High Blood Pressure & Hibiscus Tea

I read that hibiscus tea or extract is almost as effective as a drug for lowering blood pressure. My question is: How much of the tea do you need to drink a day for it to be therapeutically effective?

The web site I visited at http://www.seniorlifehealth.com/productcart/pc/viewContent.asp?idpage=29
says "In a recent study, researchers found that after 4 weeks of a treatment of 250mm of hibiscus extract, the systolic blood pressure was lowered by 11.58% and diastolic blood pressure by 12.21%.

The web site at: http://www.associatedcontent.com/article/376700/lower_your_blood_pressure_sho...
says ". Hibiscus tea has been used for centuries as an herbal remedy for high blood pressure. Recent research has proven it to be effective. Fifty-four participants, all over the age of fifty, and all on blood pressure medication, were given either hibiscus or regular tea to drink one hour before having their blood pressure taken. After twelve days, those who drank the hibiscus tea had an average drop in systolic blood pressure of 11.7% and a 10.7% drop in diastolic blood pressure below their readings at the beginning of the study. Those drinking regular tea had no such lowering of blood pressure. All participants stopped taking their blood pressure medication one week prior to the study."

Now this mentions "tea" but doesn't say how much to drink?? We bought tea... not extract.

Anyone know how much to drink a day??