The Efficacy of Individualized Dietary Advice in Improving Diet Quality and Cardiovascular Health

This study is a a randomized controlled parallel group dietary intervention conducted over six months in participants at high risk of cardiovascular disease living in Ireland (North and South) to evaluate the efficacy of individualized dietary advice incorporating biomarker profiles in improving diet quality and cardiometabolic outcomes.

Study Overview

• Status: Completed
• Conditions: Cardiovascular Diseases
• Intervention / Treatment: Behavioral: Educational material; Behavioral: Personalised dietary advice and educational material

Detailed Description

Study design: a randomized controlled parallel group dietary intervention will be conducted over six months in participants at high risk of CVD living in Ireland (North and South) to evaluate the efficacy of individualized dietary advice incorporating biomarker profiles in improving diet quality and cardiometabolic outcomes.

Population and recruitment

Population characteristics: Participants will be at high risk (>20% over 10 years) of developing CVD. Established recruitment mechanisms, used in several previous and ongoing dietary intervention studies, from general practices, hospital outpatient clinics, and from the general population (via press release, radio interviews, poster placement) will be utilized.Recruitment will take place over an 18 month period.

Inclusion criteria: Participants will be considered eligible to enroll in the study if they are overweight (BMI >27 and ≤ 45 kg/m2), have low Prime Diet Quality Score (PDQS <15)27 and a combination of risk factors which places them at high total risk (estimated multifactorial CVD risk ≥ 20% over ten years) of developing atherosclerotic CVD for the first time.

Exclusion criteria: Participants will be ineligible to enroll in the study if they have established diabetes mellitus, CVD or a medical condition or dietary restriction(s) that would substantially limit their ability to complete the study requirements, have an excessive alcohol consumption (>28 Units/week for men or >21 Units/week for women), have a low predicted likelihood to change dietary habits or are unable to provide informed consent.

Randomization: A personal health and medical history questionnaire, together with Joint British Societies CVD risk prediction charts and an assessment of participant's baseline PDQS using a 42-item questionnaire will be used to assess eligibility. This questionnaire is validated in the US, but will be validated in the Irish population. Those eligible and willing to take part will give informed written consent, and will be randomized (randomization scheme generated using www.randomization.com with random block sizes and research staff administering the randomization or conducting endpoint assessment blinded) to either an education only intervention or individually tailored food marker-based dietary advice.

The intervention will take place over a six month period. Participants will be interviewed towards the end of the intervention (for those in individually tailored support arm), or at drop-out (for all participants who drop out), to elicit their views on the intervention.

Dietary intervention: Participants will be randomized to one of two groups:

1. Control - participants will be given written educational material to encourage dietary change towards a better quality diet. Educational material will be adapted from resources used in previous dietary intervention studies.
2. Personalized dietary advice - participants will also be given the educational material, but will be encouraged to make dietary change using individualized recommendations incorporating food markers of specific components of a high quality diet. Food markers of diet quality will be used to develop an algorithm to deliver personalized dietary advice. Based on biomarker data, a system of categorization of biomarker status will be developed, alongside dietary advice related to this biomarker categorization, and decision trees created, as previously described in the Food4Me study, to ensure standardized delivery of advice within this intervention arm.

The dietary advice will be delivered via email and online, with monthly contact and the messages being reinforced during each direct contact with the study team for outcome assessment. Therefore frequency and duration of contact will be similar in both intervention groups.

Outcome measures: Outcomes will be assessed during a clinic visit at 0, 3 and 6 months, and will include dietary intake, anthropometry, other lifestyle behaviors, blood pressure, biological sample collection for nutritional status biomarker and health biomarker analysis, as well as fecal samples for metagenomic and transcriptomic profiling. Outcome data will be collected using the following methodology:

• Demographic/lifestyle information (e.g., alcohol consumption, medication use).
• Dietary intake using an online version of the PDQS. This will also be assessed six months after the intervention completes, to determine whether the intervention influences longer term adherence to a better quality diet.
• Physical activity using an objective physical activity monitor.
• Anthropometric data (weight and height measured using calibrated scales and stadiometer respectively, waist and hip circumference); body composition by bioelectrical impedence (Bodystat 1500).
• Blood pressure will be measured twice from the right arm, using an automated Omron sphygmomanometer, with the participant sitting quietly for at least five minutes.
• Fasting blood samples will be drawn from the antecubital vein and immediately separated into plasma/serum for the proposed assays detailed below. It will be stored at -70°C until analysis.
• Fasting morning urine sample stored at -70ºC until analysis.
• In a subset of participants (n=70, 35 in each arm), stool samples will be collected at baseline and the end of intervention for the analysis of changes in gut microbiota composition and functionality, as previously described.

