Hibiscus tea lowers blood pressure

Researchers from Tufts University in Boston reported during the American Heart Association 2008 Scientific Sessions in New Orleans that drinking 3 cups of hibiscus tea daily for 6 weeks lowered systolic blood pressure (SBP) by about 7 mmHg in prehypertensive and mildly hypertensive subjects.

Categories of high blood pressure

• Prehypertension: 120/80 up to 139/89 mmHg
• Stage 1 hypertension (mild): 140/90 up to 159/99 mmHg.
• Stage 2 hypertension: 160/100 mmHg or greater

First, the details.

• 65 generally healthy adults with SDP of 120 to 150 mm Hg and diastolic blood pressure (DBP) less than 95 mmHg participated.
• They took no supplements or medicines that could affect their blood pressure.
• They were randomly assigned to take 3, 8-oz servings daily of hibiscus tea for 6 weeks or a placebo beverage.
• Hibiscus tea was prepared by brewing 1 tea bag (1.25 grams of dried hibiscus calyces) in 8 oz of boiled water for 6 minutes; the tea bag was then removed.
• The placebo was prepared by adding a small amount of hibiscus-flavored concentrate to 8 oz of water.
• The beverage (hot or cold) was consumed within 12 hours of preparation with or without milk and a sweetener of the subjects’ choice.
• The placebo beverage had no anthocyanins — believed to be the active component in hibiscus.
• Changes in SBP, DBP, and mean arterial pressure (MAP; approximately the average blood pressure reading) were recorded.
• Neither the researchers nor participants knew the treatment given — double-blind.

And, the results.

• After 6 weeks, drinking hibiscus tea was associated with significantly lower SBP vs placebo (-7.2 vs. -1.3 mmHg).
• DBP and MAP did not differ from placebo.
• Among those with prehypertension, the change with hibiscus tea was almost double that seen in the overall group (-13.2 mmHg).
• In the prehypertension group, differences from placebo with regard to SBP, DBP, and MAP were all statistically significant.
• No side effects were reported.

The bottom line?
So, a person walks into the doctor’s office with a SBP of 130 mmHg (prehypertension). After 6 weeks of drinking hibiscus tea, their SBP is 117 mmHg with no side effects. And they no longer have “high blood pressure.”

The same person, 6 weeks after taking thiazides, beta-blockers, angiotensin converting enzyme (ACE) inhibitors, angiotensin II receptor antagonists, or a calcium channel blockers has lowered their SBP by about 9 mmHg, according to one study. They have a SBP of 121 mmHg, the potential for side effects listed here, and they still have prehypertension.

These results support an earlier study by researchers at Instituto Mexicano del Seguro Social (IMSS) in Argentina, México, which compared Hibiscus sabdariffa extract to the ACE inhibitor, lisinopril (Prinivil) in people with Stage 1 and 2 hypertension. In that study, H. sabdariffa extract treatment resulted in a significant reduction in SBP (-17 mmHg).

Although less than the blood pressure reduction achieved with lisinopril, the authors concluded that H. sabdariffa extract, “exerted important antihypertensive effectiveness with a wide margin of tolerability and safety, while it also significantly reduced plasma ACE activity and demonstrated a tendency to reduce serum sodium concentrations without modifying potassium levels.”

Perhaps it’s time to revise the Joint National Committee (JNC) recommendations for the treatment of high blood pressure.

11/14/08 16:12 JR