Dairy intake during adolescence and risk of colorectal adenoma later in life.

BACKGROUND: Higher dairy intake during adulthood has been associated with lower colorectal cancer risk. As colorectal carcinogenesis spans several decades, we hypothesised that higher dairy intake during adolescence is associated with lower risk of colorectal adenoma, a colorectal cancer precursor. METHODS: In 27,196 females from the Nurses' Health Study 2, aged 25-42 years at recruitment (1989), who had completed a validated high school diet questionnaire in 1998 and undergone at least one lower bowel endoscopy between 1998 and 2011, logistic regression for clustered data was used to calculate odds ratios (ORs) and 95% confidence intervals (CI). RESULTS: Colorectal adenomas were diagnosed in 2239 women. Dairy consumption during adolescence was not associated with colorectal adenoma risk (OR highest vs. lowest [≥4 vs. ≤1.42 servings/day] quintile [95% CI] 0.94 [0.80, 1.11]). By anatomical site, higher adolescent dairy intake was associated with lower rectal (0.63 [0.42, 0.95]), but not proximal (1.01 [0.80, 1.28]) or distal (0.97 [0.76, 1.24]) colon adenoma risk. An inverse association was observed with histologically advanced (0.72 [0.51, 1.00]) but not non-advanced (1.07 [0.86, 1.33]) adenoma. CONCLUSIONS: In this large cohort of younger women, higher adolescent dairy intake was associated with lower rectal and advanced adenoma risk later in life.

Black Raspberries Suppress Colorectal Cancer by Enhancing Smad4 Expression in Colonic Epithelium and Natural Killer Cells.

Innate immune cells in the tumor microenvironment have been proposed to control the transition from benign to malignant stages. In many cancers, increased infiltration of natural killer (NK) cells associates with good prognosis. Although the mechanisms that enable NK cells to restrain colorectal cancer (CRC) are unclear, the current study suggests the involvement of Smad4. We found suppressed Smad4 expression in circulating NK cells of untreated metastatic CRC patients. Moreover, NK cell-specific Smad4 deletion promoted colon adenomas in DSS-treated ApcMin/+ mice and adenocarcinomas in AOM/DSS-treated mice. Other studies have shown that Smad4 loss or weak expression in colonic epithelium associates with poor survival in CRC patients. Therefore, targeting Smad4 in both colonic epithelium and NK cells could provide an excellent opportunity to manage CRC. Toward this end, we showed that dietary intervention with black raspberries (BRBs) increased Smad4 expression in colonic epithelium in patients with FAP or CRC and in the two CRC mouse models. Also, benzoate metabolites of BRBs, such as hippurate, upregulated Smad4 and Gzmb expression that might enhance the cytotoxicity of primary human NK cells. Of note, increased levels of hippurate is a metabolomic marker of a healthy gut microbiota in humans, and hippurate also has antitumor effects. In conclusion, our study suggests a new mechanism for the action of benzoate metabolites derived from plant-based foods. This mechanism could be exploited clinically to upregulate Smad4 in colonic epithelium and NK cells, thereby delaying CRC progression.

Effects of fish oil supplementation on eicosanoid production in patients at higher risk for colorectal cancer.

Fish oil supplementation may represent a potential chemopreventive agent for reducing colorectal cancer risk. The mechanism of action of fish oil is unknown but presumed to be related to eicosanoid modification. The purpose of this study was to evaluate the effects of fish oil supplementation on the levels of urinary and rectal eicosanoids. We conducted a randomized, double-blind, controlled trial of 2.5 g of fish oil per day compared with olive oil supplementation over a 6-month period. Study participants had a history of colorectal adenomas. Randomization was stratified based on the gene variant rs174535 in the fatty acid desaturase 1 enzyme (FADS1), which affects tissue levels of arachidonic acid. A total of 141 participants were randomized. Urinary prostaglandin E2 metabolite (PGE-M) was measured at baseline, 3, and 6 months and rectal prostaglandin E2 (PGE2) at baseline and 6 months. Repeated-measures linear regression was used to determine the effect of the intervention on each outcome measure. Overall, fish oil supplementation was found to reduce urinary PGE-M production compared with olive oil (P=0.03). Fish oil did not reduce rectal PGE2 overall; however, it did significantly reduce PGE2 in the subgroup of participants not using aspirin or NSAIDs (P=0.04). FADS1 genotype did not seem to modify effects of fish oil on PGE2 production. We conclude that fish oil supplementation has a modest but beneficial effect on eicosanoids associated with colorectal carcinogenesis, particularly in those not taking aspirin or NSAIDs.

