Association between plant-based diet quality and chronic kidney disease in Australian adults.

OBJECTIVE: To examine associations between three different plant-based diet quality indices, chronic kidney disease (CKD) prevalence and related risk factors in a nationally representative sample of the Australian population. DESIGN: Cross-sectional analysis. Three plant-based diet scores were calculated using data from two 24-h recalls: an overall plant-based diet index (PDI), a healthy PDI (hPDI) and an unhealthy PDI (uPDI). Consumption of plant and animal ingredients from 'core' and 'discretionary' products was also differentiated. Associations between the three PDI scores and CKD prevalence, BMI, waist circumference (WC), blood pressure (BP) measures, blood cholesterol, apo B, fasting TAG, blood glucose levels (BGL) and HbA1c were examined. SETTING: Australian Health Survey 2011-2013. PARTICIPANTS: n 2060 adults aged ≥ 18 years (males: n 928; females: n 1132). RESULTS: A higher uPDI score was associated with a 3·7 % higher odds of moderate-severe CKD (OR: 1·037 (1·0057-1·0697); P = 0·021)). A higher uPDI score was also associated with increased TAG (P = 0·032) and BGL (P < 0·001), but lower total- and LDL-cholesterol (P = 0·035 and P = 0·009, respectively). In contrast, a higher overall PDI score was inversely associated with WC (P < 0·001) and systolic BP (P = 0·044), while higher scores for both the overall PDI and hPDI were inversely associated with BMI (P < 0·001 and P = 0·019, respectively). CONCLUSIONS: A higher uPDI score reflecting greater intakes of refined grains, salty plant-based foods and added sugars were associated with increased CKD prevalence, TAG and BGL. In the Australian population, attention to diet quality remains paramount, even in those with higher intakes of plant foods and who wish to reduce the risk of CKD.

Expansion of an Australian food composition database to estimate plant and animal intakes.

Despite evidence for favourable health outcomes associated with plant-based diets, a database containing the plant and animal content of all foods eaten is required to undertake a reliable assessment of plant-based diets within a population. This study aimed to expand an existing Australian food database to include the plant and animal content of all whole foods, beverages, multi-ingredient products and mixed dishes. Twenty-three plant- and animal-based food group classifications were first defined. The food servings per 100 g of each product were then systematically calculated using either a recipe-based approach, a food label-based approach, estimates based on similar products or online recipes. Overall, 4687 (83·5 %) foods and beverages were identified as plant or plant-containing products, and 3701 (65·9 %) were animal or animal-containing products. Results highlighted the versatility of plant and animal ingredients as they were found in various foods across many food categories, including savoury and sweet foods, as well as discretionary and core foods. For example, over 97 % of animal fat-containing foods were found in major food groups outside the AUSNUT 2011-2013 'fats and oils' group. Surprisingly, fruits, nuts and seeds were present in a greater percentage of discretionary products than in core foods and beverages. This article describes a systematic approach that is suitable for the development of other novel food databases. This database allows more accurate quantitative estimates of plant and animal intakes, which is significant for future epidemiological and clinical research aiming to investigate plant-based diets and their related health outcomes.

What is the climate footprint of therapeutic diets for people with chronic kidney disease? Results from an Australian analysis.

BACKGROUND: Immediate action is needed to stabilise the climate. Dietitians require knowledge of how the therapeutic diets they prescribe may contribute to climate change. No previous research has quantified the climate footprint of therapeutic diets. This study sought to quantify and compare the climate footprint of two types of therapeutic diets for people with chronic kidney disease (CKD) with two reference diets. METHODS: A usual diet for an individual with CKD and a novel plant-based diet for CKD were compared with the current Australian diet and the Australian-adapted EAT Lancet Planetary Health Diet (PHD). The climate footprint of these diets was measured using the Global Warming Potential (GWP*) metric for a reference 71-year-old male. RESULTS: No diets analysed were climate neutral, and therefore, all contribute to climate change. The novel plant-based diet for CKD (1.20 kg carbon dioxide equivalents [CO2 e] per day) produced 35% less CO2 e than the usual renal diet for an individual with CKD (1.83 kg CO2 e per day) and 50% less than the current Australian diet (2.38 kg CO2 e per day). The Australian-adapted EAT Lancet PHD (1.04 kg CO2 e per day) produced the least amount of CO2 e and 56% less than the current Australian diet. The largest contributors to the climate footprint of all four diets were foods from the meats and alternatives, dairy and alternatives and discretionary food groups. CONCLUSIONS: Dietetic advice to reduce the climate footprint of therapeutic diets for CKD should focus on discretionary foods and some animal-based products. Future research is needed on other therapeutic diets.

