, critical issues, such as their bioavailability and efficacy, in controlled human studies need to be addressed to translate research progress into clinical applications.

Interventional gastroenterology in oncology

Cancer is one of the foremost health problems worldwide and is among the leading causes of death in the United States. Gastrointestinal tract cancers account for almost one third of the cancer-related mortality globally, making it one of the deadliest groups of cancers. Early diagnosis and prompt management are key to preventing cancer-related morbidity and mortality. With advancements in technology and endoscopic techniques, endoscopy has become the core in diagnosis and management of gastrointestinal tract cancers. In this extensive review, the authors discuss the role endoscopy plays in early detection, diagnosis, and management of esophageal, gastric, colorectal, pancreatic, ampullary, biliary tract, and small intestinal cancers.

Short-chain fatty acid concentrations in the incidence and risk-stratification of colorectal cancer: a systematic review and meta-analysis

BACKGROUND

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.

METHODS

We performed a systematic review and meta-analysis to examine the associations of fecal SCFA concentrations to the incidence and risk of CRC. Data extraction through Medline, Embase, and Web of Science was carried out from database conception to June 29, 2022. Predefined inclusion/exclusion criteria led to the selection of 17 case-control and six cross-sectional studies for quality assessment and analyses. Studies were categorized for CRC risk or incidence, and RevMan 5.4 was used to perform the meta-analyses. Standardized mean differences (SMD) with 95% confidence intervals (CI) were calculated using a random-effects model. Studies lacking quantitation were included in qualitative analyses.

RESULTS

Combined 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). 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. Qualitative analyses identified 70.4% of studies reporting significantly lower concentrations of fecal acetic, propionic, butyric acid, or total SCFAs in those at higher risk of CRC, while 66.7% reported significantly lower concentrations of fecal acetic and butyric acid in CRC patients compared to healthy controls.

CONCLUSIONS

Overall, lower fecal concentrations of the three major SCFAs are associated with higher risk of CRC and incidence of CRC.

The effect of FTO rs9939609 polymorphism on the association between colorectal cancer and dietary fiber

Background

Gene polymorphisms may explain the controversy on the association between colorectal cancer (CRC) and dietary fibers. The purpose of this study was to investigate the effect of fat mass and obesity-associated (FTO) rs9939609 polymorphism on the association between colorectal cancer and dietary fiber.

Methods

This case-control study was conducted on 160 CRC cases and 320 healthy controls in Tehran, Iran. The participants' food intake was assessed using a semi-quantitative food frequency questionnaire (FFQ). The frequency of rs9939609 FTO polymorphism in the case and control groups was determined using the tetra-primer amplification refractory mutation (tetra-ARMS) method.

Results

In the participants with the TT genotype of the FTO rs9939609, the cases had higher BMI and lower intake of dietary fiber compared to the controls (P = 0.01). Among A allele carriers of FTO rs9939609 polymorphism, the cases had higher BMI (P = 0.04) and lower intake of total fiber (P = 0.02) and soluble fiber (P = 0.02). An inverse association was found between CRC and dietary fiber intake among those with the AA/AT FTO rs9939609 genotype after adjusting for age, sex, smoking, alcohol consumption, physical activity, BMI, and calorie intake (OR = 0.9, CI 95%:0.84-0.92, P < 0.05).

Conclusion

This study found a link between higher dietary fiber consumption and a lower risk of CRC in A-allele carriers of FTO rs9939609 polymorphism. Future studies are needed to identify the underlying mechanisms of the association between CRC and dietary fibers in people with different FTO genotypes.

Colorectal Cancer and Microbiota Modulation for Clinical Use. A Systematic Review

Colorectal cancer (CRC) is one of the top contributors to the global burden of cancer incidence and mortality, with both genetic and environmental factors contributing to its etiology. Environmental factors may be the cause of up to 60% of the risk of developing CRC, with gut microbiota being a crucial modifiable risk factor. The microbial ecosystem plays a vital role in CRC prevention and antitumoral response through modulation of the immune system and production of short-chain fatty acids. Numerous approaches have been followed to modify the gut microbiota in order to reduce the risk of cancer development, improve treatment efficacy, and reduce side effects. This study aims to perform a systematic analysis of the published literature to elucidate whether microbiota modulation through pre-, pro-, and symbiotic treatment and/or nutritional intervention can be beneficial for patients diagnosed with CRC. Our analysis finds that some prebiotics, mainly in the form of oligo- and polysaccharides, probiotics such as lactic strain producers of short-chain fatty acids, and consumption of a Mediterranean plant-based diet may be beneficial for patients diagnosed with CRC. However, there is a need for clinical data which evaluate the modulation of gut microbiota in a safe and effective manner.

Associations between dietary fiber intake and mortality from all causes, cardiovascular disease and cancer: a prospective study

OBJECTIVE

Several studies suggest that dietary fiber intake may reduce mortality risk, but this might depend on the fiber types and the evidence regarding the role of soluble fiber or insoluble fiber on death risk remain limited and inconsistent. Therefore, this study aimed to comprehensively evaluate multiple types of dietary fiber intake on mortality from all causes, cardiovascular disease and cancer in the large-scale Prostate, Lung, Colorectal, and Ovarian Cancer (PLCO) Screening Trial.

