Dear Dr. Peg,

While shopping at my local grocery store, I stopped by the pharmacy to measure my blood pressure. The machine told me that it was 127/75. Is this a healthy blood pressure? Also, what’s the relationship between blood pressure and cholesterol levels? What can I do to maintain a healthy blood pressure?

Dear grocery guy,

The short answers to your questions are: probably, nothing and plenty. But I’m not one for short answers, so pull up a chair.

What exactly is blood pressure? It is the amount of pressure that your blood exerts on your blood vessels, from within them. You might liken it to air pressure in your tires, or water pressure in your pipes.

Air pressure is measured in PSI, or pounds per square inch. Blood pressure is measured in mmHg, or millimeters of mercury. This is because blood pressure cuffs originally used a vertical column of mercury to measure pressure. A pressure reading of 100 meant the mercury column was pushed upward (against gravity) 100 millimeters.

There are two numbers in a blood pressure reading: the top number and the bottom number. Basically, they are maximum and minimum readings. The top number, 127 for you, is the systolic blood pressure. This is the pressure present in the arteries during systole, which is the active squeezing phase of the heart’s pumping action.

The bottom number, 75 for you, is the diastolic blood pressure. This is the pressure present in the arteries during diastole which is the inactive, relaxation phase of the heart.

What is normal for blood pressure? Pretty much anything less than 140/90 and still standing. Too low is when you pass out because of it. A person’s blood pressure changes throughout the day, depending on many factors. Your blood pressure is lowest when you are asleep, and highest when you are exercising strenuously.

If your blood pressure always reads between 120 and 140 systolic and/or 80 and 90 diastolic you could have pre-hypertension, meaning you could be at risk for developing the disease of hypertension, or high blood pressure. In the pre-hypertension range, lifestyle changes such as losing weight, exercising more and eating less salt are often all that’s needed to bring your blood pressure down to normal.

If you get repeated readings with a systolic pressure over 140 and/or a diastolic over 90, you may have hypertension. This is a bad thing. Imagine what would happen if you filled your bike tires with as much air pressure as you put in your car tires. Ka-blam, right? That’s what happens in your tiny blood vessels if they get too much pressure. The result is damage to all your organs, especially your heart, kidneys and brain.

What can you do to keep your blood pressure in a healthy range? Maintain a normal weight. Exercise regularly. Don’t smoke. Limit your alcohol intake, or don’t drink. Minimize your stress, or manage it as best you can.

Hypertension is sometimes genetic. If it runs in your family, you can decrease your chance of getting it by following the advice above, and by getting a professional blood pressure measurement at least every two years.

Blood pressure and cholesterol are not directly related to each other. High blood pressure doesn’t cause high cholesterol or vice versa. However, they both contribute to the same health problems (heart attacks, strokes, organ damage) and each alone can kill you. It behooves you to keep both blood pressure and cholesterol as low as possible. Beyond that, cholesterol is a topic for another day.

Finally, a word about supermarket blood pressure machines: Take them with a grain of — oops, I mean, they may not be exactly accurate. To maximize your chances of an accurate reading, rest first for ten minutes, then put your bare arm into the machine. If you get worrisome or wildly differing readings in the machine, come in to SHAC and let the professionals check it. Call 277-3136 for an appointment.

Dr. Peggy Spencer is a physician at Student Health and Counseling. She is also co-author of the book “50 Ways to Leave Your 40s.” Email your questions directly to her at All questions will be considered, and all questioners will remain anonymous.