***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Hibiscus sabdariffa L. ( Malvaceae ) has been used in different countries as an antihypertensive . Pharmacological work has demonstrated that this effect is probably produced by a diuretic activity and inhibition of the angiotensin-converting enzyme ( ACE ) . Two clinical trials have confirmed the antihypertensive effect using watery infusions , in which a natriuretic effect was also detected . To compare therapeutic effectiveness , tolerability , and safety , as well as the effect on serum electrolytes and the ACE inhibitory effect of a herbal medicinal product prepared from the dried extract of H. sabdariffa calyxes ( HsHMP ) with those of lisinopril on patients with hypertension ( HT ) , a r and omized , controlled , and double-blind clinical trial was conducted . Patients of either sex , 25 - 61 years of age , with hypertension stage I or II , were daily treated for 4 weeks with the HsHMP , 250 mg of total anthocyanins per dose ( experimental group ) , or 10 mg of lisinopril ( control group ) . Outcome variables included effectiveness ( diastolic blood pressure [ DBP ] reduction , > or= 10 mmHg ) , safety ( absence of pathological modifications in the biochemical tests of hepatic and renal function ) , tolerability ( absence of intense side effects ) , effect on serum electrolytes , and effect on ACE activity .  Basal analysis included 193 subjects ( 100 in the experimental group ) , while outcome variable analysis integrated 171 . Results showed that the experimental treatment decreased blood pressure ( BP ) from 146.48/97.77 to 129.89/85.96 mmHg , reaching an absolute reduction of 17.14/11.97 mmHg ( 11.58/12.21 % , p < 0.05 ) . The experimental treatment showed therapeutic effectiveness of 65.12 % as well as tolerability and safety of 100 % . BP reductions and therapeutic effectiveness were lower than those obtained with lisinopril ( p < 0.05 ) . Under the experimental treatment , the serum chlorine level increased from 91.71 to 95.13 mmol/L ( p = 0.0001 ) , the sodium level showed a tendency to decrease ( from 139.09 to 137.35 , p = 0.07 ) , while potassium level was not modified . ACE plasmatic activity was inhibited by HsHMP from 44.049 to 30.1 Units ( Us ; p = 0.0001 ) . In conclusion , the HsHMP exerted important antihypertensive effectiveness with a wide margin of tolerability and safety , while it also significantly reduced plasma ACE activity and demonstrated a tendency to reduce serum sodium ( Na ) concentrations without modifying potassium ( K ) levels . Further studies are necessary for evaluating the dose-dependency of HsHMP and for detecting lower effective doses ABSTRACT Introduction : The use of herbal medicines including different types of tea is among the different strategies for preventing and controlling the side-effects of diabetes . The aim of the present study was to compare the effect of sour tea and green tea on mildly hypertensive patients with diabetes . Methods : The present study was a r and omized clinical trial in which 100 mildly hypertensive patients with diabetes were r and omly assigned into sour tea group ( ST ) and green tea group ( GT ) . They were instructed to drink sour tea and green tea infusion , respectively , three times a day 2 hr after each meal for 4 weeks . The participants ’ blood pressure was measured at days 1 , 15 , and at the end of study . Results : The systolic pressure of both groups statistically decreased at the end of the study ; it decreased from 123.1 ± 15.5 to 116.8 ± 16.3 mmHg in the ST and from 119.4 ± 15.1 to 114.8 ± 15.9 mmHg in the GT . The diastolic pressure of both groups statistically decreased by the end of the study ; it decreased from 79.4 ± 11.1 to 74.5 ± 9.3 mmHg in the ST and from 78.9 ± 8.3 to 75.3 ± 7.7 mmHg in the GT . The therapeutic effectiveness of tea drinking by the end of intervention was 43.5 % in the ST and 39.6 % in the GT compared to the beginning . Conclusions : The present study revealed that mildly hypertensive type 2 diabetic individuals who drink three glasses of green or sour tea daily for 4 weeks show significant decreased systolic and diastolic blood pressures Epidemiological studies report that quercetin , an antioxidant flavonol found in apples , berries , and onions , is associated with reduced risk of coronary heart disease and stroke . Quercetin supplementation also reduces blood pressure in hypertensive rodents . The efficacy of quercetin supplementation to lower blood pressure in hypertensive humans has never been evaluated . We tested the hypothesis that quercetin supplementation reduces blood pressure in hypertensive patients . We then determined whether the antihypertensive effect of quercetin is associated with reductions in systemic oxidant stress . Men and women with prehypertension ( n = 19 ) and stage 1 hypertension ( n = 22 ) were enrolled in a r and omized , double-blind , placebo-controlled , crossover study to test the efficacy of 730 mg quercetin/d for 28 d vs. placebo .  Blood pressure ( mm Hg , systolic/diastolic ) at enrollment was 137 + /- 2/86 + /- 1 in prehypertensives and 148 + /- 2/96 + /- 1 in stage 1 hypertensive subjects .  