The relationship between fermentable carbohydrates and post-prandial bowel symptoms in patients with functional bowel disorders.

Background and aims: A low fermentable oligosaccharide, disaccharide, monosaccharide, and polyols (FODMAP) diet alleviates symptoms of irritable bowel syndrome (IBS). We aimed to investigate the relationship between habitual FODMAP intake and post-prandial bowel symptoms in adults with IBS, functional diarrhoea (FD), or constipation (FD) (functional bowel disorders), and in healthy adults (controls). Methods: 292 participants (173 with functional bowel disorders and 119 controls) completed a food and symptom times diary. Estimated meal portion sizes were entered into the Monash FODMAP Calculator to analyse FODMAP content. Wilcoxon and ANOVA tests were used to investigate the relationship between FODMAP intake and post-prandial bowel symptoms. Results: IBS participants experienced more post-prandial bowel symptoms compared to participants with other functional bowel disorders or controls. Meals associated with abdominal pain contained on average increased excess fructose (0.31 g vs. 0.18 g, p < 0.05), sorbitol (0.27 g vs. 0.10 g, p < 0.01), and total FODMAP (3.46 g vs. 2.96 g, p < 0.05) compared to meals not associated with pain. Abdominal swelling was associated with increased sorbitol (0.33 g vs. 0.11 g, p < 0.01), and total FODMAP (3.26 g vs. 3.02 g, p < 0.05) consumption. Abdominal bloating was associated with increased galacto oligosaccharide consumption (0.18 g vs. 0.14 g, p < 0.05). Conclusion: These findings support the role of FODMAP in post-prandial bowel symptom onset, however, the amount and type of FODMAP triggering symptoms vary between individuals. Future research should investigate the relationship between the effect of individual FODMAP consumption on post-prandial bowel symptoms for each subtype, the interaction of FODMAP with differing functional bowel disorders and whether longitudinally symptoms and dietary intake are stable.

Very low carbohydrate (ketogenic) diets in type 2 diabetes: A systematic review and meta-analysis of randomized controlled trials.

AIM: Very low carbohydrate/ketogenic diets (VLC/KDs) are popular but their role in managing pre-diabetes and type 2 diabetes (T2D) is uncertain. This study uses a systematic review and meta-analysis of randomized controlled trials to estimate the effect of these diets in this population. MATERIALS AND METHODS: A systematic review identified randomized controlled trials of at least 6 months duration comparing efficacy and safety of VLC/KDs (≤50 g carbohydrate or ≤10% total energy from carbohydrate per day) with a control diet (carbohydrate above the VLC/KD threshold) in adults with pre-diabetes or T2D. The primary outcome variable was glycated haemoglobin (HbA1c) after 12 months. The meta-analysis method was inverse variance weighting of mean values for continuous variables. RESULTS: Key word searches identified 2290 studies; 2221 were not in scope. A full text review of 69 studies identified eight meeting inclusion criteria; in total, it involved 606 participants. Six studies reported HbA1c (%) at 12 months; four as change from baseline with a fixed effects estimate (95% confidence interval): VLC/KD minus control of 0.01% (-0.22 to 0.25), p = .91; and two as change from baseline: -0.65% (-0.99; -0.31) [-7.1 mmol/mol (-10.8; -3.4)], p < .001. Serum triglycerides were lower with VLC/KD versus control: -0.28 mmol/L (-0.44 to -0.11), p < .001. High-density lipoprotein was higher with an estimate of 0.04 mmol/L (0.01 to 0.08), p = .03, in the five studies reporting 12-month summary data. CONCLUSIONS: A VLC/KD may cause reductions in HbA1c and triglycerides in those with pre-diabetes or T2D but evidence of an advantage over other strategies is limited. More well-designed studies are required to provide certain evidence.

The minor allele of the CREBRF rs373863828 p.R457Q coding variant is associated with reduced levels of myostatin in males: Implications for body composition.

