What is blood pressure?

Ever wondered exactly what is being measured when your blood pressure is checked? Find out all about those readings in this guide

Written by Carole Beck on January 26, 2019 Reviewed by Dr Rob Hicks on January 28, 2019

Blood is essential to our bodies, carrying vital oxygen and nutrients to our cells via blood vessels. It’s now known that the force at which this blood is pumped is critically important to both your short-term and long-term health. Here’s what it means for your body.

What is blood pressure?

It’s a measurement of the pressure of blood inside your blood vessels as your heart squeezes and relaxes.¹ There are two blood pressure numbers, both measured in millimetres of mercury (mmHg):

Systolic pressure

The first number of a blood pressure reading records the pressure in your blood vessels as the heart contracts, or in other words squeezes, making it a measurement of the force at which blood is pumped.²

Diastolic pressure:

The second number of the reading measures the pressure when the heart rests between squeezes.³

What is high blood pressure?

This is when the pressure inside your blood vessels rises higher than is healthy. As a general rule:

• high blood pressure – 140/90mmHg or higher
• ideal blood pressure – between 90/60mmHg and 120/80mmHg
• low blood pressure – 90/60mmHg or less⁴

What are the dangers of high blood pressure?

More than one in four UK adults have high blood pressure, many without knowing, according to the NHS.⁵ High blood pressure – known medically as hypertension – can contribute to a narrowing of the arteries that carry blood around your body.⁶ Narrowed arteries (atherosclerosis) restrict the flow of blood, oxygen and nutrients to certain organs, including the heart, brain, kidneys and sexual organs. This can trigger a range of health conditions, including:⁷

• heart attack
• heart failure
• stroke
• vascular dementia
• kidney failure
• sexual dysfunction, including erectile dysfunction in men

What are the symptoms of high blood pressure?

Unfortunately, most people usually experience no symptoms, even with severe hypertension. This means many people are unaware they have high blood pressure, which, over time, can damage their blood vessels. This is why it’s so important to have your blood pressure regularly checked⁸ – ideally at least every five years, or more often if your doctor advises.

Who is most at risk of high blood pressure?

You’re more likely to develop hypertension if you:^9,10

• are over 65
• take little exercise
• smoke
• are overweight
• eat an unhealthy diet, with too much salt and too little fruit and vegetables
• drink alcohol or caffeinated drinks to excess
• have a family history of high blood pressure
• are of African or Caribbean descent

Interestingly, stress isn’t thought to cause high blood pressure in the long-term – although the way you react to stress, for example drinking alcohol or smoking, can lead to high blood pressure.¹¹

How to prevent and tackle high blood pressure

Lifestyle changes can help reduce the risk of having high blood pressure and also tackle hypertension. These include:^11,12

• a healthy, balanced diet with plenty of fruit and vegetables
• regular exercise
• keeping within healthy recommended intakes of alcohol, caffeine and salt
• not smoking

If you have been diagnosed with high blood pressure, your doctor may also prescribe medication to help bring it down. Some natural remedies may offer support, too: Garlic – a 2016 Australian study found that 1.2g of aged garlic extract a day for 12 weeks can reduce blood pressure by helping blood vessels to widen¹⁴ Vitamin C – it reduced both systolic and diastolic blood pressure levels in trials, according to a 2012 study from the US’ John Hopkins Medical Institutions. Researchers suggested vitamin C supplementation can increase levels of a molecule called nitric oxide, widening blood vessels¹⁵

What about low blood pressure?

Low blood pressure, or hypotension, can restrict blood flow to organs. For some, hypotension is completely normal for their body. For others, it can be caused by:¹⁶

• dehydration
• pregnancy
• certain medication
• hormone problems
• a lack of vitamin B12 or folate in your diet

Hypotension is usually only a problem if it causes symptoms. These can include:¹⁷

• feeling lightheaded and dizzy
• nausea
• fainting
• tiredness
• trouble concentrating

Speak to your GP if you are concerned.

How to check your blood pressure

Ask your GP, or you can also buy a home blood pressure monitor. Advice is for information only and should not replace medical care. Please check with your GP before trying any remedies. Sources 1. Markus MacGill. Medical News Today. What is a normal blood pressure? 2. MedicineNet. Medical Definition of Systolic 3. MedicineNet. Medical Definition of Diastolic 4. NHS. Overview: High blood pressure (hypertension) 5. As above 6. Mayo Clinic. High blood pressure dangers: Hypertension’s effects on your body 7. As above 8. Mayo Clinic. High blood pressure (hypertension) 9. As Source 4 10. NHS. Causes: High blood pressure (hypertension) 11. Mayo Clinic. Stress and high blood pressure: What’s the connection? 12. NHS Inform. High blood pressure (hypertension) 13. As Source 12 14. Ried K, Travica N, Sali A. The effect of aged garlic extract on blood pressure and other cardiovascular risk factors in uncontrolled hypertensives: the AGE at Heart trial 15. Juraschek SP, et al. Effects of vitamin C supplementation on blood pressure: a meta-analysis of randomized controlled trials 16. Mayo Clinic. Low blood pressure (hypotension) 17. As above