Dietary fiber and risk of colorectal cancer in the Japan collaborative cohort study

Metabolomic profiling for the preventive effects of dietary grape pomace against colorectal cancer

Colorectal cancer (CRC) is one of the most common and deadly cancers worldwide. Grape pomace (GP) is a rich source of bioactive compounds with anti-inflammatory, and anticancer effects. We recently found that dietary GP had protective effects against CRC development in the azoxymethane (AOM)/dextran sulfate sodium (DSS) CRC mouse model through suppression of cell proliferation and modulation of DNA methylation. However, the underlying molecular mechanisms associated with changes in metabolites remain unexamined. This study profiled fecal metabolomic changes in a mouse CRC model in response to GP supplementation using gas chromatography-mass spectrometry (GC-MS) based metabolomic analysis. A total of 29 compounds showed significant changes due to GP supplementation, including bile acids, amino acids, fatty acids, phenols/flavonoids, glycerolipids, carbohydrates, organic acids, and others. The major changes in metabolites of feces include increased deoxycholic acid (DCA) and decreased amino acid content. Dietary GP upregulated the expression of farnesoid X receptor (FXR) downstream genes while decreasing fecal urease activity. DNA repair enzyme MutS Homolog 2 (MSH2) was upregulated by GP supplementation. Consistently, γ-H2AX, as a DNA damage marker, decreased in GP supplemented mice. Moreover, MDM2, a protein in the ataxia telangiectasia mutated (ATM) signaling, was decreased by GP supplementation. These data provided valuable metabolic clues for unraveling the protective effects of GP supplementation against CRC development.

Association between Dietary Fiber Intake and Colorectal Adenoma

Dietary fiber intake has been suggested to decrease the risks of colorectal cancer (CRC) and adenoma. This cross-sectional study aimed to evaluate the association between total dietary fiber intake and colorectal adenoma among asymptomatic Korean adults. Individuals who received a screening colonoscopy between May and December of 2011 were recruited. Multivariable-adjusted logistic regression was used to assess the odds ratios (ORs) and 95% confidence intervals (CIs) of colorectal adenoma. 558 of the 1,716 study participants were diagnosed with colorectal adenoma. No significant association between total dietary fiber intake and colorectal adenoma was found; ORs (95% CIs) for subsequent quintiles compared to the bottom quintile were 1.00 (0.69-1.46), 1.11 (0.73-1.71), 0.97 (0.57-1.65), and 0.88 (0.46-1.71; P for trend = 0.65). Dietary fiber intakes from cereal, fruit, vegetable, or legume weren't associated with colorectal adenoma. When we compared >30 g/d to ≤10 g/d of total dietary fiber intake, OR (95% CI) was 0.32 (0.10-1.02; P for trend = 0.23). In the analyses of advanced or high-risk state and location of adenoma, we didn't observe significant associations. In conclusion, dietary fiber intake was not associated with colorectal adenoma in Korean adults. However, the association for low intake of dietary fiber warrants further investigation.

Dietary fiber in the prevention of obesity and obesity-related chronic diseases: From epidemiological evidence to potential molecular mechanisms

Obesity is a mostly preventable diet-related disease and currently a major challenge for human populations worldwide. Obesity is a major risk factor for diseases such as type 2 diabetes mellitus (T2DM), cardiovascular disease (CVD) and certain cancers. Dietary fiber is a complex mixture of non-digestible molecules, mostly polysaccharides. Multiple epidemiological studies have demonstrated statistically significant reductions in risks of obesity, T2DM, CVD, colorectal cancer, and pre-menopausal breast cancer with higher dietary fiber intakes. Various direct and indirect mechanisms have been proposed including altered digestion and absorption, stimulation of gut hormones including glucagon-like-peptide-1 (GLP-1) and peptide YY (PYY), reduced appetite, and altered metabolism of bile and cholesterol. These may act via pathways involving G-protein-coupled receptors (GPRs), histone deacetylase (HDAC), and aromatase enzymes. Ultimately, fiber intake contributes to improving glucose levels and insulin sensitivity, lowering risk of T2DM, CVD and certain cancers. Therefore, diets rich in dietary fiber should be encouraged to prevent obesity and associated chronic disease.

Chemical Characterization and In Vitro Anti-Cancer Activities of a Hot Water Soluble Polysaccharide from Hulless Barley Grass

Hulless barley grass may confer many health benefits attributed to its bioactive functional components, such as polysaccharides. Here, a hot water soluble polysaccharide was extracted from hulless barley grass, and its chemical characterization and in vitro anti-cancer activities were investigated. The yield of hulless barley grass polysaccharide (HBGP) was 2.3%, and the purity reached 99.1% with a polydispersity index (PDI) of 1.11 after purification by a diethylaminoethyl cellulose (DE-32) column and an S-400 high resolution (HR) column. The molecular weight and number-average molecular weight of HBGP were 3.3 × 104 and 2.9 × 104 Da, respectively. The monosaccharide composition of HBGP included 35.1% galactose, 25.6% arabinose, 5.5% glucose, and 5.3% xylose. Based on infrared spectrum analysis, HBGP possessed pyranose and galactose residues. In addition, this water-soluble polysaccharide showed significant cell proliferation inhibitory effects against cancer cell lines HT29, Caco-2, 4T1, and CT26.WT in a dose-dependent manner, especially for HT29 (the half-inhibitory concentration IC50 value = 2.72 mg/mL). The results provide a basis for the development and utilization of hulless barley grass in functional foods to aid in preventing 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.

White Rice Consumption and Risk for Colorectal Cancer among Japanese Americans: The Multiethnic Cohort Study

BACKGROUND

White rice is a staple food for Japanese, a population at high risk for colorectal cancer (CRC). We investigated the association between white rice intake and CRC among Japanese Americans in the Multiethnic Cohort (MEC) study.

METHODS

The Multiethnic Cohort Study is a prospective study established in Hawaii and California in 1993-1996. Usual dietary intake was assessed by a validated quantitative food frequency questionnaire at baseline. Cox proportional hazards models were used to compute hazard ratios (HR) and 95% confidence intervals (CI) for quartiles of intake and to perform trend tests across sex-specific quartiles with adjustment for relevant confounders.

RESULTS

We identified 1,553 invasive CRC cases among 49,136 Japanese Americans (23,595 men and 25,541 women) during a mean follow-up of 19 years. White rice consumption was not associated with overall CRC incidence in men (p_-trend = 0.11) or women (p_-trend = 0.56). After excluding participants with a history of diabetes, the inverse associations were significant for CRC (p_-trend = 0.03, HR for quartile 4 (Q4) vs. 1 = 0.81; 95% CI: 0.64-1.03) and tumors of the distal colon (p_-trend = 0.006, HR for Q4 vs. Q1: 0.66; 0.44-0.99) among men but not women.

CONCLUSIONS

White rice consumption was not associated with an increased risk of overall CRC among Japanese Americans. An inverse association was observed with risk of CRC and distal colon cancer in men without a history of diabetes.

