The main purpose of this study is to determine if acute beetroot juice supplementation reduces peripheral chemoreflex sensitivity in patients with obstructive sleep apnea. All subjects will consume low-dose (BRL), higher-dose (BRH), and placebo (BRP) beetroot juice randomly on three independent study visits. Beetroot juice also improves blood flow thus, the investigators will also measure blood flow to the carotid chemoreceptors.

Four-weeks of daily beetroot juice supplementation reduces peripheral chemoreflex sensitivity in healthy older adults who have 'normal' responses to acute hypoxia. Patients with obstructive sleep apnea have exaggerated peripheral chemoreflex sensitivity. It remains unknown if beetroot juice supplementation reduces peripheral chemoreflex sensitivity in patients with obstructive sleep apnea. Additionally, increasing blood flow to the peripheral chemoreceptors reduces sensitivity. Given that beetroot juice improves blood flow, the investigators will also measure common carotid artery blood flow at rest and during hypoxia.

Inclusion Criteria:

• OSA group: patients recently diagnosed with mild-to-moderate OSA
• Control group: healthy individuals

Exclusion Criteria:

• Diagnosis of heart disease
• Diagnosis of diabetes
• Diagnosis of any autonomic disorders
• Diagnosis of kidney disease
• Diagnosis of central sleep apnea
• Regular physical activity exceeding 30 minutes 3 days/week
• A body mass index ≥40 kg/m2
• Current or former use of a continuous positive airway pressure machine
• Current tobacco use
• Currently prescribed hormone replacement therapy