A 2 Week, Crossover Trial of Dietary Nitrate in Obstructive Sleep Apnoea Syndrome (OSAS).

Study Overview
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Brief Summary
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Acute consumption of dietary nitrate (as beetroot juice) has been shown to decrease systemic blood pressure in multiple populations as well as increase organ perfusion in areas of interest such as the pancreas and brain. Obstructive sleep apnoea syndrome (OSAS) is associated with high blood pressure, dysglycaemia and impaired vigilance. The effect of dietary nitrate in OSAS has not been reported.

Detailed Description
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Acute consumption of dietary nitrate (as beetroot juice) has been shown to decrease systemic blood pressure in multiple populations as well as increase organ perfusion in areas of interest such as the pancreas and brain. Obstructive sleep apnoea syndrome (OSAS) is associated with high blood pressure, dysglycaemia and impaired vigilance. The effect of dietary nitrate in OSAS has not been reported. The investigators hypothesize that chronic nitrate consumption might decrease blood pressure and dysglycaemia and improve vigilance compared to a placebo beetroot juice. This study is a randomized, double-blind placebo-controlled, crossover trial. At baseline, mid-point and endpoint ambulatory blood pressure will be assessed in conjunction with demographics, questionnaires, vigilance and blood draw. After baseline measures, each subject will be randomized to consume nitrate rich beetroot juice for 14 consecutive nights when assessments will be repeated followed by 14 nights of placebo and endpoint assessments or the converse.

Official Title
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Dietary Nitrate for OSAS: a Randomized, Placebo-controlled, Crossover Trial.

Conditions
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Obstructive Sleep Apnoea Syndrome

Intervention / Treatment
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* Dietary Supplement: Dietary nitrate
* Dietary Supplement: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Clinically stable, Untreated OSAS out-patients Exclusion Criteria: Using continuous positive airways pressure therapy Pulmonary hypertension Active CVD Active musculo-skeletal conditions Taking vasodilators Diabetes mellitus

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 85 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: Supportive Care
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Nitrate rich beetroot juice<br>Concentrated, beetroot juice is a rich source of dietary nitrate. | Dietary Supplement: Dietary nitrate<br>* 140ml of nitrate rich beetroot juice provides 12.9mmol nitrate and will be consumed on a daily basis during the intervention by the study subjects.<br>* Other names: Beetroot juice;|
| Placebo Comparator: Nitrate depleted placebo beetroot juice<br>Placebo beetroot juice is identical to active beetroot juice in every way except nitrate content. | Dietary Supplement: Placebo<br>* 140ml of nitrate depleted beetroot juice provides 0.5mmol nitrate and will be consumed on a daily basis during the intervention by the study subjects.<br>* Other names: Nitrate depleted beetroot juice;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in ambulatory nocturnal blood pressure | Comparison of the change after nitrate-rich beetroot juice compared to placebo. | Day 1, day 15, day 29 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in 24h blood pressure | Comparison of the change after nitrate-rich beetroot juice compared to placebo. | Day 1, day 15, day 29 | 
| Difference in plasma nitrate and nitrite | Comparison of the change after nitrate-rich beetroot juice compared to placebo. | Day 1, day 15, day 29 | 
| Difference in fasting glucose | Comparison of the change after nitrate-rich beetroot juice compared to placebo. | Day 1, day 15, day 29 | 
| Difference in OSAS symptomatology | Comparison of the change after nitrate-rich beetroot juice compared to placebo. | Day 1, day 15, day 29 | 
| Difference in 2h post OGT glucose | Comparison of the change after nitrate-rich beetroot juice compared to placebo. | Day 1, day 15, day 29 | 
| Difference in overnight oximetry | Comparison of the change after nitrate-rich beetroot juice compared to placebo. | Day 1, day 15, day 29 | 
| Difference in exhaled nitric oxide | Comparison of the change after nitrate-rich beetroot juice compared to placebo. | Day 1, day 15, day 29 | 
| Difference in vigilance scores derived from the Conner's Continuous Performance Test. | Comparison of the change after nitrate-rich beetroot juice compared to placebo. | Day 1, day 15, day 29 |