Dietetic guidelines on food and nutrition in the secondary prevention of cardiovascular disease – evidence from systematic reviews of randomized controlled trials (second update, January 2006)

AIM: To update dietetic guidelines based on systematic review evidence on dietary advice to prevent further events in people with existing cardiovascular disease (CVD) (secondary prevention). METHODS: The Cochrane Library, MEDLINE and EMBASE were comprehensively searched to January 2005 for systematic reviews on aspects of diet and heart health. Reviews were included if they searched systematically for randomized controlled trials relating to diet and secondary prevention of CVD. Each review was critically appraised by at least two members of the UK Heart Health and Thoracic Dietitians Group. The quality and results of each review were discussed and summarized at a group meeting. RESULTS: Evidence-based strategies that reduce cardiovascular events in those with CVD include reduction in saturated fat and substitution with unsaturated fats. Individuals who have suffered a myocardial infarction may also benefit from adopting a Mediterranean type diet and increasing intake of omega 3 fats, but it is not clear whether they are beneficial for all patients with CVD. There is no systematic review evidence to support the use of antioxidant vitamins supplements, low glycaemic index diets, or homocysteine lowering therapies in this group. CONCLUSION: There remains good evidence that reducing saturated fat reduces morbidity in patients with CVD. This advice is consistent for most manifestations of CVD, with the addition of Mediterranean dietary advice and increased omega 3 fats for those who have had a myocardial infarction.     

Adoption and maintenance of a Mediterranean diet in patients with coronary heart disease from a Northern European population: a pilot randomised trial of different methods of delivering Mediterranean diet advice

Background:  A Mediterranean diet has been shown to protect against coronary heart disease (CHD). Adherence to a Mediterranean diet can be assessed using a Mediterranean diet score. The primary aim of this pilot study was to examine whether CHD patients in a Northern European population would adopt and maintain a Mediterranean diet, with a secondary aim of comparing the effectiveness of different methodologies aimed at improving compliance.
Methods:  Sixty-one patients with a diagnosis of CHD were randomised to one of three groups: either to receive conventional dietetic advice for CHD or advice to implement a Mediterranean-style diet using either behavioural counselling or nutritional counselling. Patients received a follow-up assessment at 6 months (adoption) and a subset of patients was followed up at 12 months (maintenance). The primary outcome measure was the between-group difference in the mean change in Mediterranean diet score (MDS).
Results:  The change in MDS was not significantly different between groups. However, all three groups reported a significant within-group increase in MDS ( P  < 0.01) at 6 and 12 months follow-up.
Conclusions:  All three groups made dietary changes towards a Mediterranean diet, but behavioural counselling did not have significant additional benefit over nutritional counselling in initiating and maintaining dietary change, and neither method offering specific Mediterranean diet advice had any significant benefit in terms of improvement in MDS over conventional dietetic practice.     

Egg Consumption and Human Cardio-Metabolic Health in People with and without Diabetes

The guidelines for dietary cholesterol and/or egg intake for both the general population and those at higher risk of cardiovascular disease (for example, people with type 2 diabetes mellitus (T2DM)) differ between countries, and even for different specialist societies in a country. The disparity between these guidelines is at least in part related to the conflicting evidence as to the effects of eggs in the general population and in those with T2DM. This review addresses the effect of eggs on cardiovascular disease (CVD) risk from both epidemiological research and controlled prospective studies, in people with and without cardio-metabolic disease. It also examines the nutritional qualities of eggs and whether they may offer protection against chronic disease. The evidence suggests that a diet including more eggs than is recommended (at least in some countries) may be used safely as part of a healthy diet in both the general population and for those at high risk of cardiovascular disease, those with established coronary heart disease, and those with T2DM. In conclusion, an approach focused on a person’s entire dietary intake as opposed to specific foods or nutrients should be the heart of population nutrition guidelines.     