Targeting the Gut Microbiota in Kidney Disease: The Future in Renal Nutrition and Metabolism.

There is increasing interest in the therapeutic potential of manipulating the gut microbiome of patients with chronic kidney disease (CKD). This is because there is a substantial deviation from a balanced gut microbiota profile in CKD, with many deleterious downstream effects. Nutritional interventions such as plant-based diets with reduced animal protein intake and the use of probiotics, prebiotics, and synbiotics may alter the microbiome. This article aims to briefly describe what is known about the gut microbiome in patients with CKD, factors contributing to gut dysbiosis, and outline important evidence gaps. Future potential therapies, including restoring the microbiota with food and microbiota-based and metabolomic-based therapies, are also discussed.

Expression of Cell-Adhesion Molecules in E. coli: A High Throughput Screening to Identify Paracellular Modulators.

Cell-adhesion molecules (CAMs) are responsible for cell-cell, cell-extracellular matrix, and cell-pathogen interactions. Claudins (CLDNs), occludin (OCLN), and junctional adhesion molecules (JAMs) are CAMs' components of the tight junction (TJ), the single protein structure tasked with safeguarding the paracellular space. The TJ is responsible for controlling paracellular permeability according to size and charge. Currently, there are no therapeutic solutions to modulate the TJ. Here, we describe the expression of CLDN proteins in the outer membrane of E. coli and report its consequences. When the expression is induced, the unicellular behavior of E. coli is replaced with multicellular aggregations that can be quantified using Flow Cytometry (FC). Our method, called iCLASP (inspection of cell-adhesion molecules aggregation through FC protocols), allows high-throughput screening (HTS) of small-molecules for interactions with CAMs. Here, we focused on using iCLASP to identify paracellular modulators for CLDN2. Furthermore, we validated those compounds in the mammalian cell line A549 as a proof-of-concept for the iCLASP method.

Patient-Reported Outcome and Experience Measures Administered by Dietitians in the Outpatient Setting: Systematic Review.

Understanding how patients perceive their health and the experience with the dietitian is fundamental to providing patient-centred care. The types of patient reported measures (PRMs) used by outpatient dietitians is unclear. Guidance about use of PRMs for dietitians is also lacking. The aim of this systematic review was to synthesise evidence regarding the use of PRMs by dietitians in the outpatient setting and evaluate the methodological quality of studies evaluating the psychometric properties of PRMs. Eight databases were searched systematically for studies of dietitians working in the outpatient setting and administering a PRM. Forty-four studies were evaluated and described 58 different PRMs. These included direct nutrition related (n = 12 studies), clinical (n = 21 studies), and health-related quality of life PRMs (n = 24 studies); 1 study documented use of a patient-reported experience measure. A large range of PRMs are used by outpatient dietitians. Of the most common PRMs, the majority are administered in similar populations to the original validation study. Dietitians should use a combination of 3 PRMs: a generic health-related quality of life tool, an experience measure, and at least 1 clinical or direct nutrition-related measure. This will enable dietitians to fully capture the impact of their care on patients.

The effect of nut consumption (tree nuts and peanuts) on the gut microbiota of humans: a systematic review.

