The Best Herbs for Reducing Blood Pressure

High blood pressure, also known as hypertension, is a common health complaint that is estimated to affect almost one in three adults in the US and UK. Although severity can vary, a medical diagnosis for hypertension is often given when blood pressure readings consistently exceed 140 over 90.

The leading methods to reduce blood pressure are through the use of  medication, lifestyle changes (diet, exercise) and taking dietary supplements or herbs. Here we will take a look at the herbs which can be used to treat this condition.

Whilst many herbs purport to reduce blood pressure, we are interested in only those which have been shown to work in clinical trials on human subjects and which resulted in a statistically significant reduction in blood pressure. The more trials performed on a particular herb, the more reliable the evidence relating to any health benefits. Let’s take a look.

Hibiscus

HibiscusThe first on our list is ‘Hibiscus Sabdariffa’ or ‘Roselle’ – a flowering plant which is one of over 250 different species found growing around the world. This species of hibiscus is the one most commonly used for medical purposes and is best know as a sour tasting, vivid red tea infusion.

What is interesting about this plant is that it has been shown to significantly reduce blood pressure in a number of human studies on both hypertensive and prehypertensive adults. All but one of the studies used hibiscus tea which is made from  the deep coloured magenta sepals (Collectively referred to as the calyx) of the plant. The remaining study used encapsulated hibiscus powder. The main bioactives (components which exert biological effect) found in Hibiscus are thought to be the anthocyanins. These are the pigments in a fruits skin responsible for its colour and are thought to confer the most antioxidant and anti-inflammatory effects.

Looking at four of the studies, we can calculate an average blood pressure reduction of 15.34 points systolic (the first number on a blood pressure reading) and 6.59 points diastolic (the second number on a blood pressure reading) between them. Two of the studies, compared the hibiscus directly to blood pressure medication. In one of these  10g of dried hibiscus powder, standardized to 9.6mg of total anthocyanins made into a tea and taken before breakfast was found to be just as effective as 50mg of captopril. The other study which used encapsulated hibiscus powder standardized to 250mg anthocyanins, demonstrated a significant reduction in blood pressure but just fell short of the effects found with Lisinopril at 10mg.

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Garlic

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Garlic has long been thought to possess health benefits

Garlic has been renowned for it’s health benefits throughout history, with the first documented use for medicinal purposes dating back as far as 2000BC in Ancient Egypt.

There are two main varieties of garlic supplements available– traditional garlic which is the garlic we all know and love (or loath) turned into supplement form such as tablet. Then there is aged garlic extract (AGE). This is traditional garlic which has been stored at room temperature for 20 months, resulting in changes to the composition of the garlic. The main bioactives in garlic and aged garlic are though to be allicin and S-allylcystiene (SAC) respectively. Allicin produces the compounds responsible for the garlic’s unmistakable smell. Aged garlic does not contain allicin and thus produces no odour.

When we  look at the studies, with the exception of one (which used a timed release garlic formula), we find that most of the traditional garlic supplements do not provide evidence of a significant reduction in blood pressure but do demonstrate significant improvements in arterial elasticity, blood flow, protection against oxidative stress and improved physical performance.

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Furthermore, several clinical trials have demonstrated traditional garlic to demonstrate reliable and significant reductions in total cholesterol levels, with notable reductions in LDL cholesterol and increases in HDL (good) cholesterol.

Olive leaf extract

Coming from the plant which bears the illustrious olive fruit, olive leaf extract appears to exert anti-hypertensive effects. Whilst one study showed no effect in reducing blood pressure, another 2 studies using a standardized olive leaf formulation (EFLA943) demonstrated an average of 11 points systolic and 4 points diastolic blood pressure reduction. However, it should be noted that whilst one of the trials observed this reduction using 500mg using the EFLA943, the other trial (which tested the same formulation on twins) demonstrated no significant reduction in bp for 500mg but did observe a significant reduction for those taking 1000mg of the extract.

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Several studies have also demonstrated that olive leaf can significantly reduce LDL oxidation, which is known to be a contributing factor in atherosclerosis (fat build-up in the arteries). Some of these trials have demonstrated a reduction in LDL oxidation of over 25%.

Spirulina

Garlic Vertical reduced 7Although not technically a herb, spirulina has been the subject of studies that have attempted to evaluate it’s potential blood pressure reducing benefits. Early evidence is promising with two trials demonstrating broad spectrum cardioprotection with a reduction in blood pressure and cholesterol levels when  3.5 to 4.5g spirulina was taken daily. One trial, however, failed to show improvement in blood pressure, but this could be attributed to the relatively low dose of 1g spirulina used.

Further tests to evaluate the impact that spirulina can have on blood pressure are necessary to draw stronger conclusions, but initial evidence is certainly encouraging.

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There are other herbs that through scientific studies have been shown to improve blood pressure, but either their effect in doing so is slight compared to those we have discussed, and/or not enough trials have been carried out to validate their effectiveness. We should also mention that, although not herbal, magnesium has  been shown to significantly lower blood pressure levels17,18, particularly in those who are already deficient in this nutrient.