Effect of Beetroot Juice on Blood Pressure Regulation in Post Menopausal Women

Phase 2

Completed

Brief Summary: In this study the investigators will test the hypothesis that acute consumption of inorganic nitrate (supplied in concentrated beetroot juice) reduces artery stiffness and resting blood pressure, and lessens the rise in blood pressure during handgrip exercise in postmenopausal women. Understanding and improving artery function and blood pressure regulation in women is important because they undergo accelerated arterial stiffening after menopause and have much larger increases in blood pressure when they exercise compared with either premenopausal women or men of similar age.

Detailed Description: Postmenopausal women have stiff central arteries and exaggerated blood pressure (BP) responses during exercise compared with either premenopausal women or men of similar age. Arterial stiffness and exaggerated BP responses to exercise are prognostic for heart wall thickening, future hypertension, adverse cardiovascular events, and mortality. Previous studies have reported that acute consumption of nitrate-rich beetroot juice can lower resting and exercising BP responses in older adults. However, these studies included both sexes and did not compare the effects of beetroot juice to a nitrate-depleted placebo (a true control). Thus, the potential BP lowering effects of nitrate supplementation per se have not been established in postmenopausal women. The present study examines the acute (single dose) effects of nitrate-rich beetroot juice on resting hemodynamics (peripheral and central BP, arterial wave properties, etc), and physiological responses to handgrip exercise in metabolically healthy post-menopausal women.

Recruitment & Eligibility

Inclusion Criteria

Exclusion Criteria

Overt cardiovascular, metabolic, hematologic, pulmonary, renal, musculoskeletal, and/or neurological disease(s)
Users of any tobacco and/or nicotine products (smokers, chewing tobacco, nicotine-containing patches/gum, smokeless cigarettes)
Body mass index greater than 35
Total cholesterol greater than 239 mg/dl
LDL cholesterol greater than 159 mg/dl
Fasting blood triglycerides greater than 199 mg/dl
Fasting blood glucose greater than 109 mg/dl and HbA1c greater than 6.0%
Individuals currently taking any of the following medications:
1. blood pressure lowering medication (e.g., beta blockers, ACE inhibitors, angiotensin antagonists, calcium channel blockers, diuretics)
2. lipid-lowering medication (e.g., statins)
3. nitrates (e.g. nitroglycerin) for angina
4. phosphodiesterase inhibitors (e.g., Viagra)
5. anti-inflammatory drugs
Individuals currently taking hormone replacement therapy

Arm && Interventions

Group	Intervention	Description
Nitrate rich beetroot juice	Beetroot juice	Subjects will consume 140 ml of beetroot juice (Beet-It Organic Shot) approximately 90 min before physiological testing.
Nitrate depleted beetroot juice	Beetroot juice placebo	Subjects will consume 140 ml of beetroot juice (Beet-It Organic Placebo) approximately 90 min before physiological testing.

Primary Outcome Measures

Name	Time	Method
Resting Aortic Blood Pressures	Resting systolic blood pressure at 90 minutes after beetroot juice ingestion	Aortic Blood pressures were measured in the arm (cuff) and estimated in the aorta (radial artery tonometry).

Secondary Outcome Measures

Name	Time	Method
Resting Arterial Stiffness/Wave Properties	Change from baseline resting pulse wave velocity at 90 minutes after beet root juice ingestion	Carotid to femoral artery pulse wave velocity will be assessed using arterial tonometry.
Handgrip Exercise Blood Pressure Responses (Relative Change From Baseline)	Approximately 180 minutes after ingestion of beetroot juice	Beat-to-beat blood pressure (finger cuff) will be assessed at rest and during handgrip exercise to volitional fatigue.
Handgrip Exercise Tolerance	Approximately 90 minutes after ingestion of beetroot juice	Time to fatigue (seconds) was assessed during a progressive blood flow restricted handgrip exercise protocol.
Blood Measures of Nitrate Absorption and Conversion	Change from baseline measures of plasma nitrate and nitrite at 90 minutes and at approximately 6 hours	Venous blood will be withdrawn (venipuncture) for determination of plasma nitrate and nitrite.
Peak Rate of Perceived Exertion Scores During Handgrip Exercise	Approximately 90 minutes after ingestion of beetroot juice	The Borg Rating of Perceived Exertion Scale (RPE) was used to assess exercise intensity during handgrip exercise. The RPE scale ranges from a minimum of 6 (no exertion at all) to a maximum of 20 (maximal exertion) units on a scale.