Hibiscus is a flowering plant traditionally brewed as a tart tea with a distinctively bright pink hue. This refreshing beverage is not only tasty but can also remedy a wide range of ailments. It may be especially useful for issues related to sluggish metabolism, weight gain, and high blood pressure. Read on to discover all the benefits of this gentle antioxidant-rich herb.
What Is Hibiscus?
Hibiscus is the name of a large genus of flowering plants that are native to multiple tropical, subtropical, and temperate regions. Some notable Hibiscus species are okra (H. esculentus), Chinese hibiscus (H. rosa-sinensis), and common garden hibiscus (H. syriacus) [R, R, R].
While several species in this genus are simply referred to as hibiscus, Hibiscus sabdariffa is consumed for its health benefits. This species, which is also known as roselle, red sorrel, or karkade, is usually brewed into a sour tea [R, R+].
This tea is commonly consumed in many countries such as Nigeria and Tanzania for both its taste and as a remedy for high blood pressure, anemia, liver diseases, and fever. Various parts of the plant are also used in traditional Ayurvedic medicine [R, R, R+, R].
Snapshot of Hibiscus
- Lowers high blood pressure
- May improve cholesterol levels
- Aids weight loss
- Has antioxidant effects
- Diuretic effects may be unwanted
- Can interfere with the absorption of medications
- Beneficial compounds might have low bioavailability
- L-ascorbic acid, the purest form of vitamin C naturally found in plants
- Anthocyanins antioxidants and anthocyanidins such as cyanidin-3 rutinoside and delphinidin
- Beta carotene (provitamin A)
- Beta-sitosterol, a plant sterol with potential cholesterol-lowering effects
- Citric acid, an antioxidant
- Polyphenols such as quercetin and gossypetin
- Pectin, a soluble fiber
- Alkaloids that may help fight bacteria
- Sugars such as galactose
- The seeds contain fatty acids (linoleic and stearic acid)
Mechanism of Action
Effects on Blood Pressure
Hibiscus is thought to lower blood pressure in two ways. For one, it acts as a diuretic, flushing sodium and fluids with the urine. As a result, the volume of blood decreases and blood pressure drops. Secondly, it blocks angiotensin-converting enzyme (ACE), which relaxes the blood vessels in a similar way as drugs commonly used to lower high blood pressure (ACE inhibitors) [R].
The anthocyanins which give hibiscus its color probably also carry its antioxidant properties. The two main active pigments are delphinidin-sambubioside (red) and cyanidin-sambubioside (pink) [R].
Weight Loss Action
Polyphenols in hibiscus block the enzymes that break down carbohydrates (such as alpha-amylase), which may explain its obesity-fighting benefits. Additionally, its antioxidants help neutralize high oxidative stress, which plays a role in obesity. Extracts may also block the formation and buildup of fat cells [R, R, R].
1) Metabolic Syndrome
Metabolic syndrome is a set of conditions that greatly increase the risk of heart disease, stroke, and diabetes. These conditions include insulin resistance, high blood sugar, obesity, high blood pressure, and high cholesterol. They all point to inefficient energy use in the body and high oxidative stress that often results from an unhealthy lifestyle [R].
Metabolic syndrome is very common: about 1 in 4 adults in the world suffer from it. Hibiscus may prevent or potentially improve this syndrome by helping with each condition that falls under its cluster. We go into each of these in detail below [R, R, R].
2) High Blood Pressure
Hibiscus is effective at lowering blood pressure, according to a large analysis of 5 studies and 390 people in total. Additionally, hibiscus tea lowered both systolic and diastolic blood pressure in 4 clinical trials of over 200 people with mild to moderate high blood pressure. Overall, this herb is a great option for people whose blood pressure is not too high [R, R, R, R, R].
The tea was even more effective at lowering mildly-moderately high blood pressure than hydrochlorothiazide (Microzide), a common diuretic blood pressure medication (clinical trial of 80 people). To make sure the dosage is right, the amount of tea was adjusted to each person’s weight (0.15 g/kg/day) [R].
Although drinking hibiscus tea may work well enough, extracts will have a higher concentration of important bioactive compounds. In one trial, taking a daily dose of dried hibiscus extract standardized to contain 250 mg anthocyanins reduced high blood pressure in 193 people [R].
Hibiscus calyx, the leaf-like structures at the base of a flower, can also be used. In another trial of 75 people, 10 g/day of dried hibiscus calyx worked as well as captopril (Capoten), a high blood pressure medication. This preparation lowered both systolic and diastolic blood pressure [R].
