Investigating the Prevalence of Copper and Zinc Abnormalities in Patients Pre and Post bariatric Surgery-an Australian Experience.

INTRODUCTION: Bariatric surgery predisposes patients to nutritional deficiencies. There are limited studies on zinc and copper abnormalities in this cohort. PURPOSE: The aim of this study was to identify the prevalence of these abnormalities in a cohort of Australian bariatric patients. Inflammatory markers, adherence to multivitamin supplementation (MVS) and the presence of gastrointestinal (GI) symptoms were also investigated. MATERIAL AND METHODS: Data was collected on all patients who attended a single clinic in Sydney, Australia, from August 2020 to August 2021. RESULTS: The study cohort consisted of 231 patients (76.2% female; mean pre-operative body mass index of 43.4 ± 7.1 kg/m2), most of whom underwent sleeve gastrectomy (78.8%). Data were collected preoperatively and then at ≤ 6 months, 1 and > 2 years postoperatively. Prior to surgery, low levels of zinc (2.1%) and copper (0.7%) were rare, but elevated copper levels were common (16.7%) and potentially related to an elevated C-reactive protein (CRP) (47.7%). Following surgery at > 2 years, the mean total weight loss (TWL) was 33.5 ± 12.4. CRP levels improved over time. Post operatively, low zinc (2.7-3.6%) and copper (1.5%) levels were rare. Patients with low levels in zinc and copper were a higher-risk group and generally exhibited GI symptoms, despite taking MVS. CONCLUSION: In the initial post-operative stages and with good adherence to MVS containing copper and zinc, abnormalities may not be a concern. Patients with GI symptoms appear to be at higher risk of abnormalities; increasing awareness, thorough screening, and more comprehensive supplementation are recommended.

Novel Lines of Research on the Environmental and Human Health Impacts of Nut Consumption.

Nuts have formed part of human diets throughout the ages. In recent decades, research has shown they are key foods in dietary patterns associated with lower chronic disease risk. The current state of climate change, however, has introduced an imperative to review the impact of dietary patterns on the environment with a shift to plant-based diets. Nuts emerge as a significant source of protein in plant-based diets and are a minimally processed and sustainable food. Research in this area is evolving to drive better production methods in varying climate conditions. Nevertheless, nut consumption remains an important contributor to human health. The mechanisms of action can be explained in terms of the nutrients they deliver. Studies of nut consumption have linked components such as monounsaturated fatty acids, plant omega-3 fatty acids, antioxidants, and plant sterols to improved lipoprotein profiles, lower blood pressure, and reduced cardiovascular disease risk. Preliminary research also indicates possible beneficial effects of nut consumption on reproductive health. In any case, the ultimate effects of foods on health are the results of multiple interactive factors, so where nuts fit within dietary patterns is a significant consideration for research translation. This has implications for research methodologies, including categorization within food groups and inclusion in Healthy Dietary Indices. The aim of this narrative review is to outline new focal points for investigation that examine the environmental and some novel human health impacts of nut consumption and discuss future directions for research.

Effects of Nut Consumption on Blood Lipids and Lipoproteins: A Comprehensive Literature Update.

In the present review, we provide a comprehensive narrative overview of the current knowledge on the effects of total and specific types of nut consumption (excluding nut oil) on blood lipids and lipoproteins. We identified a total of 19 systematic reviews and meta-analyses of randomized controlled trials (RCTs) that were available in PubMed from the inception date to November 2022. A consistent beneficial effect of most nuts, namely total nuts and tree nuts, including walnuts, almonds, cashews, peanuts, and pistachios, has been reported across meta-analyses in decreasing total cholesterol (mean difference, MD, -0.09 to -0.28 mmol/L), LDL-cholesterol (MD, -0.09 to -0.26 mmol/L), and triglycerides (MD, -0.05 to -0.17 mmol/L). However, no effects on HDL-cholesterol have been uncovered. Preliminary evidence indicates that adding nuts into the regular diet reduces blood levels of apolipoprotein B and improves HDL function. There is also evidence that nuts dose-dependently improve lipids and lipoproteins. Sex, age, or nut processing are not effect modifiers, while a lower BMI and higher baseline lipid concentrations enhance blood lipid/lipoprotein responses. While research is still emerging, the evidence thus far indicates that nut-enriched diets are associated with a reduced number of total LDL particles and small, dense LDL particles. In conclusion, evidence from clinical trials has shown that the consumption of total and specific nuts improves blood lipid profiles by multiple mechanisms. Future directions in this field should include more lipoprotein particle, apolipoprotein B, and HDL function studies.

