Claire T. McEvoy

Vegetarian diets, low-meat diets and health: a review

OBJECTIVE To review the epidemiological evidence for vegetarian diets, low-meat dietary patterns and their association with health status in adults. DESIGN Published literature review focusing primarily on prospective studies and meta-analyses examining the association between vegetarian diets and health outcomes. RESULTS Both vegetarian diets and prudent diets allowing small amounts of red meat are associated with reduced risk of diseases, particularly CHD and type 2 diabetes. There is limited evidence of an association between vegetarian diets and cancer prevention. Evidence linking red meat intake, particularly processed meat, and increased risk of CHD, cancer and type 2 diabetes is convincing and provides indirect support for consumption of a plant-based diet. CONCLUSIONS The health benefits of vegetarian diets are not unique. Prudent plant-based dietary patterns which also allow small intakes of red meat, fish and dairy products have demonstrated significant improvements in health status as well. At this time an optimal dietary intake for health status is unknown. Plant-based diets contain a host of food and nutrients known to have independent health benefits. While vegetarian diets have not shown any adverse effects on health, restrictive and monotonous vegetarian diets may result in nutrient deficiencies with deleterious effects on health. For this reason, appropriate advice is important to ensure a vegetarian diet is nutritionally adequate especially for vulnerable groups.

Resting energy expenditure in non-ventilated, non-sedated patients recovering from serious traumatic brain injury: comparison of prediction equations with indirect calorimetry values.

BACKGROUND & AIMS Little is known about energy requirements in brain injured (TBI) patients, despite evidence suggesting adequate nutritional support can improve clinical outcomes. The study aim was to compare predicted energy requirements with measured resting energy expenditure (REE) values, in patients recovering from TBI. METHODS Indirect calorimetry (IC) was used to measure REE in 45 patients with TBI. Predicted energy requirements were determined using FAO/WHO/UNU and Harris-Benedict (HB) equations. Bland-Altman and regression analysis were used for analysis. RESULTS One-hundred and sixty-seven successful measurements were recorded in patients with TBI. At an individual level, both equations predicted REE poorly. The mean of the differences of standardised areas of measured REE and FAO/WHO/UNU was near zero (-9 kcal) but the variation in both directions was substantial (range -591 to +573 kcal). Similarly, the differences of areas of measured REE and HB demonstrated a mean of 1.9 kcal and range -568 to +571 kcal. Glasgow coma score, patient status, weight and body temperature were significant predictors of measured REE (p<0.001; R(2)=0.47). CONCLUSIONS Clinical equations are poor predictors of measured REE in patients with TBI. The variability in REE is substantial. Clinicians should be aware of the limitations of prediction equations when estimating energy requirements in TBI patients.

Dose-response effect of fruit and vegetables on insulin resistance in people at high risk of cardiovascular disease: a randomized controlled trial.

OBJECTIVE The purpose of this randomized controlled trial was to investigate the dose-response effect of fruit and vegetable (F&V) intake on insulin resistance (IR) in people who are overweight and at high risk of cardiovascular disease (CVD). RESEARCH DESIGN AND METHODS A total of 105 participants (mean age 56 years) followed a 4-week washout diet (one to two portions of F&Vs per day). Ninety-two participants completed the washout and were randomized to receive one to two, four, or seven portions of F&Vs per day for 12 weeks. IR was assessed at the start and end of this 12-week period by the two-step euglycemic-hyperinsulinemic clamp. Compliance was monitored using a combination of 4-day food diaries and plasma biomarkers of F&V intake. RESULTS A total of 89 participants completed the study. Participants attained self-reported F&V intakes of 1.8, 3.8, and 7.0 portions per day (P < 0.001) per group. There was a significant linear increase in serum lutein status across the groups, indicating good compliance (P < 0.001), and body weight was maintained (P = 0.77). No significant difference was found between groups in terms of a change in measures of whole-body, peripheral, or hepatic IR or adiponectin multimers. CONCLUSIONS Increased consumption of F&Vs, as advocated in public-health advice, has no effect on IR in overweight individuals who are at high risk of CVD when body weight is maintained. Recent evidence from systematic reviews indicates that particular classes or types of F&Vs may have particular antidiabetic properties; hence, it is possible that benefits may only be observed in response to a more specific fruit or vegetable intervention.

Neuroprotective Diets Are Associated with Better Cognitive Function: The Health and Retirement Study

To evaluate the association between the Mediterranean diet (MedDiet) and the Mediterranean‐DASH diet Intervention for Neurodegeneration Delay (MIND diet) and cognition in a nationally representative population of older U.S. adults.