However, a study of 40 people found that 500 mg/day of its plant powder lowered only systolic blood pressure. This was also true for tea (2 g, 2x/day) in another study of 60 people with type 2 diabetes and high blood pressure [R, R].
In summary, hibiscus shows promise for lowering high blood pressure, but it is more likely to be beneficial in people with mild symptoms.
3) High Cholesterol
Drinking hibiscus tea may also help lower your cholesterol. In one trial of 53 diabetic people, it increased the “good” HDL cholesterol and decreased triglycerides and total and LDL cholesterol. It could also lower Apo-B100, a protein part of LDL particles that is specifically linked to high cholesterol [R].
Similarly, 100 mg/day of the extract decreased total cholesterol and increased HDL cholesterol. Combined with a healthy diet, it also reduced triglyceride levels in one clinical trial of 51 people with metabolic syndrome (73 healthy controls) [R].
However, in another trial of 40 people with metabolic syndrome, 500 mg/day of hibiscus powder only lowered triglyceride levels without affecting other blood fats. Similarly, a standardized extract (10 mg/day of anthocyanins) reduced triglyceride levels but did not impact cholesterol clinical trial of 104 people) [R, [R].
Could Your Genes Affect the Benefits?
Although hibiscus seems to mostly help reduce high blood fats, its effects seem hard to pin down. Sometimes it lowers LDL cholesterol, sometimes only triglycerides, and at other times it simply doesn’t work. In one trial of 60 people, the extract only lower body weight, along with diet and exercise. However, it had no effect on blood fat levels whatsoever [R].
What could be causing these inconsistencies?
Interestingly, the culprit may be genetics. While hibiscus improved triglyceride levels in some people (CETP TaqIB B2 carriers), it negatively impacted HDL levels in others (APOE E4 and CETP TaqIB B1B1 carriers). This interesting finding was confirmed in a clinical trial of 48 people with high cholesterol. Although bad news for some, such knowledge can help us make wiser, more targeted decisions and further opens the doors to nutrigenetics [R].
In summary, hibiscus may have a beneficial effect on lowering cholesterol and triglyceride levels, depending on your genetics. It’s also important to remember that the effects can vary depending on what part of the plant is used and how it is prepared.
4) Blood Sugar Levels
Hibiscus extract may be a safe herbal option for people at high risk of diabetes, such as those with metabolic syndrome. The extract (100 mg/day) reduced blood sugar levels in a clinical trial of 124 people. In another trial of 25 men with a low risk (1-10%) of heart disease, 250 mL of a liquid extract lowered both blood sugar and insulin levels [R, R].
Animal studies support this benefit. In rats with metabolic syndrome, hibiscus extract normalized levels of blood sugar and insulin [R].
5) Weight Loss
In a clinical trial of 36 overweight people, 900 mg, 2x/day of the extract reduced body weight and fat, improving BMI and the waist-to-hip ratio [R].
In another trial of 54 overweight people, the combination of hibiscus and lemon verbena lowered levels of the hunger hormone, ghrelin. Lowering ghrelin helps reduce a constant low-grade food craving that may be stopping you from adhering to your diet goals if you’re overweight. What’s more, it also increased GLP-1, a hormone that aids weight loss [R, R].
Similarly, lemon verbena and hibiscus extracts (in a product called Metabolaid) decreased body weight and body fat in obese mice. Hibiscus extract alone dampened the effects of a high-fat diet and also blocked the formation of new fat cells in hamsters [R, R].
This gentle plant seems to affect some powerful weight-loss mechanisms in the body. Taken as an extract, it can lower your oxidative stress and hunger, altogether helping you to lose weight. To truly get to the bottom of your weight issues, though, you should combine it with an adequate diet, exercise, and lifestyle changes.
6) Liver Health
Hibiscus may protect the liver from drugs and toxins or even improve liver health in disease. However, this holds true only if it’s taken at the right dose. Stick to the supplement label, as megadoses of this plant may have the opposite effect.
A typical dosage of the extract (900 mg, 3x/day) improved fatty liver disease and reduced free fatty acid blood levels in a clinical trial of 36 overweight people. In rats, it protected the liver against damage caused by the chemotherapy medication methotrexate (Xatmep, Trexall) [R, R].
