What is blood pressure?

When your heart beats, blood is pumped round your body to give it the energy and oxygen it needs. As the blood moves, it pushes against the sides of the blood vessels. The strength of this push on the blood vessels is your blood pressure. If your blood pressure is high, it means that there is too much strain on your blood vessels which can cause damage. Damage to blood vessels leading to your heart or the vessels in your brain may lead to heart attacks and strokes.

What is high blood pressure?

High blood pressure has no symptoms and so it is hard to tell if you have high blood pressure without having your blood pressure measured by your GP.

Blood pressure is measured as millimetres of mercury (mmHg) and is written as two numbers e.g. 120/80 mmHg. The first number is your systolic blood pressure. It is the highest level your blood pressure reaches when your heart beats. The second number is your diastolic blood pressure. It is the lowest level your blood pressure reaches as your heart relaxes between beats.

A blood pressure of greater than 140/90 mmHg is high. This level of pressure puts extra strain on your blood vessels and heart which over time puts you at an increased risk of having a stroke or a heart attack.  Approximately one in four adults in the UK have diagnosed high blood pressure, but many more that are unaware they have the condition.

Ideally we should all have a blood pressure of 120/80 mmHg or less. If your blood pressure is between 120/80 mmHg and 140/90 mmHg then you should take steps to lower it, including eating less salt, increasing the amount of fruit and vegetables you eat and getting more exercise.

 

What can lead to high blood pressure?

• Eating too much salt
• Being overweight 
• Not getting enough physical exercise
• Drinking too much alcohol

Evidence that relates salt to blood pressure

While some evidence suggests that obesity coupled with a lack of exercise can lead to high blood pressure, stronger evidence shows that eating too much salt is more strongly related to the development of high blood pressure, particularly the rise in blood pressure with age.

A high salt diet disrupts the natural sodium balance in the body. This causes the body to retain water, which increases the pressure of the pushing of blood against the vessel walls. As a nation, if we can cut one gram of salt from our average daily salt intake, there would be approximately 6,000 fewer deaths from strokes and heart attacks each year in the UK.  

It has been estimated that a reduction in salt intake from 10g a day to 6g would reduce blood pressure and could prevent approximately 2.6 million stroke and heart attack deaths each year worldwide.  Reducing salt is one of the quickest ways to reduce your blood pressure, particularly if you already have high blood pressure.

Who is most at risk of high blood pressure?

Anyone is at risk of a high blood pressure, as blood pressure starts to increase from childhood. People with a high salt diet, pregnant women and people of black African descent are particularly susceptible to high blood pressure.

High blood pressure is an important risk factor for a range of conditions. These include strokes, vascular dementia, diabetes, kidney disease, heart disease and mobility problems. People who already have these conditions may find a reduced salt diet beneficial in the long run.