Role of microbiota-derived short-chain fatty acids in cancer development and prevention

Following cancer, cells in a particular tissue can no longer respond to the factors involved in controlling cell survival, differentiation, proliferation, and death. In recent years, it has been indicated that alterations in the gut microbiota components, intestinal epithelium, and host immune system are associated with cancer incidence. Also, it has been demonstrated that the short-chain fatty acids (SCFAs) generated by gut microbiota are vitally crucial in cell homeostasis as they contribute to the modulation of histone deacetylases (HDACs), resulting effected cell attachment, immune cell immigration, cytokine production, chemotaxis, and the programmed cell death. Therefore, the manipulation of SCFA levels in the intestinal tract by alterations in the microbiota structure can be potentially taken into consideration for cancer treatment/prevention. In the current study, we will explain the most recent findings on the detrimental or protective roles of SFCA (particularly butyrate, propionate, and acetate) in several cancers, including bladder, colon, breast, stomach, liver, lung, pancreas, and prostate cancers.

A Critical Review of the Effect of Dietary Fiber Intake on the Prevention of Colorectal Cancer in Eastern Asian Countries

Background

Colorectal cancer has become the second most common type of cancer in females and the third most common type of cancer in males. The incidence rate of colorectal cancer is increasing along with the change of lifestyle and dietary habits in East Asia. The cause of colorectal cancer is complex; environmental factors and genetic factors affect each other. Dietary fiber is considered as the prevention of colorectal cancer. Epidemiological data in Europe and America have suggested that dietary fiber intake is negatively correlated with colorectal cancer incidence rate. However, the evidence among different populations is inconsistent, and little is known about these associations in Eastern Asian areas.

Objectives

To critically review all available human epidemiological data on the relationship between dietary fiber intake and colorectal cancer in Eastern Asian countries and make recommendations for these populations. Methodology. PubMed and Embase were used to search online research papers regarding the relationship between dietary fiber intake and the risk of colorectal cancer in Eastern Asian. We located 9 publications, of which the sample size ranged from 266 to 78, 326.

Results

Five case-control studies, as well as one prospective study, have examined significant preventive effects of dietary fiber intake on the risk of colorectal cancer while evidence from three prospective cohorts suggested no preventive effects of dietary fiber intake on colorectal cancer among these populations. There is no consistent conclusion on the protective effect of dietary fiber from different sources and types.

Conclusion

The association between dietary fiber intake and colorectal cancer risk in Chinese, Japanese, and Korean is considered to be plausible by the available literature. This current review cannot substantiate the preventive effect of dietary fiber intake on colorectal cancer due to the limited available evidence analyzed.

A review of nutrition and dietary interventions in oncology

The complex cellular mechanisms and inter-related pathways of cancer proliferation, evasion, and metastasis remain an emerging field of research. Over the last several decades, nutritional research has prominent role in identifying emerging adjuvant therapies in our fight against cancer. Nutritional and dietary interventions are being explored to improve the morbidity and mortality for cancer patients worldwide. In this review, we examine several dietary interventions and their proposed mechanisms against cancer as well as identifying limitations in the currently available literature. This review provides a comprehensive review of the cancer metabolism, dietary interventions used during cancer treatment, anti metabolic drugs, and their impact on nutritional deficiencies along with a critical review of the following diets: caloric restriction, intermittent fasting, ketogenic diet, Mediterranean diet, Japanese diet, and vegan diet.

Diet and Gut Microbes Act Coordinately to Enhance Programmed Cell Death and Reduce Colorectal Cancer Risk

Diet is an important risk factor for colorectal cancer (CRC), and several dietary constituents implicated in CRC are modified by gut microbial metabolism. Microbial fermentation of dietary fiber produces short-chain fatty acids, e.g., acetate, propionate, and butyrate. Dietary fiber has been shown to reduce colon tumors in animal models, and, in vitro, butyrate influences cellular pathways important to cancer risk. Furthermore, work from our group suggests that the combined effects of butyrate and omega-3 polyunsaturated fatty acids (n-3 PUFA) may enhance the chemopreventive potential of these dietary constituents. We postulate that the relatively low intakes of n-3 PUFA and fiber in Western populations and the failure to address interactions between these dietary components may explain why chemoprotective effects of n-3 PUFA and fermentable fibers have not been detected consistently in prospective cohort studies. In this review, we summarize the evidence outlining the effects of n-3 long-chain PUFA and highly fermentable fiber with respect to alterations in critical pathways important to CRC prevention, particularly intrinsic mitochondrial-mediated programmed cell death resulting from the accumulation of lipid reactive oxygen species (ferroptosis), and epigenetic programming related to lipid catabolism and beta-oxidation-associated genes.

Evaluation of a Quantitative Food Frequency Questionnaire for 5-Year-Old Children in an Asian Population

BACKGROUND

Food frequency questionnaires (FFQs) are often used to assess dietary intakes due to their ability to assess intake over extended periods, their low respondent burden, and their cost-effectiveness. A quantitative FFQ that includes locally appropriate food items for 5-year-old children in a multiethnic Asian population was developed, but its validity has not previously been evaluated.

OBJECTIVE

To evaluate the relative validity of a newly developed FFQ as a dietary assessment tool for 5-year-old children in a multiethnic Asian population.

DESIGN

The 112 -food item FFQ was administered by trained interviewers to caregivers of children. Frequency of food items consumed in the previous month and portion size information were collected. The FFQs were evaluated against 3-day nonweighed diet records (DRs) completed by caregivers.

PARTICIPANTS/SETTING

The dietary data of 361 children aged 5 years from the Growing Up in Singapore Towards Healthy Outcomes mother-offspring cohort were collected in 2015-2016.

MAIN OUTCOME MEASURES

Nutrients of interest included energy, macronutrients, fiber, cholesterol, vitamin A, beta carotene, calcium, and iron, calculated from the FFQs and DRs.

STATISTICAL ANALYSES PERFORMED

Nutrient intakes according to FFQs in relation to DRs were assessed using Pearson's correlation, Lin's concordance, Bland-Altman plots, quintile joint classification, and Cohen's κ statistics.

RESULTS

The highest energy-adjusted correlation (Pearson's r=0.71) and concordance (Lin's concordance=0.69) were observed for calcium. Fiber, saturated fat, polyunsaturated fatty acids (PUFA), cholesterol, and iron also showed correlation coefficients and concordance of at least 0.40. Bland-Altman plots suggested no substantial bias across ranges of intakes for the nutrients with correlations and concordance of 0.40 or above. Quintiles joint classification showed substantial agreement for calcium (κ=0.66), and moderate agreement for iron, fiber, saturated fat, polyunsaturated fat, and beta carotene (κ=0.59, 0.54, 0.49, 0.44, 0.43, respectively).

CONCLUSIONS

The newly developed FFQ is in reasonable agreement with DR for estimating intakes of calcium, fiber, saturated fat, PUFA, cholesterol, and iron. In addition, the FFQ is able to classify children according to quintiles of nutrient intakes, with moderate to substantial quintile agreements between FFQ and DR for calcium, iron, fiber, saturated fat, PUFA, and beta carotene. To assess the remaining nutrients, DR method is recommended instead of the FFQ.

