The Philosophy of Evidence-Based Principles and Practice in Nutrition

Ultra-processed foods consumption and health-related outcomes: a systematic review of randomized controlled trials

Introduction

The increase in ultra-processed foods (UPFs) intake has raised concerns about its impact on public health. Prospective observational studies have reported significant associations between higher intake of UPFs and adverse health outcomes. The aim of this study is to determine whether these associations could be confirmed in randomized controlled trials (RCTs).

Methods

We conducted a systematic review to analyze the evidence on the effects of UPFs intake on health. A systematic search was conducted in Medline, Embase, Web of Science, Scopus, LILACS, and CENTRAL up to April 22, 2024. RCTs in English, Spanish, and Portuguese evaluating the health effects of interventions to modify UPFs intake were included. The certainty of evidence was determined using the GRADE methodology.

Results

Three educational intervention studies and one controlled feeding trial were included, evaluating the effect of reducing the consumption of UPFs (455 participants, median follow-up, 12 weeks). No significant effects were observed in 30 out of the 42 outcomes evaluated. The controlled feeding trial in adults with stable weight showed a reduction in energy intake, carbohydrates, and fat (low certainty of evidence), as well as in body weight, total cholesterol, and HDL cholesterol (moderate certainty of evidence). In the educational intervention studies, a reduction in body weight and waist circumference was observed (low certainty of evidence) in women with obesity, as well as improvement in some dimensions of quality of life (very low certainty of evidence). No significant changes were observed in children and adolescents with obesity, while in overweight pregnant women, the consumption of UPFs was not reduced, so the observed benefits could be attributed to other components of the intervention.

Conclusion

Interventions aimed at reducing the consumption of UPFs showed benefits on some anthropometric and dietary intake outcomes, although significant effects were not observed for most of the evaluated outcomes. The limited number and significant methodological limitations of the studies prevent definitive conclusions. Further well-designed and conducted RCTs are needed to understand the effects of UPF consumption on health.Systematic review registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023469984.

Nature of the evidence base and approaches to guide nutrition interventions for individuals: a position paper from the Academy of Nutrition Sciences

This Position Paper from the Academy of Nutrition Sciences is the third in a series which describe the nature of the scientific evidence and frameworks that underpin nutrition recommendations for health. This paper focuses on evidence which guides the application of dietary recommendations for individuals. In some situations, modified nutrient intake becomes essential to prevent deficiency, optimise development and health, or manage symptoms and disease progression. Disease and its treatment can also affect taste, appetite and ability to access and prepare foods, with associated financial impacts. Therefore, the practice of nutrition and dietetics must integrate and apply the sciences of food, nutrition, biology, physiology, behaviour, management, communication and society to achieve and maintain human health. Thus, there is huge complexity in delivering evidence-based nutrition interventions to individuals. This paper examines available frameworks for appraising the quality and certainty of nutrition research evidence, the development nutrition practice guidelines to support evidence implementation in practice and the influence of other sources of nutrition information and misinformation. The paper also considers major challenges in applying research evidence to an individual and suggests consensus recommendations to begin to address these challenges in the future. Our recommendations target three groups; those who deliver nutrition interventions to individuals, those funding, commissioning or undertaking research aimed at delivering evidence-based nutrition practice, and those disseminating nutritional information to individuals.

Evidence-Based Practice Competencies among Nutrition Professionals and Students: A Systematic Review

BACKGROUND

Evidence-based practice (EBP) promotes shared decision-making between clinicians and patients.

OBJECTIVE

The aim was to determine EBP competencies among nutrition professionals and students reported in the literature.

METHODS

We conducted a systematic review by searching Medline, Embase, CINAHL, ERIC, CENTRAL, ProQuest Dissertations and Theses Global, BIOSIS Citation Index, and clinicaltrials.gov up to March 2023. Eligible primary studies had to assess one of the 6 predefined EBP competencies: formulating clinical questions; searching literature for best evidence; assessing studies for methodological quality; effect size; certainty of evidence for effects; and determining the applicability of study results considering patient values and preferences. Two reviewers independently screened articles and extracted data, and results were summarized for each EBP competency.