METHODS

A multivariate Cox proportional hazards model was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

This study finally included 86,642 participants with 17,536 all-cause deaths, 4842 cardiovascular deaths and 5760 cancer deaths identified after a total of 1,444,068 follow-up years. After adjusting for potential confounders, dietary total fiber intake was statistically significantly inversely associated with all-cause death (Q5 vs Q1: HR 0.71, 95% CI 0.66-0.75; P for trend < 0.001), cardiovascular death (Q5 vs Q1: HR 0.73, 95% CI 0.65-0.83; P for trend < 0.001) and cancer mortality (Q5 vs Q1: HR 0.77, 95% CI 0.69-0.86; P for trend < 0.001). Similar results were observed for both insoluble and soluble fiber intake. Restricted cubic spline model analysis suggested that there was a nonlinear association of dietary fiber intake with mortality risk (all P for nonlinearity < 0.05).

CONCLUSIONS

In this large nationally representative sample of US adult population, intakes of total fiber, soluble fiber, and insoluble fiber were associated with lower risks of all-cause, cardiovascular and cancer mortality.

Interaction between microbiota and immunity and its implication in colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of cancer-related death in the world. Besides genetic causes, colonic inflammation is one of the major risk factors for CRC development, which is synergistically regulated by multiple components, including innate and adaptive immune cells, cytokine signaling, and microbiota. The complex interaction between CRC and the gut microbiome has emerged as an important area of current CRC research. Metagenomic profiling has identified a number of prominent CRC-associated bacteria that are enriched in CRC patients, linking the microbiota composition to colitis and cancer development. Some microbiota species have been reported to promote colitis and CRC development in preclinical models, while a few others are identified as immune modulators to induce potent protective immunity against colitis and CRC. Mechanistically, microbiota regulates the activation of different immune cell populations, inflammation, and CRC via crosstalk between innate and adaptive immune signaling pathways, including nuclear factor kappa B (NF-κB), type I interferon, and inflammasome. In this review, we provide an overview of the potential interactions between gut microbiota and host immunity and how their crosstalk could synergistically regulate inflammation and CRC, thus highlighting the potential roles and mechanisms of gut microbiota in the development of microbiota-based therapies to prevent or alleviate colitis and CRC.

Cruciferous Vegetables and Their Bioactive Metabolites: from Prevention to Novel Therapies of Colorectal Cancer

The Brassicaceae family, known as cruciferous vegetables, includes many economically important species, mainly edible oil plants, vegetable species, spice plants, and feed plants. Cruciferous vegetables are foods rich in nutritive composition and are also a good source of dietary fiber. Besides, cruciferous vegetables contain various bioactive chemicals known as glucosinolates and S-methyl cysteine sulfoxide, including sulphur-containing cancer-protective chemicals. Numerous studies have reported that daily intake of sulphurous vegetables helps prevent cancer formation and reduces cancer incidence, especially in colorectal cancer, through various mechanisms. The potential mechanisms of these compounds in preventing cancer in experimental studies are as follows: protecting cells against DNA damage, inactivating carcinogenic substances, showing antiviral and antibacterial effects, triggering apoptosis in cells with disrupted structure, inhibiting tumour cell migration causing metastasis and the development of tumour-feeding vessels (angiogenesis). These beneficial anticancer effects of cruciferous vegetables are generally associated with glucosinolates in their composition and some secondary metabolites, as well as other phenolic compounds, seed oils, and dietary fiber in the literature. This review aims to examine to the roles of cruciferous vegetables and their important bioactive metabolites in the prevention and treatment of colorectal cancer.

Impact of Diets on Response to Immune Checkpoint Inhibitors (ICIs) Therapy against Tumors

Immunotherapy has revolutionized the established therapeutics against tumors. As the major immunotherapy approach, immune checkpoint inhibitors (ICIs) achieved remarkable success in the treatment of malignancies. However, the clinical gains are far from universal and durable, because of the primary and secondary resistance of tumors to the therapy, or side effects induced by ICIs. There is an urgent need to find safe combinatorial strategies that enhance the response of ICIs for tumor treatment. Diets have an excellent safety profile and have been shown to play pleiotropic roles in tumor prevention, growth, invasion, and metastasis. Accumulating evidence suggests that dietary regimens bolster not only the tolerability but also the efficacy of tumor immunotherapy. In this review, we discussed the mechanisms by which tumor cells evade immune surveillance, focusing on describing the intrinsic and extrinsic mechanisms of resistance to ICIs. We also summarized the impacts of different diets and/or nutrients on the response to ICIs therapy. Combinatory treatments of ICIs therapy with optimized diet regimens own great potential to enhance the efficacy and durable response of ICIs against tumors, which should be routinely considered in clinical settings.

Effects of pectins on colorectal cancer: targeting hallmarks as a support for future clinical trials

The intake of dietary fibers has been associated with a reduction in the risk of colorectal cancer.

Soluble and Insoluble Dietary Fiber Consumption and Colorectal Cancer Risk: A Systematic Review and Meta-Analysis

Colorectal cancer (CRC) is the third most common cancer worldwide with a high mortality rate. Dietary fibers, both soluble and insoluble, are essential for reducing the risk of CRC. In this study, a meta-analysis was performed to examine the relationship between the soluble and insoluble dietary fiber consumption and CRC risk. The highest vs. lowest fiber concentrations were compared by using PRISMA guidelines. To determine publishing bias, the Egger test; assess study heterogeneity I² statistics were used. Studies that reported adjusted relative risk estimates with 95% confidence intervals (Cl) for the associations of interest were included. The results reveal that the relationship between soluble and insoluble fiber intake and the risk of CRC is almost equal [The total fiber ES = 0.75 (95% CI = 0.66-0.86), soluble fiber ES = 0.78 (95% CI = 0.66-0.92), insoluble fiber ES = 0.77 (95% CI = 0.67-0.88)]. Funnel plot and Egger's linear regression tests demonstrated that there was no publication bias. Both soluble and insoluble fiber consumption appear to be protective against CRC, with a clinically significant reduction in CRC risk. It is critical to identify preventive steps to avoid the CRC development, especially by leading a healthier lifestyle that includes healthy diet.

