STARchy Staples: a Randomised Controlled Trial on Cardiometabolic Health

Study Overview
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Brief Summary
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An investigation into habitual potato consumption (mashed, boiled, baked) on sleep quality and chronic glycaemic control, established risk factors for cardiometabolic diseases, versus habitual consumptions of non-nutrient-dense starchy staples (white rice, pasta, and couscous).

Detailed Description
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In the last few years, researchers have undergone efforts to conduct well-controlled trials to investigate the cardiometabolic health effect of consuming potatoes as part of a healthy diet. None to our knowledge, however, have investigated the harmful dyad of poor sleep and adverse glycaemic control, 2 interrelated factors which can exacerbate cardiometabolic (CM) health outcomes. The nutrient density of potatoes, namely being the single richest source of potassium per serving, provides a plausible mechanism in which the potatoes may act to improve health markers. The primary objective of this study is to investigate whether consuming a portion of nutrient-dense potatoes in the evening meal, in place of other refined carbohydrates, can improve sleep quality, and improve nocturnal, and 24-hour, glycaemic control, both risk factors for CM diseases. Secondly, this study aims to investigate the effects of potato consumption on endothelium-dependent vasodilation, which can further interrelate to this web of interactions, and other measures of CM health. Study design: A randomised, two-parallel arm, in-clinic and remote, 12-week dietary intervention study. Study population: Healthy male and female 40-80-year-olds, who consume ≤4 fruits and vegetables per day and have sub-optimal sleep quality. The study aims to recruit a total of 80 participants, allowing for an estimated 15% dropout rate, to reach 80% power at a significance level of 0.025 (based on two outcomes). The allocation ratio is 1:1 intervention to control. Locations: Metabolic Research Unit, 4th floor, Franklin Wilkins Building, Waterloo campus, Kings College London, SE1 9NH. Screening assessment: Participants will be initially assessed for suitability against the inclusion-exclusion criteria via an online questionnaire. The outputs of the questionnaire will be assessed by the study team. Some exclusion criteria will be assessed at the baseline clinic visit before any baseline measures are provided. Study duration: There will be a 2-week run-in period, followed by a 12-week dietary intervention. Dietary intervention: The intervention (potato group) will consume at least 220 g of white potatoes (25% of energy intake from carbohydrates, or 12.5% of total energy intake, including fresh and frozen baked, boiled, and mashed potato products) in their evening meal, providing  800 mg potassium, enough to increase national median intakes up to recommended intakes. The control group will consume isoenergetic amounts of non-nutrient-dense starchy staples (white pasta, white rice, or couscous). Although participants cannot be blinded to what they're consuming, they will be blinded to whether they are in the control or the intervention group, to reduce the risk of bias. Participants will be required to source the potatoes and make these meals themselves, however, they will be provided with rotating 4-weekly recipe cards, with instructions on how to prepare meals. Participants will be required to attend several virtual one-to-ones with the study team, including an introductory call, a virtual run-in induction where they will be run through the study equipment, and 2 in-person clinic visits. Participants will be responsible for applying some study equipment from home, to reduce clinic visits and improve study retention. Compliance: Compliance will be monitored via several methods. Firstly, 24 h urinary potassium excretion, which is shown to recover 75% of potassium intake, secondly self-reported compliance will be measured through evening meal checklists. We also plan to use dietary recalls at weeks 2, 4, and 8 to reinforce dietary advice, and to make adaptations to rotating menus based on individual needs, if participants are struggling with adherence. Detailed dietary intake will be assessed through 4-day food diaries at weeks 0, 6, and 12- this data will be used for analysis. Flow-mediated dilation: A Doppler ultrasound will be utilised to capture continuous ultrasound videos to measure flow-mediated dilation. These will be analysed with automated software provided by Maastricht University. Anthropometry: Weight, height, waist and hip circumference, blood pressure, and body fat will be taken using standard procedures, in duplicates by a trained researcher at baseline and endline clinic visits. Blood samples: Fasting blood samples will be collected from a superficial antecubital vein via venepuncture before and after the dietary intervention, by a trained researcher. Participants will be asked to record and monitor the following information: Self-reported compliance with dietary intervention, weekly weight (data diaries), and habitual dietary intake (4-day diet diaries).

Official Title
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STARchy Staples: a Randomised Controlled Trial on Cardiometabolic Health

Conditions
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Cardiometabolic Health

Intervention / Treatment
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* Dietary Supplement: Habitual potato consumption
* Dietary Supplement: Habitual non-nutrient-dense staple consumption