RESULTS

We identified 12 eligible cross-sectional survey studies, comprising 1065 participants, primarily registered dietitians, across 6 countries, with the majority assessed in the United States (n = 470). The reporting quality of the survey studies was poor overall, with 43% of items not reported. Only 1 study (8%) explicitly used an objective questionnaire to assess EBP competencies. In general, the 6 competencies were incompletely defined or reported (e.g., it was unclear what applicability and critical appraisal referred to and what study designs were appraised by the participants). Two core competencies, interpreting effect size and certainty of evidence for effects, were not assessed.

CONCLUSIONS

The overall quality of study reports was poor, and the questionnaires were predominantly self-perceived, as opposed to objective assessments. No studies reported on competencies in interpreting effect size or certainty of evidence, competencies essential for optimizing clinical nutrition decision-making. Future surveys should objectively assess core EBP competencies using sensible, specific questionnaires. Furthermore, EBP competencies need to be standardized across dietetic programs to minimize heterogeneity in the training, understanding, evaluation, and application among dietetics practitioners. This study was registered at PROSPERO as CRD42022311916.

Critically appraising and utilising qualitative health research evidence in nutrition practice

BACKGROUND

Evidence-based decision-making and practice recommendations are commonly based on findings from quantitative studies or reviews. In the present study, we provide an overview of how to incorporate findings from qualitative research into the evidence-based decision-making process.

METHODS

To illustrate how qualitative evidence can be integrated into the decision-making process, we have outlined a clinical nutrition scenario and the process for sourcing credible evidence to inform decision-making. A qualitative health research study was selected and appraised using the Critical Appraisal Skill Programme (CASP) appraisal tool for qualitative research. Based on the results of the critical appraisal, the study quality is considered, and we discuss whether the qualitative evidence can be applied to practice.

RESULTS

A detailed description of how the qualitative findings can be used conceptually and instrumentally in practice to address the clinical nutrition scenario is provided.

CONCLUSIONS

Developing skills in critically appraising findings from qualitative studies will increase awareness and utilisation of this type of evidence in practice and policy, with a goal to ensure that patient/client perceptions are considered, leading to enhanced person-centred care or systems.

Standard Hypercaloric, Hyperproteic vs. Leucine-Enriched Oral Supplements in Patients with Cancer-Induced Sarcopenia, a Randomized Clinical Trial

(1) Background: Malnutrition frequently affects patients with cancer, and it negatively impacts treatment tolerance, clinical outcomes and survival. Thus, appropriate nutritional screening and early nutrition support are extremely recommended. Currently, a significant number of oral supplements (OS) are commercially available; despite this, there is a lack of evidence for recommending specific OS, including leucine-enriched OS, for nutritional support in patients with cancer. (2) Aim: To compare the clinical evolution of patients with cancer (undergoing systemic treatment) that received standard hypercaloric, whey protein-based hyperproteic oral supplements vs. hypercaloric, hyperproteic leucine-enriched OS using a novel morphofunctional nutritional evaluation. (3) Patients and methods: This paper details an open-label, controlled clinical study in which patients were randomly assigned to receive nutritional treatment with whey protein-based hyperproteic oral supplements (control group) vs. hypercaloric, hyperproteic leucine-enriched OS (intervention group) during a twelve-week period. Forty-six patients were included; epidemiological, clinical, anthropometric, ultrasound (muscle echography of the rectus femoris muscle of the quadriceps and abdominal adipose tissue) and biochemical evaluation were performed. All patients received additional supplementation with vitamin D. (4) Results: Nutritional parameters (including bioimpedance, anthropometric, ultrasound and biochemical variables) of all included patients remained stable after the nutritional intervention. Extracellular mass tended to increase in the patients that received the leucine-enriched formula. Functionality (evaluated through the stand-up test) improved in both groups (p < 0.001). Prealbumin, transferrin levels and superficial adipose tissue increased in the control group (p < 0.05), while self-reported quality of life improved in all the evaluated patients (p < 0.001). (5) Conclusions: Nutritional support with hypercaloric, hyperproteic (with whey protein) OS and vitamin D supplementation were associated with the maintenance of body composition and improvements in functionality and in quality of life in the patients with cancer undergoing systemic treatment. No significant benefits were observed when a leucine-enriched formula was used.

In Cochrane nutrition reviews assessment of dietary adherence varied considerably

OBJECTIVES

Our aim was to investigate if and how Cochrane nutrition reviews assess dietary adherence to a specific dietary regimen.

