Research - Hibiscus Sabdariffa
Hibiscus Extract Decreases Blood Pressure to a Greater Extent than Hydrochlorothiazide in Nigerian Patients with Mild to Moderate Hypertension
Nwachukwu DC, Aneke E, Nwachukwu NZ, Obika L, Nwagha UI, Eze AA. Effect of Hibiscus sabdariffa on blood pressure and electrolyte profile of mild to moderate hypertensive Nigerians: a comparative study with hydrochlorothiazide. Niger J Clin Pract. November-December 2015;18(6):762-770.
Hypertension is one of the risk factors of cardiovascular disease and the main risk factor for stroke. It affects approximately 20% of the world's population with more severe sequelae among individuals of African descent. Hypertension is likely the result of many physiologic changes which include changes in electrolyte concentrations in the blood. Blood concentrations of sodium and chloride ions are higher and potassium ions are lower in patients with hypertension than in individuals with normal blood pressure. One common method of treating hypertension involves the reduction of blood electrolytes with prescription medications, such as hydrochlorothiazide (HCTZ). Studies in animal models and in humans provide evidence that hibiscus (Hibiscus sabdariffa, Malvaceae) extracts can help lower blood pressure. The goal of this randomized, controlled study was to compare the effects of a hibiscus extract and HCTZ on blood pressure and electrolyte balance in Nigerian patients with mild to moderate hypertension.
Patients were recruited from the Medical Outpatient Clinic of the Enugu State University Teaching Hospital in Enugu, Nigeria. Patients were included if they had newly diagnosed mild to moderate hypertension. Patients were excluded if they were taking prescription medications for hypertension; had diabetes, nephropathy, hepatic disease, cardiopathy, or cancer; were pregnant; smoked; or were alcoholics. Patients were randomly assigned to 1 of 3 groups, which included a placebo group, a group that drank hibiscus tea, and a group that took HCTZ. Each treatment was administered once per day before breakfast for 4 weeks. The placebo contained an extract of black currant (Ribes nigrum, Grossulariaceae) (GlaxoSmithKline®; London, UK) that was diluted until the solution matched the color of the hibiscus extract. A preliminary study found that the black currant dose had no effect on blood pressure. For each day's supply of hibiscus extract, 20 g of dried calyces, obtained from the Ogbete Main Market in Enugu, were ground into a powder and then infused with 1 L of boiling water for 30 minutes. The extract was filtered and stored in the refrigerator. The extract was standardized to a total anthocyanin concentration of 10.04 mg from 20 g of calyces in 1 L. The HCTZ group took 25 mg of HCTZ (Esidrex®; Novartis Pharmaceuticals; Basel, Switzerland). Blood pressure, serum electrolytes, and urine electrolytes were measured at baseline; at 1, 2, 3, and 4 weeks during the study; and 1 week after the study ended. Data were analyzed with one-way analysis of variance and Bonferroni tests.
Eighty patients were recruited for the study, of which 75 completed the study. Both hibiscus and HCTZ decreased systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) compared to placebo. HCTZ significantly reduced SBP by 12.9 ± 4.31 mmHg and DBP by 9.50 ± 2.06 mmHg (P < 0.05 and P < 0.001, respectively). There was an even greater reduction in SBP (17.08 ± 5.12 mmHg) and DBP (11.12 ± 3.12 mmHg) with the hibiscus treatment than with HCTZ, and these measures also were significantly lower than the placebo (P < 0.001 for both). MAP also was significantly lower in the hibiscus and HCTZ groups than in the placebo group at the end of the study (P < 0.001 and P < 0.01, respectively). Serum sodium and potassium were significantly lower at the end of the study in both treatment groups when compared to placebo (P < 0.001). In addition, serum sodium was still significantly lower in the hibiscus group than in the placebo group 1 week after the end of the dosing (P < 0.001), though in the HCTZ group it returned to baseline levels. It should be noted that serum potassium was significantly lower in the hibiscus group than in the placebo group at baseline (P < 0.001). Serum chloride increased significantly with hibiscus treatment and decreased significantly with HCTZ treatment (P < 0.001 for both). HCTZ resulted in a significant increase in urine sodium, potassium, and chloride concentrations after 4 weeks (P < 0.001, P < 0.001, and P < 0.01, respectively). The hibiscus treatment resulted in a decrease in the urine concentration of potassium ions in weeks 2-5 (P < 0.001 for all). Again, it should be noted that urine concentrations of sodium, potassium, and chloride ions were lower in the hibiscus group than in the placebo group at baseline (P < 0.01, P < 0.01, and P < 0.001, respectively).
