The climbing vine Passiflora incarnata, commonly known as Passion Flower, is a widely recognized herbal remedy, particularly in North America and Europe. For centuries, people have used the plant’s aerial parts to address various nervous conditions. This traditional use has prompted modern scientific inquiry into whether this common herbal supplement can influence blood pressure. Given its established calming properties, researchers are examining if Passion Flower could offer a natural approach to managing blood pressure linked to stress and anxiety.
Passion Flower: Traditional Uses and Active Compounds
Passiflora incarnata is distinct from the related species cultivated for edible passion fruit; its medicinal use focuses on the above-ground parts of the plant. Traditional herbalism classifies Passion Flower as a nervine, used to support the nervous system and alleviate symptoms of anxiety, nervousness, and insomnia. The tranquilizing effects are attributed to its complex chemical makeup.
The main active components are flavonoids, such as vitexin, isovitexin, orientin, and apigenin, which can make up to 2.5% of the plant’s constituents. The plant also contains minute amounts of indole alkaloids like harman and harmaline, though the quantity is often considered subtherapeutic. Crucially, the plant’s mechanism of action is largely linked to the gamma-aminobutyric acid (GABA) system in the brain, the body’s primary inhibitory neurotransmitter. Passion Flower extracts are thought to enhance GABA’s calming effects, thereby promoting relaxation.
Examining the Scientific Evidence for Blood Pressure Effects
Research suggests that Passion Flower’s ability to lower blood pressure is primarily indirect, stemming from its established anxiolytic properties. While the plant is not a recognized treatment for high blood pressure, managing stress and anxiety can lead to secondary benefits for cardiovascular health. Human trials have shown that stress-induced spikes in heart rate and systolic blood pressure are significantly reduced following the administration of Passion Flower extract.
Animal studies offer a more direct, though species-specific, indication of a hypotensive effect. Extracts from some Passiflora species, including the rind of Passiflora edulis, have been observed to significantly lower systolic blood pressure in spontaneously hypertensive rats. This lowering effect is partly attributed to the presence of GABA within the extract, which reduces blood pressure in hypertensive rats, and partially to the vasodilatory properties of polyphenols like luteolin found in the plant.
The proposed mechanism for direct blood pressure reduction involves both the GABAergic effects and vasodilation induced by the flavonoids. Flavonoids are thought to improve endothelial function and normalize vascular tone through their antioxidant properties, contributing to a hypotensive effect. Despite promising results in animal models and the reduction in stress-related blood pressure in humans, the medical consensus is that Passion Flower cannot be recommended as a stand-alone treatment for clinical hypertension. Its main utility remains its ability to reduce anxiety and nervousness, which can contribute to elevated blood pressure in some individuals.
Safety Profile and Potential Drug Interactions
Passion Flower is generally considered safe for most people when taken orally for short periods (a few weeks to two months). The most commonly reported side effects relate to its sedative nature and include drowsiness, confusion, and dizziness. These effects are typically mild, but caution is needed when operating machinery or driving until the individual knows how the supplement affects them.
A significant concern involves potential interactions with pharmaceutical medications, particularly those affecting the central nervous system or blood clotting. Since Passion Flower acts on the GABA system, combining it with other sedatives (e.g., benzodiazepines, opioids, or alcohol) can lead to additive effects, potentially causing excessive drowsiness or slowed breathing. Furthermore, the plant contains compounds like coumarin, which may theoretically increase the risk of bleeding when taken alongside anticoagulant or antiplatelet drugs, such as warfarin or aspirin.
Individuals taking prescription antihypertensive medications should exercise particular caution. The theoretical additive effect means that taking Passion Flower concurrently with blood pressure-lowering drugs could lead to an excessive drop in blood pressure, known as hypotension. Consulting a healthcare provider is advised before starting Passion Flower, especially for those with pre-existing heart conditions or who are scheduled for surgery, as it may interact with anesthesia.
Appropriate Forms and Dosage
Passion Flower is available in several forms, including liquid extracts, tinctures, capsules, and dried herb for tea preparation. Effectiveness can vary widely depending on the preparation method, as different solvents and processes affect the final concentration of active compounds. For instance, a standardized extract might aim for a specific percentage of flavonoids, such as 0.8% vitexin, to ensure a consistent dosage.
For managing anxiety, typical dosages in clinical studies have ranged from 45 to 90 milligrams of standardized extract daily, or 400 to 500 milligrams of non-standardized extract taken twice a day. For tea, a common recommendation involves steeping about one teaspoon of the dried herb in hot water. Liquid tinctures may be dosed between 10 to 30 drops, taken one to three times daily. Since the scientific literature does not support a specific dose for treating clinical hypertension, these guidelines are based on the traditional use of promoting relaxation and sleep.