Dietary Fiber Intake and Risk of Pancreatic Cancer: Systematic Review and Meta-Analysis of Observational Studies

The burden of pancreatic cancer varies greatly across countries, with the number of deaths, incident cases, and disability-adjusted life years more than doubling in recent years, and with high-income countries having the highest incidence and mortality rates. We conducted this systematic review with meta-analysis with the goal of summarizing the current evidence on dietary fiber intake and its role in reducing the risk of pancreatic cancer, given the importance of identifying risk factors. This systematic review followed the guidelines of the Cochrane Collaboration and the Meta-analysis of Observational Studies in Epidemiology and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020. The structured literature search was conducted on PubMed/Medline and Scopus, combining free text words and medical subject headings. Our review contained 18 records at the end of the process. Our results show that dietary fiber intake reduces the risk of pancreatic cancer. When the analysis was differentiated according to the type of fiber considered, sub-grouped by gender (reduction of around 60% among women), and when case-control studies were conducted, the strength of the association increased. Clinicians and policymakers should improve interventions to raise the population's awareness regarding the consumption of high-fiber diets, both in practice and in terms of public health policy.

Lifestyle, WCRF/AICR Recommendations, and Esophageal Adenocarcinoma Risk: A Systematic Review of the Literature

One of the most notable changes in the epidemiology of esophageal cancer (EC) is the rising incidence and prevalence of esophageal adenocarcinoma (EAC) in developed countries. The aim of this systematic review was to collect and summarize all the available evidence regarding lifestyle, diet, and EAC risk. We searched the PubMed and Scopus databases in January 2021 for studies providing information about lifestyle, diet, WCRF/AICR recommendations, and EAC risk; published in English; without a time filter. The Newcastle-Ottawa Scale was used to assess risk of bias. The results are stratified by risk factor. A total of 106 publications were included. Half of the case-control studies were judged as high quality, whilst practically all cohort studies were judged as high quality. Body mass index and waist circumference were associated with increased EAC risk. Physical activity did not appear to have a significant direct role in EAC risk. A diet rich in fruit, vegetables, and whole grains appeared to be more protective than a Western diet. Alcohol does not seem to be related to EAC, whereas smokers, particularly heavy smokers, have an increased risk of EAC. Prevention remains the best option to avert EAC. Comprehensible and easy to follow recommendations should be provided to all subjects. Protocol ID number: CRD-42021228762, no funds received.

Impact of Allogeneic Leukocyte-Depleted Red Blood Cell Transfusion on Inflammatory Response and Blood Coagulation in Patients with Recurrence of Colon Cancer after Operation

Objective

Anemia inevitably affects the survival of cancer patients. In clinical practice, patients with anemia and decreased blood volume are treated by component blood transfusion. Through targeted blood transfusion therapy, the efficacy of blood transfusion treatment can be validly improved, which renders clinical benefits in reducing transfusion-induced adverse reactions (ARs). This research project mainly investigated the impact of allogeneic leukocyte-depleted red blood cell (LDRBC) transfusion on inflammatory response and coagulation status of patients with postoperative recurrence of colon cancer (CC).

Methods

A total of 80 patients with postoperative recurrence of CC admitted to Changzhou Second People's Hospital affiliated to Nanjing Medical University from September 2017 to December 2020 were selected as the study subjects. 36 patients with allogeneic suspended red blood cell (RBC) transfusion were used as the control group (CG), and 44 patients receiving allogeneic LDRBC transfusion served as the observation group (OG). The two groups were compared regarding alterations in pretransfusion and posttransfusion serum inflammatory factors, stress indicators and coagulation function, incidence of ARs, postoperative infection, and average incision healing time.

Results

After blood transfusion, serum tumor necrosis interleukin- (IL-) 6, IL-10, factor-α (TNF-α), and C-reactive protein (CRP) decreased in both cohorts, with lower parameters in CG (P < 0.05); the stress indexes, adrenocortical hormone (ACTH), adrenaline (AD), norepinephrine (NE), and cortisol (Cor) increased, especially in CG (P < 0.05); prothrombin time (PT), thrombin time (TT), and activated partial prothrombin time (APTT) in CG were lower than those in OG, and FIB was higher than that in OG with significant differences between two cohorts (all P < 0.05). The two groups had similar cases of lung infection and wound infection (P > 0.05), but the incision healing time was evidently shorter in OG as compared to CG (9.73 ± 1.86 vs 14.67 ± 2.39 d, P < 0.05). The total incidence of ARs was 16.7% in CG and 6.9% in OG, with no significant difference (P > 0.05).

Conclusions

In the blood transfusion treatment for patients with postoperative recurrence of CC, LDRBC transfusion renders significant clinical benefits, which can effectively improve the coagulation function of patients, reduce stress reaction, and shorten incision healing time without increasing ARs during treatment and postoperative infection rate, which is worth popularizing.

Indicators and Recommendations for Assessing Sustainable Healthy Diets

Research coupling human nutrition and sustainability concerns is a rapidly developing field, which is essential to guide governments' policies. This critical and comprehensive review analyzes indicators and approaches to "sustainable healthy diets" published in the literature since this discipline's emergence a few years ago, identifying robust gauges and highlighting the flaws of the most commonly used models. The reviewed studies largely focus on one or two domains such as greenhouse gas emissions or water use, while overlooking potential impact shifts to other sectors or resources. The present study covers a comprehensive set of indicators from the health, environmental and socio-economic viewpoints. This assessment concludes that in order to identify the best food option in sustainability assessments and nutrition analysis of diets, some aspects such as the classification and disaggregation of food groups, the impacts of the rates of local food consumption and seasonality, preservation methods, agrobiodiversity and organic food and different production systems, together with consequences for low-income countries, require further analysis and consideration.

