Effects of a Low-Fat Vegan Diet on Gut Microbiota in Overweight Individuals and Relationships with Body Weight, Body Composition, and Insulin Sensitivity. A Randomized Clinical Trial.

Diet modulates gut microbiota and plays an important role in human health. The aim of this study was to test the effect of a low-fat vegan diet on gut microbiota and its association with weight, body composition, and insulin resistance in overweight men and women. We enrolled 168 participants and randomly assigned them to a vegan (n = 84) or a control group (n = 84) for 16 weeks. Of these, 115 returned all gut microbiome samples. Gut microbiota composition was assessed using uBiome Explorer™ kits. Body composition was measured using dual energy X-ray absorptiometry. Insulin sensitivity was quantified with the predicted clamp-derived insulin sensitivity index from a standard meal test. Repeated measure ANOVA was used for statistical analysis. Body weight decreased in the vegan group (treatment effect -5.9 kg [95% CI, -7.0 to -4.9 kg]; p < 0.001), mainly due to a reduction in fat mass (-3.9 kg [95% CI, -4.6 to -3.1 kg]; p < 0.001) and in visceral fat (-240 cm3 [95% CI, -345 to -135 kg]; p < 0.001). PREDIcted M, insulin sensitivity index (PREDIM) increased in the vegan group (treatment effect +0.83 [95% CI, +0.48 to +1.2]; p < 0.001). The relative abundance of Faecalibacterium prausnitzii increased in the vegan group (+5.1% [95% CI, +2.4 to +7.9%]; p < 0.001) and correlated negatively with changes in weight (r = -0.24; p = 0.01), fat mass (r = -0.22; p = 0.02), and visceral fat (r = -0.20; p = 0.03). The relative abundance of Bacteroides fragilis decreased in both groups, but less in the vegan group, making the treatment effect positive (+18.9% [95% CI, +14.2 to +23.7%]; p < 0.001), which correlated negatively with changes in weight (r = -0.44; p < 0.001), fat mass (r = -0.43; p < 0.001), and visceral fat (r = -0.28; p = 0.003) and positively with PREDIM (r = 0.36; p < 0.001), so a smaller reduction in Bacteroides fragilis was associated with a greater loss of body weight, fat mass, visceral fat, and a greater increase in insulin sensitivity. A low-fat vegan diet induced significant changes in gut microbiota, which were related to changes in weight, body composition, and insulin sensitivity in overweight adults, suggesting a potential use in clinical practice.

Viscous versus nonviscous soluble fiber supplements: mechanisms and evidence for fiber-specific health benefits.

PURPOSE: This review focuses on the health benefits of viscous versus nonviscous soluble fibers, why symptoms can occur with increased fiber consumption, and how to avoid symptoms to improve adherence with a high-fiber diet. DATA SOURCES: Review of scientific literature as well as evidence-based guidelines and resources. CONCLUSIONS: While it is generally known that "fiber is good for you," it is less well known that specific health benefits are associated with specific fiber characteristics. Many of the health benefits of fiber can be directly correlated with the viscosity of soluble fibers when hydrated (i.e., gel-forming). A reduction in viscosity of a given fiber will attenuate these health benefits, and a nonviscous fiber does not exhibit these health benefits. IMPLICATIONS FOR PRACTICE: Increasing the viscosity of chyme with a viscous soluble fiber has been shown clinically to lower cholesterol for cardiovascular health, improve glycemic control in type 2 diabetes, normalize stool form in both constipation (softens hard stool) and diarrhea (firms loose/liquid stool), and improve the objective clinical measures of metabolic syndrome (glycemic control, lipoprotein profile, body mass index/weight loss, and blood pressure).

Colonoscopy issues related to women.

Colonoscopy is the preferred method of screening for colorectal cancer in women. The longer, more redundant female colon is frequently more difficult for the endoscopist to navigate and most studies show longer insertion times, lower completion rates, and more discomfort associated with the procedure in women, all of which may be exacerbated by hysterectomy. To improve female patients' compliance with colorectal cancer screening we need to understand the barriers to participation prevalent among women. This article reviews the findings of several studies and discusses some steps to improve cancer screening for women.

The frequency of peptic ulcer as a cause of upper-GI bleeding is exaggerated.

BACKGROUND: Peptic ulcer disease is considered the cause of upper-GI bleeding in 50% of cases. A recent decline in the proportion of cases of upper-GI bleeding because of a peptic ulcer was noted by us. The objectives of this study were to evaluate the frequency of peptic ulcer in patients with upper-GI bleeding and the proportion of bleeding peptic ulcers with a non-bleeding visible vessel. METHODS: Patients with upper-GI bleeding seen from December 1999 until April 2001 at a tertiary, university-affiliated medical center were studied prospectively. The Clinical Outcome Research Initiative (CORI) database was used to correlate the single institution data with nationwide data. Endoscopic data in the CORI database for patients who had endoscopy for upper-GI bleeding between December 1999 and July 2001 were retrieved and analyzed. RESULTS: A total of 126 patients were included in the prospective study. The endoscopic findings were: peptic ulcer in 31.8%: 95% confidence interval (CI) [23.7%, 40.6%] of patients; a non-bleeding visible vessel was present in 10%: 95% CI[2.8%, 23.7%] of these peptic ulcers. From the nationwide CORI database, data for 7822 patients with upper-GI bleeding were obtained. The endoscopic findings were: peptic ulcer in 20.6%:95% CI[19.7%, 21.5%] of patients with upper-GI bleeding; a non-bleeding visible vessel was present in 7.3%: 95% CI[6.1%, 8.6%] of the ulcers. CONCLUSIONS: The frequency of peptic ulcer in patients with upper-GI bleeding and the proportion of bleeding ulcers with a non-bleeding visible vessel are less than previously reported.

Colonoscopy in inflammatory bowel disease.

This article discusses the important role endoscopy plays in the diagnosis and management of inflammatory bowel disease and how the procedure adds crucial information to the constellation of history, physical examination, radiographic findings, and laboratory values. Differentiation between Crohn's disease and ulcerative colitis has important ramifications for medical therapy, surgical options, and prognosis. This distinction can be accurately made in at least 85% of patients.