Dietitians' perspectives on the role of dietetics practice in 'gut health'.

AIMS: This study aimed to explore dietitians' perspectives on the evidence surrounding the relationship between diet and 'gut health' and the current and emerging role of dietetics practice in this area. METHODS: A qualitative descriptive methodology was used. Online semi-structured interviews were conducted with Australian dietitians, focused on the perspectives related to gut health management in dietetics practice. Inductive thematic analysis was employed, commencing with initial coding by two researchers, and further coding leading to development of emergent themes. Divergent data were discussed and considered in analysis. RESULTS: Fourteen interviews were conducted (2 males, 12 females). An overarching theme identified that current evidence is insufficient to direct dietetics practice change regarding gut health. Six subthemes on dietetics practice in 'gut health' emerged including (a) practice is multifaceted, (b) current practice aligns with dietary guidelines, (c) symptom management remains the primary concern, (d) evidence-based information is sought, (e) translational evidence is required for practice change and (f) there is a role for dietetics in gut health research and translation. CONCLUSIONS: Dietitians do not appear confident in their practice regarding gut microbiome-related management and recognise there is currently limited translatable research to inform practice. Evidence to date suggests that recommendations for positive gut health do not differ substantially from Australian Dietary Guidelines. Dietitians will need additional education if further evidence emerges, however they demonstrated a strong commitment to evidence-based practice.

Gut health, the microbiome and dietary choices: An exploration of consumer perspectives.

AIMS: To explore consumer perceptions regarding dietary behaviours related to the gut microbiome, to assist in effective translation of research to practice. METHODS: Online focus groups were conducted (adults with no formal medical or nutrition training). Semi-structured open-ended questioning explored perspectives related to gut health and dietary behaviours. A qualitative descriptive analysis approach was undertaken in duplicate. RESULTS: Fourteen focus groups were conducted (n = 38, 15 males, 23 females). Four overarching themes regarding consumer perceptions were identified. These were (a) gut health equates with wellbeing, (b) there are divergent perceptions of how diet influences gut health, (c) interest in scientific evidence does not necessarily influence dietary behaviour and (d) gastrointestinal symptoms influence dietary behaviour. CONCLUSIONS: Consumers are interested in gut health and understand that diet may be important. Given that current literature regarding diet and gut health does not differ from dietary guidelines, consumer interest may provide a timely slant to promote longstanding guidelines. Consumer education to limit scepticism around government messaging, including utilisation of social media by nutrition professionals, may be key to improving adherence to guidelines.

Investigating the prevalence of nutritional abnormalities in patients prior to and following bariatric surgery.

