Can Green Tea Decrease your High Blood Pressure?

High Blood pressure, or Hypertension is a common disorder that plagues our nation. According to recent statistics over 30% of the nation are hypertensive, and many more are receiving no treatment for it [1]. An even more frightening thought is that it can cost our NHS over £2 billion every year, for a disease type that is almost always preventable[1].

What Is High Blood Pressure?

‘Blood Pressure’ is a simple measurement that describes the pressure in which blood flows in the arteries, from the heart. The measurement is given in two number the systolic and the diastolic. The systolic number is the greater of the two, it describes the force that blood flows in the vessels. Whereas, the smaller diastolic number describes the resistance against the blood flow in the vessel. All of which is measured in mmHG, millimeters of mercury.

A normal measurement is anywhere between 60/90 to 80/120. Any higher, or any lower can be a sign of illness and damage. There are different stages of Hypertension listed below.

Table 1: Types of Hypertension and their measurement boundaries.

When a person is pre-hypertensive they have done very little damage to their body and any effects caused can be reversed. It requires no medicine but instead careful consideration of nutrition and lifestyle for it to return to normal. However, as you move through the stages of hypertension the greater the damage done. Once a person reaches stage 2 hypertension they will require interventions for health, aside from lifestyle help, they may now require drugs. When a person reaches the stage of 'Hypertensive Crisis' they may need immediate medical care as symptoms will effect their breathing and consciousness [3].

What are the risks of High Blood Pressure?

• Kidney Disease
• Dementia
• Strokes
• Heart Disease
• Heart attacks etc. [3]

Ways to lower your Blood Pressure

There are a number of ways that you can lower blood pressure they are as follows:

Reduce your Sodium Intake- The recommended daily intake is 6g, but for those that are hypertensive you should consume no more than 1.5g -2.3g dependent on severity. Sodium is one of the main causes of hypertension in the body.

The DASH Diet- this stands for Dietary Approaches to Stop Hypertension, this is a diet rich in fruit and vegetables, which are good sources of Potassium.  Potassium has an antagonistic relationship with Sodium. The diet is also low in fat and cholesterol. The DASH diet is supposed to take effect in less than 14 days and can significantly reduce systolic blood pressure.

Aerobic Exercise- In adherence with regular guidelines, 30 minutes of exercise should be undertaken at least 5 times a week. Studies have shown that this can lower systolic blood pressure by 4-9 mmHG.

Reduce Caffeine Intake- Caffeine targets and stimulates the central nervous system which increases our heart rate. Increasing beats per minute can increase cardiac output and pressure on the heart. Thus, increasing blood pressure and strain on the heart. There is also some very small studies that show caffeine acts on an enzyme that prevents the arteries from staying open and wide, keeping blood pressure low.

Quit Smoking- Cigarette smoke contains numerous chemicals, of which Nicotine is one. Nicotine causes blood platelets to increase their coagulation abilities, this causes blood to become more viscous and decrease flow, this increases blood pressure in the arteries. [4,5]

Drink Green Tea- Among its many miracle properties, Green tea is supposedly brilliant at reducing blood pressure. A report in times magazine found that 12 weeks of drinking Green tea daily led to a 2.6mmHg decrease in systolic blood pressure and 2.2mmHg decrease in diastolic blood pressure [6].

How can Green Tea Help?

Green Tea is the leaf extract of the Camellia Sinensis plant. All across the world tea ranks poll position as one of the favoured beverages. It’s rich in polyphenols such as EGCG (epigallocatechin gallate) and Catechins. It’s also rich in Vitamin A. B5, C, D, E, K, manganese, chromium, selenium and zinc.

There is no clear, definitive answer as to how Green Tea acts, but the important thing is that it does. Studies have postulated that therapeutic compounds in Green Tea act on the smooth muscle of the vessel helping to keep them relaxed with a wide lumen so high pressures cannot be generated. On the other hand, it has also been shown to prevent the formation of thrombi thus reducing the frequency of blood clots, allowing blood to flow more easily.

One study undertaken in 2014, took Green tea and compared its effect on blood pressure and cholesterol (a contributor to raised blood pressure). Out of 1,536 participants, they found that regular ingestion of Green Tea led to a 1.94mmHg reduction in systolic blood pressure. Second to this, and potentially a factor in the reduction of blood pressure is the reduction of total cholesterol by 0.143mmol/l[7]. In addition, one study used supplemental Green Tea Extract. It took 2 groups, containing a total of 56 obese and hypertensive patients and gave them a daily 379mg capsule or placebo tablet. They found that after 3 months both systolic and diastolic blood pressure values had reduced. Also, Green Tea extract appeared to have beneficial effects to cholesterol levels, inflammation, and oxidative stress, all of which are co-factors to the onset of hypertension [8].

It was reported that decreases as little 2mmHg could lead to a 5%decrease in coronary heart disease, 8% decrease in stroke and 4% decrease in overall mortality [6].