Association of Sleep-Disordered Breathing With Cognitive Function and Risk of Cognitive Impairment: A Systematic Review and Meta-analysis

Importance Growing evidence suggests an association between sleep-disordered breathing (SDB) and cognitive decline in elderly persons. However, results from population-based studies have been conflicting, possibly owing to different methods to assess SDB or cognitive domains, making it difficult to draw conclusions on this association. Objective To provide a quantitative synthesis of population-based studies on the relationship between SDB and risk of cognitive impairment. Data Sources PubMed, EMBASE, and PsychINFO were systematically searched to identify peer-reviewed articles published in English before January 2017 that reported on the association between SDB and cognitive function. Study Selection We included cross-sectional and prospective studies with at least 200 participants with a mean participant age of 40 years or older. Data Extraction and Synthesis Data were extracted independently by 2 investigators. We extracted and pooled adjusted risk ratios from prospective studies and standard mean differences from cross-sectional studies, using random-effect models. This meta-analysis followed the PRISMA guidelines and also adhered to the MOOSE guidelines. Main Outcomes and Measures Cognitive outcomes were based on standard tests or diagnosis of cognitive impairment. Sleep-disordered breathing was ascertained by apnea-hypopnea index or clinical diagnosis. Results We included 14 studies, 6 of which were prospective, covering a total of 4 288 419 men and women. Pooled analysis of the 6 prospective studies indicated that those with SDB were 26% (risk ratio, 1.26; 95% CI, 1.05-1.50) more likely to develop cognitive impairment, with no evidence of publication bias but significant heterogeneity between studies. After removing 1 study that introduced significant heterogeneity, the pooled risk ratio was 1.35 (95% CI, 1.11-1.65). Pooled analysis of the 7 cross-sectional studies suggested that those with SDB had slightly worse executive function (standard mean difference, −0.05; 95% CI, −0.09 to 0.00), with no evidence of heterogeneity or publication bias. Sleep-disordered breathing was not associated with global cognition or memory. Conclusions and Relevance Sleep-disordered breathing is associated with an increased risk of cognitive impairment and a small worsening in executive function. Further studies are required to determine the mechanisms linking these common conditions and whether treatment of SDB might reduce risk of cognitive impairment.

A reduced abbreviated indirect calorimetry protocol is clinically acceptable for use in spontaneously breathing patients with traumatic brain injury

A steady state should be established when using indirect calorimetry to assess resting energy expenditure, reduce error, and improve the validity of the measurement. Steady-state criteria are often rigorous and difficult to achieve in hospitalized patients, particularly in patients recovering from traumatic brain injury. This study aimed to assess whether reducing the timeframe for steady-state conditions to 2, 3, or 4 minutes when using indirect calorimetry was significantly different from the widely accepted 5-minute steady-state protocol in patients recovering from traumatic brain injury. Indirect calorimetry using an open-circuit calorimeter was used to measure resting energy expenditure in 20 spontaneously breathing patients with traumatic brain injury. Each patient underwent repeated measurements once per day at various stages of his or her recovery. Bland-Altman methods comparison was used for statistical analysis. In total, 124 measurements were recorded, of which 59% met 5-minute, 70% met 4-minute, 76% met 3-minute, and 84% met 2-minute steady-state conditions. Mean within-patient coefficient of variation was 13% (range, 0%-35%). Agreement at the +/-10% level using Bland-Altman plots was 100% for a 4-minute steady-state protocol, 96% for a 3-minute protocol, and 90% using a 2-minute protocol. A 4-minute or 3-minute abbreviated steady-state indirect calorimetry protocol is clinically acceptable to measure resting energy expenditure in spontaneously breathing patients with a traumatic brain injury.

Increasing Fruit and Vegetable Intake Has No Dose-Response Effect on Conventional Cardiovascular Risk Factors in Overweight Adults at High Risk of Developing Cardiovascular Disease