There is increasing evidence linking the gut microbiota to various aspects of human health. Nuts are a food rich in prebiotic fibre and polyphenols, food components which have been shown to have beneficial effects on the gut microbiota. This systematic review aimed to synthesise the evidence regarding the effect of nut consumption on the human gut microbiota. A systematic search of the databases MEDLINE, PubMed, Cochrane CENTRAL and CINAHL was performed until 28 November 2019. Eligible studies were those that investigated the effects of nut consumption in humans (aged over 3 years old), utilising next-generation sequencing technology. Primary outcome measures were between-group differences in α- and ß-diversity metrics and gut microbial composition. A total of eight studies were included in the review. Included studies assessed the effects of either almonds, walnuts, hazelnuts or pistachios on the gut microbiota. Overall, nut consumption had a modest impact on gut microbiota diversity, with two studies reporting a significant shift in α-diversity and four reporting a significant shift in ß-diversity. Walnuts, in particular, appeared to more frequently explain shifts in ß-diversity, which may be a result of their unique nutritional composition. Some shifts in bacterial composition (including an increase in genera capable of producing SCFA: Clostridium, Roseburia, Lachnospira and Dialister) were reported following the consumption of nuts. Nut intake may yield a modulatory effect on the gut microbiota; however, results were inconsistent across studies, which may be explained by variations in trial design, methodological limitations and inter-individual microbiota.

Associations Among Plant-Based Diet Quality, Uremic Toxins, and Gut Microbiota Profile in Adults Undergoing Hemodialysis Therapy.

OBJECTIVE: The objective of the study was to evaluate associations among diet quality, serum uremic toxin concentrations, and the gut microbiota profile in adults undergoing hemodialysis therapy. DESIGN AND METHODS: This is a cross-sectional analysis of baseline data from a clinical trial involving adults receiving hemodialysis therapy. Usual dietary intake was determined using a diet history method administered by Accredited Practising Dietitians. Two approaches were used for diet quality assessment: (1) using three a priori defined plant-based diet indices-an overall plant-based diet index (PDI), a healthy PDI, and an unhealthy PDI and (2) classification of food group intake. Serum uremic toxins (p-cresyl sulfate and indoxyl sulfate (IS); free and total) were determined by ultra-performance liquid chromatography. Gut microbiota composition was established through sequencing the 16S rRNA gene in stool samples. RESULTS: Twenty-two adults (median age 70.5 [interquartile range: 59-76], 64% male) were included in the final analysis. Higher adherence to the PDI was associated with lower total IS levels (P = .028), independent of dialysis adequacy, urinary output, and blood albumin levels. In contrast, higher adherence to the unhealthy PDI was associated with increases in both free and total IS. Several other direct and inverse associations between diet quality with uremic toxins, microbial relative abundances, and diversity metrics were also highlighted. Diet-associated taxa showed significantly different trends of association with serum uremic toxin concentrations (P < .05). Higher adherence to the PDI was negatively associated with relative abundances of Haemophilus and Haemophilus parainfluenzae that were related to elevated total IS levels. In contrast, increased intake of food items considered unhealthy, such as animal fats, sweets and desserts, were associated with bacteria linked to higher IS and p-cresyl sulfate (total and free) concentrations. CONCLUSIONS: The quality of diet and food selections may influence uremic toxin production by the gut microbiota in adults receiving hemodialysis. Well-designed dietary intervention trials that adopt multi-omic technologies appropriate for the functional annotation of the gut microbiome are needed to validate our findings and establish causality.

The gut microbiota profile of adults with kidney disease and kidney stones: a systematic review of the literature.

BACKGROUND: There is mounting evidence that individuals with kidney disease and kidney stones have an abnormal gut microbiota composition. No studies to date have summarised the evidence to categorise how the gut microbiota profile of these individuals may differ from controls. Synthesis of this evidence is essential to inform future clinical trials. This systematic review aims to characterise differences of the gut microbial community in adults with kidney disease and kidney stones, as well as to describe the functional capacity of the gut microbiota and reporting of diet as a confounder in these studies. METHODS: Included studies were those that investigated the gut microbial community in adults with kidney disease or kidney stones and compared this to the profile of controls. Six scientific databases (CINHAL, Medline, PubMed, Scopus, Web of Science and Cochrane Library), as well as selected grey literature sources, were searched. Quality assessment was undertaken independently by three authors. The system of evidence level criteria was employed to quantitatively evaluate the alteration of microbiota by strictly considering the number, methodological quality and consistency of the findings. Additional findings relating to altered functions of the gut microbiota, dietary intakes and dietary methodologies used were qualitatively summarised. RESULTS: Twenty-five articles met the eligibility criteria and included data from a total of 892 adults with kidney disease or kidney stones and 1400 controls. Compared to controls, adults with kidney disease had increased abundances of several microbes including Enterobacteriaceae, Streptococcaceae, Streptococcus and decreased abundances of Prevotellaceae, Prevotella, Prevotella 9 and Roseburia among other taxa. Adults with kidney stones also had an altered microbial composition with variations to Bacteroides, Lachnospiraceae NK4A136 group, Ruminiclostridium 5 group, Dorea, Enterobacter, Christensenellaceae and its genus Christensenellaceae R7 group. Differences in the functional potential of the microbial community between controls and adults with kidney disease or kidney stones were also identified. Only three of the 25 articles presented dietary data, and of these studies, only two used a valid dietary assessment method. CONCLUSIONS: The gut microbiota profile of adults with kidney disease and kidney stones differs from controls. Future study designs should include adequate reporting of important confounders such as dietary intake to assist with interpretation of findings.