Hibiscus extract decreased SBP, DBP, and MAP to a greater extent than HCTZ in Nigerian patients with mild to moderate hypertension. HCTZ decreased serum concentrations of sodium, potassium, and chloride ions and increased urine concentrations of these ions. HCTZ is a diuretic, and these results are in keeping with the function of HCTZ. The patients in the hibiscus group had significantly lower baseline concentrations of serum potassium ions and urine sodium, potassium, and chloride ions than did patients in the placebo group. Because of this bias at baseline, it is difficult to draw conclusions about the effect of hibiscus on these electrolytes. Despite these discrepancies, the hibiscus treatment did reduce the serum concentration of sodium ions and the urinary concentration of potassium ions (a potassium-sparing effect), even a week after dosing stopped. Hibiscus does not affect serum and urine concentrations of dissolved ions in the same way as HCTZ. Evidence has shown that hibiscus may operate via many mechanisms and not only as a diuretic. Previous studies have shown that hibiscus appears to act as a vasodilator and diuretic, suppresses uptake of calcium ions, and inhibits angiotensin-converting enzyme. The study was limited by the small sample size, lack of description of blinding of the placebo and hibiscus groups, and the inability to blind the HCTZ group. The authors also recommend quantifying the types and concentrations of anthocyanins in the hibiscus extract.
—Cheryl McCutchan, PhD
Source : American Botanical Council - HerbClip
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Hibiscus Supplementation Resulted in a Decrease in Waist Circumference, Percent Body Fat, Free Fatty Acids, and Waist-to-hip Ratio in Obese Subjects
Chang HC, Peng CH, Yeh DM, Kao ES, Wang CJ. Hibiscus sabdariffa extract inhibits obesity and fat accumulation, and improves liver steatosis in humans. Food Funct. April 2014;5(4):734-739.
The prevalence of obesity has increased throughout the industrialized world over the past 3 decades. Obesity is correlated with a number of serious illnesses, including cardiovascular disease, type 2 diabetes, cancer, and metabolic syndrome. Individuals with metabolic syndrome generally have higher than normal body fat and abdominal fat, high serum levels of triglycerides and low-density lipoproteins (LDLs), low serum levels of high-density lipoproteins (HDLs), and low free fatty acid (FFA) flux. Liver steatosis is the accumulation of fat in the liver and is often seen in obese individuals. In severe cases of liver steatosis, the liver can become inflamed and cell death can occur. Hibiscus (Hibiscus sabdariffa) is often used for the treatment and prevention of hypertension, inflammation, and liver disease. Hibiscus has been shown to inhibit LDL oxidation and decrease serum levels of cholesterol in rats and rabbits. These effects are suggested to be due to the high levels of anthocyanins, flavonoids, and phenolic acid present in hibiscus extracts. The effect of hibiscus on weight, body fat, serum lipids, and liver enzymes was measured in this double-blind, randomized, controlled study.
Obese subjects (body mass index [BMI] ≥ 27 kg/m2) aged 18-65 who had been diagnosed with fatty liver were recruited to the Chung Shan Medical University Hospital in Taichung City, Taiwan for a study that took place from July 2007 to June 2009. Subjects were excluded if they were pregnant; taking medication to treat fatty liver; consumed more than 19 g of alcohol per day; had high alanine transaminase (ALT) or bilirubin levels; had a history of kidney, cardiovascular, or endocrine disease; or were taking over-the-counter, prescription, or alternative medications.
