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Your blood pressure (BP) is created by the heart pumping blood around a 'closed system' of blood vessels. Blood pressure naturally varies throughout the day and night, going up and down in response to factors such as your emotions, level of activity and hormone and electrolyte changes.
In the UK, around one in three men and one in four women have high blood pressure – known medically as hypertension – and for every 10 people that are diagnosed, it's estimated that a further seven have high BP but are unaware of their condition, putting them at risk of serious complications.1
The pressure within your circulation was originally measured against the weight of mercury (Hg) it could support within a long, thin, glass tube.
The length of the column was measured in millimetres (mm) and the pressures recorded in units known as millimetres of mercury (mmHg). These units, which date back to the eighteenth century, are still in use today.
Two blood pressure readings are taken:
Blood pressure is most usually measured with the aid of a cuff placed around your arm or wrist. It's important that the cuff is positioned level with your heart to get an accurate reading.
The cuff is then rapidly inflated to a pressure that is high enough to temporarily stop the flow of blood in the underlying arteries.
The pressure is then slowly deflated until blood starts to flow again. This creates a distinct tapping noise (Korotkoff sound) and the pressure at which this noise is first detected is taken as the highest pressure – your systolic blood pressure.
As pressure in the cuff continues to fall, the tapping sounds change to a dull whooshing due to turbulence, while the cuff continues to constrict blood flow.
The pressure at which this whooshing suddenly stops marks the point at which the pressure in your arteries and the cuff is identical, and this is recorded as your diastolic blood pressure.
By convention, your systolic blood pressure reading is written over your diastolic blood pressure reading (e.g. 120/80 mmHg) and is described as, for example, 'one twenty over seventy'.
An ideal blood pressure is one that is below 120/80 mmHg and above 90/60 mmHg.
In the UK, high blood pressure, or hypertension, is diagnosed when your BP is consistently greater than 140/90 mmHg. This is confirmed using a wearable monitor to record measurements at regular intervals during your normal daily activities and sleep (ambulatory blood pressure monitoring).
In some countries, such as the US, a different cut-off is used, so that hypertension is diagnosed when your blood pressure is consistently greater than 130/80 mmHg.
Hypertension is described as a 'silent' disease, as it may produce few symptoms even when your blood pressure is dangerously high. If symptoms or signs of hypertension do appear, they tend to be non-specific, such as:
These symptoms are not necessarily due to high blood pressure, but if they do occur, it's important to see your doctor for a check-up.
Having untreated high blood pressure damages artery walls and hastens hardening and furring up of the arteries.
This raises your blood pressure even more and increases your risk of heart rhythm abnormalities (atrial fibrillation), heart attack, heart failure, peripheral arterial disease, aortic aneurysm, stroke and vascular dementia.
Damage to other blood vessels also increases the risk of conditions such as chronic kidney disease, eye problems and male erectile dysfunction.
Untreated high blood pressure can lead to heart attack, heart failure, stroke and vascular dementia, among other problems.
Blood pressure naturally tends to rise with age as your arteries become more stiff and less elastic. The genes you have inherited and lifestyle factors such as smoking, alcohol intake, diet, level of exercise, long-term stress and being overweight or obese can also affect your blood pressure.2
For nine out of 10 people with high blood pressure there is no obvious single underling cause, and this is referred to as 'primary hypertension'.
For one in 10 people, there is an identifiable underlying cause such as kidney problems, hormone imbalance or taking certain drugs known to affect blood pressure.3
Systolic blood pressure rises with age but after around the age of 50 years, diastolic blood pressure tends to fall.
In your 20s, your BP may be around 115/70 mmHg, for example, but by the age of 50, average blood pressure is around 135/85 mmHg.
By the age of 60 it tends to rise to around 140/80 mmHg and by the age of 70 is 145/75 mmHg.
Everyone is different, however, and some people may have high blood pressure in their youth, while others may maintain good blood pressure readings throughout later life.
The only way to know is to have regular checks – ideally at least once every year or two, or as often as your doctor recommends.
If your blood pressure is raised, your doctor will recommend diet and lifestyle changes to help bring it down.
Follow a Mediterranean-style diet known as the DASH (Dietary Approach to Stopping Hypertension), which you can read about here. This way of eating is high in fruit, vegetables, nuts, garlic, low-fat dairy products and supplies protein in the form of fish, chicken and beans rather than red meat.
Reduce salt intake by not adding it during cooking or at the table. This is because salt can contribute to water retention, which raises blood pressure in some people. Additionally, cut back on caffeine intake, as caffeine can raise blood pressure.
Exercise for at least 30 to 60 minutes on most days – brisk walking, cycling, swimming, gardening or dancing are all good ways to increase your fitness, which helps lower BP.
If you smoke, do your utmost to stop, as chemicals found in tobacco raised blood pressure and damage artery linings. Keep alcohol intake without recommended levels – in particular, binge-drinking raises blood pressure.
A number of supplements can help to lower blood pressure. For example, DHA and EPA – the long-chain omega 3s found in fish oil and marine algae extracts – contribute to the maintenance of normal blood pressure.
You can read about other supplements, herbal medicines and lifestyle factors that can lower blood pressure at MyLowerBloodPressure.com
Dr Sarah Brewer is Healthspan's Medical Director and holds degrees in Natural Sciences, Surgery and Medicine from the University of Cambridge. Having worked as a GP and hospital doctor, Dr Sarah now holds an MSc in Nutritional Medicine from the University of Surrey and specialises in nutrition. She is also an award-winning writer and author.
Nothing beats a healthy, balanced diet to provide all the nutrients we need. But when this isn't possible, supplements can help. This article isn't intended to replace medical advice. Please consult your healthcare professional before trying supplements or herbal medicines.
1National Institute for Health and Care Excellent (2021). Hypertension: how common is it? Clinical Knowledge Summaries
2National Institute for Health and Care Excellent (2021). Hypertension: what are the risk factors? Clinical Knowledge Summaries
3National Institute for Health and Care Excellent (2021). Hypertension: what is it? Clinical Knowledge Summaries