Triptolide inhibits pituitary adenoma cell viability, migration and invasion via ADAM12/EGFR signaling pathway.

AIM: Triptolide, an effective component derived from Tripterygium wilfordii, has been well recognized to process a broad-spectrum antitumor activities in various tumor types. However, the potential role of triptolide in pituitary adenomas remains unknown. The aim of this study was to investigate the precise role of triptolide and underlying mechanism in regulating pituitary adenoma cell viability, migration and invasion. MAIN METHODS: We use mouse pituitary adenoma cells (TtT/GF and AtT20 cells) as the experiment model and treated them with varying concentrations of triptolide. The corresponding inhibitory effects on cell viability, migration, invasion and apoptosis were examined respectively, and the underlying mechanism was determined by investigating ADAM12 (a disintegrin and metalloprotease 12)/EGFR signaling. KEY FINDINGS: Triptolide significantly inhibited cell viability, migration and invasion in TtT/GF and AtT20 cells in a dose-dependent manner. Mechanistically, triptolide significantly reduced ADAM12 expression at protein levels and attenuated ADAM12/EGFR signaling. Meanwhile, triptolide treatment combined with ADAM12 silencing enhanced the suppression effects on cell viability, migration and invasion, and those effects were restored following ADAM12-rescued. Moreover, triptolide suppressed the tumorigenesis of TtT/GF and AtT20 cells in vivo. SIGNIFICANCE: Our research provides evidence that triptolide inhibits pituitary adenoma cell viability, migration and invasion via ADAM12/EGFR signaling pathway. These findings suggest a potential role for triptolide in treating pituitary adenomas.

The effects of nutritional interventions on recurrence in survivors of colorectal adenomas and cancer: a systematic review of randomised controlled trials.

BACKGROUND/OBJECTIVES: Nutrition and dietary supplementation may modulate outcomes in colorectal cancer (CRC) survivors. However, no recent systematic review has focused on randomised controlled trials (RCTs). The aim of this systematic review was to examine the effects of nutritional RCTs in survivors of colorectal adenomas and cancer. SUBJECTS/METHODS: Medline, Embase, Scopus, Web of Science and the Cochrane Library were searched to identify research between April 2006 and January 2014. The primary outcomes were colorectal adenoma and cancer recurrence. Each included study was assessed for risk of bias. A meta-analysis using a random-effects model was performed, in which two or more RCTs investigated the same dietary intervention. RESULTS: Eight completed RCTs, all in colorectal adenoma survivors, were identified, with four investigating the effect of folic acid. A meta-analysis of the four folic acid RCTs showed no statistically significant effect of folic acid on colorectal adenoma recurrence (relative risks=0.93; 95% confidence interval: 0.69, 1.25). The impact of the remaining completed RCTs, investigating antioxidant supplementation, green tea extract, prebiotic fibre and phytooestrogens/insoluble fibre, could not be reliably estimated because of the limited number and heterogeneity of the interventions. In addition, three heterogeneous ongoing RCTs were identified, investigating green tea (n=1) and eicosapentaenoic acid (n=1) in colorectal adenoma survivors and dietary modifications (n=1) in CRC survivors in remission. CONCLUSIONS: Overall, this systematic review highlights the need for further research, especially in CRC survivors, as we identified no completed and only one ongoing RCT in this population.

Black raspberries suppress colonic adenoma development in ApcMin/+ mice: relation to metabolite profiles.

