[toc]Eating more veggies, fruits, and whole grains, while reducing meat, dairy, fats, sugar, and salt are all part of the eating plan called DASH (Dietary Approaches to Stop Hypertension). (1)
But once you’ve done that, what other foods may help?
Although it’s not conclusively proven, one of the most promising based on research is drinking hibiscus tea everyday.
Even the U.S. National Library of Medicine’s MedlinePlus portal says it’s “possibly effective for high blood pressure.” They make sure to note there is “not enough evidence to draw strong conclusions” but that some preliminary human studies have suggested it as a possibility. (2)
That aside, what is hibiscus tea good for?
It turns out this might be the healthiest tea you can drink.
Even when you compare it against superfoods like matcha green tea, it wins on the most important metrics. For hibiscus tea and supplements made from that flower, you will find dozens of human clinical studies listed in the PubMed.gov database. As far as the total number of medical citations listed there, it’s over one thousand. The suspected blood pressure lowering effect is only the tip of the iceberg as to why it may be good for you.
There are over 200 species in this genus of flowers, but the kind of hibiscus used for making herbal tea is most often the Hibiscus sabdariffa. It’s made by steeping the dried red flowers (sepals) in water. Also called roselle and flor de jamaica in Hispanic cultures, both hot and cold beverages are made from it. The bright red color and tangy taste is often compared to cranberry.
Its history of medicinal use is believed to date back thousands of years. Known as karkadé in Egypt, it was reportedly drank by the pharaohs. In nearby Iran it’s called “sour tea” and Traditional Chinese Medicine has reportedly made use of it for high blood pressure and menstrual cramping pain. Today it’s being researched for cancer, kidney protection, complications from diabetes, weight loss, and much more. (3)
Of course, traditional medicine is unproven. So let’s review the science-based benefits which may not be proven, but each one does have credible evidence to back it up as a possibility.
At the end, you will also learn about one other plant which might offer some synergistic advantages when combined with the flower… science suggests it’s the best blend.
10 health benefits of hibiscus tea
1. More antioxidants than matcha
It’s a common assumption that green tea is the healthiest choice, but that assumption is wrong.
Based on testing, the ORAC value for brewed green tea is 1,253. Black is slightly lower at 1,128, while rooibos (red bush tea) is around 50% less than both of those at 610.
It’s actually yerba mate that beats all of the above at 1,704. A particular form of green tea – the finest ceremonial grade matcha in the world – is an impressive 3,163 when brewed. You can shell out big bucks for that, or you can get over double the amount of antioxidants with hibiscus flower tea. Its ORAC has come in at 6,990!
2. Caffeine-free
Is hibiscus tea caffeine free? Yep. As long as its not blended with green or black tea leaves, the flower itself contains none of the stimulant.
Now Starbucks hibiscus tea does have caffeine, 45-55 mg in a 16 oz (Grande) according to the nutrition facts. However that’s because they add green coffee extract to it.
Starbucks also adds a lot of sugar, which is why you’re better off making it, both for your health and finances!
Depending on the time of day, the fact that there is no caffeine may be a disadvantage. Since the half-life of caffeine can range from 3-7 hours, it rules out drinking matcha, regular green tea, or coffee in the afternoon and evening. At least if you want the best sleep possible and don’t want decaffeinated, a process which often involves nasty chemicals.
With this antioxidant-rich herbal tea, you can drink it around the clock without disturbing your sleep schedule.
3. May lower blood pressure
Being that it’s caffeine-free, it’s already a heart-healthy alternative to green and black teas. But that in and of itself is hardly impressive. So what’s the big story behind the purported benefit you hear most about?
Several human clinical studies have been published about this, with the first being nearly two decades ago, in 1999. (4)
- 54 men and women completed the study
- 31 were given tea made with Hibiscus sabdariffa
- 23 were given a placebo version of tea
- Each person drank their tea daily for 15 days
- It was consumed at least 1 hour prior to measuring blood pressure
The group drinking the hibiscus tea experienced an 11.2% average decrease in systolic blood pressure and a 10.7% decrease in diastolic beginning on day 12.
