Charlotte El Evans

Dietary fibre intake and risk of cardiovascular disease: systematic review and meta-analysis

Objective To investigate dietary fibre intake and any potential dose-response association with coronary heart disease and cardiovascular disease. Design Systematic review of available literature and dose-response meta-analysis of cohort studies using random effects models. Data sources The Cochrane Library, Medline, Medline in-process, Embase, CAB Abstracts, ISI Web of Science, BIOSIS, and hand searching. Eligibility criteria for studies Prospective studies reporting associations between fibre intake and coronary heart disease or cardiovascular disease, with a minimum follow-up of three years and published in English between 1 January 1990 and 6 August 2013. Results 22 cohort study publications met inclusion criteria and reported total dietary fibre intake, fibre subtypes, or fibre from food sources and primary events of cardiovascular disease or coronary heart disease. Total dietary fibre intake was inversely associated with risk of cardiovascular disease (risk ratio 0.91 per 7 g/day (95% confidence intervals 0.88 to 0.94)) and coronary heart disease (0.91 (0.87 to 0.94)). There was evidence of some heterogeneity between pooled studies for cardiovascular disease (I2=45% (0% to 74%)) and coronary heart disease (I2=33% (0% to 66%)). Insoluble fibre and fibre from cereal and vegetable sources were inversely associated with risk of coronary heart disease and cardiovascular disease. Fruit fibre intake was inversely associated with risk of cardiovascular disease. Conclusions Greater dietary fibre intake is associated with a lower risk of both cardiovascular disease and coronary heart disease. Findings are aligned with general recommendations to increase fibre intake. The differing strengths of association by fibre type or source highlight the need for a better understanding of the mode of action of fibre components.

Association between sugar-sweetened and artificially sweetened soft drinks and type 2 diabetes: systematic review and dose–response meta-analysis of prospective studies

The intake of sugar-sweetened soft drinks has been reported to be associated with an increased risk of type 2 diabetes, but it is unclear whether this is because of the sugar content or related lifestyle factors, whether similar associations hold for artificially sweetened soft drinks, and how these associations are related to BMI. We aimed to conduct a systematic literature review and dose-response meta-analysis of evidence from prospective cohorts to explore these issues. We searched multiple sources for prospective studies on sugar-sweetened and artificially sweetened soft drinks in relation to the risk of type 2 diabetes. Data were extracted from eleven publications on nine cohorts. Consumption values were converted to ml/d, permitting the exploration of linear and non-linear dose-response trends. Summary relative risks (RR) were estimated using a random-effects meta-analysis. The summary RR for sugar-sweetened and artificially sweetened soft drinks were 1·20/330 ml per d (95 % CI 1·12, 1·29, P< 0·001) and 1·13/330 ml per d (95 % CI 1·02, 1·25, P= 0·02), respectively. The association with sugar-sweetened soft drinks was slightly lower in studies adjusting for BMI, consistent with BMI being involved in the causal pathway. There was no evidence of effect modification, though both these comparisons lacked power. Overall between-study heterogeneity was high. The included studies were observational, so their results should be interpreted cautiously, but findings indicate a positive association between sugar-sweetened soft drink intake and type 2 diabetes risk, attenuated by adjustment for BMI. The trend was less consistent for artificially sweetened soft drinks. This may indicate an alternative explanation, such as lifestyle factors or reverse causality. Future research should focus on the temporal nature of the association and whether BMI modifies or mediates the association.

Glycemic Index, Glycemic Load, Carbohydrates, and Type 2 Diabetes: Systematic review and dose–response meta-analysis of prospective studies

OBJECTIVE Diets with high glycemic index (GI), with high glycemic load (GL), or high in all carbohydrates may predispose to higher blood glucose and insulin concentrations, glucose intolerance, and risk of type 2 diabetes. We aimed to conduct a systematic literature review and dose–response meta-analysis of evidence from prospective cohorts. RESEARCH DESIGN AND METHODS We searched the Cochrane Library, MEDLINE, MEDLINE in-process, Embase, CAB Abstracts, ISI Web of Science, and BIOSIS for prospective studies of GI, GL, and total carbohydrates in relation to risk of type 2 diabetes up to 17 July 2012. Data were extracted from 24 publications on 21 cohort studies. Studies using different exposure categories were combined on the same scale using linear and nonlinear dose–response trends. Summary relative risks (RRs) were estimated using random-effects meta-analysis. RESULTS The summary RR was 1.08 per 5 GI units (95% CI 1.02–1.15; P = 0.01), 1.03 per 20 GL units (95% CI 1.00–1.05; P = 0.02), and 0.97 per 50 g/day of carbohydrate (95% CI 0.90–1.06; P = 0.5). Dose–response trends were linear for GI and GL but more complex for total carbohydrate intake. Heterogeneity was high for all exposures (I2 >50%), partly accounted for by different covariate adjustment and length of follow-up. CONCLUSIONS Included studies were observational and should be interpreted cautiously. However, our findings are consistent with protective effects of low dietary GI and GL, quantifying the range of intakes associated with lower risk. Future research could focus on the type of sugars and other carbohydrates associated with greatest risk.

