Elizabeth P. Neale

Dietary Patterns and Blood Pressure in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Hypertension is a major risk factor for developing cardiovascular disease, stroke, and kidney disease. To lower blood pressure (BP), several lifestyle changes are recommended such as weight loss, exercise, and following a healthy diet. Investigating the effect of single nutrients may have positive results, but food is consumed as part of a whole diet, resulting in nutrient interactions. The aim of this systematic review and meta-analysis was to assess the effect of dietary patterns on BP in adults. Studies that were published between January 1999 and June 2014 were retrieved using Scopus, Web of Science, and the MEDLINE database. Seventeen randomized controlled trials were included in the meta-analysis. The results suggest that healthy dietary patterns such as the Dietary Approaches to Stop Hypertension diet, Nordic diet, and Mediterranean diet significantly lowered systolic BP and diastolic BP by 4.26 mm Hg and 2.38 mm Hg, respectively. These diets are rich in fruit, vegetables, whole grains, legumes, seeds, nuts, fish, and dairy and low in meat, sweets, and alcohol. Lifestyle factors such as exercise and weight loss in combination with dietary changes may also reduce BP. Further research is needed to establish the effect of dietary patterns on BP in different cultures other than those identified in this review. The review was registered on PROSPERO (International prospective register of systematic reviews) as CRD42015016272.

Consumption of a healthy dietary pattern results in significant reductions in C-reactive protein levels in adults: a meta-analysis

Consumption of healthy dietary patterns has been associated with reduced risk of cardiovascular disease and metabolic syndrome. Dietary intervention targets disease prevention, so studies increasingly use biomarkers of underlying inflammation and metabolic syndrome progression to examine the diet-health relationship. The extent to which these biomarkers contribute to the body of evidence on healthy dietary patterns is unknown. The aim of this meta-analysis was to determine the effect of healthy dietary patterns on biomarkers associated with adiposity, insulin resistance, and inflammation in adults. A systematic search of Scopus, PubMed, Web of Science, and Cochrane Central Register of Controlled Trials (all years to April 2015) was conducted. Inclusion criteria were randomized controlled trials; effects of dietary patterns assessed on C-reactive protein (CRP), total adiponectin, high-molecular-weight adiponectin, tumor necrosis factor-α, adiponectin:leptin, resistin, or retinol binding protein 4. Random effects meta-analyses were conducted to assess the weighted mean differences in change or final mean values for each outcome. Seventeen studies were included in the review. These reflected research on dietary patterns associated with the Mediterranean diet, Nordic diet, Tibetan diet, and the Dietary Approaches to Stop Hypertension diet. Consumption of a healthy dietary pattern was associated with significant reductions in CRP (weighted mean difference, -0.75 [-1.16, -0.35]; P = .0003). Non-significant changes were found for all other biomarkers. This analysis found evidence for favorable effects of healthy dietary patterns on CRP, with limited evidence for other biomarkers. Future research should include additional randomized controlled trials incorporating a greater range of dietary patterns and biomarkers.

Foods, Nutrients, and Dietary Patterns: Interconnections and Implications for Dietary Guidelines

Dietary guidelines provide evidence-based statements on food choices to meet nutritional requirements and reduce the risk of prevailing chronic disease. They involve a substantial amount of research translation, and their implementation has important health consequences. Foods, however, are complex combinations of nutrients and other compounds that act synergistically within the food and across food combinations. In addition, the evidence base underpinning dietary guidelines accesses research that reflects different study designs, with inherent strengths and limitations. We propose a systematic approach for the review of evidence that begins with research on dietary patterns. This research will identify the combinations of foods that best protect, or appear deleterious to, health. Next, we suggest that evidence be sought from research that focuses on the effects of individual foods. Finally, nutrient-based research should be considered to explain the mechanisms by which these foods and dietary patterns exert their effects, take into account the effects of ingredients added to the food supply, and enable assessments of dietary sufficiency. The consideration of individual nutrients and food components (e.g., upper limits for saturated fat, added sugar, and sodium) provides important benchmarks for evaluating overall diet quality. The concepts of core and discretionary foods (nutrient-rich and nutrient-poor foods, respectively) enable distinctions between foods, and this has implications for the relation between food policy and food manufacturing. In summary, evidence supporting healthy dietary patterns provides the foundation for the development of dietary guidelines. Further reference to individual foods and nutrients follows from the foundation of healthy dietary patterns.