BACKGROUND Improving diet and lifestyle is important for prevention of cardiovascular disease (CVD). Observational evidence suggests that increasing fruit and vegetable (FV) consumption may lower CVD risk, largely through modulation of established risk factors, but intervention data are required to fully elucidate the mechanisms by which FVs exert benefits on vascular health. OBJECTIVE The aim of this study was to examine the dose-response effect of FV intake on cardiovascular risk factors in adults at high CVD risk. METHODS This was a randomized controlled parallel group study involving overweight adults (BMI: >27 and ≤35 kg/m(2)) with a habitually low FV intake (≤160 g/d) and a high total risk of developing CVD (estimated ≥20% over 10 y). After a 4-wk run-in period where FV intake was limited to <2 portions/d (<160 g/d), 92 eligible participants were randomly assigned to 1 of 3 groups: to consume either 2, 4, or 7 portions (equivalent to 160 g, 320 g, or 560 g, respectively) of FVs daily for 12 consecutive weeks. Fasting venous blood samples were collected at baseline (week 4) and post-intervention (week 16) for analysis of lipid fractions and high-sensitivity C-reactive protein (hsCRP) concentrations. Compliance with the FV intervention was determined with use of self-reported FV intake and biomarkers of micronutrient status. Ambulatory blood pressure and body composition were also measured pre- and post-intervention. RESULTS A total of 89 participants completed the study and body composition remained stable throughout the intervention period. Despite good compliance with the intervention, no significant difference was found between the FV groups for change in measures of ambulatory blood pressure, plasma lipids, or hsCRP concentrations. CONCLUSIONS There was no evidence of a dose-response effect of FV intake on conventional CVD risk factors measured in overweight adults at high CVD risk. This trial was registered at clinicaltrials.gov as NCT00874341.

Fish, n-3 Polyunsaturated Fatty Acids, and Cardiovascular Disease

Cardiovascular disease (CVD) is a major cause of morbidity and mortality in the western world [1]. There are a number of well-established risk factors for CVD including smoking, hypertension, and family history [2]. In terms of nutrition, a diet high in fat, particularly saturated fat, has been shown to be associated with CVD incidence [3]. The observation that Greenland Eskimos (Inuit) have a low incidence of CVD despite a high saturated fat intake [4] has led to much scientific and public interest in the role of n-3 fatty acids found in fish and fish oils in the prevention and treatment of disease, and particularly CVD. In this chapter, the biochemistry and normal dietary intake of these compounds will be discussed, and the evidence linking them and their food sources with CVD reviewed. The safety of both fish oil supplements and fish will be assessed, and finally the potential effect of fish and fish oil consumption on other diseases considered.

Barriers to adopting a Mediterranean diet in Northern European adults at high risk of developing cardiovascular disease

BACKGROUND Strong evidence links the consumption of a Mediterranean diet (MD) with a reduced cardiovascular disease (CVD) risk; however, there is uncertainty as to whether non-Mediterranean regions will adopt this diet. The present qualitative research aimed to investigate attitudes towards a MD in individuals at high CVD risk in a Northern European population. This information is needed to inform development of MD interventions in non-Mediterranean high-risk populations. METHODS Focus groups (n = 12) were held with individuals at high CVD risk from Northern Europe (≥2 CVD risk factors, aged ≥50 years, no established CVD/type 2 diabetes). Attitudes to dietary change towards a MD were explored. Data were analysed using inductive thematic analysis. RESULTS Sixty-seven adults participated (60% female, mean age 64 years). There was some awareness of the term MD but limited knowledge of its composition. Barriers to general dietary change were evident, including perception of expense, concern over availability, expectation of time commitment, limited knowledge, lack of cooking skills, amount and conflicting nature of media information on diets, changing established eating habits and resistance to dietary change. Barriers specific to MD adoption were also identified, including perceived difficulty living in a colder climate, perceived impact on body weight, acceptability of a MD and cultural differences. CONCLUSIONS Knowledge of a MD was limited in this Northern European sample at high CVD risk. In addition to general barriers to dietary change, barriers specific to a MD were identified. These findings have implications for the development of interventions aiming to promote MD adoption in non-Mediterranean populations.

Adolescents’ views about a proposed rewards intervention to promote healthy food choice in secondary school canteens

Using rewards may be an effective method to positively influence adolescent eating behaviour, but evidence regarding this approach is limited. The aim of this study was to explore young adolescent views about a proposed reward intervention associated with food choice in school canteens. Focus groups were held in 10 schools located in lower socioeconomic areas within Northern Ireland and involved 90 pupils aged 11-12 years (54 girls, 36 boys). Our findings indicated a high degree of acceptability for a reward scheme but there was major diversity in the type of rewards valued by pupils, largely defined by geographical area and socio-cultural differences. Pupils from rural areas tended to emphasize group-based and longer-term rewards, whereas pupils from urban-city schools tended to suggest individualistic and immediate rewards. The major factors influencing food choice were food price, value for money, taste and visual appearance. Pupils felt that factors outside of their control, such as being assigned to the second lunch sitting placed considerable constraints on their food choice. This research not only indicated a high degree of acceptability for a rewards-based intervention but also highlighted a number of socio-cultural and environmental factors that should be considered by researchers when developing such an intervention.