Freeze-dried black raspberries (BRBs) have demonstrated chemopreventive effects in a dietary intervention trial with human colorectal cancer patients. The aim of this study was to investigate BRB-caused metabolite changes using the Apc(Min/+) mouse as a model of human colorectal cancer. Wild-type (WT) mice were fed control diet, and Apc(Min/+) mice were fed either control diet or control diet supplemented with 5% BRBs for 8 weeks. Colonic and intestinal polyp size and number were measured. A non-targeted metabolomic analysis was conducted on colonic mucosa, liver and fecal specimens. Eight weeks of BRB treatment significantly decreased intestinal and colonic polyp number and size in Apc(Min/+) mice. The apc gene mutation significantly changed 52 metabolites in colonic mucosa associated with increased amino acid and decreased lipid metabolites, as well as 39 liver and 8 fecal metabolites. BRBs significantly reversed 23 apc-regulated metabolites, including 13 colonic mucosa, 8 liver and 2 fecal metabolites that were involved in amino acid, glutathione, lipid and nucleotide metabolism. Of these, changes in eight metabolites were linearly correlated with decreased colonic polyp number and size in BRB-treated Apc(Min/+) mice. Elevated levels of putrescine and linolenate in Apc(Min/+) mice were significantly decreased by BRBs. Ornithine decarboxylase expression, the key enzyme in putrescine generation, was fully suppressed by BRBs. These results suggest that BRBs produced beneficial effects against colonic adenoma development in Apc(Min/+) mice and modulated multiple metabolic pathways. The metabolite changes produced by BRBs might potentially reflect the BRB-mediated chemopreventive effects in colorectal cancer patients.

Search for novel circulating cancer chemopreventive biomarkers of dietary rice bran intervention in Apc(Min) mice model of colorectal carcinogenesis, using proteomic and metabolic profiling strategies.

SCOPE: There is strong epidemiological evidence indicating that consumption by humans of whole-grain foods including rice bran may be associated with a low incidence of cancer, especially in the colorectum. Molecular processes associated with cancer development may be retarded by fiber consumption. Consequently, intervention with dietary fiber might be suitable as a cancer chemoprevention strategy in high-risk populations. Here, we searched for putative molecular mechanism-based efficacy biomarkers of rice fiber consumption in the plasma of mice characterized by a genetic propensity to develop gastrointestinal adenomas. The hypothesis was tested that metabolic and proteomic changes in blood reflect the chemopreventive activity of rice bran. METHODS AND RESULTS: Apc(Min) mice received diet supplemented with rice bran at 5, 15, and 30%. Blood and tissue samples were taken. Plasma was subjected to MS-based proteomic and metabolic profiling analyses as well as assessment of hematocrit values. Gastrointestinal tracts were removed and adenomas were counted and their size was measured so that total tumor burden could be calculated. The hypothesis was tested that metabolic and proteomic changes in blood reflect chemopreventive activity. CONCLUSION: Rice bran consumption reduced adenoma burden and number in a dose-related fashion when compared to controls. Metabolic profiling data demonstrated strong clustering of the groups indicating that metabolic pathways are perturbed. Proteomic analysis identified adiponectin as a molecule that was significantly altered, which may play a role in tumor suppression.

Glycogen storage disease type Ia: linkage of glucose, glycogen, lactic acid, triglyceride, and uric acid metabolism.

A female presented in infancy with hypotonia, undetectable serum glucose, lactic acidosis, and triglycerides >5000 mg/dL. The diagnosis of type 1A glycogen storage disease was made via the result of a liver biopsy, which showed increased glycogen and absent glucose-6-phosphatase enzyme activity. The patient was treated with dextrose administered orally, which was replaced by frequent feedings of cornstarch, which resulted in an improvement of her metabolic parameters. At age 18 years of age, she had marked hypertriglyceridemia (3860 mg/dL) and eruptive xanthomas and was treated with fenofibrate, atorvastatin, and fish oil. At age 29 years she was noted to have multiple liver adenomas, severe anemia, and hyperuricemia. Aggressive cornstarch therapy was commenced with a goal of maintaining her blood glucose levels >75 mg/dL and lactate levels <2 mmol/L. After 15 months on this regimen, her lipids levels (measured in mg/dL) off all medications were as follows: total cholesterol 222, triglycerides 179, high-density lipoprotein cholesterol 32, and calculated low-density lipoprotein cholesterol 154. Her weight was stable with a body mass index of 24.8 kg/m(2). Her liver adenomas had decreased in size, and her anemia and hyperuricemia had improved. She was homozygous for the R83C missense mutation in G6PC. Our data indicate that optimized metabolic control to maintain blood glucose levels >75 mg/dL is critical in the management of this disease.