AIMS: Bariatric surgery remains an effective treatment for the condition of obesity. However it predisposes patients to nutritional deficiencies and related complications. The aim of this study was to identify nutritional abnormalities, weight loss, adherence to supplements, and presence of gastrointestinal symptoms in a cohort of bariatric surgical patients. METHODS: An analysis of the electronic medical records of patients attending a multidisciplinary private clinic in Sydney, Australia from August 2020 to August 2021 was conducted. Data on anthropometric measures, nutritional indices, adherence to supplements and gastrointestinal symptoms preoperatively and then at ≤6 months, 1 and 2 years or more postoperatively were collected. RESULTS: A total of 231 patients were included in the study. The majority of patients were female (76.2%), with a sleeve gastrectomy (78.8%). Average preoperative BMI was 43.4 ± 7.1 kg/m2 . Weight loss ≥2 years postsurgery was 33.5 ± 12.4 kg. The most common abnormalities preoperatively were: C-reactive protein (47.7%), vitamin D (39%), B12 (31%), parathyroid hormone (27.6%) and ferritin (12.7%). Vitamin B12 (23.2%), parathyroid hormone (23%), vitamin D (17.7%) and ferritin (15.9%) remained common abnormalities postoperatively. Adherence to multivitamins was 90% in the first year following surgery, declining to 77% at ≥2 years. Gastrointestinal symptoms were predominantly present in the initial stages following surgery, manifesting thiamin deficiency in 6.5% of patients. CONCLUSIONS: Despite achieving durable weight loss, nutritional and related abnormalities remain an ongoing challenge for bariatric surgery. Adherence to nutrient supplements, gastrointestinal symptoms and related complications are important considerations in addressing the problem.

Nutrition and Health Claims: Consumer Use and Evolving Regulation.

PURPOSE OF REVIEW: The value of nutrition and health claims (N&HC) depends on how consumers use them and the regulatory framework that enables them. This paper aims to explore the impact of claims on consumer behaviour and identify evolving regulatory challenges, using the Australian experience as a reference point. RECENT FINDINGS: N&HC can influence consumer food purchasing and consumption, but how consumers interpret and act on specific claims is less well understood, and regulatory frameworks are evolving. In the last 10 years, changes to the Australian regulatory framework have exposed greater opportunities for promoting foods, albeit with challenges regarding self-substantiation of claims. N&HC can play a significant role in driving consumer choices towards a healthier food supply. The Australian experience demonstrates how N&HC can continue to evolve, reflecting developments in methodologies and a fundamental appreciation of the relationship between food and health.

The therapeutic relationship between a client and dietitian: A systematic integrative review of empirical literature.

AIM: Scientific evidence underpins dietetics practice; however, evidence of how the therapeutic relationship influences outcomes is limited. This integrative review aims to provide a comprehensive overview of the topic of the therapeutic relationship between clients and dietitians in the individual counselling context by summarising empirical literature into qualitative themes. METHODS: An electronic literature search of the Cumulative Index of Nursing and Allied Health Literature, PsychInfo, Scopus and Web of Science databases was conducted in October 2018 and repeated in February 2021. Studies were included if they explicitly referred to the therapeutic relationship (or associated terms), were based on study data and available in full text. Extracted data were checked by a second researcher and the methodological quality was evaluated independently by two researchers using the Mixed Methods Appraisal Tool. An iterative process of qualitatively coding, categorising and comparing data to examine recurring themes was applied. RESULTS: Seventy-six studies met the inclusion criteria. Five themes were identified which showed the extent and nature of research in this area. Studies revealed the therapeutic relationship: (i) is valued within clinical dietetic practice, (ii) involves complex and multifactorial interactions, (iii) is perceived as having a positive influence, (iv) requires skills training and (v) is embedded in practice models and tools. CONCLUSION: Studies show the therapeutic relationship is a valued and multifactorial component of clinical dietetic practice and is perceived to positively influence the client and dietitian. Observational data are needed to assess the extent to which the strength of the therapeutic relationship might contribute to clients' health outcomes.

Development of the Australian National Meal Guidelines for home-delivered and centre-based meal programs for older adults.