Blood pressure was not altered in prehypertensive patients after quercetin supplementation . In contrast , reductions in ( P < 0.01 ) systolic ( -7 + /- 2 mm Hg ) , diastolic ( -5 + /- 2 mm Hg ) , and mean arterial pressures ( -5 + /- 2 mm Hg ) were observed in stage 1 hypertensive patients after quercetin treatment . However , indices of oxidant stress measured in the plasma and urine were not affected by quercetin . These data are the first to our knowledge to show that quercetin supplementation reduces blood pressure in hypertensive subjects . Contrary to animal-based studies , there was no quercetin-evoked reduction in systemic markers of oxidative stress 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 r and omized , 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 st and ardized 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 BACKGROUND To evaluate health benefits attributed to Hibiscus sabdariffa L. a r and omized , open-label , two-way crossover study was undertaken to compare the impact of an aqueous H. sabdariffa L. extract ( HSE ) on the systemic antioxidant potential ( AOP ; assayed by ferric reducing antioxidant power ( FRAP ) ) with a reference treatment ( water ) in eight healthy volunteers . The biokinetic variables were the areas under the curve ( AUC ) of plasma FRAP , ascorbic acid and urate that are above the pre-dose concentration , and the amounts excreted into urine within 24 h ( Ae(0 - 24 ) ) of antioxidants as assayed by FRAP , ascorbic acid , uric acid , malondialdehyde ( biomarker for oxidative stress ) , and hippuric acid ( metabolite and potential biomarker for total polyphenol intake ) . RESULTS HSE caused significantly higher plasma AUC of FRAP , an increase in Ae(0 - 24 ) of FRAP , ascorbic acid and hippuric acid , whereas malondialdehyde excretion was reduced . Furthermore , the main hibiscus anthocyanins as well as one glucuronide conjugate could be quantified in the volunteers ' urine ( 0.02 % of the administered dose ) . CONCLUSION The aqueous HSE investigated in this study enhanced the systemic AOP and reduced the oxidative stress in humans . Furthermore , the increased urinary hippuric acid excretion after HSE consumption indicates a high biotransformation of the ingested HSE polyphenols , most likely caused by the colonic microbiota Considering the high prevalence of hypertension , its debilitating end organ damage , and the side effects of chemical drugs used for its treatment , we conducted this experimental study to evaluate the effect of sour tea ( Hibiscus sabdariffa ) on essential hypertension . For this purpose , 31 and 23 patients with moderate essential hypertension were r and omly assigned to an experimental and control group , respectively . Patients with secondary hypertension or those consuming more than two drugs were excluded from the study .  Systolic and diastolic blood pressures were measured before and 15 days after the intervention . In the experimental group , 45 % of the patients were male and 55 % were female , and the mean age was 52.6 + /- 7.9 years . In the control group , 30 % of the patients were male , 70 % were female , and the mean age of the patients was 51.5 + /- 10.1 years . Statistical findings showed an 11.2 % lowering of the systolic blood pressure and a 10.7 % decrease of diastolic pressure in the experimental group 12 days after beginning the treatment , as compared with the first day . The difference between the systolic blood pressures of the two groups was significant , as was the difference of the diastolic pressures of the two groups . Three days after stopping the treatment , systolic blood pressure was elevated by 7.9 % , and diastolic pressure was elevated by 5.6 % in the experimental and control groups . This difference between the two groups was also significant . This study proves the public belief and the results of in vitro studies concerning the effects of sour tea on lowering high blood pressure . More extensive studies on this subject are needed Obesity is associated with a great diversity of diseases including non-alcoholic fatty liver disease . Our previous report suggested that Hibiscus sabdariffa extracts ( HSE ) had a metabolic-regulating and liver-protecting potential . In this study , we performed a clinical trial to further confirm the effect of HSE .  Subjects with a BMI ≧ 27 and aged 18 - 65 , were r and omly divided into control ( n = 17 ) and HSE-treated ( n = 19 ) groups , respectively , for 12 weeks . Our data showed that consumption of HSE  reduced body weight , BMI , body fat and the waist-to-hip ratio . Serum free fatty acid ( FFA ) was lowered by HSE . Anatomic changes revealed that HSE  improved the illness of liver steatosis . Ingestion of HSE was well tolerated and there was no adverse effect during the trial . No alteration was found for serum α-amylase and lipase . The clinical effect should mainly be attributed to the polyphenols of HSE , since composition analysis showed that branched chain-amino acids , which is associated with obesity , is not obviously high . In conclusion , consumption of HSE  reduced obesity , abdominal fat , serum FFA and improved liver steatosis  . HSE could act as an adjuvant for preventing obesity and non-alcoholic fatty liver To compare the antihypertensive effectiveness of sour tea ( ST ; Hibiscus sabdariffa ) with black tea ( BT ) infusion in diabetic patients , this double-blind r and omized controlled trial was carried out . Sixty diabetic patients with mild hypertension , without taking antihypertensive or antihyperlipidaemic medic 
    Output:
    
These effects were inversely associated with baseline BP values , and were robust in sensitivity analyses .
This meta- analysis of RCTs showed a significant effect of H. sabdariffa in lowering both SBP and DBP .