Nitrite-boosting Therapy for Improving Physiological Function in Patients With Chronic Kidney Disease

Study Overview
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Brief Summary
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Nitric oxide (NO) is an essential molecule in the body that is decreased in patients with chronic kidney disease (CKD), leading to reductions in vascular, movement (motor) and cognitive functions. This study will determine if daily oral supplementation (3 months) with a supplement that increases NO in the body, i.e., nitrate-rich beetroot juice, improves vascular, motor and cognitive function in patients with CKD; this study will also provide insight into the biological reasons (mechanisms) by which supplementation with nitrate-rich beetroot juice improves vascular function in these patients. Overall, this research will provide scientific evidence supporting the use of nitrate-rich beetroot juice for preserving physiological function and preventing co-morbid clinical conditions and disability in CKD.

Official Title
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Nitrite-boosting Therapy for Improving Physiological Function in Patients With Chronic Kidney Disease

Conditions
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Chronic Kidney Disease

Intervention / Treatment
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* Dietary Supplement: Nitrate-rich beetroot juice
* Dietary Supplement: Nitrate-depleted beetroot juice


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: CKD stage II-IV (eGFR using the Modification of Diet in Renal Disease (MDRD) prediction equation 20-90 mL/min/1.73m2; stable renal function in the past 3 months) Ability to give informed consent Albumin > 3.0 g/dL Ability to perform motor and cognitive tests (e.g., can rise from a chair, walk for 6 min, climb 10 stairs) Free from alcohol dependence or abuse, as defined by the American Psychiatry Association, Diagnostic and Statistical Manual of Mental Disorders (DSM-V) Mini-mental state examination score >21 (rationale: to screen for subjects with major cognitive impairment) Blood pressure (BP) >100/60 mmHg for past 3 months (rationale: blood pressure below 100/60 mmHg may elevate the normally small risk of hypotension with nitrate supplementation) Not taking medications that will interfere with administered medications (e.g., sildenafil interacts with nitroglycerin) Body mass index (BMI) <40 kg/m2 (vascular function measurements can be inaccurate in severely obese patients) Exclusion Criteria: Life expectancy <1 year Uncontrolled hypertension, defined as blood pressure > 160/100 mmHg in the past 3 months History of severe liver disease History of severe congestive heart failure (i.e., ejection fraction < 35%) History of hospitalizations within the last 3 months Active infection or antibiotic therapy Warfarin use Vasculitis requiring immunosuppressive therapy within the last year High dietary nitrate intake or current nitrate/nitrite supplementation; hypersensitivity to nitrates or nitrites Glucose-6-phosphate dehydrogenase deficiency or blood methemoglobin >2% Unwilling to abstain from use of mouthwash or other oral hygiene practices (e.g., tongue scraping) outside of teeth brushing that disrupt the oral microbiome and would interfere with nitrate conversion to nitrite Blood donation within 8 weeks prior to enrolling in the study; unwilling to abstain from donating blood for 8 weeks after completing the study

Ages Eligible for Study
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Minimum Age: 30 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Nitrate-rich beetroot juice<br>Daily dose of nitrate-rich beetroot juice (70 mL) for 3 months. | Dietary Supplement: Nitrate-rich beetroot juice<br>* Daily supplementation with  100 kcal of nitrate-rich beetroot juice containing 400 mg of dietary nitrate (James White Drinks, UK).<br>|
| Placebo Comparator: Nitrate-depleted beetroot juice<br>Daily dose of nitrate-depleted beetroot juice (70 mL) for 3 months. The nitrate-depleted beetroot juice is identical in appearance, taste and caloric content to nitrate-rich beetroot juice, but with nitrate removed. | Dietary Supplement: Nitrate-depleted beetroot juice<br>* Daily supplementation with  100 kcal of nitrate-depleted beetroot juice (James White Drinks, UK).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in vascular endothelial function | as measured by brachial artery flow-mediated dilation | Baseline, 3 months | 
| Change in aortic stiffness | as measured by carotid-femoral pulse wave velocity | Baseline, 3 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in oxidative stress-associated suppression of endothelial function assessed as the increase in brachial artery flow-mediated dilation following an ascorbic acid infusion | The influence of oxidative stress on brachial artery flow-mediated dilation will be determined by infusing a supraphysiological dose of ascorbic acid known to scavenge superoxide or isovolumic saline | Baseline, 3 months | 
| Change in endothelial cell markers of oxidative stress | Endothelial cell nitrotyrosine levels will be determined | Baseline, 3 months |