ISSUE ADDRESSED: This research aimed to develop and disseminate National Meal Guidelines for Australian home-delivered and centre-based meal programs. METHODS: Development was led by a project group of dietitians and a steering group of representatives from the Australian Meals on Wheels Association. The process framework included three phases: (1) Review of existing standards and guidelines and systematic literature review (SLR), (2) stakeholder consultation conducted via six workshops, across six states (N = 212) and surveys with service providers, health professionals (N = 289) and customers (N = 337) and (3) review of the draft guidelines by stakeholders. RESULTS: The final guidelines address: nutritional needs of older adults; meal and menu planning including nutrient requirements for meal components; presentation and meal enjoyment; special diets; and enhancing the meal service. CONCLUSION: These guidelines provide consistent guidance to services providing home-delivered and centre-based meal programs. Further evaluation of their uptake and impact on service practices and customer nutrition and satisfaction is required. SO WHAT?: The National Meal Guidelines provide nationally consistent, evidence-based guidance on menu planning and nutritional quality of meals to services providing home-delivered and centre-based meal programs. The guideline development framework outlined here also provides a process for future food service guideline development.

Healthcare professionals' perspectives on the role of dietitians within multidisciplinary head and neck cancer teams: A qualitative multi-site study.

AIM: Evidence-based guidelines provide recommendations on how dietitians should work with patients with head and neck cancer for best outcomes. Research with healthcare professionals from head and neck cancer teams would provide insight into how these recommendations are implemented in practice. Therefore, the aim of this study was to explore how the role of the dietitian is perceived and enacted in different head and neck cancer teams from the perspective of healthcare professionals. METHODS: This qualitative study recruited radiation oncologists, nurses, dietitians and speech pathologists from four different head and neck cancer teams in Australia and the United States. Data were collected via semi-structured interviews and analysed using a grounded-theory approach. RESULTS: Seventeen radiation oncologists, 12 nurses, 11 dietitians and six speech pathologists participated. Perceptions on the role of dietitians were summarised by the category: "Providing expertise in nutritional care: A core role in head and neck cancer." Five categories summarised perceptions of factors that can influence how the role of the dietitian is enacted in practice: "having experience in head and neck cancer"; "initiating nutritional care plans and the role of doctors and nurses"; "clinic structuring"; "an evolving culture in healthcare services" and "the presence of evidence-based guidelines." CONCLUSIONS: While dietitians can be perceived to be the experts in nutritional care, several factors influence how their role is enacted in head and neck cancer teams. Further research on patient nutritional outcomes and on clinic structures that best use dietetic expertise is required to strengthen recommendations on how dietitians should work with head and neck cancer patients internationally.

The views, experiences and expectations of Australian Meals on Wheels customers: A national survey.

OBJECTIVE: To investigate views and expectations of Australian Meals on Wheels (MOW) customers to inform the development of National Meal Guidelines and improve current services. METHODS: A survey was designed through literature review and consultations with key stakeholders. National convenience sampling returned  337 surveys. Descriptive statistics and chi-squared analyses were applied to the survey data. RESULTS: Meals on Wheels customers reported satisfaction with their current service, with the meal itself found to be the most valuable aspect. People living in small country towns were more likely to value the social contact provided by MOW than those in major cities (P = .001). Delivery of pantry items was the most popular additional option for future services. CONCLUSION: Valuable information for inclusion in the development of the National Meal Guidelines was provided: nutritional content of meals, meal variety, packaging and presentation, opportunities for nourishing snacks and pantry items, and social contact.

Changes in Anthropometric Measures, Nutritional Indices and Gastrointestinal Symptoms Following One Anastomosis Gastric Bypass (OAGB) Compared with Roux-en-y Gastric Bypass (RYGB).