However, in another rat study, prolonged exposure to very high doses (15 doses of 250 mg/kg) increased levels of AST and ALT, which can result in liver injury. Such high doses are very unlikely when drinking tea or taking supplements in regular amounts [R].
7) Kidney Function
Overall, the benefits of this plant for people at risk of metabolic diseases extend to the kidneys. Its effects on the kidneys are not isolated from its ability to flush excessive fluids, protect tissues, and lower blood sugar and fats.
In 78 people with high blood pressure, an infusion from hibiscus powder (150 mg/kg/day) improved kidney function. It increased the urine volume and the removal of creatine. Interestingly, it even outperformed a common high blood pressure medication, lisinopril (Zestril, Prinivil) [R].
8) Antioxidant Effects
Plant polyphenols are powerful antioxidants, which help the body combat oxidative stress. Hibiscus contains a variety of polyphenols such as quercetin, gossypetin, and flavonoids (anthocyanins and anthocyanidins) [R].
Hibiscus extract (450 mg/day) improved markers of oxidative stress, decreasing malondialdehyde and increasing total antioxidant capacity in a clinical trial of 54 male athletes. What’s more, a single 10 g dose of the extract reduced oxidative stress in a clinical trial of 8 healthy people [R, R].
On the downside, anthocyanins in hibiscus probably have poor bioavailability. They may be broken down in the gut before they even reach the blood. And if they do enter the bloodstream, they are quickly removed via urine by the kidneys. To make matters more complicated, people differ a lot at how quickly they will remove these antioxidants from the body [R].
On the brighter side, hibiscus contains a number of other unique antioxidants that may have better bioavailability. The way the body absorbs, uses, and gets rid of them has yet to be studied in detail [R].
9) Urinary Tract Infections
In a clinical trial of 55 women with recurring UTIs, a supplement containing hibiscus extract, vegetable enzymes, and myrrh extract prevented the infection from coming back and improved quality of life. Since the chronic nature of UTIs is a big problem for many women, effective natural remedies that help prevent their recurrence are extremely important [R].
This plant helps with UTIs because it helps flush fluids with the urine (and with them some bacteria), and it is also high in vitamin C. Make sure to take it with a lot of water if you suffer from recurrent UTIs, talk to your doctor, and be sure to look into other preventive measures you can take to prevent the infection from coming back [R].
According to clinical observations, drinking hibiscus tea also reduces the incidence of urinary tract infections in people with catheters. These types of UTIs are more complicated and usually harder to resolve, making hibiscus tea a simple and powerful herbal option [R].
10) A Natural Contrast for Imaging Procedures
So-called contrast agents are various drugs that can make it possible for various scanners to give an image of your organs that medical professionals can see well. For many people, just the thought of taking a contrast agent before going under a scanner can double the stress. On top of that, some people have allergies or adverse reactions to drugs that are used as contrasts [R].
You may be surprised to know that hibiscus tea may also be used as a natural contrast in a specific imaging technique used to assess gallbladder health (Magnetic resonance cholangiopancreatography). In one study using this technique, taking 4g of powdered hibiscus tea reduced the signal intensity of the surrounding organs, increasing the contrast and enhancing the gallbladder imagery [R].
Animal and Cellular Studies
The following studies were performed only in animals or on cells.
11) Cancer Prevention
In rats, high doses of hibiscus extract protected against DNA damage from cyclophosphamide, a potent pharmaceutical. Similarly, in mice, extracts partially prevented DNA damage from a toxic substance, sodium arsenite. These studies suggest that hibiscus may help prevent cancer from developing, even when exposed to toxins [R, R].
In a cell study, extract from this herb protected cells against DNA damage from potent free radicals. In several other studies, these extracts and their active compounds also blocked cancer cell growth [R, R, R, R].
While the cancer-fighting potential of hibiscus remains more elusive, it is still a good preventive herbal option. Animal studies used very high doses of this herb and potent toxins. However, the average person will probably only need a typical amount from tea to potentially reduce the negative effects of toxic exposures and oxidative stress.
12) Fighting Bacteria and Yeast
Hibiscus water and ethanol extracts were effective at killing these microorganisms in test tubes [R]:
- Escherichia coli, causes food poisoning and serious infections
- Staphylococcus aureus, causes staph infections and other serious infections
- Pseudomonas aeruginosa, a common hospital-acquired infection
- Salmonella enteritidis, causes food poisoning
- Vibrio parahaemolyticus, causes food poisoning
- Bacillus cereus, causes food poisoning
- Candida albicans, causes oral thrush and vaginal yeast infections
It’s hard to say to what extent hibiscus can fight these microbes when taken as tea or extracts. This will depend on the availability of its microbe-fighting active compounds. Given its safety and antioxidant activity, though, drinking hibiscus tea may certainly contribute to good defense against bacterial and yeast infections.
