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Study protocol for a 15-week randomised controlled trial assessing the independent effects of high-cholesterol and high-saturated fat diets on LDL cholesterol.
Carter, S, Hill, AM, Yandell, C, Buckley, JD, Coates, AM
BMJ open. 2024;(1):e081664
Abstract
INTRODUCTION Previous research has associated high dietary cholesterol intake with raised low-density lipoprotein cholesterol (LDL-C) and thus increased risk for cardiovascular disease (CVD). Emerging research suggests that it is saturated fat, not dietary cholesterol, associated with increased CVD risk. Despite being high in cholesterol, eggs, low in saturated fat, are not adversely associated with blood lipids or CVD risk. This paper describes a randomised controlled counter-balanced, cross-over trial assessing the effects of a high-cholesterol/low-saturated fat (egg) diet and a low-cholesterol/high-saturated fat diet (egg free) on blood lipids and lipoproteins, while accounting for physical activity levels which can also influence these parameters. The primary aim is to demonstrate that high cholesterol intake (from eggs) within a healthy, low-saturated fat diet does not adversely affect blood lipid levels and lipoprotein profiles. Instead, we propose that adverse effects on these parameters are mediated by saturated fat intake. The secondary aim is to explore relationships between changes in blood lutein and zeaxanthin concentrations and alterations in physical activity, examining whether changes in physical activity mediate effects on blood lipids and lipoproteins. METHODS AND ANALYSIS Fifty-two adults aged 18-60 years with LDL-C less than 3.5 mmol/L will be randomly allocated to three isocaloric diets for 5 weeks each: a high-cholesterol (600 mg)/low-saturated fat (6%) (egg) diet, a low-cholesterol (300 mg)/high-saturated fat (12%) (egg free) diet and a control diet that is high in both cholesterol (600 mg) and saturated fat (12%). Lipid and lipoprotein levels, lipoprotein size and concentrations, blood pressure, blood glucose, physical activity levels, and plasma lutein and zeaxanthin concentrations will be measured. Treatment effects will be analysed using linear mixed effects models. ETHICS AND DISSEMINATION Ethics approval was obtained from the University of South Australia Human Research Ethics Committee no. 204 327. Results will be disseminated through peer-reviewed journals and national and international presentations. TRIAL REGISTRATION NUMBER NCT05267522.
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Almonds vs. carbohydrate snacks in an energy-restricted diet: Weight and cardiometabolic outcomes from a randomized trial.
Carter, S, Hill, AM, Mead, LC, Wong, HY, Yandell, C, Buckley, JD, Tan, SY, Rogers, GB, Fraysse, F, Coates, AM
Obesity (Silver Spring, Md.). 2023;(10):2467-2481
Abstract
OBJECTIVE This study evaluated weight and cardiometabolic outcomes after a 3-month energy-restricted diet (-30%) containing almonds (almond-enriched diet [AED]) or containing carbohydrate-rich snacks (nut-free control diet [NFD]) (Phase 1), followed by 6 months of weight maintenance (Phase 2). METHODS Participants (25-65 years old) with overweight or obesity (BMI 27.5-34.9 kg/m2 ) were randomly allocated to AED (n = 68) or NFD (n = 72). RESULTS Both groups lost weight during Phase 1 (p < 0.001) (mean [SE], -7.0 [0.5] kg AED vs. -7.0 [0.5] kg NFD, p = 0.858) and Phase 2 (p = 0.009) (-1.1 [0.5] kg AED vs. -1.3 [0.6] NFD, p = 0.756), with improvements in percentage lean mass after Phase 2 (4.8% [0.3%], p < 0.001). Reductions occurred in fasting glucose (-0.2 [0.07] mmol/L, p = 0.003), insulin (-8.1 [4.0] pmol/L, p = 0.036), blood pressure (-4.9 [0.8] mm Hg systolic, -5.0 [0.5] mm Hg diastolic, p < 0.001), total cholesterol (-0.3 [0.1] mmol/L), low-density lipoprotein (LDL) (-0.2 [0.1] mmol/L), very low-density lipoprotein (-0.1 [0.03] mmol/L), and triglycerides (-0.3 [0.06] mmol/L) (all p < 0.001), and high-density lipoprotein increased (0.1 [0.02] mmol/L, p = 0.011) by the end of Phase 2 in both groups. There were group by time interactions for lipoprotein particle concentrations: very small triglyceride-rich (-31.0 [7.7] nmol/L AED vs. -4.8 [7.9] nmol/L NFD, p = 0.007), small LDL (-109.3 [40.5] nmol/L AED vs. -20.7 [41.6] nmol/L NFD, p = 0.017), and medium LDL (-24.4 [43.4] nmol/L AED vs. -130.5 [44.4] nmol/L NFD, p = 0.045). CONCLUSIONS An energy-restricted AED resulted in weight loss and weight loss maintenance comparable to an energy-restricted NFD, and both diets supported cardiometabolic health. The AED resulted in greater improvements in some lipoprotein subfractions, which may enhance reductions in cardiovascular risk.