Safety and Efficacy of Using Nuts to Improve Bowel Health in Hemodialysis Patients.

OBJECTIVE: Constipation is common in patients with end-stage kidney disease. Nondrug strategies to manage constipation are challenging because of dietary potassium, phosphate, and fluid restrictions. Nuts are a high-fiber food but are excluded from the diet because of the high potassium and phosphate content. The aim of this study was to examine the safety and efficacy of using nuts to improve constipation in adults undertaking hemodialysis (HD). DESIGN AND METHODS: Adult patients undertaking HD were recruited to this nonrandomized, 10-week repeated measures, within-subject, pragmatic clinical trial, conducted in two HD units. The intervention consisted of consumption of 40g of raw almonds daily for four weeks, followed by a two-week washout and four-week control period. The primary safety outcome measures were change in predialysis serum potassium and phosphate levels. The primary efficacy outcome was reduction in constipation, measured using the Bristol Stool Form Scale and Palliative Care Outcome Scale (POS-S) renal symptom score. Secondary outcomes included quality of life, selected uremic toxins, cognition, gut microbiota profile, and symptom burden. RESULTS: Twenty patients completed the trial (median age: 67 [interquartile range: 57.5-77.8] years, 51% male). After controlling for dialysis adequacy, anuria, dietary intake, bicarbonate, and parathyroid hormone, there were no statistically significant changes in serum potassium (P = 0.21) or phosphate (P = 0.16) associated with daily consumption of almonds. However, statistically significant improvements in constipation were seen at weeks 2, 3, 4, and 10. There were statistically significant improvements in quality of life (P = 0.030), overall symptom burden (P = 0.002), vomiting (P = 0.020), itching (P = 0.006), and skin changes (P = 0.002). CONCLUSION: Daily consumption of almonds for four weeks was safe, effective, and well tolerated. Improvements in quality of life and symptom burden warrant further research to elucidate potential mechanisms. The findings support the potential reinclusion of foods such as nuts into the diet of patients who underwent HD.

Better cardiac care: health professional's perspectives of the barriers and enablers of health communication and education with patients of Aboriginal and Torres Strait Islander descent.

BACKGROUND: A body of knowledge continues to grow regarding Aboriginal perspectives on current challenges and barriers to health literacy and access to health services. However, less is known from the perspectives of health professionals who work in cardiac care. Given their role in delivering patient education, health practitioners could provide useful insights into potential solutions to improve patient-practitioner communication. The primary aim was to explore perspectives of health professionals who work in coronary care units regarding the enablers, barriers and potential solutions for patient-practitioner communication with patients of Aboriginal and Torres Strait Islanders descent. The secondary aim was to evaluate the acceptability and value of two videos developed with key stakeholders to provide culturally appropriate education. METHODS: Participants were recruited from two major regional hospitals. In-depth, semi-structured interviews were conducted with 17 health professionals (11 Nurses, five Cardiologists and one Aboriginal Health Worker). Interviews were recorded, de-identified and transcribed verbatim. Transcripts were analysed using constant comparison, interpreted through inductive thematic analysis and final themes were agreed through consensus with secondary researcher. RESULTS: Health professionals acknowledged that existing barriers resulted from organisational structures entrenched in the healthcare system, impacted on the practitioners' ability to provide culturally appropriate, patient-centred care. Lack of time, availability of culturally appropriate resources and the disconnection between Western medical and Aboriginal views of health were the most common challenges reported. The two videos evaluated as part of this study were found to be a useful addition to practice. Strengths in the videos design were the use of Aboriginal and Torres Strait Islander actors and positive messaging to convey health related topics. Further improvements included additional information related to common tests and procedures to allow for realistic expectations of patient care. CONCLUSION: Re-modelling of organisational structures is required in order to promote a more culturally-friendly and welcoming environment to encourage Aboriginal and Torres Strait Islanders to engage with mainstream cardiac care services. The videos that were developed using principles that are sensitive to Aboriginal health views, may offer an additional way in which to overcome existing barriers to effective patient-practitioner communication with Aboriginal and Torres Strait Islanders.