In 2004, there was an even larger study with a greater age range (30 to 80 years old) of people who had untreated hypertension. Some were given the blood pressure drug captopril (Capoten) while others were given the tea to drink before breakfast each day. This continued for 4 weeks. Both were reported to have a similar therapeutic effectiveness. The tea group experienced: (5)
- Systolic BP dropping from 139.05 to 123.73
- Diastolic BP dropping from 90.81 to 79.52
In 2007 a similar but even bigger study of 193 people reported that those consuming the tea had an average decrease of 146.48 to 129.89 for systolic and 97.77 to 85.96 for diastolic. (6)
A 2009 study concluded it had positive effects in diabetic patients with mild hypertension. (7)
A 2010 Tufts University study even qualified for registration with ClinicalTrials.gov. It was a randomized, double-blind, and placebo-controlled clinical trial. The difference compared to placebo can be seen in these charts. (8)
A 2013 study used hibiscus tea and green tea in type 2 diabetics. Both groups improved but the flower did best. (9)
A 2015 study pitted it against a first-line antihypertensive drug, hydrochlorothiazide (Microzide). Their conclusion (10):
“HS [Hibiscus sabdariffa] was a more effective antihypertensive agent than HCTZ [hydrochlorothiazide] 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.”
As a reminder, there’s not enough data to draw conclusions but the research so far does seem promising.
4. May reduce cholesterol
This cardiovascular benefit has less evidence and it’s weaker, since at least one study credited more physical activity for the improvement seen. (11)
In the previously mentioned clinical trial involving diabetics drinking hibiscus or green tea, there was also:
“…a significant decrease in the mean of total cholesterol, low density lipoprotein-cholesterol [LDL], triglycerides, and Apo-B100.”
The latter is apolipoprotein B, which plays a pivotal role in how cholesterol moves around your body. (9)
Patients with metabolic syndrome – which is basically pre-diabetes and pre-coronary heart disease – were treated with a hibiscus supplement (capsules) in a daily dosage of 100mg. After one month of this treatment, the patients had “significantly” reduced blood glucose, LDL cholesterol, and better insulin resistance. (12)
Lastly we come to a double blind and controlled trial for just normal men and women who have high cholesterol, which was defined as being above 220 mg/dL.
For 12 weeks, the 104 participants either received the statin pravastatin (Pravachol) or hibiscus extract supplements, which were standardized to contain either 10 or 20mg of anthocyanins (a type of antioxidant which gives the flower its red color). That prescription statin lowered cholesterol the most, but those on the supplements improved too. (13)
5. Weight loss
It has been proposed – but not proven – that this flower may be a digestive enzyme inhibitor. Those are compounds which bind to the enzymes in the digestive tract responsible for breaking down foods, such as carbs and fats. If your body doesn’t beak them down fully, its means less of them get absorbed. (14)
Although it’s not thought of as a diet drink in America, drinking hibiscus tea for weight loss has been a popular remedy in Brazil for quite some time. There are some animal and human investigations done there which support the idea that it might work, but nothing conclusive. (15) (16)
Only one human trial has been done on this topic. The 36 participants were all obese (BMI ≧ 27). They were split into 2 groups; roughly half used the flower extract for 12 weeks while the others did not. It was said (17):
“In conclusion, consumption of Hibiscus sabdariffa extracts reduced obesity, abdominal fat, serum free fatty acid and improved liver steatosis.”
There are also a couple animal studies:
- When hamsters were given Hibiscus sabdariffa extract, it was found to reduce body fat, by interfering with fat accumulation in the adipose tissue. The more that was given, the greater the effect. (18)
- A study using rats suggested it may have an anti-obesity effect, due to fat absorption vs. how much gets excreted. (19)
6. Zero-calorie beverage
Now this one is a proven advantage for losing weight. Assuming you don’t add sugar, the tea itself is zero calories.
