Are Fermented Beets Vasodilators?
Yes, fermented beets contain dietary nitrate that acts as a vasodilator through conversion to nitric oxide, though the evidence specifically addresses beetroot juice rather than fermented preparations.
Mechanism of Vasodilation
The vasodilatory effect of beets operates through the nitrate-nitrite-nitric oxide (NO₃⁻/NO₂⁻/NO) pathway 1, 2. Dietary nitrate from beetroot undergoes sequential reduction to nitrite and then to nitric oxide in the circulation 3, 4. This metabolic conversion occurs at or near the plasma membrane of vascular smooth muscle cells, where nitric oxide—an endothelium-derived relaxing factor—induces relaxation of vascular smooth muscle in veins, arteries, and arterioles 1, 2.
The primary vasodilatory actions include:
- Venodilation at low doses, reducing preload through increased venous pooling and decreased ventricular wall tension 1, 2
- Arterial dilation at higher doses, decreasing afterload and systolic wall stress 1
- Coronary artery dilation, improving subendocardial blood flow and collateral circulation 1
Clinical Evidence for Cardiovascular Effects
Blood Pressure Reduction
Beetroot juice supplementation consistently lowers blood pressure across different populations 4. In healthy men, acute ingestion of beetroot bread (containing 1.1 mmol nitrate) significantly reduced diastolic blood pressure over 6 hours compared to control bread 3. A systematic review demonstrated that beetroot juice is a cost-effective strategy for blood pressure reduction in healthy, pre-hypertensive, and hypertensive individuals 4.
However, the magnitude and duration of effect vary:
- Aortic systolic blood pressure decreased by 5.2 mmHg at 30 minutes post-ingestion, but effects were short-lived and did not persist over 24 hours 5
- The effect on aortic (central) blood pressure was more pronounced than on brachial blood pressure 5
Endothelial Function Improvement
A meta-analysis of randomized controlled trials found that inorganic nitrate and beetroot supplementation significantly improved endothelial function (standardized mean difference 0.36, P < 0.001) 6. Beetroot bread acutely increased endothelium-independent vasodilation in healthy men 3. In individuals with Raynaud's phenomenon, chronic beetroot juice supplementation (14 days) enhanced both endothelium-dependent and endothelium-independent vasodilation in the forearm 7.
The vasodilatory effects are independent of endothelial integrity because nitrates undergo bioconversion to nitric oxide in both endothelial cells and myocytes 1. This distinguishes beetroot-derived nitrate from endogenous nitric oxide production, which requires intact endothelial function.
Peripheral Blood Flow Enhancement
Chronic beetroot juice supplementation increased cutaneous vascular conductance in the thumb following cold challenge in patients with Raynaud's phenomenon 7. This occurred alongside reductions in pan-endothelin concentration and improvements in anti-inflammatory status 7.
Factors Modifying Vasodilatory Response
The effectiveness of beetroot as a vasodilator is influenced by:
- Nitrate dose: Higher doses produce greater effects on endothelial function (β = 0.04, P < 0.001) 6
- Age: Older subjects show reduced responses (β = -0.01, P = 0.02) 6
- Baseline cardiovascular risk: Subjects with higher BMI (β = -0.04, P = 0.05) and systolic blood pressure (β = -0.01, P = 0.02) demonstrate attenuated effects 6
- Small arteriole resistance: Nitrates have minimal action in the microcirculation because small arterioles are nitrate-resistant 1
Critical Caveats and Contraindications
Hypotension Risk
Beetroot-derived nitrates should be avoided or used with extreme caution in hypotensive patients (systolic blood pressure <90-110 mmHg) because they cause venodilation and further preload reduction 1, 2. The most serious adverse effect is inadvertent systemic hypotension, which may trigger reflex tachycardia and worsen myocardial ischemia 1.
Right Ventricular Infarction
Nitrates from any source, including dietary beetroot, should be carefully titrated or avoided in patients with right ventricular infarction 1, 2. These patients depend on adequate right ventricular preload to maintain cardiac output and can experience profound hypotension during nitrate exposure 1.
Drug Interactions
Check for recent phosphodiesterase inhibitor use (sildenafil/vardenafil within 24 hours, tadalafil within 48 hours) before recommending beetroot supplementation, as the combination is contraindicated 2.
Limitations in Microvascular Disease
Despite theoretical benefits in microvascular angina (characterized by endothelial dysfunction), clinical results have been disappointing 1. The nitrate-resistance of small arterioles explains why beetroot-derived nitrates provide limited benefit in pure microvascular disease 1.
Fermented vs. Non-Fermented Preparations
Important limitation: The available evidence predominantly examines beetroot juice rather than specifically fermented beet preparations 3, 4, 7, 6, 5. Fermentation may alter nitrate content or bioavailability, though this has not been systematically studied. The vasodilatory effects documented in clinical trials used fresh beetroot juice with quantified nitrate content (typically 5-7 mmol per dose).
Role in Clinical Practice
Beetroot should not replace guideline-directed medical therapy for established cardiovascular disease, including antiplatelet agents, statins, ACE inhibitors, and revascularization when indicated 8. However, beetroot supplementation may serve as an adjunctive nutritional strategy for blood pressure management in healthy and hypertensive individuals 4. Enriching staple foods like bread with beetroot may increase population-level intake of cardioprotective dietary nitrate 3.