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Acute feeding with almonds compared to a carbohydrate-based snack improves appetite-regulating hormones with no effect on self-reported appetite sensations: a randomised controlled trial.
Carter, S, Hill, AM, Buckley, JD, Tan, SY, Rogers, GB, Coates, AM
European journal of nutrition. 2023;62(2):857-866
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Long-term regulation of body weight is controlled by balancing energy intake with energy expenditure. Understanding the role of specific food items and their impact on energy intake may assist in promoting weight reduction and weight loss maintenance for people with obesity. The aim of this study was to compare the effects of eating almonds or a carbohydrate-based snack on appetite-regulating hormones, self-reported appetite ratings, and short-term energy intake. This study is based on data obtained from a parallel arm randomised controlled trial. Participants were males and females, aged between 25 and 65 years who were randomly assigned to either the almond or the snack bar treatment groups based on age, sex and body mass index. Results show that the consumption of almonds resulted in a smaller C-peptide response and a larger glucose-dependent insulinotropic polypeptide [pancreatic hormone], glucagon-like peptide 1 [peptide hormone] (timepoint comparisons only), glucagon and pancreatic polypeptide response compared to consuming an isocaloric carbohydrate-rich snack bar. Furthermore, although not significant, the almond group consumed 300 kJ less energy in the meal challenge, 270 kJ of which came from discretionary foods, which may be a clinically important benefit in weight management. Authors conclude that foods that promote satiety help to regulate energy balance and may assist with weight management. However, future studies should consider testing food dose and composition carefully as the volume of food, its sensory qualities, and the acceptance of the food respective of usual meal patterns, may be important in eliciting a feeling of fullness and satisfaction.
Abstract
PURPOSE Early satiety has been identified as one of the mechanisms that may explain the beneficial effects of nuts for reducing obesity. This study compared postprandial changes in appetite-regulating hormones and self-reported appetite ratings after consuming almonds (AL, 15% of energy requirement) or an isocaloric carbohydrate-rich snack bar (SB). METHODS This is a sub-analysis of baseline assessments of a larger parallel-arm randomised controlled trial in overweight and obese (Body Mass Index 27.5-34.9 kg/m2) adults (25-65 years). After an overnight fast, 140 participants consumed a randomly allocated snack (AL [n = 68] or SB [n = 72]). Appetite-regulating hormones and self-reported appetite sensations, measured using visual analogue scales, were assessed immediately before snack food consumption, and at 30, 60, 90 and 120 min following snack consumption. A sub-set of participants (AL, n = 49; SB, n = 48) then consumed a meal challenge buffet ad libitum to assess subsequent energy intake. An additional appetite rating assessment was administered post buffet at 150 min. RESULTS Postprandial C-peptide area under the curve (AUC) response was 47% smaller with AL compared to SB (p < 0.001). Glucose-dependent insulinotropic polypeptide, glucagon and pancreatic polypeptide AUC responses were larger with AL compared to SB (18%, p = 0.005; 39% p < 0.001; 45% p < 0.001 respectively). Cholecystokinin, ghrelin, glucagon-like peptide-1, leptin and polypeptide YY AUCs were not different between groups. Self-reported appetite ratings and energy intake following the buffet did not differ between groups. CONCLUSION More favourable appetite-regulating hormone responses to AL did not translate into better self-reported appetite or reduced short-term energy consumption. Future studies should investigate implications for longer term appetite regulation. ANZCTR REFERENCE NUMBER ACTRN12618001861246 2018.
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Effects of Cold-Water Immersion Compared with Other Recovery Modalities on Athletic Performance Following Acute Strenuous Exercise in Physically Active Participants: A Systematic Review, Meta-Analysis, and Meta-Regression.