PURPOSE: Bariatric surgery is an effective treatment for obesity with new procedures emerging. However, despite comparable weight loss and improvements in metabolic outcomes, research on nutritional and gastrointestinal symptoms remains limited. Here we compare clinical data on weight, nutritional disorders and gastrointestinal symptoms of patients before and following one anastomosis gastric bypass (OAGB) and Roux-en-Y gastric Bypass (RYGB). MATERIALS AND METHODS: In this retrospective study, data on anthropometry, nutritional indices, dietary intake and gastrointestinal symptoms were retrieved in cohorts of patients up to 2 years following OAGB and RYGB. RESULTS: Seventy-three patients had either a RYGB (28) or an OAGB (45), with 71% seeking these as a revisional procedure. Significant and higher weight loss was observed in the OAGB cohort at 1 year (%TWL 33.0 ± 8.5 vs. 26.6 ± 12.4), albeit comparable at 2 years postoperatively (%TWL 29.0 ± 11.1 vs. 34.1 ± 11.2). Disorders such as vitamin D, active B12, folate, homocystein (Hcy) and hyperparathyroidism were present following both surgeries. Levels of vitamin D, ferritin and total protein significantly worsened over time. Gastrointestinal symptoms of diarrhoea, steatorrhoea and reflux were higher in the OAGB cohort while the RYGB cohort reported more dumping syndrome (DS). CONCLUSION: Significant and similar weight loss results are seen following both OAGB and RYGB. Nutritional disorders were common in both cohorts and increased over time. However, the OAGB patients reported more gastrointestinal side effects, which may contribute to poor quality of life and nutritional consequences. Prospective and longer-term studies investigating the nutritional and gastrointestinal health of patients undergoing OAGB is recommended.

Collaborative, interprofessional nutritional care within head and neck cancer teams: an international multi-site qualitative study.

Evidence-based guidelines (EBGs) for patients with head and neck cancer (HNC) recommend that nutritional care is delivered by an interprofessional team inclusive of dietitians, doctors, nurses, and speech pathologists. Barriers to collaboration exist within interprofessional teams. However, research on this is currently lacking in the HNC setting, particularly with regard to the provision of nutritional care. This study aimed to explore what facilitates collaborative nutritional care for patients with HNC from the perspectives of different healthcare professionals. This qualitative study used a grounded theory approach. Healthcare professionals from two radiotherapy departments in the United States and two in Australia were interviewed. Forty-six interviews were completed with 17 radiation-oncologists, 12 nurses, eleven dietitians, and 6 speech-pathologists. Collaborative nutritional care for patients with HNC was underpinned by three categories and six sub-categories: access to dietitians (facilitated by funding for dietitians and the strength of evidence), communication (facilitated by team meetings, communication systems, and multidisciplinary clinics), and role-clarity (facilitated by non-clinical activities and respect). This study highlights opportunities for enhancing collaborative nutritional care within HNC teams. Further studies on the impact of the dietitian, interprofessional education, team meetings, and multidisciplinary clinics are required to promote collaborative nutritional care for HNC patients.

How is the client-dietitian relationship embedded in the professional education of dietitians? An analysis of curriculum documentation and program coordinators' perspectives in Australia.

AIM: How dietitians are trained to develop relationships with clients is not clearly articulated despite its importance being well-documented. This study aimed to describe how this relationship is expressed and addressed in curriculum documents of Australian dietetics education programs, and to explore program coordinators' perspectives of this description and how relationship development is actually taught. METHODS: Data extracted from subject outlines included subject descriptions, learning outcomes, assessments, readings and the mode of delivery (eg, lectures). Guided by a pre-existing coding framework, deductive thematic analysis was utilised to explore qualitative themes from subject outline data. Semi-structured telephone interviews were conducted with 10 program coordinators and analysed using inductive thematic analysis. RESULTS: Subject outlines for 122 subjects across all 21 accredited Australian programs were analysed. The over-arching theme was the wide "variability" in the ways that the client-dietitian relationship was expressed across subject outlines. Program coordinators perceived that findings from the analysis of subject outlines made sense, however, acknowledged limitations of analysing data from curriculum documents. The relationship appeared ambiguously defined amongst programs and was described as occurring mostly in communication, counselling and medical nutrition therapy subjects and through theoretical and practical learning. CONCLUSION: The client-dietitian relationship appears inconsistently embedded in the curriculum of Australian dietetics education programs despite widespread acceptance of its importance to practice. Further research is needed to investigate if training programs should embed more consistent language around therapeutic relationships, and how this might be achieved to reflect current competency standards.