A Reasonable Diet Promotes Balance of Intestinal Microbiota: Prevention of Precolorectal Cancer

Colorectal cancer (CRC) is a multifactorial disease and the second leading cause of cancer death worldwide. The pathogenesis of colorectal cancer includes genetics, age, chronic inflammation, and lifestyle. Increasing attention has recently been paid to dietary factors. Evidence from epidemiological studies and clinical research suggests that high-fibre diets can significantly reduce the incidence of CRC, whilst the consumption of high-fat diets, high-protein diets, red meat, and processed meat is high-risk factors for tumorigenesis. Fibre is a regulator of intestinal microflora and metabolism and is thus a key dietary component for maintaining intestinal health. Intestinal microbes are closely linked to CRC, with the growth of certain microbiota (such as Fusobacterium nucleatum, Escherichia coli, or Bacteroides fragilis) favouring carcinogenesis, whilst the dominant microbiota population of the intestine, such as Bacteroidetes, Firmicutes, Actinobacteria, and Proteobacteria, have multiple mechanisms of antitumour activity. Various dietary components have direct effects on the types of intestinal microflora: in the Western diet mode (high-fat, high-protein, and red meat), the proportion of conditional pathogens in the intestinal flora increases, the proportion of commensal bacteria decreases, and the occurrence of colorectal cancer is promoted. Conversely, a high-fibre diet can increase the abundance of Firmicutes and reduce the abundance of Bacteroides and consequently increase the concentration of short-chain fatty acids (SCFAs) in the intestine, inhibiting the development of CRC. This article reviews the study of the relationship between diet, intestinal microbes, and the promotion or inhibition of CRC and analyses the relevant molecular mechanisms to provide ideas for the prevention and treatment of CRC.

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 Protective against Colorectal Cancer Patients in Asia: A Meta-Analysis

BACKGROUND

The association between dietary fibre and colorectal cancer risk is controversial.

AIM

This systematic review and meta-analysis were performed to determine the dietary fibre protective against colorectal cancer patients in Asia.

METHODS

The authors conducted a meta-analysis of published research articles on dietary fibre protective against colorectal cancer patients in Asia published between January 2000 and March 2019 in the online article databases of PubMed, ProQuest and EBSCO. Pooled odds ratios (OR) were calculated with fixed and random-effect models. Publication bias was visually evaluated by using funnel plots and statistically assessed through Egger's and Begg's tests. Data were processed using Review Manager 5.3 (RevMan 5.3) and Stata version 14.2 (Stata Corporation).

RESULTS

This study reviewed 405 articles. There are 10 studies conducted a systematic review and continued with Meta-analysis of relevant data with several sample 49,964 patients. The results showed dietary fibre protective against colorectal cancer patients in Asia (OR = 0.66 [95% CI 0.56-0.77, p=0.008]). There was significant publication bias for studies included in dietary fibre protective against colorectal cancer patients in Asia.

CONCLUSION

This analysis confirmed dietary fibre protective against colorectal cancer patients in Asia.

Meta-analysis of homocysteine-related factors on the risk of colorectal cancer

The major objective of this meta-analysis was to examine the association between homocysteine and related measurements with the risk of colorectal cancer (CRC) and adenomatous polyps (AP). Many studies presented an association between methyltetrahydrofolate reductase (MTHFR) gene polymorphisms and risk of CRC. Yet, there have been variances on what homocysteine-related and dietary factors play on the risk of CRC or AP, in association with folate-related one carbon metabolism pathways. We pooled analyses to examine comprehensively all homocysteine related factors including blood tests measurements, dietary, and lifestyle factors for their associations with the risk of CRC and AP. We located 86 articles published from 1995 to 2017. The results revealed that elevated homocysteine levels and decreased vitamin B12 levels in the blood were associated with increased risks of CRC and AP, with case-control studies having greater significant effect sizes compared to that of cohort-control studies. Decreased methionine and vitamin B6 levels in the blood increased the risk of CRC. MTHFR 677 TT and CT polymorphisms were interacting with elevated homocysteine levels to increase the risk of CRC. Decreased dietary fiber, methionine, vitamin B9 or folate, and vitamin B6 intakes were associated with increased risks of CRC; whereas, increased dietary B12 intake, alcohol intake, and smoking were associated with increased risk of CRC. Further studies can be conducted to examine the mechanistic differences of blood levels of homocysteine-related and dietary factors, including different types of dietary fiber, for their effects on decreasing the homocysteine toxicity to prevent CRC.

Colon Cancer: What We Eat

A higher incidence of colorectal cancer (CRC) is observed in Oceania and Europe, whereas Africa and Asia have a lower incidence. CRC is largely preventable by adapting a healthy lifestyle, such as healthy diet, adequate physical activity, and avoiding obesity. This review summarizes the latest work available, mainly epidemiologic studies, to examine the relationship between diet and CRC. Higher intake of red/processed meat could increase the CRC risk, whereas fibers, especially from whole grains and cereals, as well as fruit and vegetables may decrease the CRC risk. Heterogeneity and inconsistency among studies or individuals, however, need to be taken into consideration.

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

Colorectal cancer is the third most common cancer worldwide. Growing evidence shows that about 47% of cases of colorectal cancer can be prevented by a healthy lifestyle. We performed a systematic review and meta-analysis aimed to evaluate the association between dietary fibre intake and the risk of colon cancer. We performed a structured computer search on PubMed, including epidemiological studies reporting results of dietary fibre intake and risk of colon cancer in women or men. We compared subjects exposed to the highest versus the lowest consumption. The search strategy identified 376 papers. After screening, 25 datasets were included in our meta-analysis. Results suggest a protective role of dietary fibre intake on colon cancer risk ES = 0.74 (95% CI = 0.67-0.82), p value = .000, but, moderate statistical heterogeneity (χ² = 42.73, p value = .011) was found. Due to the high mortality of colorectal cancer, it is important to identify effective preventive measures, especially those of a healthy lifestyle, such as a healthy diet.

Carotenoid intake from natural sources and colorectal cancer: a systematic review and meta-analysis of epidemiological studies

Carotenoid intake from natural sources has been hypothesized to reduce the risk of colorectal cancer (CRC). The aim of this study was to systematically review the epidemiological evidence for the association between carotenoid intake from natural sources and CRC development. We carried out a systematic review and meta-analysis of epidemiological studies to investigate whether the intake of specific carotenoids from natural sources, as well as combined carotenoids, is associated with the risk of CRC overall and by anatomic subsite. A comprehensive literature search of MEDLINE and Scopus databases was performed. Twenty-two articles were identified from the literature search, of which 16 were case-control studies and 6 were cohort studies. In the random-effects meta-analysis of case-control and cohort studies, we found no association between the intake of individual and total carotenoids and the risk of CRC overall and by anatomic subsite. Overall, our findings do not support a significant association between intake of specific carotenoids from dietary sources, as well as combined carotenoids, and the risk of CRC overall and by anatomic subsite.

Independent associations of dairy and calcium intakes with colorectal cancers in the Adventist Health Study-2 cohort

OBJECTIVE

Results associating dairy and Ca intakes with colorectal cancer (CRC) risk have been mixed. Most previous analyses have suffered from confounding between dairy and Ca intakes. We examined independent associations between these variables, also dairy foods, and CRC incidence in a population with a large range of dairy intakes.

DESIGN

Adventist Health Study-2 is a cohort study where subjects were enrolled 2002-2007. Proportional hazard regression analyses were performed to estimate hazard ratios (HR). Regression calibration was used to correct for dietary measurement error.