Association between Dietary Fibre Intake and Colorectal Adenoma: A Systematic Review and Meta-Analysis

PubMed/Medline, Excerpta Medica dataBASE (EMBASE) and Scopus were searched in January 2021 in order to retrieve evidence assessing the association between dietary fibre intake and the risk of colorectal adenoma in adults. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used for the reporting of results. Only primary observational studies were included. Publication bias was estimated through the Egger's test and the visual inspection of the funnel plot. Heterogeneity between studies was calculated with I2 statistics. The search strategy identified 683 papers, 21 of which were included in our meta-analysis. Having evaluated a total of 157,725 subjects, the results suggest a protective effect of dietary fibre intake against colorectal adenoma. Effect Size (ES) was [0.71 (95% CI = 0.68-0.75), p = 0.000)]. Moderate statistical heterogeneity (Chi2 = 61.68, df = 23, I2 = 62.71%, p = 0.000) was found. Findings show a statistically significant (p = 0.000) and robust association between a higher intake of dietary fibre and a lower risk of colorectal adenoma, considering both the prevalent and incident risk. Moreover, the meta-regression analysis showed a borderline significant negative linear correlation between the amount of dietary fibre intake and colorectal adenoma. Lastly, we performed a subgroup analysis by sex, showing a higher protective effect for men.

Colon Carcinogenesis: The Interplay Between Diet and Gut Microbiota

Colorectal cancer (CRC) incidence increases yearly, and is three to four times higher in developed countries compared to developing countries. The well-known risk factors have been attributed to low physical activity, overweight, obesity, dietary consumption including excessive consumption of red processed meats, alcohol, and low dietary fiber content. There is growing evidence of the interplay between diet and gut microbiota in CRC carcinogenesis. Although there appears to be a direct causal role for gut microbes in the development of CRC in some animal models, the link between diet, gut microbes, and colonic carcinogenesis has been established largely as an association rather than as a cause-and-effect relationship. This is especially true for human studies. As essential dietary factors influence CRC risk, the role of proteins, carbohydrates, fat, and their end products are considered as part of the interplay between diet and gut microbiota. The underlying molecular mechanisms of colon carcinogenesis mediated by gut microbiota are also discussed. Human biological responses such as inflammation, oxidative stress, deoxyribonucleic acid (DNA) damage can all influence dysbiosis and consequently CRC carcinogenesis. Dysbiosis could add to CRC risk by shifting the effect of dietary components toward promoting a colonic neoplasm together with interacting with gut microbiota. It follows that dietary intervention and gut microbiota modulation may play a vital role in reducing CRC risk.

Recent advances in clinical practice: colorectal cancer chemoprevention in the average-risk population

Colorectal cancer (CRC) is one of the most common and lethal malignancies in Western countries. Its development is a multistep process that spans more than 15 years, thereby providing an opportunity for prevention and early detection. The high incidence and mortality rates emphasise the need for prevention and screening. Many countries have therefore introduced CRC screening programmes. It is expected, and preliminary evidence in some countries suggests, that this screening effort will decrease CRC-related mortality rates. CRC prevention involves a healthy lifestyle and chemoprevention-more specifically, oral chemoprevention that can interfere with progression from a normal colonic mucosa to adenocarcinoma. This preventive effect is important for individuals with a genetic predisposition, but also in the general population. The ideal chemopreventive agent, or combination of agents, remains unknown, especially when considering safety during long-term use. This review evaluates the evidence across 80 meta-analyses of interventional and observational studies of CRC prevention using medications, vitamins, supplements and dietary factors. This review suggests that the following factors are associated with a decreased incidence of CRC: aspirin, non-steroidal anti-inflammatory drugs, magnesium, folate, a high consumption of fruits and vegetables, fibre and dairy products. An increased incidence of CRC was observed with frequent alcohol or meat consumption. No evidence of a protective effect for tea, coffee, garlic, fish and soy products was found. The level of evidence is moderate for aspirin, β-carotene and selenium, but is low or very low for all other exposures or interventions.

The Health Benefits of Dietary Fibre

Background: Dietary fibre consists of non-digestible forms of carbohydrate, usually as polysaccharides that originate from plant-based foods. Over recent decades, our diet within Westernised societies has changed radically from that of our hominid ancestors, with implications for our co-evolved gut microbiota. This includes increased ingestion of ultra-processed foods that are typically impoverished of dietary fibre, and associated reduction in the intake of fibre-replete plant-based foods. Over recent decades, there has been a transformation in our understanding of the health benefits of dietary fibre. Objective: To explore the current medical literature on the health benefits of dietary fibre, with a focus on overall metabolic health. Data Sources: We performed a narrative review, based on relevant articles written in English from a PubMed search, using the terms ‘dietary fibre and metabolic health’. Results: In the Western world, our diets are impoverished of fibre. Dietary fibre intake associates with overall metabolic health (through key pathways that include insulin sensitivity) and a variety of other pathologies that include cardiovascular disease, colonic health, gut motility and risk for colorectal carcinoma. Dietary fibre intake also correlates with mortality. The gut microflora functions as an important mediator of the beneficial effects of dietary fibre, including the regulation of appetite, metabolic processes and chronic inflammatory pathways. Conclusions: Multiple factors contribute to our fibre-impoverished modern diet. Given the plethora of scientific evidence that corroborate the multiple and varied health benefits of dietary fibre, and the risks associated with a diet that lacks fibre, the optimization of fibre within our diets represents an important public health strategy to improve both metabolic and overall health. If implemented successfully, this strategy would likely result in substantial future health benefits for the population.