Oily fish and fish oil supplements in the prevention of coronary heart disease

Dietary advice for the reduction of coronary heart disease events emphasizes the importance of a low-fat diet and advice on the consumption of oily fish may also be given. This report reviews the evidence linking fish consumption with coronary risk. On the basis of available evidence, a target of two to three portions of oily fish per week (200–400 g, 7–14 oz) is considered reasonable, particularly for secondary prevention. For those who cannot achieve the suggested dietary intake of oily fish, the partial or complete substitution of fish oil supplements may be appropriate. A range of suitable types of fish oil supplements is given, but an awareness of the potential adverse effects of fish oil supplementation is considered important. Further studies are needed to define the role of fish intake in coronary heart disease.     

Diet Quality Assessment and the Relationship between Diet Quality and Cardiovascular Disease Risk

Cardiovascular diseases (CVD) are the leading cause of morbidity and mortality in the U.S. and globally. Dietary risk factors contribute to over half of all CVD deaths and CVD-related disability. The aim of this narrative review is to describe methods used to assess diet quality and the current state of evidence on the relationship between diet quality and risk of CVD. The findings of the review will be discussed in the context of current population intake patterns and dietary recommendations. Several methods are used to calculate diet quality: (1) a priori indices based on dietary recommendations; (2) a priori indices based on foods or dietary patterns associated with risk of chronic disease; (3) exploratory data-driven methods. Substantial evidence from prospective cohort studies shows that higher diet quality, regardless of the a priori index used, is associated with a 14–29% lower risk of CVD and 0.5–2.2 years greater CVD-free survival time. Limited evidence is available from randomized controlled trials, although evidence shows healthy dietary patterns improve risk factors for CVD and lower CVD risk. Current dietary guidance for general health and CVD prevention and management focuses on following a healthy dietary pattern throughout the lifespan. High diet quality is a unifying component of all dietary recommendations and should be the focus of national food policies and health promotion.     

Alternatives for macronutrient intake and chronic disease: a comparison of the OmniHeart diets with popular diets and with dietary recommendations

BACKGROUND: Enhancements to current dietary advice to prevent chronic disease are of great clinical and public health importance. The OmniHeart Trial compared 3 diets designed to reduce cardiovascular disease (CVD) risk-one high in carbohydrate and 2 that replaced carbohydrate with either unsaturated fat or protein. The lower carbohydrate diets improved the CVD risk factors. Several popular diets claiming health benefits emphasize carbohydrate, fat, or protein or various combined approaches. OBJECTIVE: The objective of this study was to compare the macronutrient contents of the OmniHeart trial diets to those of several popular diets and to evaluate each diet for consistency with national health guidelines. DESIGN: The macronutrient contents of 7-d menu plans from the OmniHeart Study, Dietary Approaches to Stop Hypertension (DASH), Zone, Atkins, Mediterranean, South Beach, and Ornish diets were evaluated for consistency with the US Food and Nutrition Board's Acceptable Macronutrient Distribution Ranges (AMDRs) and with the dietary recommendations of several health organizations. RESULTS: The OmniHeart diets fulfilled the major AMDRs, but, of the popular diets, only the Zone diet did. The OmniHeart diets were generally consistent with national guidelines to prevent cancer, diabetes, and heart disease, whereas most popular diets had limitations for fulfilling one or more guidelines. CONCLUSIONS: Although the OmniHeart protein and unsaturated fat diets were superior to the carbohydrate diet in improving CVD risk, all 3 study diets were consistent with national guidelines to reduce chronic disease risk, which suggests that the guidelines might now be fine-tuned to optimize disease prevention. Popular diets vary in their nutritional adequacy and consistency with guidelines for risk reduction.     

Assessing the Physiological Effects of Traditional Regional Diets Targeting the Prevention of Cardiovascular Disease: A Systematic Review of Randomized Controlled Trials Implementing Mediterranean,New Nordic,Japanese, Atlantic,Persian and Mexican Dietary Interventions

