Systematic review with meta-analysis: effect of fibre supplementation on chronic idiopathic constipation in adults.

BACKGROUND: Chronic idiopathic constipation is a common symptom-based gastrointestinal disorder responsible for a substantial economic health service burden. Current guidelines recommend the use of fibre as a first-line treatment. AIM: To investigate the effect of fibre (including prebiotic) supplementation on global symptom response, stool output, gut microbiota composition and adverse events in adults with chronic idiopathic constipation. METHODS: Medline, EmBase, Web of Science, Scopus and the Cochrane central register of controlled trials were searched through to February 2016. Conference proceedings from 2003 to 2015 were hand-searched. There were no language restrictions. Forest plots with 95% CIs were generated using a random-effects model. RESULTS: The search strategy generated 1072 citations, of which seven individual randomised controlled trials were eligible. Overall, 113 of 147 (77%) patients assigned to fibre responded to therapy, compared with 61 of 140 (44%) allocated to placebo (RR of success to respond 1.71, 95% CI 1.20-2.42, P = 0.003). Fibre significantly increased stool frequency (SMD, standardised mean difference = 0.39; 95% CI 0.03-0.76; P = 0.03) and softened stool consistency (SMD = 0.35; 95% CI 0.04-0.65; P = 0.02) compared with placebo. Flatulence was significantly higher with fibre compared to placebo (SMD 0.56, 0.12-1.00, P = 0.01). Overall quality of evidence was low. CONCLUSIONS: This meta-analysis demonstrates that fibre is moderately effective, but also causes moderate gastrointestinal side effects. However, these findings need to be treated with caution due to a high risk of bias. Accordingly, further large, methodologically rigorous trials are required, before any definitive recommendation regarding its risk-benefit profile can be made. PROSPERO registration number CRD42014007005.

The effect of the classical and medium chain triglyceride ketogenic diet on vitamin and mineral levels.

BACKGROUND: The risk of nutritional deficiency in children on restrictive dietary treatments and a lack of ketogenic diet (KD)-specific UK supplements raises concerns about micronutrient status. Vitamin A, E, zinc, selenium and magnesium levels were therefore examined in children with intractable epilepsy treated with the KD. METHODS: Plasma vitamins A and E, zinc, selenium and magnesium levels were measured at baseline and after 3, 6 and 12months on the classical (n=46) or medium chain triglyceride (MCT) (n=45) KD in children aged 2-16years, as part of a randomised trial, and pairwise comparisons with baseline were performed. RESULTS: Data were available from 91 children. From baseline to 12months, mean plasma vitamin A decreased from 1.41µmol L(-1) to 1.13µmol L(-1) in the classical group (P<0.001) but increased from 1.52µmol L(-1) to 1.81µmol L(-1) in the MCT group (P<0.001). Mean plasma vitamin E increased from 22.7µmol L(-1) to 33.2µmol L(-1) in the classical group (P<0.001) and from 22.3 µmol L(-1) to 23.3µmol L(-1) in the MCT group (P<0.05). No significant change in plasma zinc was seen at 12months, although mean plasma selenium decreased from 0.95µmol L(-1) to 0.88µmol L(-1) in the group as a whole (P<0.05). Mean plasma magnesium decreased from 0.87mmol L(-1) to 0.83mmol L(-1) in the group as a whole (P<0.001); when subdivided by KD type, this was limited to the classical group. CONCLUSIONS: Changes in plasma vitamins A and E and the decline in magnesium status after 12months of KD treatment suggest that micronutrient status may be suboptimal in this group and that available formulations for KD supplementation may need reviewing.