Moore, E, Fuller, JT, Bellenger, CR, Saunders, S, Halson, SL, Broatch, JR, Buckley, JD
Sports medicine (Auckland, N.Z.). 2023;(3):687-705
Abstract
BACKGROUND Studies investigating the effects of common recovery modalities following acute strenuous exercise have reported mixed results. OBJECTIVES This systematic review with meta-analysis and meta-regression compared the effects of cold-water immersion (CWI) against other common recovery modalities on recovery of athletic performance, perceptual outcomes, and creatine kinase (CK) following acute strenuous exercise in physically active populations. STUDY DESIGN Systematic review, meta-analysis, and meta-regression. METHODS The MEDLINE, SPORTDiscus, Scopus, Web of Science, Cochrane Library, EmCare, and Embase databases were searched up until September 2022. Studies were included if they were peer reviewed, published in English, included participants who were involved in sport or deemed physically active, compared CWI with other recovery modalities following an acute bout of strenuous exercise, and included measures of performance, perceptual measures of recovery, or CK. RESULTS Twenty-eight studies were meta-analysed. CWI was superior to other recovery methods for recovering from muscle soreness, and similar to other methods for recovery of muscular power and flexibility. CWI was more effective than active recovery, contrast water therapy and warm-water immersion for most recovery outcomes. Air cryotherapy was significantly more effective than CWI for the promotion of recovery of muscular strength and the immediate recovery of muscular power (1-h post-exercise). Meta-regression revealed that water temperature and exposure duration were rarely exposure moderators. CONCLUSION CWI is effective for promoting recovery from acute strenuous exercise in physically active populations compared with other common recovery methods. PROTOCOL REGISTRATION Open Science Framework: https://doi.org/10.17605/OSF.IO/NGP7C.
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Eggs and Cardiovascular Disease Risk: An Update of Recent Evidence.
Carter, S, Connole, ES, Hill, AM, Buckley, JD, Coates, AM
Current atherosclerosis reports. 2023;(7):373-380
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PURPOSE OF REVIEW This review summarizes recent evidence published since a previous review in 2018 on the association between egg consumption and risk of cardiovascular disease (CVD) mortality, CVD incidence, and CVD risk factors. RECENT FINDINGS No recent randomized controlled trials were identified. Evidence from observational studies is mixed, with studies reporting either an increased risk or no association of highest egg consumption with CVD mortality, and a similar spread of increased risk, decreased risk, or no association between egg intake and total CVD incidence. Most studies reported a reduced risk or no association between egg consumption and CVD risk factors. Included studies reported low and high egg intake as between 0 and 1.9 eggs/week and 2 and ≥14 eggs/week, respectively. Ethnicity may influence the risk of CVD with egg consumption, likely due to differences in how eggs are consumed in the diet rather than eggs themselves. Recent findings are inconsistent regarding the possible relationship between egg consumption and CVD mortality and morbidity. Dietary guidance should focus on improving the overall quality of the diet to promote cardiovascular health.
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A Mediterranean Diet and Walking Intervention to Reduce Cognitive Decline and Dementia Risk in Independently Living Older Australians: The MedWalk Randomized Controlled Trial Experimental Protocol, Including COVID-19 Related Modifications and Baseline Characteristics.
Pipingas, A, Murphy, KJ, Davis, CR, Itsiopoulos, C, Kingsley, M, Scholey, A, Macpherson, H, Segal, L, Breckon, J, Minihane, AM, et al
Journal of Alzheimer's disease : JAD. 2023;(1):409-427
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BACKGROUND Several clinical trials have examined diet and physical activity lifestyle changes as mitigation strategies for risk factors linked to cognitive decline and dementias such as Alzheimer's disease. However, the ability to modify these behaviors longer term, to impact cognitive health has remained elusive. OBJECTIVE The MedWalk trial's primary aim is to investigate whether longer-term adherence to a Mediterranean-style diet and regular walking, delivered through motivational interviewing and cognitive-behavioral therapy (MI-CBT), can reduce age-associated cognitive decline and other dementia risk factors in older, independently living individuals without cognitive impairment. METHODS MedWalk, a one-year cluster-randomized controlled trial across two Australian states, recruited 60-90-year-old people from independent living retirement villages and the wider community. Participants were assigned to either the MedWalk intervention or a control group (maintaining their usual diet and physical activity). The primary outcome is 12-month change in visual memory and learning assessed from errors on the Paired Associates Learning Task of the Cambridge Neuropsychological Test Automated Battery. Secondary outcomes include cognition, mood, cardiovascular function, biomarkers related to nutrient status and cognitive decline, MI-CBT effectiveness, Mediterranean diet adherence, physical activity, quality of life, cost-effectiveness, and health economic evaluation.Progress and Discussion:Although COVID-19 impacts over two years necessitated a reduced timeline and sample size, MedWalk retains sufficient power to address its aims and hypotheses. Baseline testing has been completed with 157 participants, who will be followed over 12 months. If successful, MedWalk will inform interventions that could substantially reduce dementia incidence and ameliorate cognitive decline in the community. TRIAL REGISTRATION Registered on the Australia New Zealand Clinical Trials Registry ANZCTR 12620000978965 (https://www.anzctr.org.au).