Traditional regional diets are considered as sustainable dietary patterns, while many have been examined with regard to their health benefits. The aim of the present systematic review was to aggerate all evidence on the physiological effects of regional diets among adults at high risk for cardiovascular disease (CVD). Three databases were searched for randomized controlled trials (RCTs) implementing any regional diet (Mediterranean (MedD), Persian, Southern European Atlantic, Japanese, Chinese, new Nordic, or other) while examining cardiovascular risk factors among adults at increased risk. Primary outcomes included anthropometric indices and secondary outcomes involved blood lipid concentrations, glucose metabolism, inflammation and other markers of CVD progression. Twenty RCTs fulfilled the study’s criteria and were included in the qualitative synthesis, with the majority implementing a MedD. Adherence to most of the regional diets induced a reduction in the BW and anthropometric indices of the participants. The majority of RCTs with blood pressure endpoints failed to note a significant reduction in the intervention compared to the comparator arm, with the exception of some new Nordic and MedD ones. Despite the interventions, inflammation markers remained unchanged except for CRP, which was reduced in the intervention groups of one new Nordic, the older Japanese, and the Atlantic diet RCTs. With regard to blood lipids, regional diet interventions either failed to induce significant differences or improved selective blood lipid markers of the participants adhering to the experimental regional diet arms. Finally, in the majority of RCTs glucose metabolism failed to improve. The body of evidence examining the effect of regional dietary patterns on CVD risk among high-risk populations, while employing an RCT design, appears to be limited, with the exception of the MedD. More research is required to advocate for the efficacy of most regional diets with regard to CVD.     

Plasma and Dietary Antioxidant Status as Cardiovascular Disease Risk Factors: A Review of Human Studies

Extensive evidence has demonstrated that many antioxidants such as vitamin C, vitamin E, carotenoids and polyphenols have protective effects in preventing cardiovascular disease (CVD), a chronic disease that is mediated by oxidative stress and inflammation. This review focuses on evidence from prospective cohort studies and clinical trials in regard to the associations between plasma/dietary antioxidants and cardiovascular events. Long-term, large-scale, population-based cohort studies have found that higher levels of serum albumin, bilirubin, glutathione, vitamin E, vitamin C, and carotenoids were associated with a lower risk of CVD. Evidence from the cohort studies in regard to dietary antioxidants also supported the protective effects of dietary vitamin E, vitamin C, carotenoids, and polyphenols on CVD risk. However, results from large randomized controlled trials did not support long-term use of single antioxidant supplements for CVD prevention due to their null or even adverse effects on major cardiovascular events or cancer. Diet quality indexes that consider overall diet quality rather than single nutrients have been drawing increasing attention. Cohort studies and intervention studies that focused on diet patterns such as high total antioxidant capacity have documented protective effects on CVD risk. This review provides a perspective for future studies that investigate antioxidant intake and risk of CVD.     

The role of dietary patterns’ assessment in the predictive ability of cardiovascular disease risk estimation models: a review

Risk prediction scores have received much attention the past few years, especially in the primary prevention of cardiovascular disease (CVD). Although diet has been independently associated with CVD risk, its role in the accuracy of the developed scores has rarely been studied. Thus, in this review, the role of diet assessment on the performance of CVD risk scores and models was critically discussed. A computer-assisted literature search retrieved 15 relevant studies, but only two out of them evaluated the role of diet on the accuracy of the developed models; the inclusion of diet assessment improved significantly the accuracy of CVD risk models. The remaining studies suggested an independent, protective effect of healthy dietary habits on CVD risk, with an attributable risk varying from 9 to 37%. Inclusion of diet component in CVD risks scores, may increase the accuracy of the models, and better identify people at high risk.     

The primary prevention of heart disease in women through health behavior change promotion in primary care.