Interleukin-6 as a potential indicator for prevention of high-risk adenoma recurrence by dietary flavonols in the polyp prevention trial.

Serum interleukin-6 (IL-6), a proinflammatory cytokine, is considered an indicator of inflammation and may be an indicator of colorectal carcinogenesis given that inflammation can promote carcinogenesis. Flavonols, which can be found in fruits and vegetables, may inhibit colorectal carcinogenesis partly by inhibiting inflammation. We estimated odds ratios and 95% confidence intervals (95% CI) to determine whether serum IL-6 was associated with colorectal adenoma recurrence and flavonol intake and thus may serve as a risk indicator and as a response indicator to dietary flavonols. Serum IL-6 concentrations at baseline, year 1, and year 3 were measured in 872 participants from the intervention arm of the Polyp Prevention Trial, a 4-year trial that examined the effectiveness of a low-fat, high-fiber, high-fruit and vegetable diet on adenoma recurrence. Intake of flavonols, especially of isorhamnetin, kaempferol, and quercetin, was inversely associated with serum IL-6 concentrations (highest versus lowest flavonol intake quartile, 1.80 versus 2.20 pg/mL) and high-risk (OR, 0.51; 95% CI, 0.26-0.98) and advanced adenoma recurrence (OR, 0.17; 95% CI, 0.06-0.50). A decrease in IL-6 concentration during the trial was inversely associated with high-risk (OR, 0.44; 95% CI, 0.23-0.84) and advanced adenoma recurrence (OR, 0.47; 95% CI, 0.19-1.18). Individuals with above median flavonol intake and equal or below median IL-6 change after baseline had the lowest risk of recurrence of high-risk and advanced adenoma. Our results suggest that serum IL-6 may serve as a risk indicator and as a response indicator to dietary flavonols for colorectal cancer prevention.

Genetic polymorphisms in vitamin D receptor VDR/RXRA influence the likelihood of colon adenoma recurrence.

Low circulating levels of vitamin D affect colorectal cancer risk. The biological actions of the hormonal form of vitamin D, 1,25(OH)(2)D(3), are mediated by the vitamin D receptor (VDR), which heterodimerizes with retinoid X receptors (RXR). Using a single nucleotide polymorphism (SNP) tagging approach, we assessed the association between genetic variations in RXRA and VDR and odds of recurrent (metachronous) colorectal neoplasia in a pooled population of two studies. A total of 32 tag SNPs in RXRA and 42 in VDR were analyzed in 1,439 participants. A gene-level association was observed for RXRA and any (P = 0.04) or proximal (P = 0.03) metachronous neoplasia. No gene-level associations were observed for VDR, nor was any single SNP in VDR related to any metachronous adenoma after correction for multiple comparisons. In contrast, the association between RXRA SNP rs7861779 and proximal metachronous neoplasia was of borderline statistical significance [odds ratio (OR), 0.68; 95% confidence interval (95% CI), 0.53-0.86; unadjusted P = 0.001; adjusted P = 0.06], including when observed independently in each individual study. Haplotypes within linkage blocks of RXRA support an approximately 30% reduction in odds of metachronous neoplasia arising in the proximal colon among carriers of specific haplotypes, which was strongest (OR(proximal), 0.67; 95% CI, 0.52-0.86) for carriers of a CGGGCA haplotype (rs1805352, rs3132297, rs3132296, rs3118529, rs3118536, and rs7861779). Our results indicate that allelic variation in RXRA affects metachronous colorectal neoplasia, perhaps of particular importance in the development of proximal lesions.

Colorectal cancer: can nutrients modulate NF-kappaB and apoptosis?