Revisiting the impact of Health at Every Size® interventions on health and cardiometabolic related outcomes: An updated systematic review with meta-analysis.

AIMS: To (1) synthesise evidence from Health at Every Size® interventions on physical and psychological health in people with overweight and obesity and (2) report between-group differences within interventions evaluating the impact of Health at Every Size® interventions on health and health-related outcomes. METHODS: Six databases (Medline, Embase, Cochrane, PsychInfo, CINAHL, and Scopus) were searched from inception until November 2022. Included studies were conducted in adults with overweight or obesity, used Health at Every Size®-based interventions compared with control interventions and reported dietary, physical and/or psychological outcomes, including diet quality, anthropometry, or quality of life. Data on between-group differences were extracted. Risk of bias was assessed using ROB2. Random-effects meta-analyses were undertaken for outcomes with at least three studies reporting the same or comparable data. RESULTS: From 128 studies identified, 19 full-text articles (10 unique studies, 6 published since 2017), were included. Meta-analysis found a significant reduction for susceptibility to hunger in Health at Every Size® intervention groups relative to controls (p = 0.005), with no significant difference (p > 0.05) between Health at Every Size® interventions and control groups for anthropometric, psychological or cardiometabolic outcomes (total cholesterol, HDL cholesterol, triglycerides, systolic or diastolic blood pressure). CONCLUSION: Health at Every Size® interventions had similar results compared with weight-based interventions on anthropometric outcomes and cardiometabolic outcomes. Health at Every Size® interventions had a significant benefit for reducing susceptibility to hunger. The decision to use a Health at Every Size®-based intervention should be personalised to individual needs. Further research in more diverse populations is required using standardised outcome measures to facilitate future meta-analyses.

Sustainability and cost of typical and heart-healthy dietary patterns in Australia.

Study objective: The aim was to quantify and compare the environmental and financial impact of two diets: a heart-healthy Australian diet (HAD) and the typical Australian diet (TAD). Design: The study involved a secondary analysis of two modelled dietary patterns used in a cross-over feeding trial. Setting: The evaluation focused on two-week (7-day cyclic) meal plans designed to meet the nutritional requirements for a reference 71-year-old male (9000 kJ) for each dietary pattern. Main outcome measures: The environmental footprint of each dietary pattern was calculated using the Global Warming Potential (GWP*) metric, taking into account single foods, multi-ingredient foods, and mixed dishes. Prices were obtained from a large Australian supermarket. Results: The HAD produced 23.8 % less CO2 equivalents (CO2e) per day (2.16 kg CO2e) compared to the TAD (2.83 kg CO2e per day). Meat and discretionary foods were the primary contributors to the environmental footprint of the TAD, whereas dairy and vegetables constituted the largest contributors to the HAD footprint. However, the HAD was 51 % more expensive than the TAD. Conclusion: Transitioning from a TAD to a HAD could significantly reduce CO2 emissions and with benefits for human health and the environment. Affordability will be a major barrier. Strategies to reduce costs of convenient healthy food are needed. Future studies should expand the GWP* database and consider additional environmental dimensions to comprehensively assess the impact of dietary patterns. Current findings have implications for menu planning within feeding trials and for individuals seeking to reduce their carbon footprint while adhering to heart-healthy eating guidelines.

