The Combined Effect of Dietary Nitrate and Caloric Restriction on Cognitive and Vascular Function.

Study Overview
=================
Brief Summary
-----------------
This pilot study will compare the effect of combining dietary nitrate and caloric restriction versus dietary nitrate alone. The participant will be contacted, having responded to an advertisement on social media and posters, to attend the screening visit. They will be asked about their health status, suitability for MRI and availability. The investigators will use physical activity and eating attitude questionnaires. The investigators will also measure their height, weight, body mass index (BMI), and blood pressure (BP) and undertake blood tests. If they are eligible, they will be randomised to one of the two arms. The first group will consume nitrate-rich beetroot juice with a calorie-restricted diet for 28 days. The second group will drink the same juice with a weight-maintenance diet for the same period. The food and drinks will be provided. The outcome measures will be measured twice (at the baseline and end visits) to evaluate the change. The primary outcome is the cognitive function. The secondary outcomes are peripheral vascular health (BP and microvascular perfusion), cerebral vascular health (brain blood flow), anthropometry, body composition, and exhaled NO and nitrate concentrations. Also, the feasibility and accessibility of the study will be assessed.

Detailed Description
-----------------
Twenty healthy males and females, aged 60-70 years, non-smokers, and living with overweight or obesity (BMI 25-40 kg/m2) will be recruited to a 28-day pilot, randomised, parallel trial to follow one of the interventions (dietary nitrate with calorie-restricted diet or dietary nitrate with weight-maintenance diet) if they are eligible. Their energy requirement will be calculated using the Mifflin-St Jeor Equation, and the participant will be instructed to follow a healthy diet ( pre-diet standardisation) for three days before the intervention to minimise the effect of the sudden change of their habitual diet (during which their energy requirement will be met). At the Baseline Visit (Day 0), they will be randomised to one of the two arms, and the outcome measurements will be taken. Cognitive function will be measured via a pen-and-paper test (TMT) and a cognitive battery of tests (COMPASS). Clinic and home resting blood pressure (BP) will be measured using an automated BP monitor. Microvascular perfusion will be measured by a Laser Doppler monitor. Cerebral blood flow will be measured using a brain MRI scan. Height, weight, BMI, skinfold thickness, and waist circumference will be measured via a wall-mounted stadiometer, calibrated scale, BMI equation, calipers, and a tape measure, respectively. Body composition will be measured by a bioelectrical impedance analysis (BIA). Exhaled NO will be measured using a fractional exhaled nitric oxide analyser (FeNO). Blood samples will be taken to measure plasma nitrate concentrations. Physical activity will be monitored through a wearable smartwatch with an integrated accelerometer. The participants will be provided with 14 bottles of nitrate-rich beetroot juice (70 ml, which provides 6.5mmol of nitrate/day) with their allocated diet to be consumed in the next 14 days, starting from the next day (Day 1), and the remaining 14 days' supply will be delivered on Day 13. There will be an energy deficit of 1,000 kcal/day if they are allocated to the caloric restriction group. Otherwise, the energy requirement will be met. After completing the 28-day intervention, the participant will attend the End Visit (Day 29), to repeat the same study measurements they have done in the Baseline Visit. An exit feedback questionnaire will be given to collect information on the acceptability and compliance with the measurement protocols and intervention.

Official Title
-----------------
Testing the Combined Effect of Dietary Nitrate and Caloric Restriction on Cognitive and Vascular Function in Older Adults Living With Overweight or Obesity: A 28-Day Pilot Randomised Trial

Conditions
-----------------
Healthy, Older Adults, Overweight and Obesity

Intervention / Treatment
-----------------
* Other: Nitrate-rich beetroot juice plus calorie-restricted diet
* Other: Nitrate-rich beetroot juice plus weight-maintenance diet


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Participant is able to give written informed consent for their participation in the study. Healthy. Non-smoking adults. Male or female. Aged 60 to 75 years. BMI between 25 and 40 kg/m2. Exclusion Criteria: Systolic BP > 180mmHg and/or diastolic BP >110mmHg at the Clinic Screening Visit. Contraindication for MRI. Does not have adequate understanding of verbal and written information in English, sufficient to complete an MRI safety screening and to give informed consent. Any existing or previous medical condition that may affect the study outcomes (i.e., diabetes, kidney dysfunction, malignant cancer, brain surgery, stroke). Any medical treatment that may affect the study outcomes (i.e., diuretics, anti-acids, organic nitrates, anti-pyschotics or neuro-stimulants). Evidence of an eating disorder as indicated by the Three-factor eating questionnaire (Eating Attitudes Tests-26). Blood donation within the last 3 months of the anticipated intervention beginnings. Having taken part in a research study in the last 3 months involving invasive procedures or an inconvenience allowance. High-alcohol consumers (≥ 14 units/week for females, and ≥ 22 units/week for males). Vegetarianism (likely to have very high nitrate intake and food provided during the dietary intervention unsuitable). Weight change over 3.0kg in the last 2 months (important influence on vascular function).