BACKGROUND & AIMS: NF-kappaB may promote carcinogenesis by altering cell cycle, inflammatory responses and apoptosis-related gene expression, though cell mechanisms relating diet and colorectal cancer (CRC) remain unveiled in humans. This study in patients with CRC aimed to explore potential interactions between the dietary pattern, nutrient intake, expression of NF-kappaB, apoptosis and tumour histological aggressiveness. METHODS: Usual diet was assessed by diet history; nutrient composition was determined by DIETPLAN software. Histologically classified patient tissue samples (adenoma, adenocarcinoma and normal surrounding mucosa) were obtained via biopsies during colonoscopy (n=16) or surgery (n=8). NF-kappaB expression was determined by immunohistochemistry and apoptosis by TUNEL assay. RESULTS: NF-kappaB expression and apoptosis were higher in tumours (p<0.01), greater along with histological aggressiveness (p<0.01). Highest intake terciles of animal protein, refined carbohydrates, saturated fat, n-6 fatty acids and alcohol were associated with higher NF-kappaB, apoptosis and histological aggressiveness (p<0.01); the opposite tissue characteristics were associated with highest intake terciles of n-3 fatty acids, fibre, vitamin E, flavonoids, isoflavones, beta-carotene and selenium (p<0.002). Additionally, higher n-6:n-3 fatty acids ratio (median 26:1) was associated with higher NF-kappaB (p<0.006) and apoptosis (p<0.01), and more aggressive histology (p<0.01). Conversely, lower n-6:n-3 fatty acids ratio (median 6:1) was associated with lower NF-kappaB (p<0.002) and apoptosis (p<0.002), and less aggressive histology (p<0.002). CONCLUSIONS: NF-kappaB expression and apoptosis increased from adenoma to poorly differentiated adenocarcinoma. This degenerative transition, recognized as key in carcinogenesis, appear to have been influenced by a diet promoting a pro-inflammatory milieu that can trigger NF-kappaB.

The effect of strict adherence to a high-fiber, high-fruit and -vegetable, and low-fat eating pattern on adenoma recurrence.

Individual differences in dietary intake are thought to account for substantial variation in cancer incidence. However, there has been a consistent lack of effect for low-fat, high-fiber dietary interventions and risk of colorectal cancer. These inconsistencies may reflect the multistage process of cancer as well as the range and timing of dietary change. Another potential reason for the lack of effect is poor dietary adherence among participants in these trials. The authors examined the effect of strict adherence to a low-fat, high-fiber, high-fruit and -vegetable intervention over 4 years among participants (n = 1,905) in the US Polyp Prevention Trial (1991-1998) on colorectal adenoma recurrence. There was a wide range of individual variation in the level of compliance among intervention participants. The most adherent participants, defined as "super compliers" (n = 210), consistently reported that they met or exceeded each of the 3 dietary goals at all 4 annual visits. Multivariate logistic regression models were used to estimate the association between dietary adherence and adenoma recurrence. The authors observed a 35% reduced odds of adenoma recurrence among super compliers compared with controls (odds ratio = 0.65, 95% confidence interval: 0.47, 0.92). Findings suggest that high compliance with a low-fat, high-fiber diet is associated with reduced risk of adenoma recurrence.

Fiber, sex, and colorectal adenoma: results of a pooled analysis.

BACKGROUND: Evidence for an association between dietary fiber and colorectal neoplasia has been equivocal, and some data suggest that there may be sex differences in response to fiber. OBJECTIVE: We sought to determine whether fiber affects colorectal adenoma recurrence differently in men and women by combining the study populations of 2 large clinical intervention trials: the Wheat Bran Fiber Trial and the Polyp Prevention Trial. DESIGN: Data from 3209 participants combined from 2 trials were analyzed with logistic regression models to examine the effect of a dietary intervention on colorectal adenoma recurrence in the pooled population as a whole and by sex. RESULTS: The adjusted odds ratio for adenoma recurrence for those in the intervention group of either the Wheat Bran Fiber Trial or the Polyp Prevention Trial was 0.91 (95% CI: 0.78, 1.06). For men, the intervention was associated with statistically significantly reduced odds of recurrence with an odds ratio of 0.81 (95% CI: 0.67, 0.98); for women, no significant association was observed. Using a likelihood-ratio test, we found a statistically significant interaction between intervention group and sex (P = 0.03). CONCLUSION: The results of the current analyses indicate that men may experience more benefit from dietary fiber than do women and may help to explain some of the discrepant results reported in the literature.

Quality of life and diet intervention in individuals at risk for recurrence of colorectal adenomas.