STUDY DESIGN AND SETTING

Cochrane nutrition reviews fulfilling the following criteria were included: systematic review of randomized controlled trials including adults and investigating the effect of caloric restriction, dietary pattern, foods, nutrients, supplements, or other nutrition-related-interventions. Extensive data extraction and descriptive statistics were conducted.

RESULTS

Overall, 226 Cochrane reviews were included. Most reviews mentioned dietary adherence in the main text (n = 174), predominantly in the Methods and Results. Dietary adherence was assessed in 76 reviews and defined in 19. It was included in the risk of bias (RoB) assessment in 20 reviews with nine using a newly created RoB domain for dietary adherence, and considered as outcome in 37 reviews. Seventy-five reviews addressed degree of adherence and five treatment effects considering the degree of adherence.

CONCLUSION

Dietary adherence was reported in a heterogeneous manner in Cochrane nutrition reviews. Due to its high importance, we suggest that systematic reviews report the assessment and degree of dietary adherence measured in primary studies. Dietary adherence can further be examined as outcome, evaluated within the RoB (deviations from intended interventions) and included in sensitivity analyses.

Quality appraisal of clinical nutrition practice guidelines for critically ill adult patients: a systematic review using the Advancing Guideline Development, Reporting and Evaluation in Health Care instrument II (AGREE-II) and AGREE-Recommendation Excellence (AGREE-REX)

Nutritional therapy should follow evidence-based practice, thus several societies regarding nutrition and critical care have developed specific Clinical Practice Guidelines (CPG). However, to be regarded as trustworthy, the quality of the CPG for critically ill patients and its recommendations need to be high. This systematic review aimed to appraise the methodology and recommendations of nutrition CPG for critically ill patients. We performed a systematic review (protocol number CRD42020184199) with literature search conducted on PubMed, Embase, Cochrane Library and other four specific databases of guidelines up to October 2021. Two reviewers, independently, assessed titles and abstracts and potentially eligible full-text reports to determine eligibility and subsequently four reviewers appraised the guidelines quality using the Advancing Guideline Development, Reporting and Evaluation in Health Care instrument II (AGREE-II) and AGREE-Recommendation Excellence (AGREE-REX). Ten CPG for nutrition in critically ill patients were identified. Only Academy of Nutrition and Dietetics and European Society of Intensive Care Medicine had a total acceptable quality and were recommended for daily practice according AGREE-II. None of the CPG recommendations had an overall quality score above 70 %, thus being classified as moderate quality according AGREE-REX. The methodological evaluation of the critically ill adult patient CPG revealed significant discrepancies and showed a need for improvement in its development and/or reporting. In addition, recommendations about nutrition care process presented a moderate quality.

Efficacy of diet on fatigue, quality of life and disability status in multiple sclerosis patients: rapid review and meta-analysis of randomized controlled trials

Background

Multiple sclerosis is an inflammatory and neurodegenerative disease. People with multiple sclerosis (pwMS) experience chronic fatigue which is difficult to deal with therapeutically and greatly affects health-related quality of life (QOL).

PwMS are aware of the lack of generalized dietary advice related to their disease, leading to self-experimentation with diet.

It is necessary to provide objective information about dietary interventions for pwMS. We aim to provide an objective synthesis of the evidence for efficacy and safety of specific diets in pwMS through a rapid review and meta-analyses of randomized controlled trials (RCTs), examining symptomatic fatigue (MFIS), QOL, Expanded-Disability-Status-Scale (EDSS), and severe adverse events.

Methods

We have carried out a rapid review (MEDLINE and EMBASE) up to December 2021, with PRISMA methodology, and meta-analyses, of (RCTs). All statistical analyses were performed using the comprehensive meta-analysis (CMA) -RStudio 4.1.3. The analysis used weighted mean differences (WMD) and a 95% confidence interval (CI) using a random-effects model to compare the effects of the dietary intervention with the control.

Results

Eight studies met the inclusion criteria. Of these eight studies, five analyzed EDSS, three MFIS, and three QOL. A total of 515 patients were analyzed. These meta-analyses cumulative evidence support that dietary intervention is associated with a trend of reduction in fatigue (308 patients studied) -the difference between means (SMD) of the control group and intervention group was -2,033, 95%-IC (-3,195, -0,152), a p-value of 0.0341)-, an increase in QOL (77 patients studied), no significant effect on EDSS (337 patients studied), and no severe adverse events.