SETTING

The population lived in all states of the USA.

SUBJECTS

There were 77712 analytic subjects, all of whom were Seventh-day Adventists. Much of their dietary Ca came from non-dairy sources.

SUBJECTS

During a mean follow-up of 7·8 years, 380 incident colon cancer and 111 incident rectal cancer cases were observed.

RESULTS

Comparing extreme quintiles of intake in measurement error-corrected analyses, dairy intake (HR=0·31; 95 % CI 0·09, 0·88), independent of total Ca, was inversely related with risk of rectal cancer but gave little indication of association with colon cancer. However, total Ca intake (independent of dairy) was associated with risk of colon cancer (HR=0·55; 95 % CI 0·28, 0·98) and there was little indication of association with rectal cancer. Traditional regression analyses and associations with macronutrients from dairy generally supported these results. Milk intake was also negatively associated with CRC (HR=0·63; 95 % CI 0·43, 0·89).

CONCLUSIONS

Dairy intake may decrease the risk of rectal cancer, and Ca may reduce risk of colon cancer and CRC.

Plant Sterol Esters in Extruded Food Model Inhibits Colon Carcinogenesis by Suppressing Inflammation and Stimulating Apoptosis

Plant sterols in their free forms are known to inhibit colon cancer. Whether these activities persist when compounds are incorporated into processed food is not reported yet. This study aimed to test the ability of plant sterol esters (PSE) incorporated into a nonpuffed extruded food (NPE) model to inhibit colon carcinogenesis. PSE was added into NPE at four concentrations (0.0%, 0.7%, 1.4%, and 2.1%). PSE-NPE activity was tested in azoxymethane/dextran sodium sulfate-induced Balb/c mice. The groups given PSE-NPE did not show any colon tumor formation. Immunohistochemistry results revealed that the group fed with 1.4% PSE had the lowest histoscore for cyclooxygenase-2 expression and the highest histoscore for cleaved caspase-3, cleaved caspase-8, and cleaved caspase-9expressions. The results of this study indicated that even after incorporation into a food system, which is processed using high pressure and temperature, PSE retained its chemopreventive activity. The proposed mechanisms are by suppressing inflammation and inducing apoptosis.

Perceived Stress and Colorectal Cancer Incidence: The Japan Collaborative Cohort Study

Colorectal cancer is the third most common cancer worldwide, and many risk factors for colorectal cancer have been established. However, it remains uncertain whether psychological stress contributes to the onset of colorectal cancer. Therefore, we conducted a large-scale prospective cohort study to confirm the association between perceived stress and colorectal cancer incidence. We identified 680 cases of colon cancer and 330 cases of rectal cancer during a maximum of 21-year follow-up of 61,563 Japanese men and women. Cox regression analysis adjusted for potential confounders revealed a significant association of perceived stress with rectal cancer incidence but not with colon cancer incidence. This finding is partly consistent with that from only one previous study that addressed an association between perceived stress and the risk of colorectal cancer. However, studies on this topic are sparse and warrant further exploration.

The Interaction between Dietary Fiber and Fat and Risk of Colorectal Cancer in the Women's Health Initiative

Combined intakes of specific dietary fiber and fat subtypes protect against colon cancer in animal models. We evaluated associations between self-reported individual and combinations of fiber (insoluble, soluble, and pectins, specifically) and fat (omega-6, omega-3, and docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), specifically) and colorectal cancer (CRC) risk in the Women's Health Initiative prospective cohort (n = 134,017). During a mean 11.7 years (1993-2010), 1952 incident CRC cases were identified. Cox regression models computed multivariate adjusted hazard ratios to estimate the association between dietary factors and CRC risk. Assessing fiber and fat individually, there was a modest trend for lower CRC risk with increasing intakes of total and insoluble fiber (p-trend 0.09 and 0.08). An interaction (p = 0.01) was observed between soluble fiber and DHA + EPA, with protective effects of DHA + EPA with lower intakes of soluble fiber and an attenuation at higher intakes, however this association was no longer significant after correction for multiple testing. These results suggest a modest protective effect of higher fiber intake on CRC risk, but not in combination with dietary fat subtypes. Given the robust results in preclinical models and mixed results in observational studies, controlled dietary interventions with standardized intakes are needed to better understand the interaction of specific fat and fiber subtypes on colon biology and ultimately CRC susceptibility in humans.

Inhibitory effect on HT-29 colon cancer cells of a water-soluble polysaccharide obtained from highland barley

A water-soluble polysaccharide (BP-1) was obtained from highland barley (Hordeum vulgare L.) by hot water extraction and purification of sepharose column chromatography. BP-1 had an average molecular weight of about 6.7×10⁴Da and was composed of glucose (Glc), xylose (Xyl), arabinose (Ara) and rhamnose (Rha) with a relative molar ratio of 8.82:1.92:1.50:1.00. It was found that BP-1 inhibited proliferation of human colon cancer cells (HT-29) in a time- and dose-dependent manner with half maximal inhibitory concentration at 48h of 48.18μg/mL. Western blotting results showed that BP-1 enhanced the phosphorylation of c-Jun N-terminal kinase (JNK), processes associated with the reactive oxygen species (ROS) formation and inhibited nuclear factor-κB (NF-κB) translocation from cytoplasm into nucleus. Meanwhile, the BP-1-induced apoptosis was related to the regulation of apoptosis-associated proteins, such as B-cell lymphoma-2 (Bcl-2), release of cytochrome C from mitochondria to cytoplasm and activation of caspase-8 and caspase-9. These results suggest that BP-1-induced HT-29 apoptosis through ROS-JNK and NF-κB-mediated caspase pathways.

Inverse associations of dietary fiber and menopausal hormone therapy with colorectal cancer risk in the Multiethnic Cohort Study

In the Multiethnic Cohort Study, we previously reported that dietary fiber intake was inversely associated with colorectal cancer risk in men only. In women, the inverse relationship was weaker and appeared to be confounded by menopausal hormone therapy (MHT). We re-examined this observation with a greatly increased power. Using Cox proportional hazards models, we analyzed data from 187,674 participants with 4,692 cases identified during a mean follow-up period of 16 years. In multivariable-adjusted models, dietary fiber intake was inversely associated with colorectal cancer risk in both sexes: HR = 0.73, 95% CI: 0.61-0.89 for highest vs. lowest quintile, ptrend  = 0.0020 in men and HR = 0.76, 95% CI: 0.62-0.91, ptrend  = 0.0067 in women. Postmenopausal women who ever used MHT had a 19% lower risk of colorectal cancer (95% CI: 0.74-0.89) compared with MHT never users. In a joint analysis of dietary fiber and MHT, dietary fiber intake was associated with a lower colorectal cancer risk in MHT never users (HR = 0.75, 95% CI: 0.59-0.95, ptrend  = 0.045), but did not appear to further decrease the colorectal cancer risk of MHT ever users (ptrend  = 0.11). Our results support the overall protective roles of dietary fiber and MHT against colorectal cancer and suggest that dietary fiber may not lower risk further among women who ever used MHT. If confirmed, these results would suggest that MHT and dietary fiber may share overlapping mechanisms in protecting against colorectal cancer.