Interdisciplinary lifestyle intervention for weight management in a community population (HealthTrack study): Study design and baseline sample characteristics

BACKGROUND Integrating professional expertise in diet, exercise and behavioural support may provide more effective preventive health services but this needs testing. We describe the design and baseline results of a trial in the Illawarra region of New South Wales, Australia. METHODS The HealthTrack study is a 12 month randomised controlled trial testing effects of a novel interdisciplinary lifestyle intervention versus usual care. The study recruited overweight and obese adults 25-54 years resident in the Illawarra. Primary outcomes were weight, and secondary outcomes were disease risk factors (lipids, glucose, blood pressure), and behaviour (diet, activity, and psychological factors). Protocols, recruitment and baseline characteristics are reported. RESULTS Between May 2014 and April 2015, 377 participants were recruited and randomised. The median age (IQR) of the mostly female sample (74%) was 45 (37-51) years. The sample comprised obese (BMI 32 (29-35) kg/m(2)) well educated (79% post school qualifications) non-smokers (96%). A high proportion reported suffering from anxiety (26.8%) and depression (33.7%). Metabolic syndrome was identified in 34.9% of the sample. CONCLUSIONS The HealthTrack study sample was recruited to test the effectiveness of an interdisciplinary approach to preventive healthcare in self-identified overweight adults in the Illawarra region. The profile of participants gives some indication of those likely to use services similar to the trial design.

Consumers' salient beliefs regarding dairy products in the functional food era: a qualitative study using concepts from the theory of planned behaviour

BackgroundInadequate consumption of dairy products without appropriate dietary substitution may have deleterious health consequences. Social research reveals the factors that may impede compliance with dietary recommendations. This is particularly important given the recent introduction of functional dairy products. One of the challenges for public health professionals is to demonstrate the efficacy of nutrition education in improving attitudes toward nutrient rich foods. The aim of this study was to explore the salient beliefs of adult weight loss trial participants regarding both traditional and functional dairy products and to compare these with a control group not exposed to nutrition education.MethodsSix focus groups were conducted, three with weight loss trial completers (n = 15) that had received nutrition education and three with individuals from the same region (n = 14) to act as controls. Transcribed focus groups were coded using the Theory of Planned Behaviour theoretical framework.ResultsNon-trial participants perceived dairy foods as weight inducing and were sceptical of functional dairy products. A lack of time/ability to decipher dairy food labels was also discussed by these individuals. In contrast trial participants discussed several health benefits related to dairy foods, practised label reading and were confident in their ability to incorporate dairy foods into their diet. Normative beliefs expressed were similar for both groups indicating that these were more static and less amenable to change through nutrition education than control and behavioural beliefs.ConclusionsNutrition education provided as a result of weight loss trial participation influenced behavioural and control beliefs relating to dairy products. This study provides a proof of concept indication that nutrition education may improve attitudes towards dairy products and may thus be an important target for public health campaigns seeking to increase intake of this food group.

Effect of interdisciplinary care on weight loss: A randomised controlled trial

Objective To determine the effectiveness of a novel interdisciplinary treatment compared with usual care on weight loss in overweight and obese adult volunteers. Design Single blinded controlled trial. Participants randomly assigned to usual care (C, general guideline-based diet and exercise advice), intervention (I, interdisciplinary protocol) or intervention + a healthy food supplement (30 g walnuts/day) (IW). Setting Community based study, Illawarra region, south of Sydney, Australia. Participants Generally well volunteer adult residents, 25-54 years, body mass index (BMI) 25-40kg/m2 were eligible. At baseline 439 were assessed, 377 were randomised, 298 completed the 3-month intensive phase and 178 completed the 12-month follow-up. Interventions Treatment was provided at clinic visits intensively (0 months, 1 month, 2 months, 3 months) then quarterly to 12 months. Support phone calls were quarterly. All participants underwent blinded assessments for diet, exercise and psychological status. Primary and secondary measures The primary outcome was difference in weight loss between baseline and 12 months (clinically relevant target 5% loss). Secondary outcomes were changes in blood pressure, fasting blood glucose and lipids, and changes in diet, exercise and psychological parameters. Results At 12 months, differences in weight loss were identified (p<0.001). The I group lost more than controls at 3 months (91.11 (92.23,90.00), p<0.05) and the IW more than controls at 3 months (91.25 (92.35,90.15), p<0.05) and 6 months (92.20 (93.90,90.49), p<0.01). The proportion achieving 5% weight loss was significantly different at 3 months, 6 months and 9 months (p=0.04, p=0.03, p=0.03), due to fewer controls on target at 3 months, 6 months and 9 months and more IW participants at 6 months. Reductions in secondary outcomes (systolic blood pressure, blood glucose/lipid parameters and lifestyle measures) followed the pattern of weight loss. Conclusions An interdisciplinary intervention produced greater and more clinically significant and sustained weight loss compared with usual care. The intensive phase was sufficient to reach clinically relevant targets, but long-term management plans may be required. Trial registration number ANZCTRN 12614000581662; Post-results.