Being that it’s naturally sour like a cranberry, you probably will want to sweeten it. To keep it a no-calorie beverage, use monk fruit powder in lieu of sugar or stevia.
7. Cancer research
There are over 50 medical papers about hibiscus and cancer listed on PubMed.
The initial cause of all cancers starts with a cell mutation, one which distorts the instructions as to how the cell should grow and multiply. In a study with rats given the extract for 15 days, there was a 91% reduction in micronucleus frequency compared to the control group. In plain English, hibiscus seemed to help inhibit cell mutations (antimutagenic effect). (20)
But how about after the cells have already mutated and turned into this dreaded disease?
Using cultured cells in the lab, the flower extract has been found to interfere with the growth of melanoma (21) (22), breast cancer (23) (24), prostate cancer (25), malignant glioma (brain cancer) (26), lung cancer (27), gastric/stomach cancer (28), colon (29), and leukemia (30) (31) (32).
To be clear, none of that research involved living humans, but it did involve human cells which were cultured and kept alive for testing in a laboratory environment. Some used what are called xenografts; human tumors which are able to grow inside genetically altered rodents.
Why is hibiscus good for cancer possibly? Research suggests it may interfere with certain signaling pathways that the cells act through. For example with prostate cancer, based on the data it was proposed that it inhibits the cell growth by downregulating the Akt/NF-kB/MMP-9 pathway. (33)
In that specialized mouse model which used human prostate tumors growing in them, this graph shows the tumor volume in the mice with and without hibiscus extract treatment during a 42 day treatment period:
8. Acts as a nootropic
As with the skin studies, none of the brain-boosting theories have been studied in humans so they remain just that… theories. But some interesting studies suggest it does act as a nootropic in animals at least.
In a rat model which was meant to replicate the effects of Parkinson’s disease, the extract of hibiscus leaves were found to have a neuroprotective effect; less anxiety, less depression, and improved spatial memory. (40)
How do you know if a rat is depressed? Not easily, but the methodologies chosen are widely used in neurological research on animals; elevated plus-maze, forced swimming test, Y-maze and radial arm-maze tasks.
Other rodent studies have observed an “antidepressant-like profile of action” when they were treated with the flower extract. Of course that raises the question, does hibiscus make you sleepy? They specifically stated these benefits were seen “without sedative side effect.” Drinking the tea is not known for making humans feel sleepy, either. (41)
It has been theorized that the flavonoids might be causing an antidepressant activity in these studies. (42)
9. Skin healing
It’s unknown if this advantage exists for humans since they haven’t been studied. However in rats, it has been found to be beneficial for wound healing.
In one study, some rats with incisions were treated using a 5% and 10% topical hibiscus skin care treatment, while others received nitrofurazone (an antibacterial ointment). It was concluded that the flower extract produced better wound-healing activity (37):
“There was a significant increase in wound closure rate, tensile strength, dry granuloma weight, wet granuloma weight and decrease in epithelization period in H. rosa sinensis-treated group as compared to control and standard drug-treated groups.”
Other studies have had similar findings. (38) (39)
10. May help protect kidneys
A study in 2017 involved rats who were fed a kidney-damaging compound (adenine) for 28 days. Some of these rats were also given a hibiscus extract and it appeared to offer protective benefits; the effects of the adenine-induced chronic kidney disease were “significantly lessened, mostly in a dose-dependent manner.” (34)
Renal function was also evaluated in one of the studies about using hibiscus for high blood pressure. Out of the 78 people who participated, 26 were given the plant extract for a total of 4 weeks, with a once-daily dosage. Urine volume and creatinine clearance was measured at baseline and throughout the study. For the hibiscus group, those parameters “significantly increased” but they did not for the other two groups; placebo and those on the ACE inhibitor, lisinopril. (35)
In Egypt, it’s reportedly one of the most used alternative medicine treatments among those with chronic kidney disease (CKD) and organ transplant recipients of a kidney, but it is not approved or studied for such purposes. (36)
Side effects of hibiscus tea
- Hypotension (low blood pressure)
- Too low of blood sugar in diabetics
- Interaction with acetaminophen
- Interaction with blood pressure drugs
- Mild diuretic effects
- Unknown safety during pregnancy
- Unknown safety while breastfeeding
If you have diabetes or high blood pressure, consult your doctor before drinking. If the benefits suggested by research are for real, then it might cause your blood sugar and/or pressure to drop too much and that would be dangerous.
