Examining Factors Influencing Adherence to and Efficacy of a Wholegrains and Nuts Intervention to Reduce Blood Pressure in Prehypertension: a Series of N-of-1 Interventional Studies
Overview
- Phase
- Not Applicable
- Intervention
- Not specified
- Conditions
- Prehypertension
- Sponsor
- University of Aberdeen
- Enrollment
- 12
- Locations
- 1
- Primary Endpoint
- Adherence to wholegrains and nuts consumption
- Status
- Completed
- Last Updated
- 3 years ago
Overview
Brief Summary
The aim of the study is to investigate whether physiological, psychological and environmental factors, at an individual level, modify a) adherence, and b) blood pressure response, to a nuts and wholegrains intervention in participants at risk for developing high blood pressure. For 24 weeks, participants will, on a daily basis, monitor their own blood pressure using a wireless blood pressure monitor and respond to short semi-personalised questionnaires using a wrist-worn device, which also measures activity levels. Participants will receive an intervention of wholegrain foods and nuts to substitute into their diets for 8 weeks, between two 8-week observation periods. The length of the study periods will enable repeated measurements to be taken, in order to assess what factors, on an individual level, are associated with fluctuations in the outcomes. This will provide an insight into the types of factors that can help to explain individual fluctuations in adherence and physiological outcomes, such as blood pressure, that are common in nutrition studies. In the future, this should help in tailoring the way the investigators deliver effective individualised interventions, and enable researchers to be better able to consider and control for factors that can affect adherence and response to dietary interventions.
Detailed Description
The study will be conducted as an interventional N-of-1 study with an A1-B-A2 design of 8 weeks per study period. Prior to the study, participants will be screened and if eligible, will complete a number of baseline questionnaires to provide an overview of their typical eating and lifestyle-related behaviours, and general health. A second visit prior to the start of the study will then be arranged, where participants will undergo a semi-structured interview. Responses from the interview, in combination with their baseline questionnaire responses, will be used to identify factors specific to the participant that show some degree of variability. These will form the basis of the semi-personalised questionnaires delivered via the wrist-worn PRO-Diary device for the duration of the study. During the study, participants will visit the institute in a fasted state every 4 weeks (7 visits total), in order to provide a blood sample for assessment of cholesterol levels and for assessment of biomarkers of wholegrains intake. At the first visit, participants will receive the wireless blood pressure monitor and PRO-Diary wrist device programmed with twice-daily questionnaires at times convenient to the participant. After 2 weeks and every 4 weeks thereafter, participants will be sent a link by email to complete a 24-hour dietary recall. After 8 weeks, participants will begin the intervention phase and receive wholegrains equivalent to 3 portions a day and 1 portion of unsalted nuts per day for the following 8 weeks. Participants will be able to choose from a variety of wholegrain products commonly available at supermarkets. They will also receive dietary advice to follow a Dietary Approaches to Stop Hypertension (DASH) diet aimed at lowering blood pressure. All other measures will continue as previously. At week 16, the wholegrains and nuts will be withdrawn and participants will be followed up for a further 8 weeks. At their final visit to the institute, they will complete the same validated questionnaires as at baseline. Results from the study will be analysed using N-of-1 dynamic modelling to analyse trends over time and determine whether any personalised factors significantly affected adherence to intervention or blood pressure response.
Investigators
Eligibility Criteria
Inclusion Criteria
- •Mildly elevated blood pressure levels: systolic blood pressure (SBP) \>120 \<=140mmHg and/or diastolic blood pressure (DBP) \>80 \<=90mmHg.
- •Low habitual intake of wholegrains: \<=7 portions/week
- •Body Mass Index (BMI) between 18-35
- •Possessing a smartphone capable of running the Qardio app in conjunction with the QardioArm wireless blood pressure monitor
Exclusion Criteria
- •SBP \<120 or \>140mmHg or DBP \<80 or \>90mmHg. Participants with SBP \> 140 or DBP \> 90 will be advised to visit their GP to have their blood pressure reassessed in a clinical setting.
- •Diagnosed with diabetes
- •Clinically diagnosed with hypertension or hypercholesterolemia
- •Unstable or untreated thyroid disorder
- •Taking blood pressure- or cholesterol-lowering medications (e.g. beta blockers or statins)
- •Following a low carbohydrate/gluten free diet
- •Coeliac disease/gluten insensitivity
- •Any food allergies
- •Being on a weight loss diet or having lost \>5kg in the last 6 months
- •Any history of an eating disorder
Outcomes
Primary Outcomes
Adherence to wholegrains and nuts consumption
Time Frame: 8-week intervention period
Number of portions of wholegrains consumed and whether a portion of nuts were consumed, reported daily via the PRO-Diary wrist device.
Change in blood pressure
Time Frame: From start of study up to 24 weeks
Blood pressure (both systolic and diastolic) will be taken daily by participants via the QardioArm wireless blood pressure monitor. 3 measurements are taken automatically and averaged.
Change in plasma alkylresorcinol levels reflecting wholegrains intake
Time Frame: Every 4 weeks from start of study up to 24 weeks
Concentration of alkylresorcinols as a measure of wholegrains intake in nmol/L
Secondary Outcomes
- Total, LDL and HDL cholesterol levels(4-week blood samples)
- Correlation between adherence and blood pressure change(8-week intervention period)
- Determination of personal factors which correlate with study outcomes using Ecological Momentary Assessment (EMA) through the PRO-Diary device(24 weeks)
- Amount of wholegrains and nuts consumed during follow-up reported using PRO-Diary questionnaires(8-week follow-up phase)