Introduction

Blood pressure is the force exerted by the blood within the major arterial system. The blood pressure is measured in systolic and diastolic pressure.¹ Diastolic pressure occurs when the heart fills with blood, while systolic pressure occurs when the heart contracts.² While the primary concern seems to be on systolic blood pressure, diastolic pressure plays an equally vital role in ensuring that cardiovascular health is upheld.

What is diastolic blood pressure?

Diastolic blood pressure is the pressure in your arteries between contractions.¹ Diastole is the resting period of the cardiac cycle during which the heart fills up with blood just before the next contraction. During this stage, blood vessels return blood back to the heart. This happens in contrast to the systole stage wherein the blood gets pumped out of the heart. As the blood is pumped out to the rest of the body, a lot of pressure is needed. Hence, systolic blood pressure is higher than diastolic blood pressure.²

How diastolic blood pressure is measured?

Blood pressure is measured using a sphygmomanometer, which has an inflatable cuff placed around the arm. The cuff is inflated to stop blood flow, then released slowly. As the blood begins to flow again, the systolic pressure is recorded when the first heartbeat sound is heard. The diastolic pressure is recorded when the sound disappears, indicating the heart is between beats.³

A normal blood pressure reading is measured in millimetres of mercury (mm Hg) as systolic over diastolic. For example,120/80 mm Hg indicates a systolic reading of 120 and a diastolic reading of 80.¹​

Normal range of diastolic blood pressure

The normal range for diastolic blood pressure is between 60 and 80 mm Hg.¹ Maintaining this range is important because both low and high diastolic pressure can indicate potential health issues.

• Normal diastolic pressure: 60-80 mm Hg
• Low diastolic pressure (Hypotension): Below 60 mm Hg
• High diastolic pressure (Hypertension): Above 80 mm Hg

Factors affecting diastolic blood pressure

Understanding various factors affecting diastolic pressure can help individuals make informed decisions to maintain healthy blood pressure levels:

Age

As age increases, diastolic pressure decreases. Younger people have a higher diastolic pressure; whereas in older age, this number has a tendency to drop as the arteries stiffen up.

Dietary factors 

Excessive salt intake, processed food, and unhealthy fats increase blood pressure. On the other hand, DASH (Dietary Approaches to Stop Hypertension) diets containing fruits, vegetables, whole grains, lean proteins, and low-fat dairy products have proven to reduce blood pressure.

Physical activity

Regular physical exercise can help lower both systolic and diastolic blood pressure by improving heart health and circulation.

Stress management

Long-term stress can contribute to increased blood pressure.

Cutting down on alcohol and abstaining from tobacco

Excessive consumption of alcohol and smoking are two prominent risk factors for high blood pressure. Therefore, reduced intake of alcohol and abstaining from smoking would yield immediate and long-range heart health and blood pressure benefits.

Medications

Taking medications such as hormonal birth control pills, decongestants, antidepressants, and non-steroidal anti-inflammatory drugs like ibuprofen or aspirin can increase blood pressure.

Medical conditions

Certain medical conditions, such as atherosclerosis, kidney disease, and diabetes, can affect diastolic blood pressure. Additionally, thyroid disorders, adrenal gland issues, and sleep apnea may impact blood pressure regulation.

Health risks associated with abnormal diastolic blood pressure

Irregular diastolic pressure can lead to health risks, often affecting the heart and other vital organs.

Risks of high diastolic pressure (Hypertension)

Consistently high diastolic pressure can damage arteries by making them less elastic and in turn restricting blood flow. This increases the risk of heart disease, stroke, and kidney problems.⁵ 

Risks of low diastolic pressure (Hypotension)

This condition may cause dizziness, fainting, and, in severe cases, inadequate blood flow to the heart and brain. Extremely low diastolic pressure individuals are at risk of organ damage, especially when blood flow becomes constricted to vital organs such as the heart or brain.

When to consult medical services?

Self-monitoring of blood pressure is indicated for everyone with hypertension, cardiovascular diseases, or at high risk. Consult a doctor if: 

• You register a diastolic reading above 90 mm Hg⁴ 
• Feeling dizzy, chest pain, breathing difficulty, or fainting 
• A sudden hike or drop in a blood pressure reading

The conditions may be detected early in regular checkups. Those with abnormal readings shall live with the condition through modification of lifestyle and medication as prescribed. 

Summary

Diastolic blood pressure is the pressure in your arteries between contractions. Diastole is the resting period of the cardiac cycle during which the heart fills up with blood just before the next contraction. Diastolic blood pressure provides insight into cardiovascular health during the heart’s resting period. Maintaining healthy diastolic blood pressure prevents heart disease, stroke, and other related conditions. This can be managed with a healthy diet, exercise, stress management, and regular monitoring.