Subjects were randomly divided into 2 groups that consumed either 2 hibiscus tablets (450 mg hibiscus and 50 mg starch) or 2 placebo tablets (500 mg starch), 3 times per day after meals for 12 weeks. The hibiscus tablets contained aqueous, filtered, dried extracts of hibiscus flowers. The extract contained 1.43% flavonoids, 2.5% anthocyanins, and 1.7% phenolic acid. Height, waist-to-hip ratio, BMI, and body fat were measured at the beginning and end of the study, and weight at 0, 6, and 12 weeks. Serum lipids, glucose, ALT, aspartate transaminase (AST), and a number of other serum biomarkers were measured at the beginning and end of the study. An ultrasound of the liver was conducted, and a fatty liver score (FS) was calculated at the beginning and end of the study. A lower FS indicates a healthier liver. Unpaired student t-tests and paired student t-tests were used to analyze the data.
Of the 40 subjects that began the study, 4 were removed for non-compliance, leaving 17 subjects in the placebo group and 19 in the treatment group. At the beginning of the study, baseline levels of ALT and AST were significantly higher in the treatment group than in the control group (P = 0.033 and P = 0.049, respectively). No other significant differences were found between the groups at the beginning of the study.
There was a significant decrease in waist circumference, percent body fat, and waist-to-hip ratio in the hibiscus treatment group compared to the control group over the course of the study (P < 0.038, P < 0.044, and P < 0.026, respectively). On average, approximately 1.2 kg was lost in the treatment subjects compared to 0.7 kg in the control group, a statistically insignificant difference. There was no significant difference in lipids between the 2 groups. FFA decreased significantly in the hibiscus group compared to the control group (P = 0.026).
Hibiscus supplementation led to a decrease in waist circumference, percent body fat, FFA, and waist-to-hip ratio over the 12-week course of this study. Hibiscus contains a number of secondary compounds that have been shown to affect weight loss and fat metabolism, including galloyl ester, chlorogenic acid, caffeic acid, quercetin, tiliroside, and anthocyanins. The authors note that the dosage used may be too low to affect blood lipids and suggest further research on hibiscus dosage level.
–Cheryl McCutchan, PhD
Source : American Botanical Council
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Hibiscus Sabdariffa L. Tea (Tisane) Lowers Blood Pressure in Prehypertensive and Mildly Hypertensive Adults
- Diane L. McKay 5 , * ,
- C-Y. Oliver Chen 5 ,
- Edward Saltzman 6 , and
- Jeffrey B. Blumberg 5
In vitro studies show Hibiscus sabdariffa L., an ingredient found in many herbal tea blends and other beverages, has antioxidant properties, and, in animal models, extracts of its calyces have demonstrated hypocholesterolemic and antihypertensive properties. Our objective in this study was to examine the antihypertensive effects of H. sabdariffa tisane (hibiscus tea) consumption in humans. A randomized, double-blind, placebo-controlled clinical trial was conducted in 65 pre- and mildly hypertensive adults, age 30–70 y, not taking blood pressure (BP)-lowering medications, with either 3 240-mL servings/d of brewed hibiscus tea or placebo beverage for 6 wk. A standardized method was used to measure BP at baseline and weekly intervals. At 6 wk, hibiscus tea lowered systolic BP (SBP) compared with placebo (−7.2 ± 11.4 vs. −1.3 ± 10.0 mm Hg; P = 0.030). Diastolic BP was also lower, although this change did not differ from placebo (−3.1 ± 7.0 vs. −0.5 ± 7.5 mm Hg; P = 0.160). The change in mean arterial pressure was of borderline significance compared with placebo (−4.5 ± 7.7 vs. −0.8 ± 7.4 mm Hg; P = 0.054). Participants with higher SBP at baseline showed a greater response to hibiscus treatment (r = −0.421 for SBP change; P = 0.010). No effects were observed with regard to age, gender, or dietary supplement use. These results suggest daily consumption of hibiscus tea, in an amount readily incorporated into the diet, lowers BP in pre- and mildly hypertensive adults and may prove an effective component of the dietary changes recommended for people with these conditions.
Source : The Journal of Nutrition
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