PRuNUS: design and validation of a questionnaire among prisoners - data of pilot study in the Penitentiary Institute of Perugia, Italy

PURPOSE

The PRison NUtrition Surveillance (PRuNUS) questionnaire aimed to assess the eating behaviour, diet knowledge and lifestyle of Italian prisoners. The purpose of this paper is to present both data from the validation process and from the cross-sectional study.

DESIGN/METHODOLOGY/APPROACH

In order to perform the validation process, the authors evaluated the reproducibility and the consistency of the questionnaire, using Cohen's k and Cronbach's α, the agreement between the two administrations was evaluated by the Landis and Koch score. The authors performed the study in the "Capanne" Prison, Perugia. A multivariable logistic regression model adjusted for age and gender was used.

FINDINGS

Out of 300 men, 11 participated in the validation process and 68 in the survey. Among 47 women, 11 participated in the validation and 17 in the survey, with a 26.2 per cent (85/325) cumulative response rate. The questionnaire obtained a good concordance with a k-value=0.61 and 74.48 per cent of agreement and a high level of inter-correlations among items with α=0.8452. Half of the prisoners were overweight/obese and 68.6 per cent were smokers. Moreover, smoking habits were statistically associated with a low educational level, duration of conviction, body mass index and coffee consumption.

ORIGINALITY/VALUE

The results highlighted the need for an educational programme in prison. Detention period could be a good opportunity to promote healthy habits.

Red and Processed Meat Consumption and Risk of Depression: A Systematic Review and Meta-Analysis

Depression is one of the leading causes of disability worldwide, with more than 264 million people affected. On average, depression first appears during the late teens to mid-20s as result of a complex interaction of social, psychological and biological factors. The aim of this systematic review with meta-analysis is to assess the association between red and processed meat intake and depression (both incident and prevalent). This systematic review was conducted according to the methods recommended by the Cochrane Collaboration and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Relevant papers published through March 2020 were identified by searching the electronic databases MEDLINE, Embase and Scopus. All analyses were conducted using ProMeta3 software. A critical appraisal was conducted. Finally, 17 studies met the inclusion criteria. The overall effect size (ES) of depression for red and processed meat intake was 1.08 [(95% CI = 1.04; 1.12), p-value < 0.001], based on 241,738 participants. The results from our meta-analysis showed a significant association between red and processed meat intake and risk of depression. The presented synthesis will be useful for health professionals and policy makers to better consider the effect of diet on mental health status.

Associations between consumption of dietary fibers and the risk of cardiovascular diseases, cancers, type 2 diabetes, and mortality in the prospective NutriNet-Santé cohort

BACKGROUND

Mounting evidence, yet with varying levels of proof, suggests that dietary fibers (DFs) may exert a protective role against various chronic diseases, but this might depend on the DF type and source.

OBJECTIVES

Our objectives were to assess the associations between the intake of DFs of different types [total (TDF), soluble (SF), insoluble (IF)] and from different sources (fruits, vegetables, whole grains, legumes, potatoes and tubers) and the risk of cardiovascular diseases (CVDs), cancer, type 2 diabetes (T2D), and mortality in the large-scale NutriNet-Santé prospective cohort (2009-2019).

METHODS

Overall, 107,377 participants were included. Usual DF intake was estimated from validated repeated 24-h dietary records over the first 2 y following inclusion in the cohort. Associations between sex-specific quintiles of DF intake and the risk of chronic diseases and mortality were assessed using multiadjusted Cox proportional hazards models.

RESULTS

T2D risk was inversely associated with TDFs [HR for quintile 5 compared with quintile 1: 0.59 (95% CI: 0.42, 0.82), P-trend <0.001], SFs [HR: 0.77 (0.56, 1.08); P-trend = 0.02], and IFs [HR: 0.69 (0.50, 0.96); P-trend = 0.004]. SFs were associated with a decreased risk of CVD [HR: 0.80 (0.66, 0.98); P-trend = 0.01] and colorectal cancer [HR: 0.41 (0.21, 0.79); P-trend = 0.01]. IFs were inversely associated with mortality from cancer or CVDs [HR: 0.65 (0.45, 0.94); P-trend = 0.02]. TDF intake was associated with a decreased risk of breast cancer [HR:: 0.79 (0.54, 1.13); P-trend = 0.04]. DF intake from fruit was associated with the risk of several chronic diseases.

CONCLUSIONS

Our results suggest that DF intake, especially SFs and DFs from fruits, was inversely associated with the risk of several chronic diseases and with mortality. Further studies are needed, involving different types and sources of fiber. Meanwhile, more emphasis should be put on DFs in public health nutrition policies, as DF intake remains below the recommended levels in many countries. This trial was registered at clinicaltrials.gov as NCT03335644.