Conclusions

It is difficult to reach a high level of evidence in dietary studies. Our findings show that dietary intervention is associated with a trend of reduction in fatigue in MS. Taking into account the potential of dietary interventions and the benefit/risk ratio in their favor, neurologists must be aware of the great importance of making interventions on diet in MS if necessary. There are dietary interventions with some evidence of benefit for patients with MS, which could be chosen based on adherence, patient preferences, and individual outcomes. Large prospective clinical trials are needed to shed further light on this topic.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02913-w.

Empirical evidence of study design biases in nutrition randomised controlled trials: a meta-epidemiological study

BACKGROUND

Instruments to critically appraise randomised controlled trials (RCTs) are based on evidence from meta-epidemiological studies. We aim to conduct a meta-epidemiological study on the average bias associated with reported methodological trial characteristics such as random sequence generation, allocation concealment, blinding, incomplete outcome data, selective reporting, and compliance of RCTs in nutrition research.

METHODS

We searched the Cochrane Database of Systematic Reviews, for systematic reviews of RCTs, published between 01 January 2010 and 31 December 2019. We combined the estimates of the average bias (e.g. ratio of risk ratios [RRR] or differences in standardised mean differences) in meta-analyses using the random-effects model. Subgroup analyses were conducted to investigate the potential differences among the RCTs with low versus high/unclear risk of bias with respect to the different types of interventions (e.g. micronutrients, fatty acids, dietary approach), outcomes (e.g. mortality, pregnancy outcomes), and type of outcome (objective, subjective). Heterogeneity was assessed through I² and τ², and prediction intervals were calculated.

RESULTS

We included 27 Cochrane nutrition reviews with 77 meta-analyses (n = 927 RCTs). The available evidence suggests that intervention effect estimates may not be exaggerated in RCTs with high/unclear risk of bias (versus low) judgement for sequence generation (RRR 0.97, 95% CI 0.93 to 1.02; I² = 28%; τ² = 0.002), allocation concealment (RRR 1.00, 95% CI 0.96 to 1.04; I² = 27%; τ² = 0.001), blinding of participants and personnel (RRR 0.95, 95% CI 0.91 to 1.00; I² = 23%; τ² = 0), selective reporting (RRR 0.97, 95% CI 0.92 to 1.02; I² = 24%; τ² = 0), and compliance (RRR 0.95, 95% CI 0.89 to 1.02; I² = 0%; τ² = 0). Intervention effect estimates seemed to be exaggerated in RCTs with a high/unclear risk of bias judgement for blinding of outcome assessment (RRR 0.81, 95% CI 0.70 to 0.94; I² = 26%; τ² = 0.03), which was predominately driven by subjective outcomes, and incomplete outcome data (RRR 0.92, 95% CI 0.88 to 0.97; I² = 22%; τ² = 0.001). For continuous outcomes, no differences were observed, except for selective reporting.

CONCLUSIONS

On average, most characteristics of nutrition RCTs may not exaggerate intervention effect estimates, but the average bias appears to be greatest in trials of subjective outcomes. Replication of this study is suggested in this field to keep this conclusion updated.

Advancing Qualitative Health Research Approaches in Applied Nutrition Research

Applied health research methods are evolving to meet the demands of increasingly complex health research needs. Qualitative health research, focused on individual perspectives of health, wellness, illness, and recovery, has emerged as a unique sub-discipline of this field. With distinct foci, methods, and rules, qualitative health research has the potential to answer applied health research questions to inform practice, education, and policy. Despite this potential, there are challenges to the application of qualitative health research methods in nutrition and dietetics research. These include limited training and mentorship availability for the rigorous application of these methods as well as misaligned goals between the traditional social science-based qualitative approaches and emerging applied nutrition science needs. Recognizing these limitations, this review aims to provide guidance to the nutrition scientist conducting applied qualitative health research. Using nutrition and dietetic examples from the literature, this review defines qualitative health research and advances the EPPiC framework as a tool for constructing structured overarching research questions and introduces four qualitative health research designs (qualitative description, interpretive description, case study, and focused ethnography) relevant to applied nutrition science. This includes guidance on defining the sample, identifying strategies for data collection, analytic techniques, and data reporting. This article is protected by copyright. All rights reserved.

