A major new study from researchers at NUI Galway and several international institutions is changing the way scientists think about blood pressure treatment.
For many years, doctors worried that lowering the bottom number in a blood pressure reading too much could be dangerous for patients. But this new research suggests that lowering this number, called diastolic blood pressure, may actually be safer than once believed.
The findings could influence how millions of people with high blood pressure are treated in the future and may lead to important updates in medical guidelines around the world.
Blood pressure is measured using two numbers. The top number is called systolic blood pressure. It measures the pressure inside the arteries when the heart pumps blood through the body. The bottom number is called diastolic blood pressure. It measures the pressure when the heart relaxes between beats.
For decades, doctors believed that lowering diastolic pressure too much might reduce blood flow to the heart itself and increase the risk of heart attacks or other heart problems. Because of this concern, many doctors tried to avoid lowering diastolic pressure below about 70 to 90 millimeters of mercury, also known as mmHg.
This concern became especially important when treating people with high systolic blood pressure. Doctors often worried that aggressive treatment to lower the top number might accidentally push the bottom number too low.
However, the new study challenges this long-standing belief.
The research was led by Dr. Bill McEvoy and published in the medical journal Circulation. Scientists analyzed health records and genetic information from more than 47,000 people across five separate study groups. The average age of participants was around 60 years old.
The researchers carefully examined whether very low diastolic blood pressure increased the risk of heart disease, stroke, or other serious cardiovascular problems.
What they discovered surprised many experts. Even when diastolic blood pressure dropped as low as 50 mmHg, there was no clear evidence that the risk of heart disease increased. In other words, the feared dangers of “too low” diastolic pressure may not actually exist in many cases.
At the same time, the study confirmed something doctors already strongly suspected: high systolic blood pressure remains a major risk factor for heart attacks, strokes, and cardiovascular disease.
The researchers found that people with systolic blood pressure above 120 mmHg had a higher chance of developing serious heart and blood vessel problems. This suggests that lowering systolic pressure should remain one of the main goals of treatment.
These findings may change how doctors approach hypertension treatment in the future. High blood pressure affects millions of people worldwide and is one of the leading causes of death and disability. It increases the risk of heart disease, stroke, kidney damage, vision problems, and other serious conditions.
High blood pressure also became a major concern during the COVID-19 pandemic because people with hypertension were found to have a higher risk of severe illness from the virus.
Because hypertension is so common, doctors have long searched for the safest and most effective ways to lower blood pressure without causing other health problems.
In the past, some doctors hesitated to lower systolic pressure aggressively because they worried the diastolic number might fall too far. But this new research suggests that the focus should remain mainly on controlling systolic pressure, even if the diastolic number drops below traditional targets.
The researchers now suggest that systolic blood pressure should ideally be lowered to somewhere between 100 and 130 mmHg for many patients. If doing this causes diastolic pressure to fall below 70 mmHg, the study suggests that it may not necessarily be dangerous.
This could give doctors more confidence when treating patients with hypertension and help more people lower their risk of heart attacks and strokes.
The findings also highlight how medical understanding changes over time as new evidence becomes available. Some ideas that were accepted for many years may later be challenged by larger and more detailed studies.
Scientists say more research is still needed to fully understand how blood pressure affects different groups of people, especially older adults and those with existing heart disease. However, this study provides strong evidence that low diastolic pressure itself may not be as harmful as once feared.
Experts continue to emphasize that blood pressure treatment should always be personalized. Every patient is different, and factors such as age, overall health, medications, kidney function, and other medical conditions all play a role in determining the best treatment plan.
Healthy lifestyle habits also remain an important part of blood pressure control. Eating a balanced diet, reducing salt intake, exercising regularly, managing stress, avoiding smoking, limiting alcohol, and getting enough sleep can all help support healthy blood pressure levels.
For millions of people living with hypertension, this study brings encouraging news. It suggests that doctors may be able to focus more confidently on lowering the top blood pressure number, which is strongly linked to heart disease and stroke risk, without worrying as much about lowering the bottom number too far.
Researchers hope the findings will eventually improve treatment guidelines and help protect more people from serious cardiovascular diseases in the years ahead.
If you care about high blood pressure, please read studies that early time-restricted eating could help improve blood pressure, and natural coconut sugar could help reduce blood pressure and artery stiffness.
For more information about blood pressure, please see recent studies about How to eat your way to healthy blood pressure and results showing that Modified traditional Chinese cuisine can lower blood pressure.
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