Do Precision and Personalised Nutrition Interventions Improve Risk Factors in Adults with Prediabetes or Metabolic Syndrome? A Systematic Review of Randomised Controlled Trials.

This review aimed to synthesise existing literature on the efficacy of personalised or precision nutrition (PPN) interventions, including medical nutrition therapy (MNT), in improving outcomes related to glycaemic control (HbA1c, post-prandial glucose [PPG], and fasting blood glucose), anthropometry (weight, BMI, and waist circumference [WC]), blood lipids, blood pressure (BP), and dietary intake among adults with prediabetes or metabolic syndrome (MetS). Six databases were systematically searched (Scopus, Medline, Embase, CINAHL, PsycINFO, and Cochrane) for randomised controlled trials (RCTs) published from January 2000 to 16 April 2023. The Academy of Nutrition and Dietetics Quality Criteria were used to assess the risk of bias. Seven RCTs (n = 873), comprising five PPN and two MNT interventions, lasting 3-24 months were included. Consistent and significant improvements favouring PPN and MNT interventions were reported across studies that examined outcomes like HbA1c, PPG, and waist circumference. Results for other measures, including fasting blood glucose, HOMA-IR, blood lipids, BP, and diet, were inconsistent. Longer, more frequent interventions yielded greater improvements, especially for HbA1c and WC. However, more research in studies with larger sample sizes and standardised PPN definitions is needed. Future studies should also investigate combining MNT with contemporary PPN factors, including genetic, epigenetic, metabolomic, and metagenomic data.

Do Personalized Nutrition Interventions Improve Dietary Intake and Risk Factors in Adults With Elevated Cardiovascular Disease Risk Factors? A Systematic Review and Meta-analysis of Randomized Controlled Trials.

CONTEXT: Dietary modifications can improve cardiovascular disease (CVD) risk factors. Personalized nutrition (PN) refers to individualized nutrition care based on genetic, phenotypic, medical, behavioral, and/or lifestyle characteristics. PN may be beneficial in improving CVD risk factors, including diet. However, this has not been reviewed previously. OBJECTIVE: The aim was to evaluate the effectiveness of PN interventions on CVD risk factors and diet in adults at elevated CVD risk. DATA SOURCES: Six databases were searched for randomized controlled trials published between 2000 and 2023 that tested the impact of PN interventions on CVD risk factors in people at elevated risk. DATA EXTRACTION: Risk of bias was assessed using the Academy of Nutrition and Dietetics Quality Criteria checklist. Data synthesis of eligible articles included participant characteristics, intervention details, and change in primary CVD risk factor outcomes, including blood pressure (BP), plasma lipids, and CVD risk score, and secondary risk factors, including anthropometric outcomes and diet quality. Random-effects meta-analyses were conducted to explore weighted mean differences (WMDs) in change or final mean values for studies with comparable data (studies with dietary counseling interventions) for outcomes including BP, blood lipids, and anthropometric measurements. DATA ANALYSIS: Of 7676 identified articles, 16 articles representing 15 studies met the inclusion criteria. Studies included between 40 and 563 participants and reported outcomes for CVD risk factors, including hyperlipidemia (n = 5), elevated BP (n = 3), overweight/obesity (n = 1), and multiple risk factors (n = 6). Risk of bias was low. Results suggested potential benefit of PN on systolic BP (WMD: -1.91; 95% CI: -3.51, -0.31 mmHg) and diastolic BP (WMD: -1.49; 95% CI: -2.39, -0.58 mmHg) and dietary intake in individuals at high CVD risk. Results were inconsistent for plasma lipid and anthropometric outcomes. CONCLUSION: Results were promising for PN interventions that used dietary counseling on CVD risk factors in at-risk individuals. However, further evidence for other personalization methods is required, including improving methodological quality and longer study duration in future PN interventions. SYSTEMATIC REVIEW REGISTRATION: OpenScience Framework (https://doi.org/10.17605/OSF.IO/SHVWP).

Dietary Patterns, Dietary Adequacy and Nutrient Intake in Adults Commencing Peritoneal Dialysis: Outcomes from a Longitudinal Cohort Study.