PURPOSE: To summarize recent evidence-based recommendations for physical activity promotion, dietary improvement, and tobacco cessation from the U.S. Preventive Services Task Force (USPSTF) and the Task Force on Community Preventive Services (CTF), and examine their applicability to the primary prevention of cardiovascular disease (CVD) in women through primary care interventions. METHODS: For the behaviors cited, USPSTF and CTF recommendations and their associated systematic evidence reviews (SERs) were retrieved. Individual articles from the USPSTF healthy diet and physical activity SERs that met our inclusion criteria were systematically examined to determine the applicability of this research to women. We supplemented findings from these sources with comprehensive federal research summaries and SERs from focused searches of systematic review databases relevant to primary CVD prevention in women through healthy behavior change. MAIN FINDINGS: The USPSTF strongly recommends primary care interventions for tobacco cessation. Strong CTF recommendations for multicomponent systems supports for clinicians, telephone support for quitters, and reduced patient costs for effective cessation therapies guide complementary approaches to assist clinicians. The USPSTF recommends intensive behavioral dietary counseling by specialists for high-risk CVD patients, but found insufficient evidence to recommend for routine healthy diet or physical activity promotion in primary care. The evidence base for these recommendations generally applies to women. Better reporting of gender and minority subgroup outcomes will assist more in-depth understanding of potential differences in either the processes or outcomes of behavior change interventions. CONCLUSIONS: Primary care clinicians, including obstetrician-gynecologists, can contribute to preventing CVD in women through implementing credible evidence-based recommendations for clinical interventions in tobacco and healthy diet. Researchers can further our understanding of gender-specific issues in healthy behavior interventions by reporting process and outcome data for gender and minority subgroups.     

Dietary Advanced Glycation End Products and Risk Factors for Chronic Disease: A Systematic Review of Randomised Controlled Trials

Dietary advanced glycation end-products (AGEs) form during heating and processing of food products and are widely prevalent in the modern Western diet. Recent systematic reviews indicate that consumption of dietary AGEs may promote inflammation, oxidative stress and insulin resistance. Experimental evidence indicates that dietary AGEs may also induce renal damage, however, this outcome has not been considered in previous systematic reviews. The purpose of this review was to examine the effect of consumption of a high AGE diet on biomarkers of chronic disease, including chronic kidney disease (CKD), in human randomized controlled trials (RCTs). Six databases (SCOPUS, CINHAL, EMBASE, Medline, Biological abstracts and Web of Science) were searched for randomised controlled dietary trials that compared high AGE intake to low AGE intake in adults with and without obesity, diabetes or CKD. Twelve dietary AGE interventions were identified with a total of 293 participants. A high AGE diet increased circulating tumour necrosis factor-alpha and AGEs in all populations. A high AGE diet increased 8-isoprostanes in healthy adults, and vascular cell adhesion molecule-1 (VCAM-1) in patients with diabetes. Markers of CKD were not widely assessed. The evidence presented indicates that a high AGE diet may contribute to risk factors associated with chronic disease, such as inflammation and oxidative stress, however, due to a lack of high quality randomised trials, more research is required.     

Long-term nutrition support in gastrointestinal disease--a systematic review of the evidence

Objectives

Patients with gastrointestinal disease or those having undergone gastrointestinal surgery are often at nutritional risk for extended periods after they are discharged from the acute care setting. This systematic review aims to assess the evidence for the use of oral nutrition support, in the form of oral nutrition supplementation or individualized dietary advice in people with gastrointestinal illness, for a prolonged period of time, deemed greater than 2 mo.

Methods

A systematic review of relevant databases was conducted from January 1980 until December 2009. Suitable articles were appraised looking at oral nutrition support, for greater than 2 mo, and the association with nutritional outcomes in people with gastrointestinal illness.

Results

Six studies were identified for this systematic review. The range of patient groups, interventions, and outcomes differed between studies. Overall evidence supports the use of oral nutrition support for improving outcomes such as weight, function, caloric intake, and quality of life. There was a trend toward improved outcomes with individualized dietary advice as the study period increased.

Conclusions

There is strong evidence to support the use of oral nutrition support in a long-term setting for gastrointestinal patients. It appears that as the timeframe increases, there may be a greater role for the use of individualized dietary advice over oral nutrition supplementation alone. However, more research is needed in this area.     

Interventions to enhance adherence to dietary advice for preventing and managing chronic diseases in adults: a study protocol

Background

Adoption of a healthy diet has been identified as the cornerstone in the prevention and management of chronic diseases. However, non-adherence to lifestyle changes raises an important issue since adherence level to dietary advice is a key determinant of the effectiveness of dietary treatment. Therefore, based on the results of a Cochrane systematic review on interventions for enhancing adherence to dietary advice for preventing and managing chronic diseases in adults, the aim of this study is to assess the importance and applicability of interventions enhancing adherence to dietary advice in the Canadian context.