Laboratory methodology: All methods are in routine use in participating laboratories and are performed with careful attention to quality control and with participation in external quality control schemes where available. All laboratory analysis will be conducted blind, i.e. the analyst will not know to which intervention the participant has been assigned.

Biomarkers of cardiometabolic risk: Serum lipids (total cholesterol, HDL-C, and TG) and whole blood HbA1c will be assessed by enzymatic assays (Randox Ltd, Crumlin, NI and Glen Bio, Antrim, NI) on an I-Lab 600 auto-analyzer. LDL-C will be calculated.

Biomarkers of diet quality: the following biomarkers will be used to assess nutritional status response to the dietary intervention: red meat - methylhistidines and carnosine; white meat - TMAO, guanidoacetate, anserine; fruit and vegetables -- proline betaine, isothiocyanates, S-methyl-L-cysteine sulfoxide, and tartaric acid; wholegrains - alkylresorcinols; coffee - phenolic acids, N-methylpyridinium, trigonelline, 2-furoylglycine; SSBs -- formate, citrulline, taurine, and isocitrate)red meat- methylhistidines; oily fish- omega-3 index; fruit and vegetables- total carotenoids and proline betaine; wholegrain- alkylresorcinols.

Gut microbiota composition and functionality: Sample handling and nucleic acid purifications will be performed following an established protocol.166 Illumina DNA-seq libraries with fragment length of ~300 bp will be generated, with Pippen prep size selection. For RNA-seq, 5ug of RNA will be enriched for mRNA and subjected to strand-specific cDNA synthesis using established protocols. Paired-end sequencing (e.g. 150x150 nt) will be performed on the Illumina HiSeq platform.

Primary Outcome: Change in Prime Diet Quality Score.

Secondary Outcomes:

1. Change in markers of cardiometabolic risk, including blood pressure, lipid profile, HbA1c, body weight.
2. Change in biomarkers of diet quality
3. Gut microbiota composition and functionality (to be conducted in a subset).

Power calculation: Sample size calculations will be confirmed during the validation of the PDQS within an Irish population. However, based on published US data, with a standard deviation (SD) of PDQS of 2.3, and an assumption of a difference in increase in PDQS of 5 between the personalized dietary advice and control groups then, if there are 60 participants in each group, the study would have over 90% power to detect this difference in mean PDQS as statistically significant, at the α=0.05 level. A total of 134 participants will be recruited to allow for approximately 10% drop-out. For the health outcomes, and, based on what was observed in a dietary intervention based on improving diet quality in similar high CVD risk participants, if there are 60 participants in each group, and it is assumed that (i) the SD of the change in diastolic blood pressure (DBP) is 9 mmHg at the end of the study; (ii) a difference in DBP of 4.5 mmHg between the individualized dietary advice and control groups; then the study would have 80% power to detect, as statistically significant at the 5% level, these differences in mean change between the two groups. The investigators will have similar levels of power (~80%) to detect effect sizes of similar magnitude in total cholesterol, HbA1c and body weight. The analysis of gut microbiota composition and functionality will be exploratory in nature.

Data analytical strategy: The repeated end-point measures generated by the study design will be analyzed with techniques appropriate for longitudinal data using the xt panel study procedures available in Stata release 11 (College Station, TX). Initial examination of the correlation structure of the repeated measures will help guide model fitting. The influence of the dietary intervention under study will be assessed by comparing the means of changes in measurements from baseline to 6 months between the biomarker-based individually tailored advice and education only groups. This difference in means will provide an estimate of the effect of intervention and 95% confidence limits will be calculated to indicate its precision. If appropriate, measurements will be logarithmically transformed prior to analysis and interpretation will be made in ratio terms on the original scale.

• Study Type: Interventional
• Enrollment (Actual): 162
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Northern Ireland
    • Belfast, Northern Ireland, United Kingdom, BT12 6BA
      • Centre for Public Health, Institute of Clinical Sciences A, Queen's University Belfast, Grosvenor Road, Royal site. Road

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 75 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Participants will be at high risk (>20% over 10 years) of developing CVD.

Inclusion Criteria:

Participants will be considered eligible to enroll in the study if they are:

1. overweight (BMI >27 and ≤ 45 kg/m2),
2. have low Prime Diet Quality Score (PDQS <15) and
3. have a combination of risk factors which places them at high total risk (estimated multifactorial CVD risk ≥ 20% over ten years) of developing atherosclerotic CVD for the first time.