Canadian Adults with Moderate Intakes of Total Sugars have Greater Intakes of Fibre and Key Micronutrients: Results from the Canadian Community Health Survey 2015 Public Use Microdata File

Background: Global dietary guidelines recommend reducing free sugars intake, which may affect choices of sugars-containing foods, including important sources of key micronutrients. The purpose of the study was to compare the intakes of nutrients stratified by intakes of sugars in Canadian adults. Methods: The first-day 24-h dietary recalls from adults (n = 11,817) in the 2015 Canadian Community Health Survey-Nutrition were used to compare macronutrients, micronutrients and food categories across quintiles of total sugars [by %energy (%E)], adjusted for misreporting status and covariates. Results: Canadian adults consumed on average 86.9 g/day (18.8 %E) from total sugars and 47.5 g/day (9.9 %E) from free sugars. Mean intakes for the 1st (Q1), 3rd (Q3) and 5th (Q5) quintiles of total sugars were 7.9%E, 18.3%E and 33.3%E, respectively. Q3 had higher fibre, calcium, vitamin D, vitamin A, vitamin C and potassium intakes than Q1 (p < 0.001), reflecting higher fruit, milk and yogurt (p < 0.001) consumption. Compared to Q5, Q3 had higher intakes of folate, vitamin B₁₂, iron and zinc. Conclusion: This study provides the first detailed analyses of Canadian adults’ macro- and micro-nutrient intakes stratified by different intakes of total sugars. Moderate intakes of total sugars may result in greater intakes of fibre and micronutrients. Overall nutrient intake should be considered when making food choices.

Low-Carbohydrate Diets in the Management of Obesity and Type 2 Diabetes: A Review from Clinicians Using the Approach in Practice

Low-carbohydrate diets are increasingly used to help patients with obesity and type 2 diabetes. We sought to provide an overview of the evidence for this treatment approach, considering the epidemiology and pathophysiology of obesity and diabetes in terms of carbohydrate excess. We describe the mechanistic basis for the clinical benefits associated with nutritional ketosis and identify areas of practice where the evidence base could be improved. We summarize the key principles which inform our approach to treating patients with low-carbohydrate diets. The scientific controversy relating to these diets is real but is consistent with the known challenges of any dietary interventions and also the limitations of nutritional epidemiology. Secondly, notwithstanding any controversy, international guidelines now recognize the validity and endorse the use of these diets as a therapeutic nutritional approach, in appropriate patients. Thirdly, we have found that early de-prescription of diabetes medications is essential, in particular insulin, sulphonylureas, and sodium-glucose cotransporter (SGLT2) inhibitors. Fourthly, we encourage patients to eat ad libitum to satiety, rather than calorie counting per se. Furthermore, we monitor cardiovascular risk factors frequently, as with all patients with obesity or diabetes, but we do not necessarily consider an increase in low-density lipoprotein (LDL)-cholesterol as an absolute indication to stop these diets, as this is usually related to large LDL particles, which are not associated with increased cardiovascular risk. In the absence of large randomized controlled trials with cardiovascular and other hard endpoints, adopting a low-carbohydrate diet is a legitimate and potentially effective treatment option for patients with diabetes or obesity.

The interplay between dietary factors, gut microbiome and colorectal cancer: a new era of colorectal cancer prevention

Colorectal cancer is the third most common cancer in the world and its incidence is on the rise. Dietary intervention has emerged as an attractive strategy to curtail its occurrence and progression. Diet is known to influence the gut microbiome, as dietary factors and gut bacteria can act in concert to cause or protect from colorectal cancer. Several studies have presented evidence for such interactions and have pointed out the different ways by which the diet and gut microbiome can be altered to produce beneficial effects. This review article aims to summarize the interrelationship between diet, gut flora and colorectal cancer so that a better preventive approach can be applied.

Fruits

Fruits come in a wide variety of colors, shapes, and flavors. This chapter will cover selected fruits that are known to be healthy and highly nutritious. These fruits were chosen due to their common usage and availability. Since it is not possible to cover all health benefits or essential nutrients and important phytochemicals of the fruit composition, this chapter will focus on the key valuable constituents and their potential health effects.

Lack of association between dietary fibres intake and childhood obesity: an epidemiological study among preadolescents in Greece

The aim of this study was to evaluate whether dietary fibres intake is associated with childhood obesity. From 2014 to 2016, a sample of 1728 Greek boys and girls students, 10-12 years and their parents were enrolled in the study. Dietary fibres intake was assessed through food questionnaires and child's body mass status was defined according to the International Obesity Task Force (IOTF)'s criteria. Prevalence of combined overweight/obesity was 26.7%, with boys having significantly higher prevalence than girls (31.5 versus 24.7%, p < 0.001). Logistic regression analysis, after various adjustments were made, revealed no association between dietary fibres intake and obesity/overweight (Odds Ratio = 0.76; 95% CI 0.48, 1.19). The lack of an association between dietary fibres intake and overweight/obesity status among pre-adolescents could be attributed to various reasons such as, methodological issues reflecting the study's design, the measurement of exposure or due to true absence of a relationship. Nevertheless, fibres consumption should not be prevented, but, promoted under the context of a balanced diet, because of their numerous pleiotropic health effects.

Differences in dietary fibre intake and associated familial factors in a longitudinal study at two time points across adolescence

OBJECTIVE

Dietary fibre is essential for a healthy diet; however, intake is often inadequate. Understanding of sources of dietary fibre and familial factors associated with intake in adolescents is limited, hampering efforts to increase intake. We aimed to determine adequacy of dietary fibre intake in adolescents, examine how intake changes from mid to late adolescence, identify major food sources and explore associations with familial factors.

DESIGN

Dietary fibre intake measured with semi-quantitative FFQ and sources calculated with the AUSNUT database. Familial factors determined by questionnaire.

SETTING

Western Australian Pregnancy Cohort (Raine) Study.

PARTICIPANTS

Generation 2 adolescents from the 14- (n 1626) and 17-year (n 835) follow-ups.