(1) Background: Optimal dietary intake is integral to good health in people receiving peritoneal dialysis (PD). We investigated how dietary patterns, dietary adequacy and nutrient intake may change over time in people commencing PD. (2) Methods: Participants were attending the PD training unit for the commencement of peritoneal dialysis, aged ≥18 years and willing to complete food records. Misreporters were excluded from the analysis. Dietary intake was compared at PD commencement and at 12 months. Intake was also compared to reference standards. Dietary patterns were derived using principal component analysis. (3) Results: There were no significant changes between baseline and 12 months for grains, fruit, vegetables and meat. Dairy and added sugar intake was significantly lower (p = 0.01). The intake of energy and protein was adequate and did not change. There was a significant reduction in dietary phosphorus and calcium, and increased vitamin C intake. Three dietary patterns were identified: the 'Bread and Cereal' pattern; 'Milk and Potatoes' pattern; and the 'Semi Vegetarian' pattern. (4) Conclusions: In this longitudinal cohort study, the diet quality was suboptimal and there were limited changes in intake after the commencement of PD. Further exploration of how dietary patterns may impact outcomes and quality of life is warranted.

Recommendations for Designing, Conducting, and Reporting Feeding Trials in Nutrition Research.

Double-blind, placebo-controlled, randomized controlled trials are the gold standard for clinical trials in nutrition science. For trials of whole diets, dietary counseling is advantageous as they offer clinical translatability although can vary in the fidelity of the intended intervention from participant to participant and across studies. Feeding trials, in which most or all food is provided, offer high precision and can provide proof-of-concept evidence that a dietary intervention is efficacious and can also better evaluate the effect of known quantities of foods and nutrients on physiology. However, they come with additional methodological complexities. Feeding trials also call for a variety of unique methodological considerations, not least of which relate to the design and delivery of diets to participants. This review aims to provide a comprehensive summary of recommendations for design and conduct of feeding trials, encompassing domiciled and nondomiciled feeding trials. Several pertinent aspects of trial design and methodology are discussed, including defining the study population to maximize retention, safety, and generalizability of findings, recommendations for design of control interventions and optimizing blinding, and specific considerations for clinical populations. A detailed stepwise process for menu design, development, validation, and delivery are also presented. These recommendations aim to facilitate methodologic consistency and execution of high-quality feeding trials, ultimately facilitating improved understanding of the role of diet in treating disease and the underpinning mechanisms.

Dietary Assessment and Metabolomic Methodologies in Human Feeding Studies: A Scoping Review.

Dietary metabolomics is a relatively objective approach to identifying new biomarkers of dietary intake and for use alongside traditional methods. However, methods used across dietary feeding studies vary, thus making it challenging to compare results. The objective of this study was to synthesize methodological components of controlled human feeding studies designed to quantify the diet-related metabolome in biospecimens, including plasma, serum, and urine after dietary interventions. Six electronic databases were searched. Included studies were as follows: 1) conducted in healthy adults; 2) intervention studies; 3) feeding studies focusing on dietary patterns; and 4) measured the dietary metabolome. From 12,425 texts, 50 met all inclusion criteria. Interventions were primarily crossover (n = 25) and parallel randomized controlled trials (n = 22), with between 8 and 395 participants. Seventeen different dietary patterns were tested, with the most common being the "High versus Low-Glycemic Index/Load" pattern (n = 11) and "Typical Country Intake" (n = 11); with 32 providing all or the majority (90%) of food, 16 providing some food, and 2 providing no food. Metabolites were identified in urine (n = 31) and plasma/serum (n = 30). Metabolites were quantified using liquid chromatography, mass spectroscopy (n = 31) and used untargeted metabolomics (n = 37). There was extensive variability in the methods used in controlled human feeding studies examining the metabolome, including dietary patterns tested, biospecimen sample collection, and metabolomic analysis techniques. To improve the comparability and reproducibility of controlled human feeding studies examining the metabolome, it is important to provide detailed information about the dietary interventions being tested, including information about included or restricted foods, food groups, and meal plans provided. Strategies to control for individual variability, such as a crossover study design, statistical adjustment methods, dietary-controlled run-in periods, or providing standardized meals or test foods throughout the study should also be considered. The protocol for this review has been registered at Open Science Framework (https://doi.org/10.17605/OSF.IO/DAHGS).