Dietary Fiber Intake and Risk of First Stroke: A Systematic Review and Meta-Analysis

Background and Purpose— Fiber intake is associated with reduced stroke risk in prospective studies, but no meta-analysis has been published to date. Methods— Multiple electronic databases were searched for healthy participant studies reporting fiber intake and incidence of first hemorrhagic or ischemic stroke, published between January 1990 and May 2012. Results— Eight cohort studies from the United States, northern Europe, Australia, and Japan met inclusion criteria. Total dietary fiber intake was inversely associated with risk of hemorrhagic plus ischemic stroke, with some evidence of heterogeneity between studies (I2; relative risk per 7 g/day, 0.93; 95% confidence interval, 0.88–0.98; I2=59%). Soluble fiber intake, per 4 g/day, was not associated with stroke risk reduction with evidence of low heterogeneity between studies, relative risk 0.94 (95% confidence interval, 0.88–1.01; I2=21%). There were few studies reporting stroke risk in relation to insoluble fiber or fiber from cereals, fruit, or vegetables. Conclusions— Greater dietary fiber intake is significantly associated with lower risk of first stroke. Overall, findings support dietary recommendations to increase intake of total dietary fiber. However, a paucity of data on fiber from different foods precludes conclusions regarding the association between fiber type and stroke. There is a need for future studies to focus on fiber type and to examine risk for ischemic and hemorrhagic strokes separately.

A cross-sectional survey of children's packed lunches in the UK: food- and nutrient-based results

Background Standards for school meals were recently introduced in the UK; however, no such standards exist for packed lunches. This study measures the provision and consumption of a range of food types and nutrients in British childrens packed lunches and compares the results with the prevailing school meal standards in England. Methods Cross-sectional survey data was collected from 1294 children, age 8–9 years, attending 89 British primary schools. Eighty-seven primary schools declined to take part. The outcomes were the weight of food types and nutrients, provided and consumed in packed lunches and the proportion meeting the government food and nutrient school meal standards for England. Results Fourteen out of 1294 (1.1%) of packed lunches met all the food-based standards for school meals in England. Eighty-five per cent of children were provided with a sandwich, 19% with vegetables, 54% with fruit, 17% with cheese, 44% with a milk-based dessert, 82% with restricted snacks (crisps or confectionery) and 61% with a sweetened drink. The nutrient standards most likely to be met were protein and vitamin C. The nutrient standards least likely to be met were non-milk extrinsic sugars (NMES) and sodium. Girls were provided with, and consumed, more fruit, vegetables and milk-based desserts. Children at schools with lower percentage free school meals eligibility (% FSME) were provided with, and consumed, more vegetables. Conclusion Few packed lunches meet the school meal standards. Future research should address policy, interventions, and programmes to educate parents about the nutritional content of packed lunches.

Family meals can help children reach their 5 A Day: a cross-sectional survey of children's dietary intake from London primary schools

Background This study aims to explore how the home food environment and parental attitudes and values affect childrens fruit and vegetable (F&V) intake. Methods The sample consists of 2383 children with a mean age of 8.3 years (95% CI 8.2 to 8.3) attending 52 primary schools in London. These children are taking part in two randomised controlled trials to evaluate a school gardening programme. Diet was assessed using a validated 24-h food tick list, the Child And Diet Evaluation Tool (CADET). Results The CADET tool found that children consumed on average 293 g F&V (95% CI 287 to 303) per day. Clustered (by school) multilevel regression models with total F&V as the primary outcome were conducted to explore how the home environment affects childrens F&V intake. Children of families who reported ‘always’ eating a family meal together at a table had 125 g (95% CI 92 to 157; p=<0.001) more F&V than families who never ate a meal together. Daily consumption of F&V by parents was associated with higher F&V (88 g, 95% CI 37 to 138) intake in children compared with rarely/never consumption of F&V by parents. Cutting up fruit and vegetables for children was associated with higher consumption. Families who reported always cutting up F&V for their children had 44 g (95% CI 18 to 71) more F&V than families who never cut up F&V. Conclusions This study identified that cutting up F&V and family consumption of F&V facilitates childrens intake. Eating a family meal together regularly could increase childrens F&V intake and help them achieve the recommended intake. Trial registration ISRCTN11396528.

Development of a UK online 24-h dietary assessment tool: myfood24

Assessment of diet in large epidemiological studies can be costly and time consuming. An automated dietary assessment system could potentially reduce researcher burden by automatically coding food records. myfood24 (Measure Your Food on One Day) an online 24-h dietary assessment tool (with the flexibility to be used for multiple 24 h-dietary recalls or as a food diary), has been developed for use in the UK population. Development of myfood24 was a multi-stage process. Focus groups conducted with three age groups, adolescents (11–18 years) (n = 28), adults (19–64 years) (n = 24) and older adults (≥65 years) (n = 5) informed the development of the tool, and usability testing was conducted with beta (adolescents n = 14, adults n = 8, older adults n = 1) and live (adolescents n = 70, adults n = 20, older adults n = 4) versions. Median system usability scale (SUS) scores (measured on a scale of 0–100) in adolescents and adults were marginal for the beta version (adolescents median SUS = 66, interquartile range (IQR) = 20; adults median SUS = 68, IQR = 40) and good for the live version (adolescents median SUS = 73, IQR = 22; adults median SUS = 80, IQR = 25). Myfood24 is the first online 24-h dietary recall tool for use with different age groups in the UK. Usability testing indicates that myfood24 is suitable for use in UK adolescents and adults.