The tea should not be considered safe to drink while pregnant. In one study where mother rats consumed the extract while lactating, a delay in the puberty of their female offspring was observed. Another study observed sperm abnormalities in male offspring, when their mother had consumed the extract while pregnant with them. (43) (44)
Nor should it be viewed as safe for toddlers and babies, because another study – albeit by the same scientists – found that giving it to young rats may have affected their growth and timing of puberty. (45)
That evidence for pregnancy dangers may be weak, but it’s better to be safe than sorry.
When it comes to healthy adults, it’s hard finding a reason as to why it could be bad for you.
WebMD lists interaction with acetaminophen (Tylenol) as a side effect. That interaction was based on a small study of just 6 men in Nigeria who were tested using zobo drink, which is a beverage made with the tea. We include it in our list of possible adverse reactions, but there is not a strong case to be made for it. (46)
The other four papers out there are actually about the plant protecting against liver damage caused by acetaminophen … that would be a good drug interaction! (47) (48) (49) (50) (51)
Hormonal interactions
Does hibiscus tea lower estrogen levels? In a study using pregnant mice out of India, it was said the extract had “antiestrogenic activity, as judged by increase in uterus weight” of the animals. However an earlier study which drew the opposite conclusion; that the flower might increase secretion of estrogen. (52) (53)
Hibiscus sabdariffa has been found to be a rich source of the quercetin and daidzein. The former is flavonoid known for being an anti-inflammatory, while the latter is an isoflavone with phytoestrogen properties. (54)
Daidzein is also found in soy, but it’s considered to be weaker than the other primary phytostrogen in soy, which is genistein. (55)
The amount of phytoestrogen in tea made with hibiscus would be a drop in the bucket compared to food sources, which probably explains why the data about it affecting estrogen levels is limited and contradictory.
In fact, when rat testicle slices were treated with extract in the lab, it was said those cells boosted testosterone production. In another study using living rats, after 15 days of receiving the extract it was said blood serum levels of testosterone increase 80%. (56) (57)
The takeaway? There’s no evidence of the plant adversely affecting hormone levels in humans. The animal data is contradictory and the observed increases of testosterone production in males and higher estrogen in females – if they’re happening – might be beneficial, for those middle-aged and above.
How to make the tea even better
The best hibiscus tea brand will be a blend, not one that is 100% pure.
Why? Because if you buy hibiscus and rose hips tea, it might be the best anti-aging duo.
Both resveratrol and rose hips are believed to activate the AMPK pathway.
Resveratrol is believed to work through both the SIRT1 and AMPK pathways. However research during the last decade suggests it’s the latter – AMPK – which might be more useful in anti-aging research than SIRT1.
What is AMPK? It’s an enzyme found in every cell of your body. It’s an important signaling tool for cell growth, metabolism, and other factors. As we age, the AMPK activity of our cells decreases. Research to date suggests that rose hips might be one of the best natural AMPK activators.
So why not boost your beverage with some rose hips, too?
To be clear, at this point any and all health benefits remain theoretical and unproven for both rose hips and hibiscus. They should not be used to treat, cure, or prevent any disease. But given the promising research so far – and the lack of side effects – you could argue this duo is the best choice among all teas.
Here at Superfoodly, we buy this organic rose hips and hibiscus tea on Amazon and drink it everyday.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.