Last Updated: September 28, 2022

    Hibiscus Sabdariffa (Roselle or Sour Tea) is a tea where the usually dark colored flowers are used to brew. It appears to inhibit carbohydrate absorption to a degree and appears to be effective in reducing blood pressure.

    Roselle is most often used for .


    Hibiscus Sabdariffa (Roselle) is a supplemental herb that is derived from the plant's calyces, which are the collection of sepals separating the blooming flower from the stem. The calyces have traditionally been steeped into tea where the anthocyanins (red-blue pigmentation) is steeped into the water and drank for medicinal purposes.

    Although Roselle has a variety of claims medicinally, it appears to have evidence to support its role in reducing blood pressure in persons with elevated blood pressure. This may be through its ACE inhibitory potential (although this is admittedly weak) or by benefiting the endothelium via nitric oxide related mechanisms (appears to be in better accordance with the amount of anthocyanins that reach the blood). Reductions in both diastolic and systolic blood pressure have been noted, and for the most part appear to be reliable in presence although not so much in magnitude of benefit (ie. blood pressure is reliably reduced, but the degree of reduction seems to vary).

    In regards to diabetes and blood glucose control, Roselle appears to have limited evidence to support these claims but the evidence is so far in support. Mechanisms are not known, and the remarkable potency in animal studies seems to be markedly less in the limited human interventions looking at it. Roselle does appear to weakly inhibit carbohydrate absorption enzymes, yet is synergistic with Morus Alba (White Mulberry) in doing so; a tea made of White Mulberries and Roselle, although currently not supported in vivo, is possibly an effective carbohydrate absorption inhibitory tea.

    The interactions of Roselle and weight loss are not too clear-cut, and it seems to be highly intertwined with studies on Roselle toxicity; Roselle is known to be toxic in higher doses, and weight loss more often than not precedes chronic toxicity. For studies that note weight loss without toxicity, it seems to be related to reduced food intake in rats and mice rather than direct fat burning effects.

    The appetite suppressing effects seem to be fairly reliable in rats, but caution should be taken in applying these effects to humans. Aside from not being reported as a side-effect in any human study, the bioactive known as Hibiscus Acid is similarly structured to (-)-Hydroxycitric acid from Garcinia Cambogia which is known to reduce appetite in rats reliably but not humans.

    Low doses of Roselle tea or supplements appear to be effective in reducing blood pressure, and may be anti-diabetic. It is unlikely that Roselle can cause weight loss independent of a reduction of appetite

    The toxicity itself seems to occur in mice and rats in a similar idea as the blood pressure reducing effects in humans, as in they occur reliably although the dose required to induce toxicity and what exactly occurs seems to vary from one study to another. This may be related to the exact molecules mediating toxicity not being known right now. For the majority of toxic effects, the lowest they have occurred is 200mg/kg in rats (2.2g dried calyx for a 150lb human). Human studies have used this dose or above with no apparent side effects though. The toxicity of these doses of Roselle need to be evaluated more.

    One concern that does exist is testicular toxicity, which occurs fairly reliably at 200mg/kg or above in animals but has not been investigated in humans. Roselle appears to be anti-fertility in men, inducing abnormal sperm morphology. In females, there was a series of studies suggesting Roselle could cause abnormal (higher) birth weights in offspring with a delay of pubertal onset; for the most part these are attributed to the appetite suppressing effect causing maternal malnutrition, with no per se mechanisms harming the pup (via lactation) currently known.

    Although these toxic effects can possibly be avoided by adhering to proper dosing, the amount of safety information in humans is not as expansive as would be desired; the therapeutic threshold (degree of 'safety buffer' between the active dose and toxic dose) is also lower than desirable, so possible toxic effects with overdosing Roselle is probably more relevant than other supplements.

    Higher doses of Roselle do exert toxic effects, although none of these toxic effects have been reported in humans (that being said, they have not conclusively been disproven either). It would be prudent to avoid taking too much Roselle, especially since many benefits of Roselle (elaborating on in complete summary) are not dose-dependent above the lowest observable toxic dose of 2.2g/150lb human

    What are other names for Roselle

    Note that Roselle is also known as:
    • Roselle
    • Isakpa
    • Krachiap Daeng
    • Sour Tea
    • Hibiscus Sabdariffa
    Roselle should not be confused with:

    Dosage information

    When using Hibiscus Sabdariffa as a tea, a dried calyx (the part of the blooming top of a flower that is not the petals, but beneath them) weighing about a gram is steeped into tea; drunk either once in the morning or twice a day with 8 hours between doses.