Gut microbiome responses to dietary intake of grain-based fibers with the potential to modulate markers of metabolic disease: a systematic literature review.

CONTEXT: Cereal fiber modulates the gut microbiome and benefits metabolic health. The potential link between these effects is of interest.0. OBJECTIVE: The aim for this systematic review was to assess evidence surrounding the influence of cereal fiber intake on microbiome composition, microbiome diversity, short-chain fatty acid production, and risk factors for metabolic syndrome. DATA SOURCES AND EXTRACTION: The MEDLINE, PubMed, CINAHL, and Cochrane Library databases were searched systematically, and quality of studies was assessed using the Cochrane Risk of Bias 2.0 tool. Evidence relating to study design, dietary data collection, and outcomes was qualitatively synthesized on the basis of fiber type. DATA ANALYSIS: Forty-six primary publications and 2 secondary analyses were included. Cereal fiber modulated the microbiome in most studies; however, taxonomic changes indicated high heterogeneity. Short-chain fatty acid production, microbiome diversity, and metabolic-related outcomes varied and did not always occur in parallel with microbiome changes. Poor dietary data were a further limitation. CONCLUSIONS: Cereal fiber may modulate the gut microbiome; however, evidence of the link between this and metabolic outcomes is limited. Additional research is required with a focus on robust and consistent methodology. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42018107117.

Identifying Usual Food Choice Combinations With Walnuts: Analysis of a 2005-2015 Clinical Trial Cohort of Overweight and Obese Adults.

Consumption of nuts has been associated with a range of favorable health outcomes. Evidence is now emerging to suggest that walnuts may also play an important role in supporting the consumption of a healthy dietary pattern. However, limited studies have explored how walnuts are eaten at different meal occasions. The aim of this study was to explore the food choices in relation to walnuts at meal occasions as reported by a sample of overweight and obese adult participants of weight loss clinical trials. Baseline usual food intake data were retrospectively pooled from four food-based clinical trials (n = 758). A nut-specific food composition database was applied to determine walnut consumption within the food intake data. The a priori algorithm of association rules was used to identify food choices associated with walnuts at different meal occasions using a nested hierarchical food group classification system. The proportion of participants who were consuming walnuts was 14.5% (n = 110). The median walnut intake was 5.14 (interquartile range, 1.10-11.45) g/d. A total of 128 food items containing walnuts were identified for walnut consumers. The proportion of participants who reported consuming unsalted raw walnut was 80.5% (n = 103). There were no identified patterns to food choices in relation to walnut at the breakfast, lunch, or dinner meal occasions. A total of 24 clusters of food choices related to walnuts were identified at others (meals). By applying a novel food composition database, the present study was able to map the precise combinations of foods associated with walnuts intakes at mealtimes using data mining. This study offers insights into the role of walnuts for the food choices of overweight adults and may support guidance and dietary behavior change strategies.

Using the Delphi process to identify priorities for Dietetic research in Australia 2020-2030.

AIM: This research aimed to use a consensus process to develop a framework and definition for nutrition and dietetic research, and to identify dietetic research priorities for Australia for the period 2020 to 2030. METHODS: A three-round Delphi process was selected to enable dietitians with demonstrated research expertise to contribute to the national priority development. All Fellows of the Dietitians Association of Australia, Advanced Accredited Practising Dietitians and research leaders were invited to participate (n = 84). The questionnaire was distributed electronically using a 7-point Likert scale. Rounds 1 and 2 asked participants to comment on the proposed research framework, definition of dietetic research and to rate a set of priorities categorised within seven themes. Fields were available for comments for revisions to each section. Approval was considered when ≥70% of participants ranked priorities as Agree or Strongly agree. In Round 3, participants were asked to rank the resultant priorities within themes. RESULTS: Through this Delphi process, Australian dietitians with demonstrated expertise contributed to and confirmed a framework and definition for dietetic Research. A ranked list of 15 priorities within five themes for dietetic Research in Australia for the period 2020-2030 was developed: Healthy ageing; Vulnerable populations; Food systems and health/nutrition promotion; Informatics and evidence based practice and Achieving a balance between prevention and treatment approaches. CONCLUSIONS: It is anticipated that results will lead to the development of a research strategy to focus future dietetic research efforts, including the development of professional position papers as well as informing research competencies for dietetic education.

