The BE GONE trial study protocol: a randomized crossover dietary intervention of dry beans targeting the gut microbiome of overweight and obese patients with a history of colorectal polyps or cancer.

BACKGROUND: Mouse and human studies support the promise of dry beans to improve metabolic health and to lower cancer risk. In overweight/obese patients with a history of colorectal polyps or cancer, the Beans to Enrich the Gut microbiome vs. Obesity's Negative Effects (BE GONE) trial will test whether and how an increase in the consumption of pre-cooked, canned dry beans within the context of usual diet and lifestyle can enhance the gut landscape to improve metabolic health and reduce cancer risk. METHODS/DESIGN: This randomized crossover trial is designed to characterize changes in (1) host markers spanning lipid metabolism, inflammation, and obesity-related cancer risk; (2) compositional and functional profiles of the fecal microbiome; and (3) host and microbial metabolites. With each subject serving as their own control, the trial will compare the participant's usual diet with (intervention) and without (control) dry beans. Canned, pre-cooked dry beans are provided to participants and the usual diet continually assessed and monitored. Following a 4-week run-in and equilibration period, each participant provides a total of 5 fasting blood and 6 stool samples over a total period of 16 weeks. The intervention consists of a 2-week ramp-up of dry bean intake to 1 cup/d, which is then continued for an additional 6 weeks. Intra- and inter-individual outcomes are assessed across each crossover period with consideration of the joint or modifying effects of the usual diet and baseline microbiome. DISCUSSION: The BE GONE trial is evaluating a scalable dietary prevention strategy targeting the gut microbiome of high-risk patients to mitigate the metabolic and inflammatory effects of adiposity that influence colorectal cancer risk, recurrence, and survival. The overarching scientific goal is to further elucidate interactions between diet, the gut microbiome, and host metabolism. Improved understanding of the diet-microbiota interplay and effective means to target these relationships will be key to the future of clinical and public health approaches to cancer and other major diet- and obesity-related diseases. TRIAL REGISTRATION: This protocol is registered with the U.S. National Institutes of Health trial registry, ClinicalTrials.gov, under the identifier NCT02843425. First posted July 25, 2016; last verified January 25, 2019.

n-3 polyunsaturated fatty acids reverse the development of polyps in Apc(Min/+) transgenic mice.

Dietary n-3 polyunsaturated fatty acids (n-3 PUFAs) have been demonstrated to reduce tumor load in Apc(Min/+) mice, supporting a role for n-3 PUFAs in the inhibition of colon carcinogenesis and progression. The aim of the present study was to investigate whether a diet enriched with n-3 PUFAs, known already to have anti-neoplastic efficacy in Apc(Min/+) mice, would reverse the development of intestinal polyps. For this purpose, Apc(Min/+) mice were randomly divided into 3 groups of 5 animal each and fed as follows: control ST1 and ST2 groups, received a purified AIN-93M standard diet for 5 and 10 weeks, respectively; the OM-3R group received a purified AIN-93M standard diet for 5 weeks and a diet supplemented with salmon oil, rich in n-3 PUFAs, for another 5 weeks. After dietary treatment, in intestinal tissue, we evaluated the polyp number and volume, expression levels of cell proliferation- and apoptosis-related proteins, as well as the protein expression of LDL receptor and the levels of fatty acid synthase (FAS) activity. The results showed the ability of a diet enriched with n-3 PUFAs to suppress intestinal polyps in Apc(Min/+) mice, and to significantly reverse polyp development associated with the downregulation of cell proliferation markers and with the induction of estrogen receptor ß and LDL receptor, which are negative modulators of cellular proliferation. This noteworthy finding is important for a translational study evaluating the therapeutic role of n-3 PUFAs in the prevention and treatment of subjects with gastrointestinal diseases.

Highly purified eicosapentaenoic acid as free fatty acids strongly suppresses polyps in Apc(Min/+) mice.