Dietary fibre and the risk of colorectal cancer: a case- control study

BACKGROUND

Colorectal cancer is one of the most commonly occurring cancers in China. Dietary fibre has been thought to decrease the risk of colorectal cancer in Western countries. However, studies investigating the association between dietary fibre (particularly soluble and insoluble fibres) and colorectal cancer have hitherto been lacking in China.

OBJECTIVE

This case-control study examined the effect of dietary fibre intake on the risk of colorectal cancer, stratified by tumour site.

MATERIALS AND METHODS

The study included 265 cases (colon cancer, 105; rectal cancer, 144; colon and rectal cancer, 16) and 252 controls residing in Qingdao. A food frequency questionnaire that included 121 food items was used to collect dietary information. Odds ratio (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression analysis.

RESULTS

For food groups, controls in the study consumed more vegetables, soy food and total fibre than did colorectal cancer patients (p<0.05). The intakes of fruit, meat and sea-food did not differ significantly between cases and controls. However, we did not find any association between soy food intake and colon cancer. We observed inverse associations between total fibre intake and colorectal, colon and rectal cancer (Q4 vs Q1: OR=0.44, 95%CI, 0.27- 0.73; OR=0.40, 95%CI, 0.21-0.76; OR=0.52, 95%CI, 0.29-0.91). Vegetable fibre intake showed similar inverse associations (Q4 vs Q1: OR=0.51, 95%CI, 0.31-0.85; OR=0.48, 95%CI, 0.25-0.91; OR=0.53, 95%CI, 0.29-0.97). In addition, inverse associations were observed between soluble fibre and insoluble fibre and both colorectal cancer and colon cancer. No relationship was found between colorectal cancer and fruit, soy or grain fibre intakewhen the results were stratified by tumour site.

CONCLUSIONS

The present study suggests that vegetable fibre and total fibre play very important roles in protecting against colorectal cancer. Soluble and insoluble fibres were inversely associated with only colorectal cancer and colon cancer.

Dietary fiber and fiber fraction intakes and colorectal cancer risk in Chinese adults

Few studies have been conducted in Chinese adults to investigate the effect of fiber intake on colorectal cancer risk. The present study aimed to examine the associations of dietary fiber and fiber fraction intakes with colorectal cancer risk in Chinese adults. A total of 613 cases with colorectal cancer were consecutively recruited between July 2010 and October 2012 and frequency matched to 613 controls by age (5-yr interval) and gender. Dietary information was collected through a validated food frequency questionnaire by face-to-face interviews. Multivariate logistic regression models were used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) after adjustment for potential confounders. Total dietary fiber and fiber fraction intakes were found to be inversely associated with colorectal cancer risk. Compared with the lowest quartile, the adjusted ORs (95% CIs) for the highest quartile were 0.38 (0.27-0.55) for total dietary fiber, 0.45 (0.32-0.64) for vegetable fiber, and 0.41 (0.28-0.58) for fruit fiber, respectively. In addition, no significant association was found between soy fiber intake and colorectal cancer risk. This study showed that a high intake of dietary fiber, particularly derived from vegetables and fruit, was inversely associated with colorectal cancer risk in Chinese adults.

Nutrients, foods, and colorectal cancer prevention

Diet has an important role in the development of colorectal cancer. In the past few decades, findings from extensive epidemiologic and experimental investigations have linked consumption of several foods and nutrients to the risk of colorectal neoplasia. Calcium, fiber, milk, and whole grains have been associated with a lower risk of colorectal cancer, and red meat and processed meat have been associated with an increased risk. There is substantial evidence for the potential chemopreventive effects of vitamin D, folate, fruits, and vegetables. Nutrients and foods also may interact, as a dietary pattern, to influence colorectal cancer risk. Diet likely influences colorectal carcinogenesis through several interacting mechanisms. These include the direct effects on immune responsiveness and inflammation, and the indirect effects of overnutrition and obesity-risk factors for colorectal cancer. Emerging evidence also implicates the gut microbiota as an important effector in the relationship between diet and cancer. Dietary modification therefore has the promise of reducing colorectal cancer incidence.

Dietary legume consumption reduces risk of colorectal cancer: evidence from a meta-analysis of cohort studies

Previous epidemiological studies on the relation between dietary legume consumption and risk of colorectal cancer (CRC) remain controversial. We conducted a meta-analysis based on prospective cohort studies to investigate the association between dietary legume consumption and risk of CRC. Fourteen cohort studies were finally included, containing a total of 1,903,459 participants and 12,261 cases who contributed 11,628,960 person-years. We found that higher legume consumption was associated with a decreased risk of CRC (RR, relative risk = 0.91; 95% CI, confidence interval = 0.84-0.98). Subgroup analyses suggested that higher legume consumption was inversely associated with CRC risk in Asian (RR = 0.82; 95% CI = 0.74-0.91) and soybean intake was associated with a decreased risk of CRC (RR = 0.85; 95% CI = 0.73-0.99). Findings from our meta-analysis supported an association between higher intake of legume and a reduced risk of CRC. Further studies controlled for appropriate confounders are warranted to validate the associations.

Fiber intake and risk of subsequent prostate cancer in Japanese men

BACKGROUND

Dietary fiber may reduce the risk of prostate cancer, possibly by increasing circulating concentrations of sex hormone-binding globulin and improving insulin sensitivity. However, results from previous epidemiologic studies of fiber intake and prostate cancer are inconsistent, and to our knowledge, no study has comprehensively evaluated the effects of soluble and insoluble fiber on prostate cancer in Asia.

OBJECTIVE

The objective was to examine the association between fiber intake and prostate cancer in Japanese men.

DESIGN

We conducted a population-based prospective study in 43,435 Japanese men aged 45-74 y. Participants responded to a validated questionnaire, which included 138 food items. Follow-up was from 1995 through 2009. HRs and 95% CIs of incidence were calculated according to quartiles of fiber intake.

RESULTS

During the 11.6-y follow-up, of the 825 men newly diagnosed with prostate cancer, 213 had advanced-stage cancer, 582 had organ-localized disease, and 30 had an undetermined stage of disease. Among them, 217 cases were detected by subjective symptoms. Total fiber was not associated with total or advanced prostate cancer, with respective multivariable HRs for the highest and lowest quartiles of 1.00 (95% CI: 0.77, 1.29; P-trend = 0.97) and 0.67 (95% CI: 0.42, 1.07; P-trend = 0.30). Total fiber and insoluble fiber intake were associated with a decreased risk of advanced cancers detected by subjective symptoms, with multivariate HRs (95% CIs) across increasing quartiles of 1.00, 0.58, 0.62, and 0.44 (0.21, 0.92; P-trend = 0.05) for total fiber and 1.00, 0.60, 0.52, and 0.46 (0.22, 0.93; P-trend = 0.04) for insoluble fiber. Soluble fiber intake showed no association with prostate cancer.

CONCLUSIONS

Dietary fiber is inversely associated with advanced prostate cancer detected by subjective symptoms even among populations with relatively low intake, such as Japanese. These results suggest that a very low intake of dietary fiber is associated with an increased risk of prostate cancer.

