If you’ve ever had your blood pressure checked, you might remember hearing two numbers. They sound like “120 over 80.”
For a long time, doctors mainly focused on the first number, which is the top one. This number is called the systolic pressure.
But now, new research says the second number, the bottom one—called diastolic pressure—is also very important. Both numbers can affect your chances of getting heart disease or having a stroke.
Let’s take a quick look at what these numbers mean. The systolic pressure is the force of your blood when your heart is beating and pushing blood through your body. The diastolic pressure is the pressure when your heart is resting between beats. Both are measured in millimeters of mercury (mmHg).
In the past, doctors believed systolic pressure was more dangerous. That’s because high systolic pressure has long been linked to serious problems like strokes and heart attacks. Many people thought the bottom number wasn’t as important. But that idea is changing.
A big new study from Kaiser Permanente looked at more than 36 million blood pressure readings from 1.3 million adults in Northern California. This data was collected over nine years, from 2007 to 2016.
The results showed that both numbers matter. Higher systolic pressure still showed a stronger risk overall, but high diastolic pressure also increased the chance of heart problems. So even if your top number looks okay, a high bottom number can still mean trouble.
The study found this to be true no matter which blood pressure guidelines were used—either the older definition of high blood pressure (140 over 90) or the newer, stricter one (130 over 80). This supports recent changes in medical advice that suggest keeping tighter control over blood pressure.
So what does this mean for you?
It means you should pay attention to both numbers when checking your blood pressure. Don’t ignore the bottom number. If either number is too high, it’s time to take action. This might include eating more fruits and vegetables, eating less salt, exercising more, finding ways to manage stress, and, if needed, taking medicine that your doctor gives you.
This study was led by Dr. Alexander C. Flint and published in the New England Journal of Medicine. It’s a good reminder that science changes as we learn more. But one thing stays the same: checking your blood pressure often and talking with your doctor about the results can help keep your heart healthy.
If you care about high blood pressure, please read studies about unhealthy habits that may increase high blood pressure risk, and drinking green tea could help lower blood pressure.
For more information about high blood pressure, please see recent studies about what to eat or to avoid for high blood pressure, and 12 foods that lower blood pressure.
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