Effects of dietary fibre type on blood pressure: a systematic review and meta-analysis of randomized controlled trials of healthy individuals.

Objective: To determine the effect of different types of dietary fibre on SBP and DBP. Methods: A systematic review of the literature and a meta-analysis of randomized controlled trials using random-effects models. Eligibility criteria for studies included randomized controlled trials of at least 6 weeks duration, testing a fibre isolate or fibre-rich diet against a control or placebo published between 1 January 1990 and 1 December 2013. Results: Twenty-eight trials met the inclusion criteria and reported fibre intake and SBP and/or DBP. Eighteen trials were included in a meta-analysis. Studies were categorized into 1 of 12 fibre-type categories. The pooled estimates for all fibre types were −0.9 mmHg [95% confidence interval (CI) −2.5 to 0.6 mmHg] and −0.7 mmHg (95% CI −1.9 to 0.5 mmHg) for SBP and DBP, respectively. The median difference in total fibre was 6 g. Analyses of specific fibre types concluded that diets rich in beta-glucans reduce SBP by 2.9 mmHg (95% CI 0.9 to 4.9 mmHg) and DBP by 1.5 mmHg (95% CI 0.2 to 2.7 mmHg) for a median difference in beta-glucans of 4 g. Heterogeneity for individual fibre types was generally low. Conclusions: Higher consumption of beta-glucan fibre is associated with lower SBP and DBP. The results of this review are consistent with recommendations to increase consumption of foods rich in dietary fibre, but some additional emphasis on sources of beta-glucans, such as oats and barley, may be warranted.

A comparison of British school meals and packed lunches from 1990 to 2007: meta-analysis by lunch type

Primary school children in the UK have the choice of a school meal provided by the school or a packed lunch provided from home. Currently, more than half of primary school children have a packed lunch. New food-based standards for school meals were introduced in English primary schools in 2006, followed by nutrient-based standards in 2008. No formal comparisons of primary school lunches by lunch type have been undertaken to date. The present review identified seven studies from 1990 to 2007 measuring lunchtime nutrient intake in children aged 5-11 years having a school meal and children having a packed lunch. Pooled estimates for each nutrient were as follows: energy intake was 543 (95 % CI 233, 854) kJ higher in packed lunches; total sugar intake was 14.0 (95 % CI 10.3, 17.7) g higher in packed lunches; non-milk extrinsic sugar intake was 11.7 (95 % CI 7.3, 16.2) g higher in packed lunches; saturated fat intake was 4.7 (95 % CI 2.4, 7.1) g higher in packed lunches and Na intake was 357 (95 % CI 174, 539) mg higher in packed lunches. Differences between school meals and packed lunches were larger for all nutrients after the introduction of food-based standards compared with the period of no standards. However, differences between before and after standards did not reach statistical significance. The nutritional quality of packed lunches is poor compared with school meals. The introduction of food-based standards for school meals in 2006 has moderately improved the nutrient content of school meals, slightly widening the nutritional gap between school meals and packed lunches.

SMART lunch box intervention to improve the food and nutrient content of children's packed lunches: UK wide cluster randomised controlled trial

Background Government standards are now in place for childrens school meals but not for lunches prepared at home. The aim of this trial is to improve the content of childrens packed lunches. Methods A cluster randomised controlled trial in 89 primary schools across the UK involving 1291 children, age 8–9 years at baseline. Follow-up was 12 months after baseline. A “SMART” lunch box intervention programme consisted of food boxes, bag and supporting materials. The main outcome measures were weights of foods and proportion of children provided with sandwiches, fruit, vegetables, dairy food, savoury snacks and confectionery in each packed lunch. Levels of nutrients provided including energy, total fat, saturated fat, protein, non-milk extrinsic sugar, sodium, calcium, iron, folate, zinc, vitamin A and vitamin C. Results Moderately higher weights of fruit, vegetables, dairy and starchy food and lower weights of savoury snacks were provided to children in the intervention group. Children in the intervention group were provided with slightly higher levels of vitamin A and folate. 11% more children were provided with vegetables/salad in their packed lunch, and 13% fewer children were provided with savoury snacks (crisps). Children in the intervention group were more likely to be provided with packed lunches meeting the government school meal standards. Conclusions The SMART lunch box intervention, targeting parents and children, led to small improvements in the food and nutrient content of childrens packed lunches. Further interventions are required to bring packed lunches in line with the new government standards for school meals. Current controlled trials ISRCTN77710993.