Antitumor activity of the β-glucan paramylon from Euglena against preneoplastic colonic aberrant crypt foci in mice

In the present study, the effects of β-glucans isolated from Euglena on the formation of preneoplastic aberrant crypt foci (ACF) in the colon were examined in mice. Mice were fed a semi-purified AIN-93M diet containing cellulose or the same diet but with the cellulose replaced with β-glucans in the form of Euglena, paramylon, or amorphous paramylon, for 11 weeks. After consuming these dietary supplements for 8 days, half of the mice were intraperitoneally administered 1,2-dimethylhydrazine (DMH) at a dose of 20 mg kg(-1) body weight every week for 6 weeks. Among the DMH-treated groups, the paramylon- and amorphous paramylon-fed mice displayed a significantly lower number of ACF than the control group. Also, the liver weight of the paramylon group was markedly decreased compared with those of the control and Euglena groups, whereas the cecal content weight and fecal volume of the paramylon group were significantly increased. As for the levels of organic acids in the cecal contents, the paramylon group displayed significantly increased lactic acid levels compared with the control and Euglena groups. From these findings, although the mechanism of the ACF-inhibiting effects of paramylon remains unclear, it is considered that β-glucans, such as paramylon and its isomer amorphous paramylon, have preventive effects against colon cancer and are more effective against the condition than Euglena.

Associations between dietary fiber and colorectal polyp risk differ by polyp type and smoking status

The association of dietary fiber intake with colorectal cancer risk is established. However, the association may differ between cigarette smokers and nonsmokers. We evaluated this hypothesis in a large colonoscopy-based case-control study. Dietary fiber intakes were estimated by self-administered food frequency questionnaire. Unconditional logistic regression analysis was used to estimate ORs and 95% CIs with adjustment for potential confounders. Analysis also was stratified by cigarette smoking and sex. High dietary fiber intake was associated with reduced risk of colorectal polyps (P-trend = 0.003). This association was found to be stronger among cigarette smokers (P-trend = 0.006) than nonsmokers (P-trend = 0.21), although the test for multiplicative interaction was not statistically significant (P = 0.11). This pattern of association was more evident for high-risk adenomatous polyps (ADs), defined as advanced or multiple ADs (P-interaction smoking and dietary fiber intake = 0.09). Among cigarette smokers who smoked ≥23 y, a 38% reduced risk of high-risk ADs was found to be associated with high intake of dietary fiber compared with those in the lowest quartile fiber intake group (P-trend = 0.004). No inverse association with dietary fiber intake was observed for low-risk ADs, defined as single nonadvanced ADs. Cigarette smoking may modify the association of dietary fiber intake with the risk of colorectal polyps, especially high-risk ADs, a well-established precursor of colorectal cancer.

Dietary intakes of fat and total mortality among Japanese populations with a low fat intake: the Japan Collaborative Cohort (JACC) Study

BACKGROUND

It may be useful to examine associations of fat intakes with total mortality as a basis for dietary recommendations. We aimed to elucidate associations between dietary fat and total mortality among Japanese populations with low fat intake.

METHODS

We conducted a prospective study consisting of 58,672 men and women aged 40 to 79 years. Fat intakes were estimated using a food frequency questionnaire. Multivariate-adjusted hazard ratios (HRs) for mortality by sex were computed according to quintiles of energy-adjusted fat intakes.

RESULTS

During the follow-up period (median duration, 19.3 years), 11,656 deaths were recorded. In men, we found no clear association between total fat and total mortality. HRs across quintiles of total fat intake were 1.00, 1.03 (95% confidence interval [CI], 0.95-1.12), 1.02 (0.94-1.10), 0.98 (0.90-1.07), and 1.07 (0.98-1.17). No significant association was detected in regard to types of fat. In women, HR was lowest in the fourth quintile of total fat intake followed by the top quintile; HRs across quintiles were 1.00, 1.03 (0.94-1.11), 1.00 (0.92-1.09), 0.88 (0.81-0.96), and 0.94 (0.86-1.03). Regarding types of fat in women, total mortality was inversely associated with intakes of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA); the lowest HR was in the top quintile of intake for SFA, MUFA, and PUFA: 0.91 (95% CI, 0.83-1.00), 0.91 (0.83-0.99) and 0.88 (0.80 - 0.97), respectively (trend P across quintiles, 0.020, 0.012, and 0.029, respectively). Causes of death other than cancer and cardiovascular disease contributed most to decreases in HRs for total and types of fat. In women, analysis with finer categories revealed that the lowest risk for total mortality appeared at total fat intake of 28% of energy.

CONCLUSIONS

Our findings from a large cohort study among populations with relatively low fat intake provide evidence regarding optimal levels of fat intakes.

Rice, bread, noodle and cereal intake and colorectal cancer in Japanese men and women: the Japan Public Health Center-based prospective Study (JPHC Study)

Background:

Colorectal cancer (CRC) incidence rate increased rapidly in Japan between the 1950s and 1990s. We examined the association between rice intake and CRC risk in comparison with bread, noodles and cereal among Japanese adults enrolled in the Japan Public Health Center-based prospective Study.

Methods:

A total of 73 501 Japanese men and women were followed-up from 1995 to 1999 until the end of 2008 for an average of 11 years. During 801 937 person-years of follow-up, we identified 1276 incident cases of CRC. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) of CRC for rice, noodle, bread and cereal intake were calculated by Cox proportional hazards model.

Results:

Overall, no significant association was observed for the highest quartile of rice intake compared with the lowest and the risk of CRC and its subsites in men (HR, 0.77; 95% CI, 0.56–1.07) and women (HR, 1.10; 95% CI, 0.71–1.68). However, a non-significant inverse trend was observed between rice intake and rectal cancer in men. No clear patterns of association were observed in bread, noodle and cereal intake.

Conclusion:

Our findings suggest that the consumption of rice does not have a substantial impact on the risk of CRC in the Japanese population.

Trends in dietary patterns, alcohol intake, tobacco smoking, and colorectal cancer in Polish population in 1960-2008

The study examined the relationships between long-term trends in food consumption, alcohol intake, tobacco smoking, and colorectal cancer (CRC) incidence. Data on CRC incidence rates were derived from the National Cancer Registry, on food consumption from the national food balance sheets; data on alcohol and tobacco smoking reflected official statistics of the Central Statistical Office. It was shown that CRC incidence rates were increasing between 1960 and 1995, which could have been affected by adverse dietary patterns (growing consumption of edible fats, especially animal fats, sugar, red meat, and declining fibre and folate intake), high alcohol consumption, and frequent tobacco smoking noted until the end of the 1980s. Since 1990, the dietary pattern changed favourably (decrease in consumption of red meat, animal fats, and sugar, higher vitamin D intake, increase in vegetables and fruit quantities consumed, and decline in tobacco smoking). These changes could contribute to the stabilisation of CRC incidence among women seen after 1996 and a reduction in the rate of increase among men.

Effects of legume kernel fibres and citrus fibre on putative risk factors for colorectal cancer: a randomised, double-blind, crossover human intervention trial

Background

In some studies, high intake of dietary fibre has been associated with a lower risk of colorectal cancer. The present study aimed to compare physiological effects of three legume kernel fibres and citrus fibre on blood lipids (primary outcome: LDL cholesterol) and colonic health.