RESULTS

Mean intake of dietary fibre did not meet national dietary guidelines other than for females aged 14 years. Mean intake of both sexes was lower at 17 years (23·0 (sd 10·0) g/d) than at 14 years (24·3 (sd 9·0) g/d, P < 0·001). The quantity of dietary fibre consumed per megajoule also decreased (2·6 (sd 0·7) g/MJ at 14 years, 2·5 (sd 0·9) g/MJ at 17 years, P = 0·007). The greatest source of dietary fibre was cereals and grains, followed by fruits, then vegetables. In multivariable mixed-model analysis, female sex, Caucasian race, age 14 years, good family functioning, high level of parental education and high energy intake were independently associated with higher dietary fibre intake.

CONCLUSIONS

Our study highlights an age range and characteristics of adolescents lacking in dietary fibre, thereby identifying target populations for interventions to improve dietary fibre intake across adolescence, which would lead to better health.

Definition of the Traditional Mexican Diet and Its Role in Health: A Systematic Review

Promoting traditional diets could potentially reduce the current high rates of non-communicable diseases (NCDs) globally. While the traditional Mexican diet (TMexD) could be specifically promoted in Mexico, a concise definition of the TMexD and evidence of its association with NCDs are needed before its promotion. To evaluate what constitutes this diet pattern, we aimed to systematically review, for the first time, how the TMexD has been described in the literature to date. A secondary aim was to examine whether the TMexD, as described by available definitions, is associated with NCD outcomes. We searched for records describing a whole TMexD up to July 2019 in 12 electronic databases, reference lists, a relevant journal, and by contacting experts on the topic. We reported the results using the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. We included 61 records for the definition of the diet and six for the association with NCD outcomes. The food groups characterising the TMexD that were consistently mentioned in all the study subgroups were grains and tubers, legumes, and vegetables; specific foods included maize, beans, chile, squash, tomato, and onion. Other groups also mentioned, although with lesser frequency, were maize products, fruits, beverages, fish and seafood, meats, sweets and sweeteners, and herbs and condiments. Only a few studies reported on the frequency of consumption or the amounts in which these foods were consumed in the TMexD. It was not possible to reach strong conclusions for the association between adherence to the TMexD and NCD outcomes. The TMexD was weakly associated with developing breast cancer, not associated with triglyceride levels, and inconsistently associated with obesity and diabetes outcomes. However, results were limited by the small number of studies (n = 6), of which most were of observational nature and evaluated diets using different TMexD definitions. These findings provide systematically identified evidence of the characteristics of the TMexD. More studies are needed to ascertain the exact quantities by which foods were consumed in the TMexD in order to establish whether this dietary pattern is associated with health and should be promoted within the Mexican population.

Primary Outcomes of a Randomized Controlled Crossover Trial to Explore the Effects of a High Chlorophyll Dietary Intervention to Reduce Colon Cancer Risk in Adults: The Meat and Three Greens (M3G) Feasibility Trial

Preclinical and observational research suggests green leafy vegetables (GLVs) may reduce the risk of red meat (RM)-induced colonic DNA damage and colon cancer (CC). We sought to determine the feasibility of a high GLV dietary intervention in adults with an increased risk of CC (NCT03582306) via a 12-week randomized controlled crossover trial. Participants were randomized to immediate or delayed (post-4-week washout) intervention groups. During the 4-week intervention period, participants were given frozen GLVs and counseled to consume one cooked cup equivalent daily. The primary outcomes were: accrual—recruiting 50 adults in 9 months; retention—retaining 80% of participants at completion; and adherence—meeting GLV intake goals on 90% of days. Adherence data were collected twice weekly and 24-h dietary recalls at each time point provided nutrient and food group measures. The Food Acceptability Questionnaire (FAQ) was completed to determine acceptability. On each of the four study visits, anthropometrics, stool, saliva, and blood were obtained. Fifty adults were recruited in 44 days. Participants were 48 ± 13 years of age, 62% female, and 80% Caucasian, with an average BMI at screening of 35.9 ± 5.1. Forty-eight (96%) participants were retained and completed the study. During the intervention phase, participants consumed GLVs on 88.8% of days; the adherence goal of one cup was met on 73.2% of days. Dietary recall-derived Vitamin K and GLVs significantly increased for all participants during the intervention periods. Overall satisfaction did not differ between intervention and control periods (p = 0.214). This feasibility trial achieved accrual, retention and acceptability goals, but fell slightly short of the benchmark for adherence. The analysis of biological specimens will determine the effects of GLVs on gut microbiota, oxidative DNA damage, and inflammatory cytokines.

A healthy lifestyle pattern has a protective association with colorectal polyps

BACKGROUND

Colorectal cancer is associated with lifestyle characteristics such as diet, physical inactivity, obesity, and smoking, but these are not incorporated in screening recommendations. Moreover, the joint association of these factors with various colorectal polyps is not established.

METHODS

A case-control study, among consecutive subjects aged 40-70 years, undergoing colonoscopy. Cases with colorectal polyps were compared with controls. Detailed information was gathered regarding polyp histology and anatomic location, demographics, medical history, anthropometrics, and lifestyle. The healthy lifestyle index was estimated as the sum of: non-smoking, maintaining a healthy weight, healthy diet, and physical activity.

RESULTS

A total of 788 participants were included (cases n = 403, controls n = 385). The healthy lifestyle index had a negative association with colorectal polyps (OR = 0.72, 95% CI 0.62-0.85, P < 0.001), both adenomas and serrated polyps (OR = 0.75, 0.64-0.89, and OR = 0.59, 0.44-0.79, respectively), and both proximal and distal adenomas (OR = 0.77, 0.62-0.95, and OR = 0.73, 0.59-0.90, respectively). Adherence to ≥ 2 healthy lifestyle components was strongly related with colorectal polyps (OR = 0.50, 0.34-0.75, P = 0.001). Abstinence from smoking, and a healthy diet were the factors most strongly associated with lower odds of colorectal polyps (OR = 0.58, 0.42-0.79, and OR = 0.61, 0.44-0.85, respectively).