Methods/Design

In phase 1, dietitians' opinion will be assessed through a Delphi study regarding the importance and the applicability in the Canadian context of the interventions found the most effective to enhance adherence to dietary advice through a Cochrane systematic review. In phase 2, findings of the Cochrane systematic review assessing the effects of interventions for enhancing adherence to dietary advice will be reported in a practical format on an online knowledge translation tool for dietitians and other health professionals.

Discussion

In recent years, there has been an increasing recognition of the failure to translate research findings into clinical practice. Therefore, knowledge translation efforts need to prioritize effective interventions that will be the most relevant for practice and end-users by adapting them to the local context. Our study will provide decision makers in the field of dietetic practice with essential knowledge on adherence for elaborating educational activities for academic or professional settings that will respond to dietitians' priorities in terms of importance and applicability to day-to-day practice.     

Dietary patterns, smoking, and subclinical heart disease in women: opportunities for primary prevention from the Framingham Nutrition Studies

OBJECTIVES: To investigate the relationship between a heart-healthy dietary pattern and subclinical heart disease in women, and to identify potential opportunities for primary prevention. DESIGN: Prospective analysis in which dietary patterns and cardiovascular disease (CVD) risk factors were assessed at baseline. Presence of subclinical heart disease was assessed using carotid atherosclerosis (stenosis >or=25%) measured by ultrasound at 12-year follow-up. SUBJECTS/SETTING: We studied 1,423 women in the population-based Framingham Offspring/Spouse (FOS) Study cohort, Framingham, Massachusetts. Subjects did not have CVD at baseline. STATISTICAL ANALYSES: CVD risk factor differences among the dietary clusters were evaluated using analysis of covariance and logistic regression. The relationship between heart-healthy and less heart-healthy dietary patterns and the presence of subclinical heart disease at follow-up was examined using odds ratios calculated from multivariate logistic regressions; stratification by smoking status (current, former, never) was also explored. RESULTS: Women who ate a heart-healthy diet had more favorable baseline CVD risk factor profiles. The age-adjusted odds of subclinical heart disease at follow-up was 40% lower for heart-healthy women (OR 0.60, P=.02). Multivariate adjustment for BMI, blood lipid levels, and blood pressure only slightly attenuated these odds. The odds remained reduced after adding pack-years of smoking to the multivariate model, but statistical significance was attenuated (OR 0.74, P=.20). In analyses stratified by smoking status, women who consumed a heart-healthy diet and who had never smoked had more than 80% less odds for subclinical heart disease compared with smokers whose diets were less heart-healthy (adjusted OR 0.17; P=.0001). CONCLUSIONS: Women who achieve a heart-healthy eating pattern, in combination with the avoidance of smoking, have a lower odds of subclinical heart disease. Among former smokers, the avoidance of smoking seemed to have somewhat more influence than diet on stenosis risk. A public health priority for women to promote the primary prevention of heart disease is the adoption of positive lifestyle behaviors, especially healthful eating (dietary patterns rich in fruits, vegetables, low-fat dairy foods, leaner protein sources, and lower in fats) and the avoidance of smoking.     

Association between Plant-Based Dietary Patterns and Risk of Cardiovascular Disease: A Systematic Review and Meta-Analysis of Prospective Cohort Studies

Plant-based diets, characterized by a higher consumption of plant foods and a lower consumption of animal foods, are associated with a favorable cardiovascular disease (CVD) risk, but evidence regarding the association between plant-based diets and CVD (including coronary heart disease (CHD) and stroke) incidence remain inconclusive. A literature search was conducted using the PubMed, EMBASE and Web of Science databases through December 2020 to identify prospective observational studies that examined the associations between plant-based diets and CVD incidence among adults. A systematic review and a meta-analysis using random effects models and dose–response analyses were performed. Ten studies describing nine unique cohorts were identified with a total of 698,707 participants (including 137,968 CVD, 41,162 CHD and 13,370 stroke events). Compared with the lowest adherence, the highest adherence to plant-based diets was associated with a lower risk of CVD (RR 0.84; 95% CI 0.79–0.89) and CHD (RR 0.88; 95% CI 0.81–0.94), but not of stroke (RR 0.87; 95% CI 0.73–1.03). Higher overall plant-based diet index (PDI) and healthful PDI scores were associated with a reduced CVD risk. These results support the claim that diets lower in animal foods and unhealthy plant foods, and higher in healthy plant foods are beneficial for CVD prevention. Protocol was published in PROSPERO (No. CRD42021223188).     