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Minimal changes in telomere length after a 12-week dietary intervention with almonds in mid-age to older, overweight and obese Australians: results of a randomised clinical trial.
Ward, SJ, Hill, AM, Buckley, JD, Banks, S, Dhillon, VS, Holman, SL, Morrison, JL, Coates, AM
The British journal of nutrition. 2022;(6):872-884
Abstract
Diet is a modifiable risk factor for chronic disease and a potential modulator of telomere length (TL). The study aim was to investigate associations between diet quality and TL in Australian adults after a 12-week dietary intervention with an almond-enriched diet (AED). Participants (overweight/obese, 50-80 years) were randomised to an AED (n 62) or isoenergetic nut-free diet (NFD, n 62) for 12 weeks. Diet quality was assessed using a Dietary Guideline Index (DGI), applied to weighed food records, that consists of ten components reflecting adequacy, variety and quality of core food components and discretionary choices within the diet. TL was measured by quantitative PCR in samples of lymphocytes, neutrophils, and whole blood. There were no significant associations between DGI scores and TL at baseline. Diet quality improved with AED and decreased with NFD after 12 weeks (change from baseline AED + 9·8 %, NFD - 14·3 %; P < 0·001). TL increased in neutrophils (+9·6 bp, P = 0·009) and decreased in whole blood, to a trivial extent (-12·1 bp, P = 0·001), and was unchanged in lymphocytes. Changes did not differ between intervention groups. There were no significant relationships between changes in diet quality scores and changes in lymphocyte, neutrophil or whole blood TL. The inclusion of almonds in the diet improved diet quality scores but had no impact on TL mid-age to older Australian adults. Future studies should investigate the impact of more substantial dietary changes over longer periods of time.
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Sport Participation and Subjective Outcomes of Health in Middle-Aged Men: A Scoping Review.
Blake, HT, Buckley, JD, Stenner, BJ, O'Connor, EJ, Burgess, SA, Crozier, AJ
American journal of men's health. 2022;(2):15579883221084493
Abstract
Although sport participation is intrinsically motivating and improves the physical health of middle-aged men, its influence on subjective health measures, such as health-related quality of life, self-rated health, or well-being is unclear. The purpose of this scoping review was to describe the existing literature that has assessed male sport participants and their subjective health. MEDLINE, Embase, Emcare, PsycInfo, SPORTDiscus, Cochrane Library, and Web of Science were searched, and reference lists of included studies were pearled. Included were original peer-reviewed studies reporting a marker of subjective health in males, 35 to 54 years (average), who participated in sport. The search identified 21 eligible articles, 18 quantitative, 2 mixed-methods, and 1 qualitative, from 13 different countries. Eighteen studies were cross-sectional. A broad range of outcomes were assessed, with the most common being quality of life/health-related quality of life (n = 6) and self-rated health (n = 6). Most studies assessing quality of life, health-related quality of life, or self-rated health demonstrated a positive association with sport participation, while sport participation was not related to measures of life satisfaction, flourishing, happiness or global well-being; however, limited studies examined these latter outcomes. Sport participation appears to be related to better select subjective health outcomes in middle-aged men. However, most available data are cross-sectional and thus causation cannot be determined. Randomized intervention trials are required to determine whether sport participation improves the subjective health of middle-aged men.Open Science Framework registration: https://osf.io/zypds.
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Impact of Cold-Water Immersion Compared with Passive Recovery Following a Single Bout of Strenuous Exercise on Athletic Performance in Physically Active Participants: A Systematic Review with Meta-analysis and Meta-regression.
