STARchy Staples: a Randomised Controlled Trial on Cardiometabolic Health

NCT ID: NCT05994313

Last Updated: 2025-09-16

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 71 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2023-09-09
• Study Completion Date: 2025-05-01

Brief Summary

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

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.

Statistical analysis: Differences between groups (minimized for age, gender, BMI) will be analysed using Linear mixed models for outcomes with 3 timepoints (urinary outcomes, dietary intake data), with change being the dependent factor, subject ID as a random effect, treatment and season as fixed effects, and baseline outcome and BMI as covariates. Variables with 2 timepoints will be assessed with an ANCOVA regression model.

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 230 g of white potatoes (including fresh and frozen baked, boiled, and mashed potato products) in their evening meal, providing ~1000 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).

Conditions

Cardiometabolic Health

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: SINGLE

Study Groups

Habitual potato consumption

At least 230g 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.

Group Type: EXPERIMENTAL

Habitual potato consumption

Intervention Type: DIETARY_SUPPLEMENT

Potatoes are to be consumed in the evening meal, every evening for 12-weeks.

Habitual non-nutrient-dense staple consumption

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.

Group Type: ACTIVE_COMPARATOR

Habitual non-nutrient-dense staple consumption

Intervention Type: DIETARY_SUPPLEMENT

White rice, white pasta or white couscous are to be consumed in the evening meal, every evening for 12-weeks.

Interventions

Habitual potato consumption

Potatoes are to be consumed in the evening meal, every evening for 12-weeks.

Intervention Type: DIETARY_SUPPLEMENT

Habitual non-nutrient-dense staple consumption

White rice, white pasta or white couscous are to be consumed in the evening meal, every evening for 12-weeks.

Intervention Type: DIETARY_SUPPLEMENT

Eligibility Criteria

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.

• Minimum Eligible Age: 40 Years
• Maximum Eligible Age: 80 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Alliance for Potato Research and Education

OTHER

Sponsor Role: collaborator

Maastricht University

OTHER

Sponsor Role: collaborator

King's College London

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Wendy Hall, PhD

Role: PRINCIPAL_INVESTIGATOR

King's College London

Locations

Department of Nutritional Sciences, Franklin Wilkins Building, Waterloo campus.

Lambeth, London, United Kingdom

Countries

United Kingdom

References

Robertson TM, Alzaabi AZ, Robertson MD, Fielding BA. Starchy Carbohydrates in a Healthy Diet: The Role of the Humble Potato. Nutrients. 2018 Nov 14;10(11):1764. doi: 10.3390/nu10111764.

Reference Type: BACKGROUND

PMID: 30441846 (View on PubMed)

McGill CR, Kurilich AC, Davignon J. The role of potatoes and potato components in cardiometabolic health: a review. Ann Med. 2013 Nov;45(7):467-73. doi: 10.3109/07853890.2013.813633. Epub 2013 Jul 15.

Reference Type: BACKGROUND

PMID: 23855880 (View on PubMed)

Stone MS, Martin BR, Weaver CM. Short-Term RCT of Increased Dietary Potassium from Potato or Potassium Gluconate: Effect on Blood Pressure, Microcirculation, and Potassium and Sodium Retention in Pre-Hypertensive-to-Hypertensive Adults. Nutrients. 2021 May 11;13(5):1610. doi: 10.3390/nu13051610.

Reference Type: BACKGROUND

PMID: 34064968 (View on PubMed)

Johnston EA, Petersen KS, Kris-Etherton PM. Daily intake of non-fried potato does not affect markers of glycaemia and is associated with better diet quality compared with refined grains: a randomised, crossover study in healthy adults. Br J Nutr. 2020 May 14;123(9):1032-1042. doi: 10.1017/S0007114520000252. Epub 2020 Jan 22.

Reference Type: BACKGROUND

PMID: 31964428 (View on PubMed)

Macdonald-Clarke CJ, Martin BR, McCabe LD, McCabe GP, Lachcik PJ, Wastney M, Weaver CM. Bioavailability of potassium from potatoes and potassium gluconate: a randomized dose response trial. Am J Clin Nutr. 2016 Aug;104(2):346-53. doi: 10.3945/ajcn.115.127225. Epub 2016 Jul 13.

Reference Type: BACKGROUND

PMID: 27413123 (View on PubMed)

D'Elia L, Masulli M, Cappuccio FP, Zarrella AF, Strazzullo P, Galletti F. Dietary Potassium Intake and Risk of Diabetes: A Systematic Review and Meta-Analysis of Prospective Studies. Nutrients. 2022 Nov 12;14(22):4785. doi: 10.3390/nu14224785.

Reference Type: BACKGROUND

PMID: 36432472 (View on PubMed)

Provided Documents

Document Type: Study Protocol, Statistical Analysis Plan, and Informed Consent Form

View Document

Other Identifiers

RCT-DNS-SS-2023

Identifier Type: -

Identifier Source: org_study_id