OBJECTIVE: The minor allele (A) of the rs373863828 variant (p.Arg457Gln) in CREBRF is restricted to indigenous peoples of the Pacific islands (including New Zealand Maori and peoples of Polynesia), with a frequency of up to 25% in these populations. This allele associates with a large increase in body mass index (BMI) but with significantly lower risk of type-2 diabetes (T2D). It remains unclear whether the increased BMI is driven by increased adiposity or by increased lean mass. METHODS: We undertook body composition analysis using DXA in 189 young men of Maori and Pacific descent living in Aotearoa New Zealand. Further investigation was carried out in two orthologous Arg458Gln knockin mouse models on FVB/NJ and C57BL/6j backgrounds. RESULTS: The rs373863828 A allele was associated with lower fat mass when adjusted for BMI (p < 0.05) and was associated with significantly lower circulating levels of the muscle inhibitory hormone myostatin (p < 0.05). Supporting the human data, significant reductions in adipose tissue mass were observed in the knockin mice. This was more significant in older mice in both backgrounds and appeared to be the result of reduced age-associated increases in fat mass. The older male knockin mice on C57BL/6j background also had increased grip strength (p < 0.01) and lower levels of myostatin (p < 0.05). CONCLUSION: Overall, these results prove that the rs373863828 A-allele is associated with a reduction of myostatin levels which likely contribute to an age-dependent lowering of fat mass, at least in males.

The CREBRF diabetes-protective rs373863828-A allele is associated with enhanced early insulin release in men of Maori and Pacific ancestry.

AIMS/HYPOTHESIS: The minor A allele of rs373863828 (CREBRF p.Arg457Gln) is associated with increased BMI, but reduced risk of type 2 and gestational diabetes in Polynesian (Pacific peoples and Aotearoa New Zealand Maori) populations. This study investigates the effect of the A allele on insulin release and sensitivity in overweight/obese men without diabetes. METHODS: A mixed meal tolerance test was completed by 172 men (56 with the A allele) of Maori or Pacific ancestry, and 44 (24 with the A allele) had a frequently sampled IVGTT and hyperinsulinaemic-euglycaemic clamp. Mixed linear models with covariates age, ancestry and BMI were used to analyse the association between the A allele of rs373863828 and markers of insulin release and blood glucose regulation. RESULTS: The A allele of rs373863828 is associated with a greater increase in plasma insulin 30 min following a meal challenge without affecting the elevation in plasma glucose or incretins glucagon-like polypeptide-1 or gastric inhibitory polypeptide. Consistent with this point, following an i.v. infusion of a glucose bolus, participants with an A allele had higher early (p < 0.05 at 2 and 4 min) plasma insulin and C-peptide concentrations for a similar elevation in blood glucose as those homozygous for the major (G) allele. Despite increased plasma insulin, rs373863828 genotype was not associated with a significant difference (p > 0.05) in insulin sensitivity index or glucose disposal during hyperinsulinaemic-euglycaemic clamp. CONCLUSIONS/INTERPRETATION: rs373863828-A allele associates with increased glucose-stimulated insulin release without affecting insulin sensitivity, suggesting that CREBRF p.Arg457Gln may increase insulin release to reduce the risk of type 2 diabetes.

Measuring Diet Intake and Gastrointestinal Symptoms in Irritable Bowel Syndrome: Validation of the Food and Symptom Times Diary.

INTRODUCTION: Patients with irritable bowel syndrome (IBS) identify food as a trigger for the onset or worsening of gastrointestinal symptoms. Despite this, there is no published validated contemporaneous food and symptom diary to investigate the association between diet and IBS symptoms. The objective of this prospective observational study was to assess the construct validity of a novel food diary and symptom questionnaire, the Food and Symptom Times (FAST) diary, and the predictive validity of the food diary component with relation to fiber and fermentable oligosaccharides, disaccharides, monosaccharides, and polyols consumption and subsequent gastrointestinal symptoms. METHODS: Fifty-one participants with IBS completed the FAST diary and several legacy instruments. The relationship between the FAST gastroenterological symptoms and legacy instruments was examined using Spearman correlation coefficients. Further statistical analysis investigated the relationship between diet and postprandial gastrointestinal symptoms. RESULTS: Consistent with a priori predictions, the FAST symptoms showed moderate correlations with the most similar Patient-Reported Outcome Measurement Information System gastrointestinal scales (0.328-0.483, P < 0.05) and the most similar Gastrointestinal Symptom Rating Scale questions (0.303-0.453, P < 0.05), with the exception of the weakly correlated subscale constipation for both instruments (-0.050 to -0.119, P > 0.05). The IBS-Quality of Life instrument showed moderate correlations with the FAST symptom abdominal swelling/distension (0.313-0.416, P < 0.05). The consumption of a high fermentable oligosaccharides, disaccharides, monosaccharides, and polyols meal was associated with participants with IBS-D experiencing abdominal bloating and participants with IBS-C not experiencing abdominal swelling (P < 0.05). The consumption of fiber was correlated with abdominal fullness and bloating in participants with IBS-C (P < 0.05). DISCUSSION: The FAST diary validly measures gastrointestinal symptoms as they occur in people with IBS and correlates these symptoms with specific aspects of diet.