NUQUEST-NUtrition QUality Evaluation Strengthening Tools: development of tools for the evaluation of risk of bias in nutrition studies

BACKGROUND

Dietary exposure assessments are a critical issue in evaluating human nutrition studies; however, nutrition-specific criteria are not consistently included in existing bias assessment tools.

OBJECTIVES

Our objective was to develop a set of risk of bias (RoB) tools that integrated nutrition-specific criteria into validated generic assessment tools to address RoB issues, including those specific to dietary exposure assessment.

METHODS

The Nutrition QUality Evaluation Strengthening Tools (NUQUEST) development and validation process included 8 steps. The first steps identified 1) a development strategy; 2) generic assessment tools with demonstrated validity; and 3) nutrition-specific appraisal issues. This was followed by 4) generation of nutrition-specific items and 5) development of guidance to aid users of NUQUEST. The final steps used established ratings of selected studies and feedback from independent raters to 6) assess reliability and validity; 7) assess formatting and usability; and 8) finalize NUQUEST.

RESULTS

NUQUEST is based on the Scottish Intercollegiate Guidelines Network checklists for randomized controlled trials, cohort studies, and case-control studies. Using a purposive sample of 45 studies representing the 3 study designs, interrater reliability was high (Cohen's κ: 0.73; 95% CI: 0.52, 0.93) across all tools and at least moderate for individual tools (range: 0.57-1.00). The use of a worksheet improved usability and consistency of overall interrater agreement across all study designs (40% without worksheet, 80%-100% with worksheet). When compared to published ratings, NUQUEST ratings for evaluated studies demonstrated high concurrent validity (93% perfect or near-perfect agreement). Where there was disagreement, the nutrition-specific component was a contributing factor in discerning exposure methodological issues.

CONCLUSIONS

NUQUEST integrates nutrition-specific criteria with generic criteria from assessment tools with demonstrated reliability and validity. NUQUEST represents a consistent and transparent approach for evaluating RoB issues related to dietary exposure assessment commonly encountered in human nutrition studies.

A Nutritional Comparison of Cow's Milk and Alternative Milk Products

OBJECTIVE

Alternative milk products are becoming more visible and popular, but nutrient data to compare these products to traditional cow's milk are not easily accessible. By summarizing this nutritional information, this project aims to help primary care providers take better care of their patients by providing easy to access nutritional comparison between cow's milk and milk alternatives such as plant-based milks and goat's milk.

METHODS

This project uses data from the United States Department of Agriculture's Food Data Central database and publicly available nutrition label data to compare the nutritional content of selected milk.

RESULTS

Almond and oat milks provide less than half of the protein provided by soy, goat's, and cow's milk. Goat's milk contains the most fat of the products surveyed, while skim milk contains the lowest fat per serving. Soy milk, almond milk, and oat milk contain at least half the fat of cow's milk. Almond milk contained the most calcium of the milks surveyed. Quantities of folate and vitamin B12 were most notably decreased in goat's milk and almond milk while soy milk had almost double the amount of folate and vitamin B12 present in cow's milk.

CONCLUSION

Cow's milk still remains the best source of fats, protein, and micronutrients. For parents who prefer an alternative to cow's milk, the child's health should be considered. Parents may consider nutrition information when making decisions for their families, and primary care pediatricians should be able to provide current nutritional data on frequently advertised products.

The essentiality of nutrients: a challenge to methodological monism in the scientific substantiation of health claims

This paper analyzes the way in which the EFSA has addressed the limitations that the essentiality of nutrients presents to the requirement of obtaining evidence from RCTs for the scientific substantiation of health claims. By redefining the requirements to affirm causality in the case of essentiality of nutrients, the EFSA has constrained the debate on the relevance of different methodologies in the field of nutrition research. However, avoiding this methodological debate does not settle the controversy as to whether the EFSA's evidentiary hierarchy is the best for both investigating causal relationships in nutrition and for achieving social objectives such as fostering innovation and public health.