    Supplemental Hibiscus Sabdariffa is taken according to the content of anthocyanins; 10mg of anthocyanins derived from Hibiscus Sabradiffa (which would be 1g of a 1% extract or 500mg of a 2% extract) appears to be effective.

    Higher doses are associated with toxicity in rats, and it would be prudent to not exceed the above doses unnecessarily.

    Examine Database: Roselle

    Research FeedRead all studies

    Examine Database References

    1. Triglycerides - Kuriyan R, Kumar DR, R R, Kurpad AVAn evaluation of the hypolipidemic effect of an extract of Hibiscus Sabdariffa leaves in hyperlipidemic Indians: a double blind, placebo controlled trialBMC Complement Altern Med.(2010 Jun 17)
    2. Triglycerides - Hernández-Pérez F, Herrera-Arellano ATherapeutic use Hibiscus sabadariffa extract in the treatment of hypercholesterolemia. A randomized clinical trialRev Med Inst Mex Seguro Soc.(2011 Sep-Oct)
    3. Triglycerides - Mozaffari-Khosravi H, Jalali-Khanabadi BA, Afkhami-Ardekani M, Fatehi FEffects of sour tea (Hibiscus sabdariffa) on lipid profile and lipoproteins in patients with type II diabetesJ Altern Complement Med.(2009 Aug)
    4. Blood glucose - Gurrola-Díaz CM, García-López PM, Sánchez-Enríquez S, Troyo-Sanromán R, Andrade-González I, Gómez-Leyva JFEffects of Hibiscus sabdariffa extract powder and preventive treatment (diet) on the lipid profiles of patients with metabolic syndrome (MeSy)Phytomedicine.(2010 Jun)
    5. Blood Pressure - Mozaffari-Khosravi H, Jalali-Khanabadi BA, Afkhami-Ardekani M, Fatehi F, Noori-Shadkam MThe effects of sour tea (Hibiscus sabdariffa) on hypertension in patients with type II diabetesJ Hum Hypertens.(2009 Jan)
    6. Blood Pressure - Herrera-Arellano A, Miranda-Sánchez J, Avila-Castro P, Herrera-Alvarez S, Jiménez-Ferrer JE, Zamilpa A, Román-Ramos R, Ponce-Monter H, Tortoriello JClinical effects produced by a standardized herbal medicinal product of Hibiscus sabdariffa on patients with hypertension. A randomized, double-blind, lisinopril-controlled clinical trialPlanta Med.(2007 Jan)
    7. Blood Pressure - M Haji Faraji, A Haji TarkhaniThe effect of sour tea (Hibiscus sabdariffa) on essential hypertensionJ Ethnopharmacol.(1999 Jun)
    8. Blood Pressure - Herrera-Arellano A, Flores-Romero S, Chávez-Soto MA, Tortoriello JEffectiveness and tolerability of a standardized extract from Hibiscus sabdariffa in patients with mild to moderate hypertension: a controlled and randomized clinical trialPhytomedicine.(2004 Jul)
    9. Blood Pressure - McKay DL, Chen CY, Saltzman E, Blumberg JBHibiscus sabdariffa L. tea (tisane) lowers blood pressure in prehypertensive and mildly hypertensive adultsJ Nutr.(2010 Feb)
    10. Oxidative Stress Biomarkers - Frank T, Netzel G, Kammerer DR, Carle R, Kler A, Kriesl E, Bitsch I, Bitsch R, Netzel MConsumption of Hibiscus sabdariffa L. aqueous extract and its impact on systemic antioxidant potential in healthy subjectsJ Sci Food Agric.(2012 Aug 15)
    11. Inflammation - R Beltrán-Debón, C Alonso-Villaverde, G Aragonès, I Rodríguez-Medina, A Rull, V Micol, A Segura-Carretero, A Fernández-Gutiérrez, J Camps, J JovenThe aqueous extract of Hibiscus sabdariffa calices modulates the production of monocyte chemoattractant protein-1 in humansPhytomedicine.(2010 Mar)