No evidence that red tea (Roselle) lowers blood pressure in adults

Hypertension is a serious health problems worldwide. Controlling and lowering blood pressure have a significant benefit to the hypertensive patients because hypertension is a risk factor for stroke, heart disease and cardiovascular disease. A tropical plant called Roselle or red tea has been used as a thirst-quenching drink and for medical purposes. We searched for evidence from clinical studies to evaluate the effectiveness of red tea compared with placebo or no treatment in hypertensive patients. There is a lack of evidence from randomised control trials to demonstrate a benefit of Roselle tea in reducing blood pressure. Rigorous studies need to be done in order to answer this question.

Authors' conclusions: 

There is insufficient evidence to support the benefit of Roselle for either controlling or lowering blood pressure in patients with hypertension. Based on the information of this review, there is a clear need to develop well-designed studies to assess the efficacy of Roselle on hypertensive patients.

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Background: 

Hypertension is considered a serious health problem worldwide. Controlling and lowering blood pressure have a significant benefit to the hypertensive patients because hypertension is a risk factor for stroke, heart disease and cardiovascular disease. A tropical plant called Roselle, or Red Sorrel in English-speaking countries, has been used both as a thirst-quenching drink and for medical purposes.

Objectives: 

To explore the effect of Roselle on blood pressure in hypertensive adult patients.

Search strategy: 

The following databases were searched (Date of most recent search was September 2009):
- Cochrane Database of Systematic Reviews (2nd Quarter 2009)
- DARE (2nd Quarter 2009)
- Ovid MEDLINE (1950 to Present with Daily Update)
- EMBASE (1980 to 2009 Week 22)
- AMED (1985 to May 2009)
- EBSCO CINAHL
- BIOSIS (1969 to 2008)
- AGRICOLA (1970 to May 2009)
- Food Science and Technology Abstract (1969 to 2009 June Week 1)
- International Pharmaceutical Abstracts
- International Bibliographic Information on Dietary Supplements
- Clinical Trials.gov and Current Controlled Trials
- OpenSIGLE
- Hand searching of journals
- ISI Web of Knowledge

Selection criteria: 

We sought randomised control trials (RCTs) evaluating use of any forms of Roselle with placebo or no treatment in hypertensive patients. Change in trough and/or peak systolic and diastolic blood pressure were primary outcomes. Secondary outcomes were withdrawals due to adverse effects, change of pulse pressure and change of heart rate.

Data collection and analysis: 

Two review authors (C Ngamjarus, CN and P Pattanittum, PP) independently scanned titles and abstracts, as well as independently screened the full reports of the potentially relevant studies. At each stage, the results were compared and disagreements were solved by discussion.

Main results: 

No studies were identified that met the inclusion criteria. However, one abstract of an ongoing study is likely to meet the inclusion criteria, when completed.

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