PURPOSE: Although cyclooxygenase (COX)-2 inhibitors could represent the most effective chemopreventive tool against colorectal cancer (CRC), their use in clinical practice is hampered by cardiovascular side effects. Consumption of ω-3-polyunsaturated fatty acids (ω-3-PUFAs) is associated with a reduced risk of CRC. Therefore, in this study, we assessed the efficacy of a novel 99% pure preparation of ω-3-PUFA eicosapentaenoic acid as free fatty acids (EPA-FFA) on polyps in Apc(Min/+) mice. EXPERIMENTAL DESIGN: Apc(Min/+) and corresponding wild-type mice were fed control diet (Ctrl) or diets containing either EPA-FFA 2.5% or 5%, for 12 weeks while monitoring food intake and body weight. RESULTS: We found that both EPA-FFA diets protected from the cachexia observed among Apc(Min/+) animals fed Ctrl diet (P < 0.0054), without toxic effect, in conjunction with a significant decrease in lipid peroxidation in the treated arms. Moreover, both EPA-FFA diets dramatically suppressed polyp number (by 71.5% and 78.6%, respectively; P < 0.0001) and load (by 82.5% and 93.4%, respectively; P < 0.0001) in both small intestine and colon. In addition, polyps less than 1 mm in size were predominantly found in the EPA-FFA 5% arm whereas those 1 to 3 mm in size were more frequent in the Ctrl arm (P < 0.0001). Interestingly, in the EPA-FFA groups, mucosal arachidonic acid was replaced by EPA (P < 0.0001), leading to a significant reduction in COX-2 expression and ß-catenin nuclear translocation. Moreover, in the EPA-FFA arms, we found a significant decrease in proliferation throughout the intestine together with an increase in apoptosis. CONCLUSIONS: Our data make 99% pure EPA-FFA an excellent candidate for CRC chemoprevention.

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.

Soy protein containing isoflavones does not decrease colorectal epithelial cell proliferation in a randomized controlled trial.

BACKGROUND: Soy isoflavones have numerous biological properties that suggest that they may protect against colorectal cancer. Colorectal epithelial cell proliferation has been used extensively as an intermediate endpoint biomarker for colorectal neoplasia. OBJECTIVE: We tested the hypothesis that supplementation with soy protein containing isoflavones decreases colorectal epithelial cell proliferation. DESIGN: A 12-mo randomized intervention was conducted in men and women aged 50-80 y with recently diagnosed adenomatous polyps. One hundred fifty participants were enrolled and randomly assigned to an active treatment group (58 g protein powder/d containing 83 mg isoflavones/d; +ISO) or a control group (ethanol-extracted soy-protein powder containing 3 mg isoflavones; -ISO). Biopsy specimens from the cecum, sigmoid colon, and rectum were collected at baseline and at the 12-mo follow-up. Ki-67 antibody immunohistostaining was used to detect cell proliferation. One hundred twenty-five participants completed the study, and proliferation was measured in the first 91 who completed the study. RESULTS: In the sigmoid colon, cell proliferation increased by 0.9 (95% CI: 0.09, 1.9) labeled nuclei per crypt more (11%) in the +ISO group than in the -ISO group over the 12-mo intervention, which was opposite the direction predicted. The number of labeled nuclei per 100 mum crypt height also increased more in the +ISO than in the -ISO group. In the cecum and sigmoid colon, but not in the rectum, the proliferation count increased as the serum genistein concentration increased. Proliferation distribution and crypt height were not changed by treatment at any site. CONCLUSIONS: Supplementation with soy protein containing isoflavones does not reduce colorectal epithelial cell proliferation or the average height of proliferating cells in the cecum, sigmoid colon, and rectum and increases cell proliferation measures in the sigmoid colon.

Implementation of a 4-y, high-fiber, high-fruit-and-vegetable, low-fat dietary intervention: results of dietary changes in the Polyp Prevention Trial.