Methods

Ninety-two subjects were recruited for the double-blind, controlled crossover trial. Seventy-eight participants were randomly divided into three groups. Following run-in, half the volunteers from each group consumed 25 g/d of a legume fibre, comprising blue lupin fibre, white lupin fibre, and soya fibre for two weeks. The other half received the same amount of citrus fibre (active comparator). The intervention was crossed within each group after two weeks wash-out. At the end of run-in and intervention, a quantitative faeces collection took place and fasting blood samples were drawn. Repeated measures ANOVA with the general linear model were applied to evaluate changes following interventions.

Results

Seventy-six subjects completed the study. Dietary fibre intake during all interventions was approximately twice the fibre intake at run-in. The lupin fibre supplementations increased daily faecal dry matter and faecal weight compared to run-in, representing an increase of 1.76 g faeces/g additional dietary fibre contributed by blue lupin and of 1.64 g faeces/g by white lupin, respectively. Both lupin interventions led to a significantly enhanced formation of short-chain fatty acids, and blue lupin fibre to a decrease in faecal pH compared to run-in (0.27 units, P < 0.01). Further, blue lupin increased primary bile acids-excretion (P = 0.02). All legume fibres reduced faecal concentrations of total and secondary bile acids (blue lupin: 16%; white lupin: 24%; soya: 16%). Blood lipids were not influenced by any intervention. No serious adverse effects were observed.

Conclusions

The tested fibre preparations do not affect lipid metabolism through bile acid-binding in normocholesterolaemic subjects. However, particularly blue lupin kernel fibre improve colonic function and have beneficial effects on putative risk factors for colorectal cancer such as faecal mass, transit time, SCFA, faecal pH, and secondary bile acid concentration. Therefore, enhancing dietary fibre intake through blue lupin up to about 50 g/d can be recommended.

Trial registration

NCT01036308

Nutritional and Phytochemical Study ofIlex paraguariensisFruits

Yerba mate is defined as the product constituted by the dried, slightly roasted, and milled leaves ofIlex paraguariensis. However, the fruits of this species are often found in the commercial product. Nowadays the fruits are considered a byproduct. The objective of this work was to obtain the preliminary data of minerals, lipids, methylxanthines and polyphenols in the ripe fruits ofI. paraguariensis. The results showed a considerable amount of total dietary fiber (42.0±1.6 g/100 g) and nutritionally valuable minerals: potassium (1324±15 mg/100 g), iron (6.4±0.5 mg/100 g), magnesium (168±15 mg/100 g), calcium (150±12 mg/100 g), copper (1.1±0.1 mg/100 g), zinc (2.3±0.3 mg/100 g), and sodium (1.3±0.1 mg/100 g). The lipid content was 4.5 g/100 g. Oleic acid was the predominant unsaturated fatty acid (38.74±0.75 g/100 g). Linoleic acid (1.83±0,01 g/100 g) was also present. Methylxanthines were quantified: caffeine (0.118±0.001) and theobromine (0.0125±0.0002) g/100 g. The total polyphenol content was0.717±0.001 g/100 g. The results obtained in this work suggest the potential value of the fruits ofI. paraguariensisfor the development of novel products in the food and pharmaceutical industries. This paper aims to contribute to the scientific knowledge of a natural by-product from industry regarding the need of foods and medicines for the new millennium.

Dietary fibre intake and risks of cancers of the colon and rectum in the European prospective investigation into cancer and nutrition (EPIC)

BACKGROUND

Earlier analyses within the EPIC study showed that dietary fibre intake was inversely associated with colorectal cancer risk, but results from some large cohort studies do not support this finding. We explored whether the association remained after longer follow-up with a near threefold increase in colorectal cancer cases, and if the association varied by gender and tumour location.

METHODOLOGY/PRINCIPAL FINDINGS

After a mean follow-up of 11.0 years, 4,517 incident cases of colorectal cancer were documented. Total, cereal, fruit, and vegetable fibre intakes were estimated from dietary questionnaires at baseline. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models stratified by age, sex, and centre, and adjusted for total energy intake, body mass index, physical activity, smoking, education, menopausal status, hormone replacement therapy, oral contraceptive use, and intakes of alcohol, folate, red and processed meats, and calcium. After multivariable adjustments, total dietary fibre was inversely associated with colorectal cancer (HR per 10 g/day increase in fibre 0.87, 95% CI: 0.79-0.96). Similar linear associations were observed for colon and rectal cancers. The association between total dietary fibre and risk of colorectal cancer risk did not differ by age, sex, or anthropometric, lifestyle, and dietary variables. Fibre from cereals and fibre from fruit and vegetables were similarly associated with colon cancer; but for rectal cancer, the inverse association was only evident for fibre from cereals.

CONCLUSIONS/SIGNIFICANCE

Our results strengthen the evidence for the role of high dietary fibre intake in colorectal cancer prevention.

Association of total energy intake and macronutrient consumption with colorectal cancer risk: results from a large population-based case-control study in Newfoundland and Labrador and Ontario, Canada

Background

Diet is regarded as one of the most important environmental factors associated with colorectal cancer (CRC) risk. A recent report comprehensively concluded that total energy intake does not have a simple relationship with CRC risk, and that the data were inconsistent for carbohydrate, cholesterol and protein. The objective of this study was to identify the associations of CRC risk with dietary intakes of total energy, protein, fat, carbohydrate, fiber, and alcohol using data from a large case-control study conducted in Newfoundland and Labrador (NL) and Ontario (ON), Canada.

Methods

Incident colorectal cancer cases (n = 1760) were identified from population-based cancer registries in the provinces of ON (1997-2000) and NL (1999-2003). Controls (n = 2481) were a random sample of residents in each province, aged 20-74 years. Family history questionnaire (FHQ), personal history questionnaire (PHQ), and food frequency questionnaire (FFQ) were used to collect study data. Logistic regression was used to evaluate the association of intakes of total energy, macronutrients and alcohol with CRC risk.

Results

Total energy intake was associated with higher risk of CRC (OR: 1.56; 95% CI: 1.21-2.01, p-trend = 0.02, 5^th versus 1^st quintile), whereas inverse associations emerged for intakes of protein (OR: 0.85, 95%CI: 0.69-1.00, p-trend = 0.06, 5^th versus 1^st quintile), carbohydrate (OR: 0.81, 95%CI: 0.63-1.00, p-trend = 0.05, 5^th versus 1^st quintile) and total dietary fiber (OR: 0.84, 95% CI:0.67-0.99, p-trend = 0.04, 5^th versus 1^st quintile). Total fat, alcohol, saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, and cholesterol were not associated with CRC risk.

Conclusion

This study provides further evidence that high energy intake may increase risk of incident CRC, whereas diets high in protein, fiber, and carbohydrate may reduce the risk of the disease.