Nutritional Care of Patients Admitted to Hospital for Alcohol Withdrawal: A 5-Year Retrospective Audit.

AIM: The aim of this study was to describe the characteristics and the nutritional approaches implemented with patients undergoing alcohol withdrawal. METHODS: A retrospective analysis of medical records for patients admitted to a tertiary hospital for alcohol withdrawal was completed over a 5-year period 2013-2017. Data on nutrition-related assessment and management were extracted and descriptively analysed. RESULTS: A total of 109 medical records were included (M = 73, F = 36), with the mean age of patients 47.3 years (SD ± 11.2, range 22-70). The average length of stay was 3.7 days (SD ± 3.9, range 0.70-27.8). Approaches towards nutritional care emerged from micronutrient assessment and supplementation and/or dietetic consultation. Nutrition-related biochemistry data was available for most patients, notably serum levels of sodium, urea and creatinine (102 patients; 93.5%) and magnesium and phosphate (66 patients, 60.5%). There was evidence of some electrolyte abnormalities on admission to hospital. Eight patients had serum micronutrient status assessed; no patients had serum thiamine levels assessed. Parenteral thiamine was provided to 96 patients (88.0%) for 1.9 days (SD ± 1.1, range 1.0-6.0) with a mean dose of 2458.7 mg (SD ± 1347.6, range 300-6700 mg). Multivitamin supplementation was provided to 24 patients (22.0%). Only 23 patients (21.2%) were seen by a dietician of whom 16 underwent a comprehensive nutritional assessment and 3 were screened using the malnutrition screening tool. CONCLUSION: Inconsistent nutritional assessment and management practices were identified across a diverse population group, whilst nutritional professionals were underutilized. Future research should benchmark current guidelines and multidisciplinary approaches considering the role of nutritional specialists in the team.

Effect of walnut consumption on markers of blood glucose control: a systematic review and meta-analysis.

Type 2 diabetes mellitus is a chronic disease increasing in global prevalence. Although habitual consumption of walnuts is associated with reduced risk of CVD, there is inconsistent evidence for the impact of walnut consumption on markers of glycaemic control. This systematic review and meta-analysis aimed to examine the effect of walnut consumption on markers of blood glucose control. A systematic search of Medline, PubMed, CINAHL and Cochrane databases (to 2 March 2019) was conducted. Inclusion criteria were randomised controlled trials conducted with adults which assessed the effect of walnut consumption on fasting blood glucose and insulin, glycated Hb and homeostatic model assessment of insulin resistance. Random effects meta-analyses were conducted to assess the weighted mean differences (WMD) for each outcome. Risk of bias in studies was assessed using the Cochrane Risk of Bias tool 2.0. Sixteen studies providing eighteen effect sizes were included in the review. Consumption of walnuts did not result in significant changes in fasting blood glucose levels (WMD: 0·331 mg/dl; 95 % CI -0·817, 1·479) or other outcome measures. Studies were determined to have either 'some concerns' or be at 'high risk' of bias. There was no evidence of an effect of walnut consumption on markers of blood glucose control. These findings suggest that the known favourable effects of walnut intake on CVD are not mediated via improvements in glycaemic control. Given the high risk of bias observed in the current evidence base, there is a need for further high-quality randomised controlled trials.