BACKGROUND: The Polyp Prevention Trial (PPT) was a multicenter randomized clinical trial designed to determine the effects of a high-fiber (4.30 g/MJ), high-fruit-and-vegetable (0.84 servings/MJ), low-fat (20% of energy from fat) diet on the recurrence of adenomatous polyps in the large bowel. OBJECTIVE: Our goal was to determine whether the PPT intervention plan could effect change in 3 dietary goals and to examine the intervention's effect on the intake of other food groups and nutrients. DESIGN: Participants with large-bowel adenomatous polyps diagnosed in the past 6 mo were randomly assigned to either the intervention (n = 1037) or the control (n = 1042) group and remained in the trial for 4 y. Three dietary assessment instruments were used to measure dietary change: food-frequency questionnaires (in 100% of the sample), 4-d food records (in a 20% random cohort), and 24-h dietary recalls (in a 10% random sample). RESULTS: Intervention participants made and sustained significant changes in all PPT goals as measured by the dietary assessment instruments; the control participants' intakes remained essentially the same throughout the trial. The absolute differences between the intervention and control groups over the 4-y period were 9.7% of energy from fat (95% CI: 9.0%, 10.3%), 1.65 g dietary fiber/MJ (95% CI: 1.53, 1.74), and 0.27 servings of fruit and vegetables/MJ (95% CI: 0.25, 0.29). Intervention participants also reported significant changes in the intake of other nutrients and food groups. The intervention group also had significantly higher serum carotenoid concentrations and lower body weights than did the control group. CONCLUSION: Motivated, free-living individuals, given appropriate support, can make and sustain major dietary changes over a 4-y period.

Transforming growth factor alpha distribution in rectal crypts as a biomarker of decreased colon cancer risk in patients consuming cellulose.

Data from rat experimental carcinogenesis studies indicate that supplemental dietary cellulose reduces the incidence of colon cancer. Epidemiology studies also indicate that high dietary fiber reduces the risk of colorectal cancer in humans. Patients diagnosed with sporadic adenomas were entered into a randomized clinical trial to determine if supplemental dietary cellulose would reduce the patients' risk for colon cancer. Immunohistochemical staining for transforming growth factor alpha (TGF-alpha) was done on biopsies of rectal mucosa taken from patients at the time of initial polypectomy and 1 year later. Results were evaluated for utility as a surrogate end point biomarker for reduction in colon cancer risk. There was a significant decrease in the fraction of the rectal crypt cells that stained for TGF-alpha in six of seven of the patients given the cellulose supplements but in only one of six of the patients not given cellulose. Thus, whether evaluated as a group or in individual patients, there was a significant decrease in TGF-alpha in rectal crypts due to cellulose intervention, which correlated with the expected ability of supplemental dietary cellulose to decrease the risk for colon cancer. Long-term testing of the ability of dietary cellulose to reduce adenoma recurrence is under way to validate the use of TGF-alpha as a surrogate end point biomarker.

The polyp prevention trial I: rationale, design, recruitment, and baseline participant characteristics.

The Polyp Prevention Trial (PPT) is a multicenter randomized controlled trial examining the effect of a low-fat (20% of total energy intake), high-fiber (18 g/1000 kcal), high-vegetable and -fruit (5-8 daily servings) dietary pattern on the recurrence of adenomatous polyps of the large bowel, precursors of most colorectal malignancies. Eligibility criteria include one or more adenomas removed within 6 months of randomization; complete nonsurgical polyp removal and complete colonic examination to the cecum at the qualifying colonoscopy: age 35 years of more; no history of colorectal cancer, inflammatory bowel disease, or large bowel resection; and satisfactory completion of a food frequency questionnaire and 4-day food record. Of approximately 38,277 potential participants with one or more polyps recently resected, investigators at eight clinical centers randomized 2,079 (5.4%; 1,037 in the intervention and 1,042 in the control arm) between June 1991 and January 1994, making the PPT the largest adenoma recurrence trial ever conducted. Of PPT participants, 35% are women and 10% are minorities. At study entry, participants averaged 61.4 years of age; 14% of them smoked, and 22% used aspirin. At the baseline colonoscopy, 35% of participants had two or more adenomas, and 29% had at least one large (> of = 1 cm) adenoma. Demographic, behavioral, dietary, and clinical characteristics are comparable across the two study arms. Participants have repeat colonoscopies after 1 (T(1)) and 4 (T(4)) years of follow-up. The primary end point is adenoma recurrence; secondary end points include number, size, location, and histology of adenomas. All resected lesions are reviewed centrally by gastrointestinal pathologists. The trial provides 90% power to detect a reduction of 24% in the annual adenoma recurrence rate. The primary analytic period, on which sample size calculations were based is 3 years (T(1) to T(4)), which permits a 1-year lag time for the intervention to work and allows a more definitive clearing of lesions at T(1), given that at least 10-15% of polyps may be missed at baseline. The final (T(4)) colonoscopies are expected to be completed in early 1998.

