articleAn evaluation of the hypolipidemic effect of an extract of Hibiscus Sabdariffa leaves in hyperlipidemic Indians a double blind placebo controlled trial

Hibiscus sabdariffa is used regularly in folk medicine to treat various conditions.  The study was a double blind, placebo controlled, randomized trial. Sixty subjects with serum LDL values in the range of 130 190 mg/dl and with no history of coronary heart disease were randomized into experimental and placebo groups. The experimental group received 1 gm of the extract for 90 days while the placebo received a similar amount of maltodextrin in addition to dietary and physical activity advice for the control of their blood lipids. Anthropometry, blood biochemistry, dietary and physical activity were assessed at baseline, day 45 and day 90.  While body weight, serum LDL cholesterol and triglyceride levels decreased in both groups, there were no significant differences between the experimental and placebo group.  It is likely that the observed effects were as a result of the patients following the standard dietary and physical activity advice. At a dose of 1 gm/day, hibiscus sabdariffa leaf extract did not appear to have a blood lipid lowering effect.  This plant is well known in Asia and Africa and is commonly used to make jellies, jams and beverages. In folk medicine, it has been used to treat hypertension  inflammatory disease [4] and cancer  The flowers of Hibiscus sabdariffa contain anthocyanins, flavonoids and polyphenols [6] Studies have highlighted the role of polyphenolic acid, flavonoids and anthocyanins that may act as antioxidants or have other mechanisms contributing to the cardio protective actions [7,8] Correspondence: rebecca@sjri.res.in 1 Division of Nutrition, St. John's Research Institute, St. John's National Academy of Health Sciences, Bangalore 560034, India Full list of author information is available at the end of the article (c) 2010 Kuriyan et al; licensee BioMed Central Ltd.  Page 2 of 8 Animal studies have demonstrated that the extract of Hibiscus sabdariffa inhibited low density oxidation in vitro and decreased serum cholesterol levels in cholesterol fed rats and rabbits [9,10] The only study in humans by Lin et al. 2007  demonstrated that 2 capsules of hibiscus sabdariffa extract (1 g) given 3 times a day (for a total of 3 g/day) significantly lowered serum cholesterol in hypercholesterolemic patients. However, this study was done for a short duration (4 weeks) and importantly, it was not clear whether the body weight or dietary habits changed during the course of the treatment. Thus, the aim of the present study was to carefully evaluate the efficacy of an aqueous extract of Hibiscus sabdariffa leaves on the blood lipid levels of patients with hyperlipidemia requiring only dietary or lifestyle management.  Subjects The study was a double blind, placebo controlled, randomized trial. Sixty subjects with serum LDL values in the range of 130 190 mg/dl and with no history of coronary heart disease were recruited into the study. Three subjects dropped out of the study and 57 subjects completed the study, such that there were 29 subjects in the placebo group and 28 subjects in the experimental group. The subjects (31 male and 26 female subjects) were aged between 35 and 60 years. Exclusion criteria were the presence of any chronic disease and the concurrent use of any medication for the control of lipid levels. The subjects were recruited from the Nutrition and Lifestyle Management Clinic, St. John's Medical College Hospital, Bangalore. After recruitment, the subjects were randomly assigned into the placebo or experimental group. The study was approved by the institutional ethical review committee of St. John's Medical College and informed consent was obtained from the subjects. Experimental Protocol The extract of Hibiscus Sabdariffa was obtained from the plant Hibiscus Sabdariffa Linn, which was cultivated by Green Chem, Bangalore, India. This is a common edible plant grown in Tamil Nadu and Andhra Pradesh. The leaves were harvested, sun dried for 3 4 days, powdered and stored under dry conditions. The extract was prepared using a Hydro Alcoholic mixture (50% Ethyl alcohol and 50% water) and heating at 70 75degC for about 4 hours in a closed system by re pumping the extract to the herb bed. This process was repeated twice. The stability of hibiscus extract was tested by heating it at 100 105degC for 1 hr, 2 hr, 4 hr, 8 hr and 16 hours and checking the product profile and estimating the phenolic compound content. It was observed that there was no change in the phenolic compound content and no change in the product profile. After heating, the extracts were then transferred to a thin film evaporator. It was concentrated initially to remove the solvent and then concentrated under vacuum to remove water at temperature less than 60degC. The product was purified and dried using a spray drier unit. The product was then powdered in a multimill to a fine mesh size. The powder was then sieved using a sifter to make uniform particle size, mixed in a blender to make a uniform and homogenous mixture. It was then packed in food grade, virgin, double polythene bags. Twelve kg of Hibiscus sabdariffa dried leaves or 60 kg of fresh leaves produced 1 g of the extract. Maltodextrin capsules (1 g/day) were used as placebo, and both capsules were prepared by Green Chem, Bangalore, India. Prior to the intervention, the subjects underwent baseline investigations which included anthropometric, biochemical, dietary and physical activity assessment. The extract was administered as two 500 mg capsules daily (1 g/day) for 90 days, during which the subjects reported weekly to the Nutrition Clinic to record their body weight, collect their weekly capsule supply and report adverse events, if any. The compliance of the subjects to the ingestion of capsules was documented every week when they reported to the Nutrition Clinic. The subjects were provided with a capsule calendar on which they were required to tick mark boxes relating to the daily intake of capsules and also to note down any missed capsule. The calendar and the 'missed' pill count were monitored every week. All the study subjects were provided with standard dietary and physical activity advice for the control of their lipid levels using the National Cholesterol Education programme (NCEP) guidelines. In case of overweight patients, advice was provided to achieve moderate weight loss of about 5% The standard advice also included regular physical activity, with dietary strategies to increase dietary fiber (legume, fruits and vegetables) and decrease intake of fat and saturated fat. The compliance of the subjects to the prescribed diet and physical activity was assessed weekly by asking the subjects to rate their compliance on a scale of 0 100% Anthropometric measurements Body weight, height, skinfold thickness and mid arm, waist and hip circumferences measurements were standardized  Skinfold measurements in triplicates were carried out using Holtain skinfold calipers, at four sites (i.e. biceps, triceps, subscapular and suprailiac. The average sum of four skinfold measurements were used to compute body density using the age and gender specific equation [13] and percent body fat was derived from body density  These equations were previously validated in a group of Indian men and women  The Kuriyan et al. BMC Complementary and Alternative Medicine 2010, 10:27 http:/www.biomedcentral.com/1472 6882/10/27 Page 3 of 8 measurements were taken at baseline and repeated at day 45 and day 90 of the intervention period. Biochemical measurements Fasting and post prandial blood glucose (collected 2 hours after breakfast) hemoglobin and lipid profile were measured at baseline, day 45 and day 90 of the study period. The blood glucose, triglyceride, total and HDL cholesterol were estimated by spectrophotometric assays on automated clinical chemistry analyzer Dimension RxL (Dade Behring, Newark, USA) while LDL cholesterol was calculated from primary measurements using the empirical formula of Friedewald equation  All assays were calibrated by use of Dade Dimension human calibrator (Dade Behring Inc, Newark, USA) The analytical coefficient of variation (inter assay) for total cholesterol, triglycerides and HDL choleste