Do you know the difference between systolic and diastolic blood pressure? The first number in your reading, systolic, gets far more mentions. But it’s important to keep a close eye on diastolic blood pressure too.

Here, we’ll explain more about diastolic blood pressure and why it’s significant. We’ll look at what causes high diastolic blood pressure and what you can do to lower your reading safely.

What is diastolic blood pressure?

Your blood pressure reading has two numbers. The top one is systolic pressure – the force your heart uses to pump blood out to your body. The bottom, lower number is diastolic pressure – the pressure in your blood vessels between beats.

Typically, people  are more interested in the top number, systolic blood pressure. Isolated systolic hypertension – when the top number is elevated and the bottom one is normal – is actually the most common type of high blood pressure in people aged 65 and over. It also carries a greater risk of stroke and heart disease than elevated diastolic blood pressure, especially in people over 50.

However, we now know that both numbers are important, and either an elevated systolic or diastolic blood pressure reading may be used to diagnose high blood pressure.

Here’s how to understand your diastolic blood pressure number:

Why is diastolic blood pressure important?

A 2019 study published in the New England Journal of Medicine reviewed 36 million blood pressure readings from 1.3 million adults in Northern California, taken between 2007 and 2016. Dr Alexander Flint, who led the study, said: ‘Although systolic does count for a little bit more in terms of the risk of heart attack and stroke, diastolic high blood pressure is a close second, and it’s an independent predictor of those risks.’

If you have an elevated diastolic blood pressure but a normal systolic reading then, like fewer than 20% of hypertension cases, you have isolated diastolic hypertension (IDH). Like other types of high blood pressure, IDH can increase the risk of conditions including stroke, heart disease, heart attack, heart failure, aneurysm, vision loss, and kidney disease.

What causes isolated diastolic hypertension?

Isolated diastolic hypertension is linked to endocrine and renovascular disorders. A 2012 study also demonstrated a link between severe sleep apnoea and raised diastolic blood pressure.

Of course, lifestyle can make you more likely to have an elevated diastolic blood pressure, too. A study of 8,475 patients aged 18 and above in China revealed three significant risk factors:

• Age: patients with IDH are much younger than those with ISH
• BMI: a high BMI is a significant risk factor for IDH, but not for ISH
• Smoking: is significantly associated with IDH but not with ISH

The study results suggest that keeping fit and giving up smoking might be particularly efficient for young patients looking to manage diastolic blood pressure.

How can you reduce diastolic blood pressure?

There are many things you can do to lower your blood pressure overall. Your doctor may recommend a few lifestyle changes, such as increasing exercise and improving your diet, as well as blood pressure medication.

However, if you only have high diastolic blood pressure, it’s important to work closely with your doctor to make sure it doesn’t reduce too much. Low diastolic blood pressure (under 60 mmHg) means your heart muscles won’t get enough oxygenated blood, which can lead to a condition called diastolic heart failure. In fact, people with a diastolic blood pressure below 60 mmHg are 50% more likely to have heart damage.

Sensible lifestyle changes to reduce diastolic blood pressure include:

• Losing weight, or maintaining a healthy weight
• Staying physically active with a form of exercise you enjoy
• Eating a balanced diet with plenty of fruits, vegetables, whole grains, lean protein and low-fat dairy
• Reducing your salt intake to between 1.5 and 4 grams per day
• Drinking plenty of fluids, and avoiding alcohol
• Giving up smoking
• Monitoring blood pressure levels at home and keeping a closer eye on your health

Since studies have traditionally focused on systolic blood pressure, we’re still discovering the true significance of diastolic blood pressure. If you’re affected, by far the best approach is to work with your doctor to develop an appropriate treatment plan.