Pomegranate’s Impact On Managing Blood Pressure

What is blood pressure?

Blood pressure, as defined by the NHS, is a measure of the force your heart uses to circulate blood around your body. It’s important to keep your blood pressure within a healthy range to maintain your overall health.

High blood pressure (often referred to as hypertension) is very common, but serious if it’s not treated. Sustained hypertension can lead to various health complications further down the line, as it can do a lot of damage to organs including your heart and kidneys.

According to the World Health Organisation (WHO), worldwide an estimated 1.28 billion adults aged 30-79 years have high blood pressure and roughly 46% of affected adults are unaware that they have the condition.

Blood pressure is partially determined by genetics, although lifestyle factors including diet and exercise have a large impact too. Although drugs that lower blood pressure are available on prescription, lifestyle modifications such as increased exercise and maintaining a ‘heart healthy’ diet are important.¹

This is useful as you can implement these lifestyle modifications yourself, and even if you have healthy blood pressure, maintaining a good exercise routine and diet can help prevent you from developing high blood pressure in the future.

The potential impact of some foods on blood pressure, specifically certain nutrients and minerals within fruit and vegetables, is being increasingly researched.² Any benefits gained from your diet are less invasive to your body than drugs, and so could be beneficial. Pomegranates have been shown to contain various nutrients that could positively impact blood pressure. 

Understanding blood pressure 

Blood pressure is written as two numbers. The first number represents the systolic pressure, which refers to the pressure with which your blood pushes against the artery walls when your heart contracts (beats). The second number represents the diastolic pressure, which is the pressure when your heart relaxes between beats.³ 

Therefore when you see blood pressure written out, it looks like systolic/diastolic mmHg. It is always measured in units of millimetres of mercury (mmHg). 

A healthy blood pressure is between 90/60mmHg and 120/80mmHg. 

• High blood pressure (hypertension): 140/90mmHg or higher is when the force of blood against the artery walls is consistently too high
• Low blood pressure (hypotension): 90/60mmHg or lower is when the force of blood against the artery walls is consistently too low

Although high blood pressure is relatively common, sustained hypertension can significantly increase your risk of developing several serious long-term health conditions. For example, hypertension is the most common preventable risk factor for cardiovascular disease, which includes heart failure, stroke and coronary heart disease. Hypertension can also lead to chronic kidney disease and cognitive impairment.³

In the body, blood pressure is determined by blood volume, cardiac output (quantity of blood pumped by the heart in a given time), and arterial tone (the contractile activity of vascular smooth muscle cells in the walls of arteries).³ Any disruption or change in these factors can directly or indirectly cause increased blood pressure. 

Pomegranates 

Overview and key nutrients

The pomegranate (Punica granatum) is a fruit-bearing deciduous shrub.^1,4 Pomegranate fruits are round, with a thick outer skin, often deep red or purple. When you cut open a pomegranate, you can see it contains clusters of arils (fleshy seed coverings). Each aril contains a seed surrounded by a juicy pulp; the edible part of the fruit. The arils have a sweet, refreshing flavour, and vary in colour from deep red to pink, depending on the variety and ripeness of the fruit.

Pomegranates have been shown to contain key nutrients that have potential antioxidant, anti-inflammatory, and anti-carcinogenic (anti-cancer) effects.⁵ These include:

• Vitamin C - its antioxidant properties promote healthy skin and aid wound healing
• Fibre - is important for digestive health
• Vitamin K - is important for blood clotting and bone health
• Potassium - maintains fluid balance, helping to regulate blood pressure
• Folate - important in DNA synthesis (creation), cell division and production of red blood cells
• Antioxidants (e.g. polyphenols) 
• Other nutrients such as vitamin E, vitamin B6, calcium and iron

In addition, pomegranates are low in calories and do not contain saturated fat. Studies have shown the medicinal properties of pomegranates, including in cancer, diabetes, cardiovascular disease, obesity, arthritis and Alzheimer's disease.² 

Pomegranates and blood pressure: research

Due to pomegranate’s range of nutrients and antioxidant properties, many studies have examined whether eating pomegranates could impact blood pressure. 

One study observed the effect of pomegranate juice consumption on blood pressure in patients with high blood pressure.⁶ The patients consumed fresh pomegranate juice for two weeks which results found were associated with significant reductions in systolic and diastolic blood pressure compared to the control group who did not consume pomegranate juice. 