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Self-reported healthy adults Aged 40-80 years old Intake of ≤4 portions of fruits and vegetables (excluding potatoes) per day Low sleep quality index of >5 (Pittsburgh sleep quality index). Exclusion Criteria: Shift workers and those with multiple jobs or carers who are required to wake through the night Unwilling to refrain from dietary supplements Unwilling to follow protocol and/or give informed consent Diagnosed with Cardiovascular Disease (CVD), Type 2 Diabetes, Celiac disease, Insomnia, Sleep apnoea Presence of gastrointestinal disorder Users of drugs that are likely to alter gastrointestinal motility or nutrient absorption History of substance abuse or alcoholism Currently pregnant, planning pregnancy, breastfeeding, or having had a baby 12 months prior Weight change of >3kg in the preceding 2 months BMI <18.5kg/m2 or > 35kg/m2, Current smokers, or individuals who quit smoking in the last 6-months Frequently consume wholemeal products (1-2 times per day, in the short screening FFQ) Never consumed refined starchy staples, such as white pasta or rice (rarely or never, in the short screening FFQ) High potato consumption (4-6 times per week, in the short screening FFQ) High risk of obstructive sleep apnoea (answer yes to >3 questions, in STOP-Bang questionnaire) Vegetarian, Vegan, or pescatarian dietary preferences. Diagnosed with mental health disorders, and/or on medicine for their mental health (antipsychotics, antidepressants, beta-blockers) Chronic user of antihistamines Fasting glucose >7mmol/l (finger prick test at baseline clinic) Is taking weight loss, or glucose regulating medications. Has been unstable on blood pressure lowering medications for at least 3-months prior to enrollment.

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: 12-week Randomised controlled trial
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Habitual potato consumption<br>At least 220g of white potatoes, including fresh and frozen, baked, boiled, and mashed potatoes, will be consumed in the evening meal, in replacement of non-nutrient-dense starchy staples, for 12 weeks. | Dietary Supplement: Habitual potato consumption<br>* Potatoes are to be consumed in the evening meal, every evening for 12-weeks.<br>|
| Active Comparator: Habitual non-nutrient-dense staple consumption<br>Isocaloric amounts of non-nutrient-dense starchy staples, such as white rice, white pasta, and white couscous, will be consumed in the evening meal for 12 weeks. | Dietary Supplement: Habitual non-nutrient-dense staple consumption<br>* White rice, white pasta or white couscous are to be consumed in the evening meal, every evening for 12-weeks.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in 7-day sleep efficiency | Differences in % sleep efficiency at endline vs baseline. Sleep efficiency % is described as the total time spent asleep/ total time spent in bed x 100. | 12 weeks | 
| Change in 12-day nocturnal glycaemic control | Differences in glycaemic variability, time in range and continuous glucose data, calculated using the total area under the curve (tAUC) model. Measured with a continuous glucose monitor. | Pre- and post-intervention: 12 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in 12-day daytime glycaemic control | Differences in glycaemic variability, time in range and continuous glucose data, calculated using the total area under the curve (tAUC) model. Measured with a continuous glucose monitor. | Pre- and post-intervention: 12 weeks | 
| Change in 24-hour nocturnal glycaemic control | Differences in glycaemic variability, time in range and continuous glucose data, calculated using the total area under the curve (tAUC) model. Measured with a continuous glucose monitor. | Pre- and post-intervention: 12 weeks | 
| Change in heart rate variability during mental stress | A combination of time domain, frequency domain and non-linear methods (NN intervals, Heart rate, rMSSD, SDNN, SD1/SD2, High frequency, Low frequency: high frequency ratio) will be compared from pre- to post-mental stress. The differences will be compared to pre- and post-intervention. | Pre- and post-intervention: 12 weeks | 
| Change in 24-hour heart rate variability | A combination of time domain, frequency domain and non-linear methods (NN intervals, Heart rate, rMSSD, SDNN, SD1/SD2, High frequency, Low frequency: high frequency ratio) will be compared to pre- and post-intervention. | Pre- and post-intervention: 12 weeks | 
| Change in Endothelial function | Mean differences in flow mediated dilation. | Pre- and post-intervention: 12 weeks | 
| 12-week nighttime continuous blood pressure | Measured with an Aktiia Photoplethysmography watch. | Whole 12 week period. | 
| 12-week daytime continuous blood pressure | Measured with an Aktiia Photoplethysmography watch. | Whole 12 week period. | 
| Change in blood pressure | Diastolic and systolic blood pressure, measured by oscillometry. | Pre- and post-intervention: 12 weeks | 
| Change in plasma lipids | Including: total lipids, HDL and LDL-cholesterol, and Triacylglycerols. | Pre- and post-intervention: 12 weeks | 
| Change in fasting plasma glucose | Fasting plasma glucose concentration | Pre- and post-intervention: 12 weeks | 
| Change in fasting insulin | Fasting insulin concentration | Pre- and post-intervention: 12 weeks | 
| Change in fasting HbA1C | Fasting HbA1C concentration | Pre- and post-intervention: 12 weeks | 
| Change in sleep duration, in minutes | Sleep duration (minutes) | Pre- and post-intervention: 12 weeks | 
| Change in sleep duration, in % | Sleep duration (%) | Pre- and post-intervention: 12 weeks | 
| Change in sleep latency | Sleep latency is defined as the time it takes to fall asleep from the time intended to fall asleep. | Pre- and post-intervention: 12 weeks | 
| Change in body fat % | Body fat % measured using TANITA bioelectrical impedance scales | Pre- and post-intervention: 12 weeks | 
| Change in waist circumference (cm) | Waist circumference (cm) | Pre- and post-intervention: 12 weeks | 
| Change in BMI kg/m2 | BMI kg/m2, measured using a stadiometer and TANITA scales | Pre- and post-intervention: 12 weeks | 
| Change in diet quality | Measured by several indices: plant-based diet index, alternative Mediterranean score, alternative healthy eating index and high-fat index. | Pre- and post-intervention: 12 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Sleep efficiency, Glycemic control, Flow mediated dilation