CONCLUSIONS

Adherence to a healthy lifestyle (≥2 healthy lifestyle components) is inversely associated with colorectal polyps, especially serrated and distal polyps, with no dose-response association. Components most strongly associated with lower odds of colorectal polyps were maintaining a healthy diet and abstinence from smoking. Lifestyle-related characteristics may assist in risk stratification and are potential goals for colorectal neoplasia prevention.

Rectal Cancer: 20% Risk Reduction Thanks to Dietary Fibre Intake. Systematic Review and Meta-Analysis

The aim of this systematic review and meta-analysis was to evaluate the association between dietary fibre intake and rectal cancer (RC) risk. In January 2019, a structured computer search on PubMed/Medline, Excerpta Medica dataBASE (EMBASE) and Scopus was performed for studies reporting the results of primary research evaluating dietary fibre intake in women and men as well as the risk of developing RC. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations were followed. Highest vs. lowest fibre concentrations was compared. The Egger test was used to estimate publication bias. Heterogeneity between studies was evaluated with I² statistics. The search strategy identified 912 papers, 22 of which were included in our meta-analysis. Having evaluated a total of 2,876,136 subjects, the results suggest a protective effect of dietary fibre intake on RC prevention. The effect Size (ES) was [0.77 (95% CI = 0.66–0.89), p-value = 0.001)]. Moderate statistical heterogeneity (Chi² = 51.36, df = 21, I² = 59.11%, p-value = 0.000) was found. However, no publication bias was found, as confirmed by Egger’s linear regression test (Intercept −0.21, t = −0.24, p = 0.816). The findings suggest that dietary fibre intake could be protective against RC, with a clinically relevant reduction of RC risk. Identifying preventive measures to avoid the development of RC, especially by following a healthy lifestyle including healthy diet, is pivotal.

Dietary fibre and cardiovascular health: a review of current evidence and policy

Dietary fibre comprises many different, mainly plant-based, compounds that are not fully digested in the human gut. Insoluble fibres include cellulose, hemi-celluloses and lignin and soluble fibres include pectins, β-glucan and hydro-colloids. In the UK, the daily recommended amount has increased to 30 g but only 13 % of men and 4 % of women meet this recommendation. Currently the mean intake for adults is 21 g for men and 17 g for women. There is a wealth of epidemiological evidence based on systematic reviews of trials and cohorts to support the higher fibre recommendation. This includes evidence of reductions in the risk for CVD (both heart disease and stroke) and lower risk of type 2 diabetes, lower blood pressure, lower LDL-cholesterol, as well as some cancers. Beneficial effects of fibre operate via a diverse range of mechanisms throughout the digestive system including the mouth, stomach and small and large intestine; some of which are still not completely understood. The updated recommendation for fibre is a long way from a typical British diet and requires several daily portions of fruit and vegetables and wholegrain foods. Improving dietary fibre intakes will require a variety of actions and policies from stakeholders; however, there is currently more of a focus on reducing sugar than increasing fibre. In order to increase the number of adults meeting the fibre recommendation, social marketing and labelling of high-fibre foods are warranted as well as reformulation and wider availability of wholegrain versions of popular foods.

Fecal Short-Chain Fatty Acids Are Not Predictive of Colonic Tumor Status and Cannot Be Predicted Based on Bacterial Community Structure

Colonic bacterial populations are thought to have a role in the development of colorectal cancer with some protecting against inflammation and others exacerbating inflammation. Short-chain fatty acids (SCFAs) have been shown to have anti-inflammatory properties and are produced in large quantities by colonic bacteria that produce SCFAs by fermenting fiber. We assessed whether there was an association between fecal SCFA concentrations and the presence of colonic adenomas or carcinomas in a cohort of individuals using 16S rRNA gene and metagenomic shotgun sequence data. We measured the fecal concentrations of acetate, propionate, and butyrate within the cohort and found that there were no significant associations between SCFA concentration and tumor status. When we incorporated these concentrations into random forest classification models trained to differentiate between people with healthy colons and those with adenomas or carcinomas, we found that they did not significantly improve the ability of 16S rRNA gene or metagenomic gene sequence-based models to classify individuals. Finally, we generated random forest regression models trained to predict the concentration of each SCFA based on 16S rRNA gene or metagenomic gene sequence data from the same samples. These models performed poorly and were able to explain at most 14% of the observed variation in the SCFA concentrations. These results support the broader epidemiological data that questions the value of fiber consumption for reducing the risks of colorectal cancer. Although other bacterial metabolites may serve as biomarkers to detect adenomas or carcinomas, fecal SCFA concentrations have limited predictive power.IMPORTANCE Considering that colorectal cancer is the third leading cancer-related cause of death within the United States, it is important to detect colorectal tumors early and to prevent the formation of tumors. Short-chain fatty acids (SCFAs) are often used as a surrogate for measuring gut health and for being anticarcinogenic because of their anti-inflammatory properties. We evaluated the fecal SCFA concentrations of a cohort of individuals with different colonic tumor burdens who were previously analyzed to identify microbiome-based biomarkers of tumors. We were unable to find an association between SCFA concentration and tumor burden or use SCFAs to improve our microbiome-based models of classifying people based on their tumor status. Furthermore, we were unable to find an association between the fecal community structure and SCFA concentrations. Our results indicate that the association between fecal SCFAs, the gut microbiome, and tumor burden is weak.