Dietary fats and cardiovascular health: a summary of the scientific evidence and current debate

Abstract

This narrative review summarises the main studies of the role of the different fatty acids in coronary heart disease (CHD) and cardiovascular disease (CVD) risk and the current scientific debate on dietary recommendations. Reduction and substitution of the saturated fatty acids (SFAs) with the polyunsaturated fatty acids (PUFAs) are still the main dietary recommendation to prevent CHD and CVD. In the last few years, however, the strength of the scientific evidence underlying this dietary advice has been questioned. Recent investigations reappraise the previously declared deleterious role of the SFAs and reduce the positive role of PUFAs, mainly the omega-6, whereas the role of monounsaturated fatty acids (MUFAs) remains unclear. In contrast, the negative effects of trans fatty acids (TFAs) seem stronger than previously thought. Finally, criticisms have emerged from a dietary recommendation approach focussed on individual components rather than on wide food items and eating habits.     

Nutrigenetics and CVD: what does the future hold?

CVD is a common killer in both the Western world and the developing world. It is a multifactorial disease that is influenced by many environmental and genetic factors. Although public health advice to date has been principally in the form of prescribed population-based recommendations, this approach has been surprisingly unsuccessful in reducing CVD risk. This outcome may be explained, in part, by the extreme variability in response to dietary manipulations between individuals and interactions between diet and an individual's genetic background, which are defined by the term 'nutrigenetics'. The shift towards personalised nutritional advice is a very attractive proposition. In principle an individual could be genotyped and given dietary advice specifically tailored to their genetic make-up. Evidence-based research into interactions between fixed genetic variants, nutrient intake and biomarkers of CVD risk is increasing, but still limited. The present paper will review the evidence for interactions between dietary fat and three common polymorphisms in the apoE, apoAI and PPARgamma genes. Increased knowledge of how these and other genes influence dietary response should increase the understanding of personalised nutrition. While targeted dietary advice may have considerable potential for reducing CVD risk, the ethical issues associated with its routine use need careful consideration.     

The dietitians challenge: the implementation of nutritional advice for people with diabetes*

The evidence base for current nutritional recommendations has been extensively reviewed on behalf of the European Association for the Study of Diabetes (EASD) 1998 and the American Diabetes Association (ADA) 2002. The nutrition Sub‐Committee of Diabetes UK is in general agreement with those recommendations. This paper provides consensus‐based recommendations that emphasize the practical implementation of nutritional advice for people with diabetes, and describe the provision of dietetic services required to provide the information. Important changes from previous Diabetes UK (previously British Diabetic Association Diabet. Med. 9 , 189) recommendations include greater flexibility in the proportions of energy derived from carbohydrate and monounsaturated fat, further liberalization in the consumption of sucrose, more active promotion of foods with a low glycaemic index, and greater emphasis on the provision of nutritional advice in the context of wider lifestyle changes, particularly physical activity. Monounsaturated fats are now promoted as the main source of dietary fat because of their lower susceptibility to lipid peroxidation – and consequent lower atherogenic potential. Consumption of sucrose for patients who are not overweight can be increased up to 10% of daily energy derived from carbohydrate provided that this is eaten in the context of a healthy diet and distributed throughout the day. The role of the dietitian is outlined in facilitating lifestyle changes and evidence is presented for the effectiveness of advice provided by trained dietitians. The increasing evidence for the importance of good metabolic control and the growing requirement for measures to prevent Type 2 diabetes in an increasingly obese population will require major expansion of dietetic services if the standards in National Service Frameworks are to be successfully implemented at local level.