The effect of participation in a diet intervention study on self-reported quality of life (QOL) with subjects at risk of recurrence of colorectal adenomas was explored in 77 men and women, aged 18-80 years, with a history of adenomatous polyps. Participants were randomly assigned to intervention and control groups and followed for 1 year. Dietary goals for the intervention group included reduced intake of fat and increased intakes of fiber, calcium, and vegetables and fruit. Diet counseling was provided by telephone. Anthropometric measurements were obtained and dietary intakes were assessed at baseline and 6 and 12 months. The quality of life factors questionnaire (QF), designed to explore the absolute effects of the diet intervention on participants' perceived QOL, was administered at baseline and study end. Based on repeated 24-h dietary recalls, the intervention group reported significantly higher consumption of vegetables, fruit, low-fat dairy products, fiber, and calcium at 12 months. There were no significant differences in total QF scores for the two groups at study end, and no significant changes within groups between baseline and study end. Findings suggest that even though the intervention participants made significant modifications in their eating behavior, these changes did not impact their perceived QOL negatively.

Diet and lifestyle intervention among patients with colorectal adenomas: rationale and design of a Malaysian study.

Comprehensive evaluation of the large body of consistent evidence from laboratory, epidemiologic and clinical studies has led to the conclusion that modification of the dietary and lifestyle patterns of populations has considerable potential for reducing cancer risk. This paper describes a randomized-controlled trial involving a diet and lifestyle intervention for patients with history of colorectal adenomas. The primary aim of this trial is to evaluate the effectiveness of the intervention with reference to recurrence of adenomatous polyps over a two year period--the first year being the intervention period and the second year of the study allowing for post-intervention follow-up. Subjects found to fit the inclusion criteria are recruited and randomized to two groups: the intervention group and the control group. The intervention group subjects will attend a monthly lecture-discussion session for 10 months and small group counseling on modification of lifestyle behavior and diet as well as receive educational materials which were adapted from the WCRF Diet and Health Recommendations for Cancer Prevention. Control subjects will be provided with the usual care given to such patients. One hundred and sixteen patients who were diagnosed with colorectal adenomatous polyps in the previous twelve months at the Hospital Kuala Lumpur have already been enrolled in this trial. Baseline data collection is on-going.

Colorectal adenoma risk is modified by the interplay between polymorphisms in arachidonic acid pathway genes and fish consumption.

Associations between polymorphisms in genes (SNPs) involved in the arachidonic acid (AA) pathway and colorectal adenomas have been investigated in a Dutch case control study including 384 cases and 403 polyp-free controls. Twenty-one polymorphisms in seven candidate genes were studied and a potential modifying effect of fish consumption was considered. A protective effect on colorectal adenomas was found for the CT genotype of SNP H477H in PPARgamma and the GC genotype of SNP V102V in COX-2 (OR 0.63, 95% CI 0.45-0.89 and OR 0.65, 95% CI 0.46-0.92, respectively) compared with the homozygous major genotypes. An increase in adenoma risk was observed for the TC genotype of SNP c.2242T-->C in COX-2 (OR 1.47, 95% CI 1.07-2.00) compared with the TT genotype. Analysis with estimated haplotypes confirmed these associations and revealed three additional associations with COX-2, sPLA(2) and 15LOX haplotypes. Fish consumption modified the associations with COX-2 and PPARdelta genotypes. For SNP c.-789C-->T in PPARdelta the major genotype showed a decrease in adenoma risk for those in the highest tertile of fish consumption (T3), as compared with the lowest tertile (T1) (OR 0.65, 95% CI 0.41-1.02). Protective effects were also observed for SNPs V102V and c.2242T-->C in COX-2 and high fish intake. The interaction between fish consumption and c.2242T-->C was statistically significant, with an OR for the TT genotype and high fish consumption of 0.52 (95% CI 0.27-1.01) as compared with low fish intake. These results indicate that SNPs in genes involved in the AA pathway are associated with colorectal adenoma risk. Some of these associations are modified by fish consumption.

Vitamin C intake and apoptosis in normal rectal epithelium.