The polyp prevention trial II: dietary intervention program and participant baseline dietary characteristics.

The Polyp Prevention Trial (PPT) is a multicenter randomized controlled trial to evaluate whether a low-fat, high-dietary fiber, high-fruit and -vegetable eating pattern will reduce the recurrence of adenomatous polyps of the large bowel. Men and women who had one or more adenomas removed recently were randomized into either the intervention (n = 1037) or control (n = 1042) arms. Food frequency questionnaire data indicate that PPT participants at the beginning of the trial consumed 36.8% of total energy from fat, 9.7 g of dietary fiber/1000 kcal, and 3.8 daily servings of fruits and vegetables. Baseline dietary characteristics, including intake of fat, fiber, and fruits and vegetables, as well as other macro- and micronutrients, were similar in the two study groups. The intervention participants receive extensive dietary and behavioral counseling to achieve the PPT dietary goals of 20% of total energy from fat, 18 g/1000 kcal of dietary fiber, and 5-8 daily servings (depending on total caloric intake) of fruits and vegetables. Control participants do not receive such counseling and are expected to continue their usual intake. Dietary intake in both groups is mentioned annually using a 4-day food record (also completed at 6 months by intervention participants only) and a food frequency questionnaire, with a 10% random sample of participants completing an annual unscheduled 24-h telephone recall. Blood specimens are drawn and analyzed annually for lipids and carotenoids. This article provides details on the rationale and design of the PPT dietary intervention program and describes the participant baseline dietary intake data characteristics.

Effects of oral calcium supplementation on intestinal bile acids and cytolytic activity of fecal water in patients with adenomatous polyps of the colon.

Calcium has been proposed to prevent colon cancer in subjects at risk for this tumour. This effect is supposed to be due at least in part to binding the bile acids to calcium, making them insoluble and harmless. To evaluate the effects of oral calcium supplementation on intestinal bile acids, 19 patients with adenomatous colonic polyps were supplemented with 35.5 mmol Ca2+ daily for 12 weeks. Duodenal bile, 24-h feces and 24-h urine were collected before and at the end of the 12-week period. In duodenal bile proportional concentration of cholic acid increased (38 +/- 4 vs. 51 +/- 3%, P < 0.001), whereas that of chenodeoxycholic acid decreased (35 +/- 3 vs. 25 +/- 2%, P < 0.01). Total fecal bile acid excretion increased (950 +/- 126 vs. 1218 +/- 137 mumol 24 h-1, P < 0.01), with proportional concentrations of the main primary and secondary bile acids remaining the same. Cytolytic activity of fecal water, measured by the degree of lysis of erythrocytes by the water, decreased (45 +/- 8 vs. 30 +/- 7%, P < 0.05). Total excretion of calcium increased as expected from the supplementary dose. It is concluded that calcium supplementation markedly affects intestinal bile acids and lytic activity of fecal water and that, in view of similar results during 1-week calcium supplementation in young healthy subjects, these effects remain constant over at least 3 months and occur both in healthy persons and in patients at increased risk for colon cancer.

Sample size for studying intermediate endpoints within intervention trails or observational studies.

An intermediate endpoint is a biologic event or marker that is a precursor to a given health outcome. Examples of potential intermediate endpoints include serum cholesterol for coronary heart disease, endogenous steroid hormones for breast cancer, and CD4 count for acquired immunodeficiency syndrome. When one is studying a potential intermediate endpoint in the context of an intervention trial, five types of questions may be investigated: 1) Does the intervention affect the intermediate endpoint? 2) Is the intermediate endpoint associated with prognostic or risk factors? 3) Is the intermediate endpoint associated with the main outcome? 4) Is the intervention effect on the main outcome mediated by the intermediate endpoint? 5) Are the prognostic or risk factor effects mediated by the intermediate endpoint? In this paper, the authors show that each of these questions had different sample size requirements, and they illustrate their point with a discussion of an ancillary study of large bowel epithelial proliferation in the National Cancer Institute's Polyp Prevention Trial. The same methods may be used in an observational study, in which case questions 2, 3, and 5 are relevant. However, much larger numbers than those used in the Polyp Prevention Trial example will be required when the main outcome is rare.