Processed pork is the most frequently consumed type of pork in a survey of Australian children

Pork represents a core food that provides key nutrients to the diet. Dietary guidelines recommend limiting processed meat intake because of adverse health outcomes. The aims of this study were to describe pork consumption, assess the contribution of pork to nutrient intakes, and compare anthropometric characteristics between pork consumers and nonconsumers in a survey of Australian children. We hypothesized that pork consumption will contribute to intakes of key nutrients and that the weight status of children who consume pork will be similar to nonconsumers. This study involved a secondary analysis of the 2007 Australian National Childrens Nutrition and Physical Activity Survey. Pork and pork-containing dishes were identified and classified as fresh or processed pork. The contributions of pork to nutrient intakes were calculated. Weight, waist circumference, and body mass index were compared between pork consumers and nonconsumers. Data from 4487 children were available for use. Of this sample, 2245 reported consuming pork, 14% (n = 310) of whom consumed fresh pork, whereas 93% (n = 2084) consumed processed pork. All types of pork contributed to intakes of protein, niacin, and zinc. In addition, fresh pork contributed to intakes of thiamine, long-chain omega-3, phosphorous, and potassium. Total and processed pork contributed 12.2% and 13.0% of sodium, respectively. There were no significant differences between weight, waist circumference, and body mass index in consumers and nonconsumers of total, fresh, or processed pork. In a survey of Australian children, processed pork was the most frequently consumed form of pork, suggesting a deviation from dietary guidelines.

Impact of providing walnut samples in a lifestyle intervention for weight loss: a secondary analysis of the HealthTrack trial

ABSTRACT Background: Being more specific about individual food choices may be advantageous for weight loss. Including a healthy food (e.g. walnuts) may help to expose effects. Objective: To examine the impact of including walnuts in diets for weight loss. Design: Secondary analysis of the HealthTrack lifestyle intervention trial. Overweight and obese participants were randomized to: usual care (C), interdisciplinary intervention including individualized dietary advice (I), or interdisciplinary intervention including 30 g walnuts/day (IW). Changes in body weight, energy intake, intake of key foods, physical activity, and mental health over three and 12 months were explored. Results: A total of 293 participants completed the intensive three-month study period, and 175 had data available at 12 months. The IW group achieved the greatest weight loss at three months. IW reported significant improvements in healthy food choices, and decreased intakes of discretionary foods/beverages, compared to C. Weight loss remained greatest in IW at 12 months. Discussion: Significant effects were seen after three months, with the IW group achieving greater weight loss and more favorable changes in food choices. Conclusions: Including 30 grams walnuts/day in an individualized diet produced weight loss and positive changes in food choice.

The effect of nut consumption on markers of inflammation and endothelial function: a systematic review and meta-analysis of randomised controlled trials

Objectives To examine the effect of nut consumption on inflammatory biomarkers and endothelial function. Design A systematic review and meta-analysis. Data sources MEDLINE, PubMed, Cumulative Index to Nursing and Allied Health Literature and Cochrane Central Register of Controlled Trials (all years to 13 January 2017). Eligibility criteria Randomised controlled trials (with a duration of 3 weeks or more) or prospective cohort designs conducted in adults; studies assessing the effect of consumption of tree nuts or peanuts on C-reactive protein (CRP), adiponectin, tumour necrosis factor alpha, interleukin-6, intercellular adhesion molecule 1, vascular cell adhesion protein 1 and flow-mediated dilation (FMD). Data extraction and analysis Relevant data were extracted for summary tables and analyses by two independent researchers. Random effects meta-analyses were conducted to explore weighted mean differences (WMD) in change or final mean values for each outcome. Results A total of 32 studies (all randomised controlled trials) were included in the review. The effect of nut consumption on FMD was explored in nine strata from eight studies (involving 652 participants), with consumption of nuts resulting in significant improvements in FMD (WMD: 0.79%(95% CI 0.35 to 1.23)). Nut consumption resulted in small, non-significant differences in CRP (WMD: −0.01 mg/L (95% CI −0.06 to 0.03)) (26 strata from 25 studies), although sensitivity analyses suggest results for CRP may have been influenced by two individual studies. Small, non-significant differences were also found for other biomarkers of inflammation. Conclusions This systematic review and meta-analysis of the effects of nut consumption on inflammation and endothelial function found evidence for favourable effects on FMD, a measure of endothelial function. Non-significant changes in other biomarkers indicate a lack of consistent evidence for effects of nut consumption on inflammation. The findings of this analysis suggest a need for more research in this area, with a particular focus on randomised controlled trials. PROSPERO registration number CRD42016045424.

The Effect of Interdisciplinary Interventions on Risk Factors for Lifestyle Disease A Literature Review

Interventions that comprise interdisciplinary collaboration including behavioral elements are effective in addressing lifestyle disease risk factors. However, it is not known how best to conduct this collaboration for sustainable change. The aim of this study was to systematically examine the evidence for the effects of interdisciplinary interventions on lifestyle disease risk factors including weight, lipid levels, glycemic control, and blood pressure. To do so, a systematic review of the literature was conducted using the databases Scopus, Medline, and Web of Science (all years to September 2014). Eighteen articles describing 16 studies of interdisciplinary interventions were identified. Consistent results were found for effects on weight loss but not for effects on blood lipids, blood glucose, and blood pressure. Effective interventions involved collaborations between dieticians, exercise physiologists, and psychologists and incorporated intensive initial participant engagement. Few studies investigated the long-term effect of interventions, but where this was done, the maintenance of favorable changes required ongoing participant support. Current evidence suggests that interdisciplinary interventions are effective in promoting weight loss and that ongoing support of participants is key to maintaining results beyond initial study duration. Future studies should examine long-term effects in pragmatic trials that address translation to practice.