Sorrel (Hibiscus sabdariffa), often called roselle or “sour tea,” has a long history of use in traditional medicine across Africa, Asia, and the Caribbean. The bright red calyxes are frequently steeped to create a tart, refreshing beverage. Traditionally, this infusion has been used to address various health complaints, including cardiovascular issues. Current scientific inquiry is focused on evaluating the impact of sorrel consumption on high blood pressure (hypertension). This article examines the evidence from clinical research to determine the effectiveness and safety of incorporating sorrel into a blood pressure management regimen.
Clinical Findings on Sorrel and Hypertension
Multiple human clinical trials have investigated the effect of consuming sorrel, typically as a tea or extract, on blood pressure levels. The consistent finding is that regular consumption leads to a significant reduction in both systolic and diastolic blood pressure in individuals with prehypertension or mild-to-moderate hypertension. A meta-analysis showed that sorrel consumption resulted in a stronger reduction in systolic blood pressure compared to a placebo, with the most pronounced effects seen in those who had higher baseline readings.
The reported reductions are often clinically meaningful. For example, some trials demonstrated mean systolic blood pressure reductions of 7 to 17 mmHg and diastolic reductions of 4 to 12 mmHg over periods ranging from a few weeks to a few months. In comparative studies, the blood pressure-lowering effect of sorrel extract was similar to that achieved by certain prescription antihypertensive medications, such as captopril or lisinopril, particularly in patients with mild hypertension. This suggests sorrel may offer a supplementary approach for managing elevated blood pressure, especially in its earlier stages.
How Sorrel Affects Blood Pressure
The beneficial effects of sorrel on blood pressure are attributed to the synergistic action of various bioactive compounds present in its calyxes. The deep red color of the infusion comes from a high concentration of polyphenols, particularly anthocyanins. These compounds act as potent antioxidants and are the primary drivers of the hypotensive effect.
One proposed mechanism involves the inhibition of the Angiotensin-Converting Enzyme (ACE), which is a target of a common class of blood pressure medications. By mimicking ACE inhibitors, sorrel compounds help relax blood vessels, leading to vasodilation and a subsequent drop in blood pressure. Sorrel also exhibits a mild diuretic effect, promoting the excretion of water and sodium, thereby decreasing the total fluid volume. Furthermore, the compounds in sorrel may enhance the release of nitric oxide from the endothelium, signaling the smooth muscles in blood vessel walls to relax and improving blood flow.
Recommended Preparation and Dosage
Sorrel is most commonly consumed as an aqueous infusion, or tea, prepared from the dried calyxes of the plant. Research protocols have utilized a range of preparation methods and dosages for health purposes. A common preparation involves steeping approximately 10 grams of dried sorrel calyxes in water, often resulting in an infusion standardized to a specific level of active compounds.
Clinical studies have used dosages of sorrel tea made from 1.25 grams to 3.75 grams of dried calyxes consumed daily, often divided into two or three cups. Other successful trials have tested dosages of up to 10 grams of dried calyxes per day, typically consumed as a decoction or infusion. Consistency is important, as the blood pressure-lowering effects are observed after a few weeks of continuous daily consumption. Standardized extracts in capsule form are also available, with effective daily doses in trials ranging from 100 mg to 500 mg, depending on the concentration of anthocyanins.
Important Considerations for Consumption
While sorrel is generally considered safe in typical food amounts, individuals with high blood pressure must consider potential interactions, especially if they are already taking prescription medication. Sorrel’s ability to inhibit ACE and act as a diuretic suggests it could have an additive effect when combined with certain antihypertensive drugs. Taking sorrel along with prescription ACE inhibitors, such as lisinopril, or with diuretics could potentially cause blood pressure to drop too low, a condition known as hypotension.
Sorrel may also interact with other medications, including those for diabetes, by potentially lowering blood sugar levels. Furthermore, it has been shown to alter the metabolism of certain drugs, such as the antimalarial chloroquine and the pain reliever diclofenac, which could reduce their effectiveness. Side effects are usually mild, but can include temporary dizziness due to the drop in blood pressure or mild gastrointestinal upset. Anyone with a pre-existing medical condition or who is taking regular medication, particularly for blood pressure, should consult with a healthcare professional before incorporating sorrel into their daily regimen.