Apoptosis, or programmed cell death, may lower the risk of neoplasia by removing genetically damaged or mutated cells. A high rate of apoptosis has been linked to a reduced risk of colorectal adenomas; therefore, it is important to understand factors that impact apoptosis. Antioxidants (e.g., vitamin C) protect cells from harmful oxidation processes but may interfere with apoptosis by protecting genetically damaged cells from reactive oxygen species-dependent cell death. The objective of this study was to evaluate the association between vitamin C intake and apoptosis in normal rectal mucosa. Study participants were part of a large, cross-sectional study, the Diet and Health Study III. Participants were recruited from consecutive, consenting patients who underwent colonoscopy at University of North Carolina Hospitals between August 1, 1998 and March 4, 2000. Vitamin C intake, obtained from a food frequency questionnaire, included both dietary sources and vitamin supplements. Apoptosis was measured by morphological evaluation of H&E-stained sections obtained from pinch biopsy samples of normal rectal mucosa in consenting participants (n = 503). The relationship between vitamin C and apoptosis varied by adenoma status. Among individuals with adenomas, there was an inverse linear association between apoptosis and total vitamin C intake. Similarly, individuals with adenomas in the highest quintile of total vitamin C intake were substantially less likely than those in the lowest quintile to have increased colonic apoptosis (odds ratio, 0.05; 95% confidence interval, 0.01-0.46). Vitamin C was not significantly associated with apoptosis in adenoma-free patients. High vitamin C intake was associated with reduced colorectal apoptosis among individuals with adenomas in this study population. Given that high apoptosis may lower colorectal cancer risk, vitamin C supplements may be contraindicated for patients with a history of adenomas.

Calcium or resistant starch does not affect colonic epithelial cell proliferation throughout the colon in adenoma patients: a randomized controlled trial.

Patients with a history of sporadic adenomas have increased epithelial cell proliferative activity, an intermediate risk marker for colorectal cancer. Reduction of proliferation by dietary intervention may reflect a decreased colorectal cancer risk. To evaluate whether calcium or resistant starch could reduce proliferative activity throughout the colon, we performed a randomized controlled trial in 111 sporadic adenoma patients. Patients received two placebos, 1 g of calcium + placebo, or 30 g of amylomaize (19 g of resistant starch) + placebo. After 2 mo, biopsies were collected from the cecum, transverse and sigmoid colon, and rectum during colonoscopy. Epithelial cell proliferation was determined by dividing the number of 5-bromo-2-deoxyuridine-labeled nuclei by the total number of nuclei x 100 (labeling index, LI). LI of luminal, mid, and basal compartments was determined. Twenty-five patients dropped out. In the remaining 86 patients (28 treated with placebo, 30 with calcium + placebo, and 28 with resistant starch + placebo), no difference was observed in total LI, the LI of the three compartments, or the crypt length in the four areas of the colorectum. Colonic epithelial cell proliferative activity throughout the colon of sporadic adenoma patients is not affected by supplementation with 1 g of calcium or 19 g of resistant starch.

Intake of supplemental and total fiber and risk of colorectal adenoma recurrence in the wheat bran fiber trial.

The Wheat Bran Fiber (WBF) trial was a double-blind Phase III clinical trial in which participants were randomized to a cereal fiber supplement of either 13.5 or 2.0 g/day. No protective effect for adenoma recurrence was observed for those randomized to the high-fiber group as compared with those in the low-fiber group. However, the high-fiber group had significantly lower adherence to the supplement as assessed by cereal box counts. The aim of this study was to determine whether reported supplemental and total fiber intake affected colorectal adenoma recurrence in the WBF trial population, regardless of treatment group assignment. A total of 1208 participants who completed the WBF trial had a colonoscopy before the date of the last cereal box count and/or at least one colonoscopy within 90 days after it and, thus, were eligible for the current analyses. Statistical analyses were done using multivariate logistic regression models that included potentially confounding variables. Compared with individuals consuming less than 1.8 g/day of supplemental fiber, the adjusted odds ratio (95% confidence interval) for adenoma recurrence for those consuming greater than 11.0 g/day was 0.94 (0.66-1.33). The odds ratio (95% confidence interval) for participants whose total fiber intake was greater than 30.3 g/day was 0.98 (0.68-1.42) compared with those whose intake was less than 17.9 g/day. The results of this study show that neither fiber intake from a wheat bran supplement nor total fiber intake affects the recurrence of colorectal adenomas, thus lending further evidence to the body of literature indicating that consumption of a high-fiber diet, especially one rich in cereal fiber, does not reduce the risk of colorectal adenoma recurrence.