The role of dietitian clinical judgement in the nutrition care process within the acute care setting: a qualitative study

BACKGROUND

Dietitian clinical decision making in the acute care setting likely incorporates a practitioner's clinical judgement to effectively support patient care. The term 'dietitian clinical judgement' is well used in clinical practice, yet is poorly defined and often used interchangeably with other concepts. The aim of this research was to describe the nature of dietitians' clinical judgement in the acute care setting.

METHODS

A qualitative design within the interpretative paradigm was used guided by principles of philosophical hermeneutics. Dietitians with at least 3 years experience were invited to participate in two 60-min in-depth semi-structured interviews which were recorded, transcribed and interpreted using hermeneutic principles. A reference group was used to increase rigour and further interpretation of the findings.

RESULTS

Ten dietitians participated in the interviews and five of these same participants in the reference focus group. The findings revealed clinical judgement to be a sophisticated practitioner dependent meta-reasoning process that helps the dietitian manage complexity, guide interpersonal interactions and individualise patient care. It is characterised by tacit and efficient use of various reasoning strategies reliant on the dietitian's clinical experience, used to synthesise and weigh up various types of information and knowledge with respect to delivering context-relevant care.

CONCLUSIONS

Dietitian clinical judgement is a necessary part of clinical decision making that extends beyond logical or critical thinking. It facilitates a person-centredness to patient care and professional relationships that are key dimensions to dietitian clinical decision making. These findings provide training and professional development insights to managers, educators and supervisors.

Doing the Same Thing and Expecting a Different Outcome: It Is Time for a Questioning Philosophy and Theory-Driven Chiropractic Research

OBJECTIVE

The purpose of this commentary is to discuss the philosophical and hypothetical underpinnings of chiropractic and consider whether there is a need for chiropractic to have a questioning philosophy and theory-driven process to guide future scientific endeavors in the profession.

DISCUSSION

The earliest beliefs of the chiropractic founders centered on chiropractic vertebral subluxation but differed on whether this was a static, bone-out-of-place misalignment or a lesion whereby joints had lost their normal direction or range of motion. More recently, new hypotheses such as dyskinesia, inflammation, and neuroplasticity attempt to explain the purported clinical effects of chiropractic. Yet practitioners and students advocate for both traditional viewpoints that typically tout misalignment and embrace a science of chiropractic. I propose that chiropractors should not have to choose between philosophy and science. Instead, they should advocate for adoption of a modern questioning philosophy that not only informs their clinical questions and drives their theories, but also that is in turn influenced by outcomes from their research. Such a questioning philosophy is in stark contrast with the dogma that some have mislabeled as "philosophy" in the profession. I recommend that a review of chiropractic hypotheses and a theory-driven research process is needed to help guide the profession's research agenda given its wide range of clinical activities and limited resources. As the chiropractic profession increasingly embraces evidence-informed practice, enhanced integration within the wider health care community may then result in further gains in utilization.

CONCLUSION

Theory-driven research that results from and subsequently informs a questioning philosophy may expose truths related to practice behaviors, activities, and outcomes, and spur more complete integration of chiropractic within the wider health care community.

Unprocessed Red Meat and Processed Meat Consumption: Dietary Guideline Recommendations From the Nutritional Recommendations (NutriRECS) Consortium

This article has been corrected. The original version (PDF) is appended to this article as a Supplement.

DESCRIPTION

Dietary guideline recommendations require consideration of the certainty in the evidence, the magnitude of potential benefits and harms, and explicit consideration of people's values and preferences. A set of recommendations on red meat and processed meat consumption was developed on the basis of 5 de novo systematic reviews that considered all of these issues.

METHODS

The recommendations were developed by using the Nutritional Recommendations (NutriRECS) guideline development process, which includes rigorous systematic review methodology, and GRADE methods to rate the certainty of evidence for each outcome and to move from evidence to recommendations. A panel of 14 members, including 3 community members, from 7 countries voted on the final recommendations. Strict criteria limited the conflicts of interest among panel members. Considerations of environmental impact or animal welfare did not bear on the recommendations. Four systematic reviews addressed the health effects associated with red meat and processed meat consumption, and 1 systematic review addressed people's health-related values and preferences regarding meat consumption.

RECOMMENDATIONS

The panel suggests that adults continue current unprocessed red meat consumption (weak recommendation, low-certainty evidence). Similarly, the panel suggests adults continue current processed meat consumption (weak recommendation, low-certainty evidence).

