HIBUSCUS TEA, THE SUPERFOOD FOR HIGH BLOOD PRESSURE
Hibiscus sabdarrifa (also known as roselle, Zobo, or Karkadeh, Red sorrel, Agua de Jamaica, Lo-Shen, Sudan tea) is considered a medicinal plant in some cultures.
It is consumed as beverage in Nigeria, Egypt, West Africa, Iran, India, Southeast Asia, Thailand, and United States. It is believed to have numerous health benefits, consumed for its antihypertensive, cholesterol lowering and antioxidant benefits. (35-40).The flowers, calyxes are usually prepared in the form of hot or cold tea, or infusion. Due to it’s deep pigmentation, it is also used as food colorant. Among the vital constituents are anthocyanins, malic acid, glucose, alpha tocopherol, linoleic acid which have all been proven to be beneficial to overall health. (41-45)
Anti-hypertensive Benefits of Hibiscus sabdarifa
1. Reduction in Blood Pressure
Daily consumption of HS tea has been reported to lower elevated blood pressure in people with pre-hypertension and hypertension. Several studies support the blood pressure lowering effect of HS tea. A study by Faraji et al observed that HS in the form of tea reduced elevated BP in individuals with hypertension. Participants of the study were individuals with hypertension and were divided into 2 groups. Participants in one of the groups were given ordinary tea while the other group received HS tea, all participants discontinued their anti hypertensive medications and were strictly on tea treatment. The group that consumed HS tea showed a significant reduction in their blood pressure. The authors recommend daily consumption of HS tea in-order to get the maximum benefit, while closely monitoring your blood pressure.(9,10, 13, 15,18)
Several studies have compared the effect of HS extract on blood pressure to Captopril, a commonly prescribed anti-hypertensive and found it to be as effective with no adverse effect. (11, 12,). HS extract has been observed to function in ways similar to the ACE (Angiotensin converting enzyme) inhibitor anti-hypertensives. Angiotensin is a hormone that causes narrowing of the blood vessels, increases blood pressure and promotes sodium and fluid retention by the kidneys. HS extract blocks the release of angiotensin, consequently relaxing the blood vessels and reducing blood pressure.(17)
Another way HS reduces blood pressure is through diuresis. Diuretics such as hydrochlorothiazide are often prescribed in the treatment of hypertension. They work mainly by excreting excess body fluids through urine. The principle is that if there is reduction in blood volume, the arterial blood pressure will be reduced, and the heart would not have to work as hard to pump blood effectively. One of the main side effects of pharmacologic diuretics is electrolyte imbalance. However, HS has been shown not induce electrolyte imbalance. (2)
2. HS Prevents Heart Enlargement from Hypertension
In hypertension, pressure in the arteries become elevated and the heart has to work harder to pump blood into the high pressure vessels. Consequently, the heart muscles increase in mass because of the strain and over time, its ability to pump blood is diminished resulting in heart failure. Early diagnosis and good control go a long way in preventing or delaying the onset of these changes in the heart. (14)
Several research studies suggest that long term use of HS leads to a reduction in blood pressure, heart rate and prevents heart enlargement associated with hypertension(1, 5, 16).
3. Rich in Antioxidants (Anthocyanins)
Several metabolic processes in the body produce free radicals as by-products. Free radicals are unstable substances that react with certain biological molecules, fats and proteins in tissues of the body to become stable while causing oxidative damage in the process. The body produces antioxidants as defense mechanisms against oxidative damages of free radicals. When there is an imbalance between free radicals and antioxidants oxidative damage occurs. (26, 27 ).
Some researchers have explored the role of oxidative stress on the development of hypertension and found some evidence that it indeed does play a role. Free radicals damage the inner lining of the blood vessels, narrowing it which further worsens the hypertension.(19-25).
HS is rich in anthocyanins (flavonoids). Several studies have reported the antioxidant effects of the anthocyanins found in HS. Anthocyanins in HS extract have been reported to prevent fat and protein oxidation, have antibacterial and antifungal properties. (6-8).
4. Reduction in Total Cholesterol
High cholesterol increases the risk of Hypertension and high cholesterol often go hand in hand. When the level of cholesterol in the blood is high, it becomes deposited in the inner lining of the arteries. These fat deposits induce local inflammation (swelling and injury), form cholesterol plaques that harden and narrow the blood vessels. High blood pressure may result from these narrowed blood vessels. When cholesterol plaque deposits in the arteries supplying blood to the heart, it results in heart disease, in the arteries of the brain it may lead to a stroke. High blood pressure alone damages the blood vessels, increasing the risk of cholesterol deposits.
A 2011 study by Hernández-Pérez et al compared the efficacy of Hibiscus sabadariffa extract versus pravastatin in reducing high cholesterol in the blood. The randomized clinical study included 104 participants with blood cholesterol levels ≥ 220 mg/dL (normal is less than 200 mg/dL). They observed a significant reduction in cholesterol levels in both groups of patients who took HS and pravastatin. However they reported pravastatin to have superior cholesterol control over HS. (28) This implies that, taking pravastatin and HS tea may have synergistic effect in lowering blood cholesterol. Several other studies also report reduction in blood cholesterol following daily HS consumption. (29-33)
5. Effective in Improving Symptoms of Metabolic Syndrome.
Hypertension coexisting with either diabetes or obesity is referrreedd as metabolic syndrome. Having one of the components of metabolic syndrome increases the risk of the others. Gurrolla-Diaz et al studied the effect of consuming 100 mg daily of HS extract for a month and found HS extract to significantly reduce blood glucose, improve insulin resistance, reduce total cholesterol and low density lipoprotein while increasing the good cholesterol; HDL-c. (3, 4)
Several studies report HS to be safe both in the short and long term. Hs is not toxic to the liver, kidneys, heart, and other organs of the body. (34)
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