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Sour Tea for Diabetes and Hypertension

June 28, 2013 Written by JP       [Font too small?]

Recently, a Persian reader of this site relayed a positive testimonial about a traditional drink from his homeland called “sour tea”. When I was listening to his account of how he used this tart, vibrantly colored beverage to avert diabetes and high blood pressure, I thought to myself – sour tea? It sounds sort of familiar, but I can’t place it. As it turns out, sour tea is the commonly used name in Iran for hibiscus tea. The next question that popped into my mind was whether this gentleman’s experience could be bolstered and substantiated by reviewing the medical literature.

As it turns out, sour tea (Hibiscus sabdariffa) has been found effective in multiple trials involving hypertensive patients. What’s more, at least three of the studies have specifically involved type 2 diabetics. The latest, appearing in the June 2013 edition of the Journal of Dietary Supplements, compared the hypotensive activity of green tea vs. sour tea. The lead researchers instructed 100 diabetic, mildly hypertensive participants to drink either 3 glasses/day green tea or sour tea, 2 hours after each meal for a total of 4 weeks. Blood pressure was measured on the first day, the 15th day and at the end of the trial. Both green tea and sour tea use resulted in a meaningful reduction in blood pressure. In the green tea group, there was an approximately 4% decline in diastolic and systolic blood pressure. Consumption of sour tea resulted in an over 7% and 5% reduction in diastolic and systolic blood pressure respectively. These compelling findings are corroborated by several other, peer reviewed studies dating back to 1999.

In order for a natural substance to be welcomed into the mainstream of medicine, mechanisms of action generally need to be established. Simply put, many physicians want to know how any given remedy works. Thankfully, in the case of sour tea, this has been largely established in several carefully controlled experiments. What’s more, not only do we know how sour tea lowers hypertension, but we also have a good idea why it benefits diabetics and those with metabolic syndrome. On the blood pressure front, sour tea functions in a similar manner as certain antihypertensive medications. Namely, it has an ACE inhibiting and diuretic effect. However, unlike comparable medications, sour tea does not appear to induce the same side effects. In terms of its antidiabetic activity, this comes about because of an interference with the digestion of certain carbohydrates and an improvement in insulin sensitivity. As an added bonus, multiple studies have discovered that sour tea alters lipid profiles (lowers LDL or “bad” cholesterol and triglycerides, raises HDL or “good” cholesterol) in such a manner as to lower cardiovascular risk. Maybe it’s time to reconsider this tea’s name!

Note: Please check out the “Comments & Updates” section of this blog – at the bottom of the page. You can find the latest research about this topic there!

To learn more about the studies referenced in today’s column, please click on the following links:

Study 1 - Effect of Green & Sour Tea on Blood Pressure of Patients w/ Type 2 (link)

Study 2 - Effects of Sour Tea (Hibiscus Sabdariffa) on Lipid Profile & Lipoproteins (link)

Study 3 - The Effects of Sour Tea (Hibiscus Sabdariffa) on Hypertension in(link)

Study 4 – The Effect of Sour Tea (Hibiscus S.) on Essential Hypertension (link)

Study 5 - Hibiscus Sabdariffa in the Treatment of Hypertension & Hyperlipidemia (link)

Study 6 – Inhibition of Angiotensin Converting Enzyme (ACE) Activity by (link)

Study 7 - Effects of Hibiscus Sabdariffa Extract Powder & Preventive Treatment (link)

Study 8 – Aqueous Extracts of Roselle (Hibiscus S.) Varieties Inhibit A-Amylase (link)

Study 9 - Hibiscus S. Polyphenolic Extract Inhibits Hyperglycemia, Hyperlipidemia (link)

Study 10 - Chemopreventive Properties & Molecular Mechanisms of the Bioactive (link)

Daily Sour Tea Use Lowers High Blood Pressure

Source: J Nutr. 2010 Feb;140(2):298-303. (link)

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Posted in Diabetes, Food and Drink, Heart Health

5 Comments & Updates to “Sour Tea for Diabetes and Hypertension”

  1. Jo Says:

    I recently started drinking hibiscus and rosehip tea every morning with my breakfast – because it’s so delicious! Nice to know it also has health benefits :) might step up my consumption. Looks good iced too.

  2. JP Says:

    Thank you, Jo. That blend is my wife’s favorite herbal tea. She often adds a squeeze of fresh lemon juice as well. I’ve tried it and like it too. In my case, I typically add a few drops of liquid stevia to the mix. Very tasty!

    Be well!


  3. JP Says:

    Update 04/26/15:


    J Hypertens. 2015 Apr 14.

    Effect of sour tea (Hibiscus sabdariffa L.) on arterial hypertension: a systematic review and meta-analysis of randomized controlled trials.

    BACKGROUND: Hibiscus sabdariffa L. is a tropical wild plant rich in organic acids, polyphenols, anthocyanins, polysaccharides, and volatile constituents that are beneficial for the cardiovascular system. Hibiscus sabdariffa beverages are commonly consumed to treat arterial hypertension, yet the evidence from randomized controlled trials (RCTs) has not been fully conclusive. Therefore, we aimed to assess the potential antihypertensive effects of H. sabdariffa through systematic review of literature and meta-analysis of available RCTs.

