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Monday, 1 July 2013

Does roselle tea is as effective as Captopril ??


The roselle (Hibiscus sabdariffa) is a species of Hibiscus native to the Old World tropics, used for the production of bast fibre and as an infusion. It is an annual or perennial herb or woody-based subshrub, growing to 2–2.5 m (7–8 ft) tall. The leaves are deeply three- to five-lobed, 8–15 cm (3–6 in) long, arranged alternately on the stems.

The flowers are 8–10 cm (3–4 in) in diameter, white to pale yellow with a dark red spot at the base of each petal, and have a stout fleshy calyx at the base, 1–2 cm (0.39–0.79 in) wide, enlarging to 3–3.5 cm (1.2–1.4 in), fleshy and bright red as the fruit matures. It takes about six months to mature.

Roselle is associated with traditional medicine and is reported to be used as treatment for several diseases such as hypertension and urinary tract infections.

The effectiveness of Hibiscus sabdariffa L. (HS) in the treatment of risk factors associated with cardiovascular disease is assessed in this review by taking a comprehensive approach to interpreting the randomized clinical trial (RCT) results in the context of the available ethnomedical, phytochemical, pharmacological, and safety and toxicity information. HS decoctions and infusions of calyxes, and on occasion leaves, are used in at least 10 countries worldwide in the treatment of hypertension and hyperlipidemia with no reported adverse events or side effects. HS extracts have a low degree of toxicity with a LD50 ranging from 2,000 to over 5,000mg/kg/day. There is no evidence of hepatic or renal toxicity as the result of HS extract consumption, except for possible adverse hepatic effects at high doses. There is evidence that HS acts as a diuretic, however in most cases the extract did not significantly influence electrolyte levels. Animal studies have consistently shown that consumption of HS extract reduces blood pressure in a dose dependent manner. In RCTs, the daily consumption of a tea or extract produced from HS calyxes significantly lowered systolic blood pressure (SBP) and diastolic blood pressure (DBP) in adults with pre to moderate essential hypertension and type 2 diabetes. In addition, HS tea was as effective at lowering blood pressure as the commonly used blood pressure medication Captropril, but less effective than Lisinopril. Total cholesterol, low-density lipoprotein cholesterol (LDL-C), and triglycerides were lowered in the majority of normolipidemic, hyperlipidemic, and diabetic animal models, whereas high-density lipoprotein cholesterol (HDL-C) was generally not affected by the consumption of HS extract. Over half of the RCTs showed that daily consumption of HS tea or extracts had favorable influence on lipid profiles including reduced total cholesterol, LDL-C, triglycerides, as well as increased HDL-C. Anthocyanins found in abundance in HS calyxes are generally considered the phytochemicals responsible for the antihypertensive and hypocholesterolemic effects, however evidence has also been provided for the role of polyphenols and hibiscus acid. A number of potential mechanisms have been proposed to explain the hypotensive and anticholesterol effects, but the most common explanation is the antioxidant effects of the anthocyanins inhibition of LDL-C oxidation, which impedes atherosclerosis, an important cardiovascular risk factor. This comprehensive body of evidence suggests that extracts of HS are promising as a treatment of hypertension and hyperlipidemia, however more high quality animal and human studies informed by actual therapeutic practices are needed to provide recommendations for use that have the potential for widespread public health benefit.
 
Although Roselle has well documented hypotensive effects, there is currently insufficient evidence to support the benefit of Roselle for either controlling or lowering blood pressure due to a lack of of well designed studies that measure the efficacy of Roselle on patients with hypertension.
Ngamjarus, Chetta; Pattanittum, Porjai; Somboonporn, Charoonsak (2010). "Roselle for hypertension in adults". In Ngamjarus, Chetta. Cochrane Database of Systematic Reviews. doi:10.1002/14651858.CD007894.pub2

A double blind, placebo controlled, randomized trial was conducted to determine the effect of Roselle leaf extract on a group of 60 subjects with serum LDL values in the range of 130-190 ml/dl (<130 ml/dl is a goal value for most patients) and no history of coronary heart disease. The experimental group received 1g of Roselle leaf extract while the placebo group received a similar amount of maltodextrin in addition to dietary and physical activity advice. Both groups had decreases in body weight, LDL cholesterol, and triglycerides that can likely be attributed to the dietary and physical activity advice. At a dose of of 1g/day, Roselle leaf extract did not appear to have a blood lipid lowering effect.

Also Hibiscus sabdariffa has shown in vitro antimicrobial activity against E. coli.
Fullerton M, Khatiwada J, Johnson JU, Davis S, Williams LL"Determination of Antimicrobial Activity of Sorrel (Hibiscus sabdariffa) on Esherichia coli O157:H7 Isolated from Food, Veterinary, and Clinical Samples." J Med Food. 2011 May 6

A review stated that specific extracts of H. sabdariffa exhibit activities against atherosclerosis, liver disease, cancer, diabetes and other metabolic syndromes.
Lin, HH; Chen, JH; Wang, CJ (2011). "Chemopreventive properties and molecular mechanisms of the bioactive compounds in Hibiscus sabdariffa Linne". Current medicinal chemistry 18 (8): 1245–54. PMID 21291361.


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