Cissus quadrangularis and Blood Pressure
Based on the available evidence, Cissus quadrangularis appears to reduce blood pressure in hypertensive animal models, though human clinical data is lacking. The most relevant study demonstrates significant antihypertensive effects in spontaneously hypertensive rats, with reductions in systolic blood pressure, mean arterial pressure, and heart rate after 6 weeks of treatment 1.
Evidence from Animal Studies
The primary evidence comes from a 2022 study using spontaneously hypertensive rats (SHR), which showed that ethanolic extract of Cissus quadrangularis (EECQ) at 200 mg/kg for 6 weeks produced several beneficial cardiovascular effects 1:
- Reduced systolic blood pressure and mean arterial blood pressure in genetically hypertensive rats 1
- Decreased heart rate compared to untreated hypertensive controls 1
- Alleviated cardiac and renal hypertrophy indices, suggesting protection against end-organ damage from hypertension 1
Mechanism of Blood Pressure Reduction
The blood pressure-lowering effects appear to work through multiple pathways 1:
- Improved endothelium-dependent vasodilation by enhancing acetylcholine-induced aortic relaxation 1
- Restored nitric oxide (NO) levels and endothelial NO synthase (eNOS) expression in the aorta, which is critical for vascular relaxation 1
- Reduced oxidative stress and inflammatory markers, both of which contribute to endothelial dysfunction and hypertension 1
The mechanism centers on improving endothelial function through eNOS activation and inhibition of reactive oxygen species (ROS) production, which increases NO bioavailability and promotes vasodilation 1.
Safety Profile
Safety data from a 90-day subchronic toxicity study in rats showed no adverse effects at doses up to 2500 mg/kg body weight/day, establishing this as the no-observed-adverse-effect level (NOAEL) 2. The extract showed no genotoxicity in Ames assay, chromosomal aberration tests, or micronucleus assays 2.
Critical Limitations and Clinical Caveats
The major limitation is the complete absence of human clinical trials specifically examining blood pressure effects. All blood pressure data comes from a single animal study using genetically hypertensive rats 1. The dose used (200 mg/kg in rats) cannot be directly extrapolated to human dosing without proper pharmacokinetic studies.
Additional considerations include:
- No human dose-response data exists for blood pressure effects
- No data on interactions with antihypertensive medications in humans
- Duration of effect and long-term safety in humans is unknown
- The plant has documented effects on multiple metabolic pathways (glucose metabolism, lipid metabolism) that could theoretically interact with blood pressure regulation 3
Clinical Bottom Line
If considering Cissus quadrangularis for blood pressure management, it should only be used as an adjunct to proven antihypertensive therapies, not as monotherapy. The animal data is promising but insufficient to recommend it as a primary treatment for hypertension 1. Patients taking this supplement should have regular blood pressure monitoring, and any changes to prescription antihypertensive medications should be made cautiously with close monitoring for hypotension if combining therapies.
The antioxidant and anti-inflammatory properties documented in this plant may provide cardiovascular benefits beyond blood pressure reduction, but these require validation in human studies 1, 4.