A meta-analysis (a statistical analysis that combines the results of several studies) found that pomegranate juice did appear to reduce systolic and diastolic blood pressure modestly, in a dose-dependent manner. However, the benefit was lost after two months of pomegranate juice intake.⁷

A minor reduction in blood pressure can reduce the chances of myocardial infarction (heart attack) or a stroke, so even if pomegranates only have a modest effect, this could still be beneficial to health.²

Suggested mechanisms of action 

Blood pressure lowering properties have been linked to several components within pomegranates, such as ellagic acid, ellagitannins, punicic acid, flavonoids, anthocyanins, estrogenic flavonols and flavones, which are all found in different proportions in different parts of the fruit.²

• Antioxidant properties: pomegranate juice contains high levels of polyphenols, which have very high antioxidant properties. Hypertension can be triggered by the interaction of reactive oxygen species (ROS) with lipids, proteins and other components of cells, which then causes endothelial dysfunction and vascular resistance. The antioxidant content means consumption of pomegranate juice may inhibit ROS activity and lower blood pressure⁷
• Reduction in LDL cholesterol: has been shown to prevent low-density lipoprotein (LDL) cholesterol oxidation - high levels of LDL raise your risk of heart disease⁷
• Decrease in ACE activity: Decreases angiotensin-converting enzyme (ACE) activity secondarily, or directly affects serum ACE activity. ACE inhibitors are medicines that help relax the veins to lower blood pressure. Therefore, a reduction in ACE activity could lower blood pressure⁷ 
• Decrease in cortisol levels: involved in inhibition of the conversion of cortisone to cortisol - the amount of the stress hormone, cortisol, circulating in the body plays an important role in blood pressure regulation⁷

Antioxidant and anti-inflammatory properties 

Antioxidants protect the body’s cells from damage, reducing the risk of chronic (long-term) diseases such as heart disease, cancer, and neurodegenerative disorders. Pomegranates have a high antioxidant content, largely due to their polyphenol content.⁸ Pomegranate juice has more antioxidant activity than other commonly consumed drinks containing antioxidants, such as green tea, red wine, orange, grapefruit or cranberry juice.⁴

The principal polyphenols in pomegranate juice include ellagitannins and anthocyanins.⁸ Ellagitannins account for 92% of the antioxidant activity of pomegranate juice and are concentrated in the peel, membranes and piths of the fruit. Studies have shown pomegranate juice contains a wide spectrum of compounds with strong antioxidant capacity including tannins, flavonoids and phenolic acids.⁴ 

Cardiovascular health benefits beyond blood pressure management 

Intake of dietary nutrients such as polyphenols is associated with a reduced risk of cardiovascular disease.⁷ 

Pomegranate polyphenols can protect low-density lipoprotein (LDL) cholesterol (the ‘bad’ cholesterol) against oxidative stress (an imbalance of free radicals and antioxidants that leads to cell damage). LDL makes up the majority of your body’s cholesterol, but when there is too much, it can build up on the walls of your blood vessels in a process known as atherosclerosis.

This is known as plaque, and it narrows and blocks arteries, which can ultimately reduce blood flow to vital organs and increase the risk of heart disease and stroke. The plaques become increasingly unstable over time, which can block blood flow altogether when blood clots form.

Pomegranate polyphenols can protect LDL against cell-mediated oxidation via two pathways - either via direct interaction of polyphenols with lipoprotein, or an indirect effect through the accumulation of polyphenols in arterial macrophages (a type of white blood cell that helps eliminate foreign substances by engulfing foreign materials and kick-starting immune responses). 

This links nicely to blood pressure management, as LDL cholesterol can contribute to high blood pressure, which weakens blood vessels making them more prone to rupture or forming clots. 

Incorporating pomegranate into your diet 

Pomegranate arils have a sweet and tangy flavour, so once they are scooped out, you can enjoy them however you wish. For example: 

• Fresh: you can cut the pomegranate in half, and scoop out the arils to eat. You can then eat them as they are, or sprinkle them over salads or yoghurt for added flavour
• Juice: you can buy pomegranate juice or make it yourself by extracting the juice from the arils using a citrus juicer or blender. Then you can incorporate it into smoothies or cocktails or drink it on its own
• In recipes: pomegranate arils can be incorporated into various recipes, such as salads, salsa, chutney or porridge. They add a burst of flavour

Supplements

As well as fresh pomegranate, there are also pomegranate supplements that contain concentrated extracts from the fruit, seeds or peel.⁸ When considering pomegranate supplements for their proposed health benefits, it is important to be aware of:

• Active ingredients: Pomegranate supplements must contain bioactive compounds such as punicalagins (a type of polyphenol), as these are the parts that are believed to be responsible for many of the associated health benefits
• Dosage: Always follow the recommended dose instructions provided on the supplement packaging or advised by a healthcare professional. Exceeding the recommended dosage may lead to adverse effects
• Interactions and side effects: Pomegranate supplements may interact with certain medications, such as blood thinners (anticoagulants). They also may cause side effects including gastrointestinal discomfort or allergic reactions in some individuals

It is always important to consult with a healthcare professional before starting any new supplement, especially if you have underlying health conditions or are taking any medications.

Consuming fresh pomegranate or pomegranate juice as part of a balanced diet may result in similar health benefits to those provided by supplements, making it the preferred option for many people. 

Summary

Although pomegranates, both fresh and as a supplement, may offer various health benefits, there is relatively limited scientific evidence supporting the claims. There are positive studies, particularly about heart health, but more studies are needed to confirm the positive effects. Further research is necessary to establish whether consuming pomegranate has a significant, positive impact on blood pressure.

However, pomegranates do appear to have other health benefits including antioxidant activity and reduction in LDL cholesterol levels, so even if there is not a dramatic positive effect, there shouldn’t be a negative effect as long as you consume them in moderation as part of a balanced diet.