Moore, E, Fuller, JT, Buckley, JD, Saunders, S, Halson, SL, Broatch, JR, Bellenger, CR
Sports medicine (Auckland, N.Z.). 2022;(7):1667-1688
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BACKGROUND Studies investigating the effects of cold-water immersion (CWI) on the recovery of athletic performance, perceptual measures and creatine kinase (CK) have reported mixed results in physically active populations. OBJECTIVES The purpose of this systematic review was to investigate the effects of CWI on recovery of athletic performance, perceptual measures and CK following an acute bout of exercise in physically active populations. STUDY DESIGN Systematic review with meta-analysis and meta-regression. METHODS A systematic search was conducted in September 2021 using Medline, SPORTDiscus, Scopus, Web of Science, Cochrane Library, EmCare and Embase databases. Studies were included if they were peer reviewed and published in English, included participants who were involved in sport or deemed physically active, compared CWI with passive recovery methods following an acute bout of strenuous exercise and included athletic performance, athlete perception and CK outcome measures. Studies were divided into two strenuous exercise subgroups: eccentric exercise and high-intensity exercise. Random effects meta-analyses were used to determine standardised mean differences (SMD) with 95% confidence intervals. Meta-regression analyses were completed with water temperature and exposure durations as continuous moderator variables. RESULTS Fifty-two studies were included in the meta-analyses. CWI improved the recovery of muscular power 24 h after eccentric exercise (SMD 0.34 [95% CI 0.06-0.62]) and after high-intensity exercise (SMD 0.22 [95% CI 0.004-0.43]), and reduced serum CK (SMD - 0.85 [95% CI - 1.61 to - 0.08]) 24 h after high-intensity exercise. CWI also improved muscle soreness (SMD - 0.89 [95% CI - 1.48 to - 0.29]) and perceived feelings of recovery (SMD 0.66 [95% CI 0.29-1.03]) 24 h after high-intensity exercise. There was no significant influence on the recovery of strength performance following either eccentric or high-intensity exercise. Meta-regression indicated that shorter time and lower temperatures were related to the largest beneficial effects on serum CK (duration and temperature dose effects) and endurance performance (duration dose effects only) after high-intensity exercise. CONCLUSION CWI was an effective recovery tool after high-intensity exercise, with positive outcomes occurring for muscular power, muscle soreness, CK, and perceived recovery 24 h after exercise. However, after eccentric exercise, CWI was only effective for positively influencing muscular power 24 h after exercise. Dose-response relationships emerged for positively influencing endurance performance and reducing serum CK, indicating that shorter durations and lower temperatures may improve the efficacy of CWI if used after high-intensity exercise. FUNDING Emma Moore is supported by a Research Training Program (Domestic) Scholarship from the Australian Commonwealth Department of Education and Training. PROTOCOL REGISTRATION Open Science Framework: 10.17605/OSF.IO/SRB9D.
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Effects of very low-carbohydrate vs. high-carbohydrate weight loss diets on psychological health in adults with obesity and type 2 diabetes: a 2-year randomized controlled trial.
Kakoschke, N, Zajac, IT, Tay, J, Luscombe-Marsh, ND, Thompson, CH, Noakes, M, Buckley, JD, Wittert, G, Brinkworth, GD
European journal of nutrition. 2021;(8):4251-4262
Abstract
AIMS: Very low-carbohydrate (LC) diets are popular for type 2 diabetes (T2DM) management; however, long-term effects on psychological health remain largely unknown. This study reports the effects of a LC diet on mood and cognitive function after 2 years and explores the potential predictors of changes in psychological health. METHODS 115 adults (57% males; age: 58.5 ± 7.1 years) with obesity and T2DM were randomized to consume an energy reduced (~ 500 to 1000 kcal/day deficit), LC diet [14% energy as carbohydrate, 28% protein, 58% fat (< 10% saturated fat)] or an isocaloric high unrefined carbohydrate, low-fat diet [HC: 53% carbohydrate, 17% protein, 30% fat (< 10% saturated fat)] for 2 years. Both diets were combined with aerobic/resistance exercise (1 h, 3 days/week). Mood/well-being [Beck Depression Inventory (BDI), Spielberger State Anxiety Inventory (SAI), Profile of Mood States (POMS)], diabetes-related quality of life [Diabetes-39 (D-39)] and distress [Problem Areas in Diabetes (PAID) Questionnaire], and cognitive function were assessed during and post-intervention. RESULTS 61 (LC: 33, HC: 28) participants completed the study. Weight loss was 9.1% after 12 months and 6.7% after 2 years with no difference between diet groups. There were no differences between the groups for the changes in any psychological health outcome (smallest p ≥ 0.19 for all time x diet interactions). Overtime, improvements in BDI, POMS [Total Mood Disturbance (TMD); four subscales], PAID, and D-39 (three subscales) scores occurred (p ≤ 0.05, time). Stepwise regression analysis showed improvements in BDI, POMS (TMD; two subscales), D-39, SAI, and PAID scores were significantly (p < 0.05) correlated with reductions in body weight and glycated hemoglobin. CONCLUSION In adults with obesity and T2DM, energy-restricted LC and HC diets produced comparable long-term improvements on a comprehensive range of psychological health outcomes. The findings suggest both diets can be used as a diabetes management strategy as part of a holistic lifestyle modification program without concern of negative effects on mental well-being or cognition. TRIAL REGISTRATION ACTRN12612000369820, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=362168&isReview=true . Data described in the manuscript, code book, and analytic code will not be made available because approval has not been granted by participants.