    METHODS: The search included PUBMED, Cochrane Library, Scopus, and EMBASE (up to July 2014) to identify RCTs investigating the efficacy of H. sabdariffa supplementation on SBP and DBP values. Two independent reviewers extracted data on the study characteristics, methods, and outcomes. Quantitative data synthesis and meta-regression were performed using a fixed-effect model, and sensitivity analysis using leave-one-out method. Five RCTs (comprising seven treatment arms) were selected for the meta-analysis. In total, 390 participants were randomized, of whom 225 were allocated to the H. sabdariffa supplementation group and 165 to the control group in the selected studies.

    RESULTS: Fixed-effect meta-regression indicated a significant effect of H. sabdariffa supplementation in lowering both SBP (weighed mean difference -7.58 mmHg, 95% confidence interval -9.69 to -5.46, P < 0.00001) and DBP (weighed mean difference -3.53 mmHg, 95% confidence interval -5.16 to -1.89, P < 0.0001). These effects were inversely associated with baseline BP values, and were robust in sensitivity analyses.

    CONCLUSION: This meta-analysis of RCTs showed a significant effect of H. sabdariffa in lowering both SBP and DBP. Further well designed trials are necessary to validate these results.

    Be well!


  4. JP Says:

    Update 05/19/15:


    PLoS One. 2015 May 15;10(5):e0126469.

    Coffee Consumption, Newly Diagnosed Diabetes, and Other Alterations in Glucose Homeostasis: A Cross-Sectional Analysis of the Longitudinal Study of Adult Health (ELSA-Brasil).

    INTRODUCTION: Observational studies have reported fairly consistent inverse associations between coffee consumption and risk of type 2 diabetes, but this association has been little investigated with regard to lesser degrees of hyperglycemia and other alterations in glucose homeostasis. Additionally, the association between coffee consumption and diabetes has been rarely investigated in South American populations. We examined the cross-sectional relationships of coffee intake with newly diagnosed diabetes and measures of glucose homeostasis, insulin sensitivity, and insulin secretion, in a large Brazilian cohort of middle-aged and elderly individuals.

    METHODS: We used baseline data from 12,586 participants of the Longitudinal Study of Adult Health (ELSA-Brasil). Logistic regression analyses were performed to examine associations between coffee consumption and newly diagnosed diabetes. Analysis of covariance was used to assess coffee intake in relation to two-hour glucose from an oral glucose tolerance test, fasting glucose, glycated hemoglobin, fasting and -2-hour postload insulin and measures of insulin sensitivity.

    RESULTS: We found an inverse association between coffee consumption and newly diagnosed diabetes, after adjusting for multiple covariates [23% and 26% lower odds of diabetes for those consuming coffee 2-3 and >3 times per day, respectively, compared to those reporting never or almost never consuming coffee, (p = .02)]. An inverse association was also found for 2-hour postload glucose [Never/almost never: 7.57 mmol/L, ≤1 time/day: 7.48 mmol/L, 2-3 times/day: 7.22 mmol/L, >3 times/day: 7.12 mol/L, p<0.0001] but not with fasting glucose concentrations (p = 0.07). Coffee was additionally associated with 2-hour postload insulin [Never/almost never: 287.2 pmol/L, ≤1 time/day: 280.1 pmol/L, 2-3 times/day: 275.3 pmol/L, >3 times/day: 262.2 pmol/L, p = 0.0005) but not with fasting insulin concentrations (p = .58).

    CONCLUSION: Our present study provides further evidence of a protective effect of coffee on risk of adult-onset diabetes. This effect appears to act primarily, if not exclusively, through postprandial, as opposed to fasting, glucose homeostasis.

    Be well!


  5. JP Says:

    Updated 08/28/15:


    Niger J Clin Pract. 2015 Nov-Dec;18(6):762-70.

    Effect of Hibiscus sabdariffaon blood pressure and electrolyte profile of mild to moderate hypertensive Nigerians: A comparative study with hydrochlorothiazide.

    BACKGROUND: Hibiscus sabdariffa (HS) is widely consumed in Nigeria as a refreshing beverage and also as an antihypertensive agent. Since three decades ago when its antihypertensive activities were reported in several animal experiments, its consumption has greatly increased.

    AIM: The aim of this study is to investigate the effect of HS consumption on blood pressure (BP) and electrolytes of mild to moderate hypertensive Nigerians and compare it with that of hydrochlorothiazide (HCTZ), a diuretic widely used asfirst-line antihypertensive drug.

    SUBJECTS AND METHODS: Eighty newly diagnosed, but untreated mild to moderate hypertensive subjects attending Medical Out-Patients clinic of Enugu State University Teaching Hospital, Enugu, were recruited for the study. They were randomly divided into three groups: A, B and C. Those in Groups A were given placebo; those in Group B took HCTZ while those in Group C were given HS. Treatment lasted for 4 weeks. BP, serum, and urine electrolytes were measured at baseline, weekly during treatment and 1 week after withdrawal of treatment.

    RESULTS: At the end of treatment, both HCTZ and HS significantly (P < 0.001) reduced systolic BP, diastolic BP, mean arterial pressure and serum Na+ compared to placebo. When compared to each other, HCTZ significantly (P < 0.001) reduced serum Na+ and Cl- compared to HS and significantly (P < 0.001) increased K+ and Cl- output in urine. After withdrawal of treatment, the fall in BP and serum Na+ in HS group were significant compared to HCTZ where they returned to baseline values. No side effect was reported during the study.

    CONCLUSION: HS was a more effective antihypertensive agent than HCTZ in mild to moderate hypertensive Nigerians and did not cause electrolyte imbalance. HS showed longer duration of action compared to HCTZ and reduction in serum Na+ may be another antihypertensive mechanism of action of HS.

    Be well!


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