Evidence-based guideline of the German Nutrition Society: carbohydrate intake and prevention of nutrition-related diseases

The relative contribution of nutrition-related chronic diseases to the total disease burden of the society and the health care costs has risen continuously over the last decades. Thus, there is an urgent necessity to better exploit the potential of dietary prevention of diseases. Carbohydrates play a major role in human nutrition - next to fat, carbohydrates are the second biggest group of energy-yielding nutrients. Obesity, type 2 diabetes mellitus, dyslipoproteinaemia, hypertension, metabolic syndrome, coronary heart disease and cancer are wide-spread diseases, in which carbohydrates could have a pathophysiologic relevance. Correspondingly, modification of carbohydrate intake could have a preventive potential. In the present evidence-based guideline of the German Nutrition Society, the potential role of carbohydrates in the primary prevention of the named diseases was judged systematically. The major findings were: a high carbohydrate intake at the expense of total fat and saturated fatty acids reduces the concentrations of total, LDL and HDL cholesterol. A high carbohydrate consumption at the expense of polyunsaturated fatty acids increases total and LDL cholesterol, but reduces HDL cholesterol. Regardless of the type of fat being replaced, a high carbohydrate intake promotes an increase in the triglyceride concentration. Furthermore, a high consumption of sugar-sweetened beverages increases the risk of obesity and type 2 diabetes mellitus, whereas a high dietary fibre intake, mainly from whole-grain products, reduces the risk of obesity, type 2 diabetes mellitus, dyslipoproteinaemia, cardiovascular disease and colorectal cancer at varying evidence levels. The practical consequences for current dietary recommendations are presented.

Dietary fibre, whole grains, and risk of colorectal cancer: systematic review and dose-response meta-analysis of prospective studies

OBJECTIVE

To investigate the association between intake of dietary fibre and whole grains and risk of colorectal cancer.

DESIGN

Systematic review and meta-analysis of prospective observational studies.

DATA SOURCES

PubMed and several other databases up to December 2010 and the reference lists of studies included in the analysis as well as those listed in published meta-analyses.

STUDY SELECTION

Prospective cohort and nested case-control studies of dietary fibre or whole grain intake and incidence of colorectal cancer.

RESULTS

25 prospective studies were included in the analysis. The summary relative risk of developing colorectal cancer for 10 g daily of total dietary fibre (16 studies) was 0.90 (95% confidence interval 0.86 to 0.94, I(2) = 0%), for fruit fibre (n = 9) was 0.93 (0.82 to 1.05, I(2) = 23%), for vegetable fibre (n = 9) was 0.98 (0.91 to 1.06, I(2) = 0%), for legume fibre (n = 4) was 0.62 (0.27 to 1.42, I(2) = 58%), and for cereal fibre (n = 8) was 0.90 (0.83 to 0.97, I(2) = 0%). The summary relative risk for an increment of three servings daily of whole grains (n = 6) was 0.83 (0.78 to 0.89, I(2) = 18%).

CONCLUSION

A high intake of dietary fibre, in particular cereal fibre and whole grains, was associated with a reduced risk of colorectal cancer. Further studies should report more detailed results, including those for subtypes of fibre and be stratified by other risk factors to rule out residual confounding. Further assessment of the impact of measurement errors on the risk estimates is also warranted.

Dietary fibre, whole grains, and risk of colorectal cancer: systematic review and dose-response meta-analysis of prospective studies

OBJECTIVE

To investigate the association between intake of dietary fibre and whole grains and risk of colorectal cancer.

DESIGN

Systematic review and meta-analysis of prospective observational studies.

DATA SOURCES

PubMed and several other databases up to December 2010 and the reference lists of studies included in the analysis as well as those listed in published meta-analyses.

STUDY SELECTION

Prospective cohort and nested case-control studies of dietary fibre or whole grain intake and incidence of colorectal cancer.

RESULTS

25 prospective studies were included in the analysis. The summary relative risk of developing colorectal cancer for 10 g daily of total dietary fibre (16 studies) was 0.90 (95% confidence interval 0.86 to 0.94, I(2) = 0%), for fruit fibre (n = 9) was 0.93 (0.82 to 1.05, I(2) = 23%), for vegetable fibre (n = 9) was 0.98 (0.91 to 1.06, I(2) = 0%), for legume fibre (n = 4) was 0.62 (0.27 to 1.42, I(2) = 58%), and for cereal fibre (n = 8) was 0.90 (0.83 to 0.97, I(2) = 0%). The summary relative risk for an increment of three servings daily of whole grains (n = 6) was 0.83 (0.78 to 0.89, I(2) = 18%).

CONCLUSION

A high intake of dietary fibre, in particular cereal fibre and whole grains, was associated with a reduced risk of colorectal cancer. Further studies should report more detailed results, including those for subtypes of fibre and be stratified by other risk factors to rule out residual confounding. Further assessment of the impact of measurement errors on the risk estimates is also warranted.

Dietary fibre, whole grains, and risk of colorectal cancer: systematic review and dose-response meta-analysis of prospective studies

OBJECTIVE

To investigate the association between intake of dietary fibre and whole grains and risk of colorectal cancer.

DESIGN

Systematic review and meta-analysis of prospective observational studies.

DATA SOURCES

PubMed and several other databases up to December 2010 and the reference lists of studies included in the analysis as well as those listed in published meta-analyses.

STUDY SELECTION

Prospective cohort and nested case-control studies of dietary fibre or whole grain intake and incidence of colorectal cancer.

RESULTS

25 prospective studies were included in the analysis. The summary relative risk of developing colorectal cancer for 10 g daily of total dietary fibre (16 studies) was 0.90 (95% confidence interval 0.86 to 0.94, I(2) = 0%), for fruit fibre (n = 9) was 0.93 (0.82 to 1.05, I(2) = 23%), for vegetable fibre (n = 9) was 0.98 (0.91 to 1.06, I(2) = 0%), for legume fibre (n = 4) was 0.62 (0.27 to 1.42, I(2) = 58%), and for cereal fibre (n = 8) was 0.90 (0.83 to 0.97, I(2) = 0%). The summary relative risk for an increment of three servings daily of whole grains (n = 6) was 0.83 (0.78 to 0.89, I(2) = 18%).

CONCLUSION

A high intake of dietary fibre, in particular cereal fibre and whole grains, was associated with a reduced risk of colorectal cancer. Further studies should report more detailed results, including those for subtypes of fibre and be stratified by other risk factors to rule out residual confounding. Further assessment of the impact of measurement errors on the risk estimates is also warranted.

Foods and food groups associated with the incidence of colorectal polyps: the Adventist Health Study

Colorectal cancer (CRC) is a leading cause of cancer death in the United States. The majority of CRC arise in adenomatous polyps and 25-35% of colon adenoma risk could be avoidable by modifying diet and lifestyle habits. We assessed the association between diet and the risk of self-reported physician-diagnosed colorectal polyps among 2,818 subjects who had undergone colonoscopy. Subjects participated in 2 cohort studies: the AHS-1 in 1976 and the AHS-2 from 2002-2005. Multivariate logistic regression analysis was used to estimate the period risk of incident cases of polyps; 441 cases of colorectal polyps were identified. Multivariate analysis adjusted by age, sex, body mass index, and education showed a protective association with higher frequency of consumption of cooked green vegetables (OR 1 time/d vs. <5/wk = 0.76, 95% CI = 0.59-0.97) and dried fruit (OR 3+ times/wk vs. <1 time/wk = 0.76, 95%CI = 0.58-0.99). Consumption of legumes at least 3 times/wk reduced the risk by 33% after adjusting for meat intake. Consumption of brown rice at least 1 time/wk reduced the risk by 40%. These associations showed a dose-response effect. High frequency of consumption of cooked green vegetables, dried fruit, legumes, and brown rice was associated with a decreased risk of colorectal polyps.