Dietary metabolome profiles of a Healthy Australian Diet and a Typical Australian Diet: protocol for a randomised cross-over feeding study in Australian adults.

INTRODUCTION: Traditional dietary assessment methods such as 24-hour recalls and food frequency questionnaires rely on self-reported data and are prone to error, bias and inaccuracy. Identification of dietary metabolites associated with different dietary patterns can provide objective markers of whole diet patterns that account for metabolism and individual responses to dietary interventions. Additionally, few studies have investigated country-specific healthy and unhealthy dietary patterns using metabolomics. Therefore, the current study aims to identify urinary and plasma metabolites that characterise a 'healthy' (aligned with current national dietary guidelines) and an 'unhealthy' dietary pattern (Typical Australian Diet) in Australian adults. METHODS AND ANALYSIS: The Diet Quality Feeding Study (DQFS) is an 8-week cross-over feeding study that will recruit 40 healthy adults from the Hunter region (NSW, Australia). Data collected includes biospecimens (whole blood, urine, stool) for quantification of dietary metabolite biomarkers; questionnaires (medical history/demographic, physical activity, quality of life); physical measures (anthropometry, body composition, waist circumference, blood pressure, arterial pressure); skin carotenoids and dietary intake (24-hour recalls, food frequency questionnaire). Participants will attend the research facility every 2 weeks (end of the run-in, each diet intervention and washout period) for collection of physical measures. All food will be provided to participants for each dietary intervention period, and participants will return to their usual diet during the run-in and washout periods. Targeted and untargeted metabolomics using liquid chromatography-mass spectrometry and/or proton nuclear magnetic resonance (1H-NMR) spectroscopy will be used to identify metabolites in biospecimens associated with dietary intake. ETHICS AND DISSEMINATION: This study is approved by the Hunter New England Human Research Ethics Committee (HNEHREC; 2022/ETH01649) and the University of Newcastle's Human Research Ethics Committee (HREC; H-2022-0330). Findings will be disseminated to study participants, funding bodies supporting the DQFS, peer-review publications and presented at scientific conferences within the field of research. TRIAL REGISTRATION NUMBER: Australian New Zealand Clinical Trials Registry (ACTRN12622001321730).

Red Blood Cell Membrane Fatty Acid Composition, Dietary Fatty Acid Intake and Diet Quality as Predictors of Inflammation in a Group of Australian Adults.

Evidence suggests that diet can play a role in modulating systemic inflammation. This study aims to examine the relationship between fatty acids (FAs) (self-reported dietary intake and red blood cell (RBC) membrane fatty acid concentrations), three diet quality scores, and the plasma concentrations of inflammatory markers (interleukin-6, IL-6; tumour necrosis factor alpha, TNF-α; and C-reactive protein, CRP) in a group of Australian adults (n = 92). Data were collected on their demographic characteristics, health status, supplement intake, dietary intake, RBC-FAs and plasma inflammatory markers over a nine-month period. Mixed-effects models were used to determine the relationship between RBC-FAs, dietary intake of FAs, diet quality scores and inflammatory markers to determine which variable most strongly predicted systemic inflammation. A significant association was identified between dietary saturated fat intake and TNF-α (ß = 0.01, p < 0.05). An association was also identified between RBC membrane saturated fatty acids (SFA) and CRP (ß = 0.55, p < 0.05). Inverse associations were identified between RBC membrane monounsaturated fatty acids (MUFAs) (ß = -0.88, p < 0.01), dietary polyunsaturated fatty acids (PUFAs) (ß = -0.21, p < 0.05) and CRP, and the Australian Eating Survey Modified Mediterranean Diet (AES-MED) score and IL-6 (ß = -0.21, p < 0.05). In summary, using both objective and subjective measures of fat intake and diet quality, our study has confirmed a positive association between saturated fat and inflammation, while inverse associations were observed between MUFAs, PUFAs, the Mediterranean diet, and inflammation. Our results provide further evidence that manipulating diet quality, in particular fatty acid intake, may be useful for reducing chronic systemic inflammation.