High blood pressure affects huge numbers of adults and is one of the most important risk factors for heart disease and stroke.
Because it often causes no obvious symptoms, a person can have dangerously high blood pressure for years without realizing it.
A blood pressure reading contains two numbers. The top number, called systolic blood pressure, shows the pressure in the arteries when the heart contracts and pumps blood, while the bottom number, called diastolic blood pressure, measures pressure when the heart relaxes between beats.
For many years, doctors have paid close attention to both numbers when treating high blood pressure. There has also been concern that lowering the bottom number too much could reduce blood flow to important organs, particularly the heart.
Research involving more than 47,000 patients, however, challenged some of those concerns. The international study was led by researchers including Dr. Bill McEvoy of NUI Galway, now known as University of Galway, and examined whether very low diastolic blood pressure was dangerous during treatment.
The researchers analyzed information from several major clinical trials involving people who had their blood pressure lowered with medication. Their findings were published in Circulation, a scientific journal of the American Heart Association.
The study found no convincing evidence that lowering diastolic blood pressure to levels previously considered concerning caused additional harm. Instead, the researchers found that the systolic number appeared to be the more important target when deciding how aggressively blood pressure should be treated.
The results suggested that people may benefit when systolic blood pressure is brought into a range of about 100 to 130 mmHg. Importantly, doctors may not need to reduce treatment simply because the diastolic number becomes relatively low, provided the patient is otherwise tolerating treatment.
This matters because untreated high systolic blood pressure puts constant strain on arteries and organs. Over time, it can damage blood vessels and increase the risk of heart attack, stroke, heart failure, kidney disease and other serious health problems.
Systolic blood pressure also tends to become more important as people get older. Arteries naturally become stiffer with age, which can push the top number higher even when the bottom number stays normal or becomes lower.
The findings do not mean that people should try to lower their blood pressure as much as possible on their own. Blood pressure treatment needs to consider a person’s age, health conditions, medications and possible side effects, and treatment decisions should be made with a healthcare professional.
Lifestyle changes can also play an important role in controlling blood pressure. Maintaining a healthy weight and eating plenty of vegetables, fruits, whole grains and other nutritious foods can support both blood vessel and heart health.
Reducing excess sodium can also help because too much sodium can cause the body to retain fluid and raise blood pressure in people who are sensitive to it. Many health guidelines recommend limiting sodium to less than about 2,300 milligrams per day, although some people may be advised to aim lower.
Regular physical activity is another powerful tool. Exercise helps strengthen the heart, improves blood vessel health and can help with weight control, all of which can contribute to healthier blood pressure.
Limiting alcohol and avoiding smoking are also important. Smoking damages blood vessels and sharply increases cardiovascular risk, while drinking too much alcohol can contribute to higher blood pressure.
Sleep and stress deserve attention as well. Long-term stress, poor sleep and conditions such as sleep apnea can make blood pressure more difficult to control, so addressing these problems may be part of a complete treatment plan.
Regular blood pressure checks remain essential because hypertension is often called a silent condition. Finding it early gives people more time to make lifestyle changes or begin medication before serious damage develops.
The Circulation study adds to evidence that systolic blood pressure deserves particular attention when treating hypertension. By safely controlling the top number rather than becoming overly concerned about a low bottom number alone, doctors may be able to provide stronger protection against heart attacks and strokes.
If you care about blood pressure, please read studies about unhealthy habits that could increase high blood pressure risk, and eating eggs in a healthy diet may reduce risks of diabetes, high blood pressure.
For more information about blood pressure, please see recent studies that early time-restricted eating could help improve blood pressure, and results showing 12 foods that lower blood pressure.
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