A study of hibiscus tea on blood pressure (BP) was presented at the American Heart Association’s 2008 meeting in New Orleans. Dr. Diane L. McKay at Tufts University conducted a randomized placebo-controlled, double-blind study of 65 people ages 30 to 70 with systolic BP between 120 to 150 mmHg and diastolic BP no higher than 95mmHg. None were taking BP drugs. Half the subjects consumed 3 cups of hibiscus tea for 6 weeks and the other half received a placebo tea drink.

The hibiscus tea was prepared by brewing 1.25g of dried hibiscus calyces in 1 cup of water for 6 minutes. The subjects were told to consume the drinks within 12 hours of preparation either hot or cold. In subjects with a systolic BP of 130 to 150mmHg the average drop in systolic BP was 13.2mmHg after 6 weeks compared to only a drop of 1.3mmHg in the control group.A drop of just 3mmHg in SBP would be expected to cut the risk of dying from a stroke, heart attack or from any cause by 8%, 5% and 4%, respectively. Assuming the drop in BP observed in her study could be sustained, this could cut the risk of having a stroke, heart attack, or dying from any cause by about 32%, 20%, and 16%, respectively. The BP-lowering effect of hibiscus tea appears as great as any BP-drug. In Nigeria where people consume far more hibiscus daily there has been no evidence of harm.More than 60 million Americans have hypertension (HTN) and many millions more have pre-HTN. Treating all these people with drugs to lower their BP is very costly and all HTN medications have adverse metabolic effects and unpleasant side effects. Nearly all people with pre-HTN and the vast majority of those with HTN could get off all their BP drugs if they adopted a healthy diet and exercise program. For those who still need something more than diet and exercise to bring their elevated blood pressure down a common herbal tea may be as effective as any of the BP drugs.Bottom Line: Hibiscus tea appears to be a safer yet effective alternative to prescription drugs for lowering elevated BP but more research is needed.By James J. Kenney, PhD, RD, FACN.