PRIMARY FUNDING SOURCE

None. (PROSPERO 2017: CRD42017074074; PROSPERO 2018: CRD42018088854).

Effect of Lower Versus Higher Red Meat Intake on Cardiometabolic and Cancer Outcomes: A Systematic Review of Randomized Trials

This article has been corrected. The original version (PDF) is appended to this article as a Supplement.

BACKGROUND

Few randomized trials have evaluated the effect of reducing red meat intake on clinically important outcomes.

PURPOSE

To summarize the effect of lower versus higher red meat intake on the incidence of cardiometabolic and cancer outcomes in adults.

DATA SOURCES

EMBASE, CENTRAL, CINAHL, Web of Science, and ProQuest from inception to July 2018 and MEDLINE from inception to April 2019, without language restrictions.

STUDY SELECTION

Randomized trials (published in any language) comparing diets lower in red meat with diets higher in red meat that differed by a gradient of at least 1 serving per week for 6 months or more.

DATA EXTRACTION

Teams of 2 reviewers independently extracted data and assessed the risk of bias and the certainty of the evidence.

DATA SYNTHESIS

Of 12 eligible trials, a single trial enrolling 48 835 women provided the most credible, though still low-certainty, evidence that diets lower in red meat may have little or no effect on all-cause mortality (hazard ratio [HR], 0.99 [95% CI, 0.95 to 1.03]), cardiovascular mortality (HR, 0.98 [CI, 0.91 to 1.06]), and cardiovascular disease (HR, 0.99 [CI, 0.94 to 1.05]). That trial also provided low- to very-low-certainty evidence that diets lower in red meat may have little or no effect on total cancer mortality (HR, 0.95 [CI, 0.89 to 1.01]) and the incidence of cancer, including colorectal cancer (HR, 1.04 [CI, 0.90 to 1.20]) and breast cancer (HR, 0.97 [0.90 to 1.04]).

LIMITATIONS

There were few trials, most addressing only surrogate outcomes, with heterogeneous comparators and small gradients in red meat consumption between lower versus higher intake groups.

CONCLUSION

Low- to very-low-certainty evidence suggests that diets restricted in red meat may have little or no effect on major cardiometabolic outcomes and cancer mortality and incidence.

PRIMARY FUNDING SOURCE

None (PROSPERO: CRD42017074074).

Diet, Diabetes Status, and Personal Experiences of Individuals with Type 2 diabetes Who Self-Selected and Followed a Low Carbohydrate High Fat diet

BACKGROUND

Low carbohydrate high fat (LCHF) diets are increasing in popularity amongst patients with type 2 diabetes (T2D), however it is unclear what constitutes a sustainable LCHF diet in a real-world setting.

METHODS

This descriptive multi-method study characterized the diets, T2D status, and personal experiences of individuals with T2D who claimed to have followed an LCHF diet for at least 6 months. Participants completed a medications history, mixed-method dietary assessment, provided a blood sample, and were interviewed in-depth about their experiences with the diet (First-Assessment). Past medical records were obtained corresponding to T2D diagnosis and prior to starting their LCHF diets. Additionally, participants were followed up 15 months later to assess T2D remission (Follow-Up).

RESULTS

Twenty-eight participants completed First-Assessment and 24 completed Follow-Up. Habitual carbohydrate intake was 20 to 50 g/d for 10 participants and 50 to 115 g/d for 17 participants. Commonly reported foods were full-fat dairy, non-starchy vegetables, coconut oil, eggs, nuts, olives and avocados, olive oil, and red meat and poultry with fat. Median (interquartile range) for HbA1c was 7.5 (6.5-9.5) % prior to starting their diets, 5.8 (5.4-6.2) % at First-Assessment and 5.9 (5.3-6.6) % at Follow-Up. Reported body weight and glucose-lowering medication requirements were considerably lower at both assessments than when starting the diet. At Follow-Up, 24 participants had been following their LCHF diets for 35 (26-53) months, the majority of which were in full or partial T2D remission. Participants perceived reduced hunger and cravings as one of the most important aspects of their diets. Of concern, many participants felt unsupported by their doctors.

CONCLUSION

This study described the foods and characteristics of an LCHF "lifestyle" that was sustainable and effective for certain T2D patients in a real-world setting.