Ages Eligible for Study
-----------------
Minimum Age: 60 Years
Maximum Age: 75 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Pilot, randomised, parallel trial
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Dietary nitrate plus caloric restriction<br>Participants will drink beetroot juice with a calorie-restricted diet for 28 days. | Other: Nitrate-rich beetroot juice plus calorie-restricted diet<br>* One daily bottle (70ml) of nitrate-rich beetroot juice with a calorie-restricted diet (1,000kcal deficit).<br>|
| Active Comparator: Dietary nitrate alone<br>Participants will drink beetroot juice with a weight-maintenance diet for 28 days. | Other: Nitrate-rich beetroot juice plus weight-maintenance diet<br>* One daily bottle (70ml) of nitrate-rich beetroot juice with a weight-maintenance diet (energy will be met).<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cognitive function (TMT-B) | Change in cognitive function from the baseline after 28 days intervention using a pen-and-paper cognitive test (TMT-B) compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Composite score of cognitive function | Change in the composite score of cognitive function from the baseline after 28 days intervention using a computerised cognitive battery (COMPASS) compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Cognitive function individual tasks (alphabetic working memory) | Change in the cognitive function of individual task (alphabetic working memory) from the baseline after 28 days of intervention using a computerised cognitive battery (COMPASS) compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Cognitive function individual task (serial subtraction) | Change in the cognitive function of individual task (serial subtraction) from the baseline after 28 days of intervention using a computerised cognitive battery (COMPASS) compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Cognitive function individual task (stroop) | Change in the cognitive function of individual task (stroop) from the baseline after 28 days of intervention using a computerised cognitive battery (COMPASS) compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Cognitive function individual task (peg and ball) | Change in the cognitive function of individual task (peg and ball) from the baseline after 28 days of intervention using a computerised cognitive battery (COMPASS) compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Cognitive function individual task (simple reaction time) | Change in the cognitive function of individual task (simple reaction time) from the baseline after 28 days of intervention using a computerised cognitive battery (COMPASS) compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Cognitive function (TMT-A) | Change in cognitive function from the baseline after 28 days intervention using a pen-and-paper cognitive test (TMT-A) compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Clinic blood pressure for systolic and diastolic pressure | Change in clinic blood pressure (systolic and diastolic pressure) from the baseline after 28 days intervention using automated blood pressure device compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Continuous home blood pressure for systolic and diastolic pressure | Changes in home blood pressure (systolic and diastolic pressure) from the first day of the intervention until last day using an automated blood pressure device compared to the comparator. | Every three days starting from Day 1 until Day 28 of the intervention. | 
| Microvascular perfusion | Change in microvascular perfusion from the baseline after 28 days intervention using a Laser Doppler monitor compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Cerebral blood flow | Change in cerebral blood flow from the baseline after 28 days intervention using a brain MRI scan compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Anthropometry (weight) | Change in weight in kilograms from the baseline after 28 days intervention using a calibrated scale compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Anthropometry (BMI) | Change in BMI in kg/m^2 from the baseline after 28 days intervention using the BMI equation (weight and height will be combined to report BMI in kg/m^2) compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Anthropometry (skinfold thickness) | Change in skinfold thickness in millimetre from the baseline after 28 days intervention using a skinfold calipers, compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Anthropometry (waist circumference) | Change in waist circumference from the baseline after 28 days intervention using a tape measure compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Body composition (fat mass) | Change in body composition (fat mass in kg) from the baseline after 28 days intervention using a bioelectrical impedance analysis (BIA) compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Body composition (fat-free mass) | Change in body composition (fat-free mass in kg) from the baseline after 28 days intervention using a bioelectrical impedance analysis (BIA) compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Exhaled nitric oxide | Change in nitric oxide from the baseline after 28 days intervention using a fractional exhaled nitric oxide analyser (FeNO) compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Nitrate concentrations | Change in plasma nitrate concentrations from the baseline after 28 days intervention using an Ozone-based chemiluminescence compared to the comparator. | Baseline Visit (Day 0)-one day before intervention, and End Visit (Day 29)-one day after intervention. | 
| Feasibility and accessibility | A paper exit feedback questionnaire will be administered at the end of the study to collect information on the acceptability and compliance with the measurement protocols and intervention. | End Visit (Day 29). |