Exclusion Criteria:

Participants will be ineligible to enroll in the study if they have:

1. established diabetes mellitus, CVD or a medical condition or dietary restriction(s) that would substantially limit their ability to complete the study requirements,
2. have an excessive alcohol consumption (>28 Units/week for men or >21 Units/week for women),
3. have a low predicted likelihood to change dietary habits
4. are unable to provide informed consent.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Educational material; Participants will be given written educational material to encourage dietary change towards a better quality diet. Educational material will be adapted from resources used in previous dietary intervention studies.	Behavioral: Educational material; As within arm/group description
Experimental: Personalised dietary advice and educational material; Participants will also be given the educational material, but will be encouraged to make dietary change using individualized recommendations incorporating food markers of specific components of a high quality diet. Food markers of diet quality will be used to develop an algorithm to deliver personalized dietary advice. Based on biomarker data, a system of categorization of biomarker status will be developed, alongside dietary advice related to this biomarker categorization, and decision trees created, as previously described in the Food4Me study, to ensure standardized delivery of advice within this intervention arm.	Behavioral: Personalised dietary advice and educational material; As within arm/group description

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Difference in Mean Change in Prime Diet Quality Score Between Groups Between Months 0 and 6	Dietary quality will be assessed using an online version of the Prime Diet Quality Score (PDQS). Foods are classified as healthy and unhealthy. Points are assigned according to the following criteria: 0-1 serving/wk (0 point) compared with 2-3 servings/wk (1 point) compared with ≥4 servings/wk (2 points) for the healthy food groups. Scoring is reversed and points deducted for the unhealthy food groups. Points for each food group are summed to give an overall score. The PDQS has 21 food groups and ranges from 0 to 42 total score (scores on a scale), with a higher score indicating a better diet quality.	Baseline and six months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Alcohol Consumption	Questionnaire to assess number of units consumed weekly	Baseline and six months
Medication Use	Questionnaire to assess usual medication use (drug name, dose and frequency of use)	Baseline and six months
Physical Activity	Physical activity using an accelerometer; data to be used will be total step count	Baseline and six months
Anthropometric Data - Weight	Weight will be measured in kg using calibrated scales.	Baseline and six months
Anthropometric Data - Waist to Hip Ratio	Waist and hip circumference will be measured in cm according to standardised operating procedures using a tape measure.	Baseline and six months
Anthropometric Data - Height	Height will be measured in metres using a stadiometer.	Baseline and six months
Anthropometric Data - Body Composition.	Body composition (% body fat) will be measured using bioelectrical impedence (Bodystat 1500).	Baseline and six months
Blood Pressure	Blood pressure will be measured twice from the right arm, using an automated Omron sphygmomanometer, with the participant sitting quietly for at least five minutes.	Baseline and six months
Biomarkers of Cardiometabolic Risk	Serum lipids (total cholesterol, HDL-C, and TG) and whole blood HbA1c will be assessed by enzymatic assays (Randox Ltd, Crumlin, NI and Glen Bio, Antrim, NI) on an I-Lab 600 auto-analyzer. LDL-C will be calculated.	Baseline and six months
Biomarkers of Diet Quality	The following biomarkers will be used to assess nutritional status response to the dietary intervention: red meat - methylhistidines and carnosine; white meat - TMAO, guanidoacetate, anserine; fruit and vegetables -- proline betaine, isothiocyanates, S-methyl-L-cysteine sulfoxide, and tartaric acid; wholegrains - alkylresorcinols; coffee - phenolic acids, N-methylpyridinium, trigonelline, 2-furoylglycine; SSBs -- formate, citrulline, taurine, and isocitrate) red meat- methylhistidines; oily fish- omega-3 index; fruit and vegetables- total carotenoids and proline betaine; wholegrain- alkylresorcinols.	Baseline and six months
Gut Microbiota Composition (Subset of Participants Only)	Sample handling and nucleic acid purifications will be performed following an established protocol. Illumina DNA-seq libraries with fragment length of ~300 bp will be generated as previously described, with Pippen prep size selection. For RNA-seq, 5ug of RNA will be enriched for mRNA and subjected to strand-specific cDNA synthesis using established protocols. Paired-end sequencing (e.g. 150x150 nt) will be performed on the Illumina HiSeq platform.	Baseline and six months

Collaborators and Investigators

• Sponsor: Queen's University, Belfast
• Collaborators: University College Dublin; Harvard School of Public Health (HSPH)

Study record dates

Study Major Dates

• Study Start (Actual): January 1, 2022
• Primary Completion (Actual): March 31, 2024
• Study Completion (Actual): March 31, 2024

Study Registration Dates

• First Submitted: February 19, 2019
• First Submitted That Met QC Criteria: February 22, 2019
• First Posted (Actual): February 26, 2019

Study Record Updates

• Last Update Posted (Actual): August 17, 2025
• Last Update Submitted That Met QC Criteria: August 14, 2025
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Keywords: biomarkers; diet quality; cardiometabolic health; individualised dietary advice
• Additional Relevant MeSH Terms: Cardiovascular Diseases
• Other Study ID Numbers: DK120870-01

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: At early planning stage of study - undecided.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No