The following studies found that hibiscus had little to no effect on the tested variable.
1) Kidney Stones
In traditional Thai medicine, hibiscus tea is used for healing and preventing kidney stones. However, limited evidence suggests it works to reduce kidney stones [R].
Hibiscus tea (1.5 g, 2x/day) increased the excretion of uric acid through the urine in a trial of 18 people. According to the prevailing belief, excess excretion of uric acid may actually contribute to kidney stones. But since many other important factors can trigger the formation of kidney stones, the effect of hibiscus on uric acid is probably not detrimental [R, R].
In Tanzania, hibiscus tea is commonly used for anemia. However, drinking 1-2 L hibiscus juice (water extract) did not improve iron levels in a clinical trial of 82 people. The iron content in hibiscus is too low to improve iron status in people who are deficient. It may, however, very slightly boost ferritin thanks to its vitamin C content [R].
Side Effects & Precautions
However, in rats, very high doses damaged the liver and the testicles. The megadose used 15X the typical amount. Even at up to 10X the normal dose, the negative effect was mild. Don’t take very high amounts of hibiscus, especially when it comes to extracts. Rather, make sure to adhere to the proven, safe dosage [R, R].
Pregnant women should avoid drinking or consuming Hibiscus plants as they can potentially induce labor [R].
Limitations and Caveats
Hibiscus tea can interact with pharmaceuticals in a variety of ways. Please discuss with your doctor before taking it with any of your medication.
Because this plant is a diuretic, it should not be used with other diuretics, such as hydrochlorothiazide (Microzide) [R].
- Diclofenac (Solaraze, Voltaren, Voltaren-XR, Zorvolex, and more)
- Acetaminophen (Tylenol, Ofirmev, FeverAll, Tylophen, and more)
It also interacts with the cholesterol medication, simvastatin (Zocor and FloLipid), reducing its effect [R].
Hibiscus affects cholesterol levels differently depending on what versions of the APOE and CETP TaqIB genes you have. It decreased HDL levels in people with APOE E4 and CETP TaqIB B1B1 variants, which is not beneficial. On the other hand, it lowered triglycerides only in people with the CETP TaqIB B2 variant but not in APOE E4 carriers [R].
Supplements & Tea Recipes
Hibiscus supplements are available in a variety of forms:
Dried hibiscus calyces or flowers
Sweetener of choice (optional)
- Use a ratio of 1 cup of water per 1/2 tbsp of hibiscus.
- Bring water to a boil.
- Add hibiscus to the hot water and steep for at least 10 minutes.
- Add sweetener, if desired.
Tea and Infusions
The dosages for tea mostly ranged from 3-10 g/day of dried hibiscus calyxes or flowers.
Infusions can be made with dried hibiscus at 150 mg/kg/day. This would translate to a slightly higher range of 7-15 g/day of the dried herb for most people (110-220 lbs).
Dried, Water, and Standardized Extracts
Since hibiscus extracts have larger concentrations of active compounds, lower dosages are used.
For dried extracts, the dosages ranged from 450 mg-2700 mg/day.
A common dosage for water extracts was 250 mL/day.
With standardized extracts, the dosage is adjusted to the concentration of anthocyanins, which widely ranged from 10-250 mg/day.
A common dosage for hibiscus plant powder was 500 mg/day.
Hibiscus is a plant that offers many health benefits to people who struggle with a slow metabolism or are at risk of metabolic diseases. It helps lower blood pressure, blood fats, and blood sugar while charging the body with useful antioxidants.
To get the most benefits out of this plant, you can brew it as a tea or take standardized extracts. It might not lower your blood fats as well if you’re an APOE E4 carrier and its benefits will also depend on the part of the plant used and how it’s processed.
Even if you’re just looking to expand your tea assortment with a tasty and invigorating herb, hibiscus will help boost your wellness and detox. It can also aid weight loss and reduce feelings of hunger, especially in combination with lemon verbena. With that in mind, it does act as a diuretic, so be sure to consult your doctor if you’re taking prescription medications.