Blood pressure refers to the force exerted in arteries with every heartbeat. About 1 in 3 Americans — 75 million people — have high blood pressure, which increases the risk of suffering a heart attack or stroke, or developing kidney disease, according to reports from the Centers for Disease Control and Prevention (CDC).

Currently, only about half of those diagnosed with high blood pressure have the condition under control.

But those numbers don’t take into account the new guidelines recently endorsed by the American College of Cardiology and the American Heart Association.

Under these guidelines, about 30 million people will be added to the ranks of those with high blood pressure.

Blood pressure measurement provides a high (systolic) and a low (diastolic) value. The upper threshold for systolic high blood pressure has been 140 since 1993, but a more recent study found heart risks were much lower in people who aimed for 120.

These are the new blood pressure guidelines endorsed by the American College of Cardiology and the American Heart Association:

Normal: Under 120 over 80

Elevated: Top number 120-129 and bottom less than 80

Stage 1: Top of 130-139 or bottom of 80-89

Stage 2: Top at least 140 or bottom at least 90

The new numbers mean that 46 percent of American adults have high blood pressure (stages 1 or 2) compared to just 32 percent under the old levels. The new guidelines also do away with the category known as “borderline” high blood pressure.

This will roughly triple the incidence of high blood pressure in men under 45 (to 30 percent) and double it in women of that age, to 19 percent.

These new guidelines also undo the controversial change in which higher blood pressure was recommended for people over the age of 65.

Now, seniors are directed to aim for a systolic pressure of 130 or below, unless they’re too frail or have conditions that make it unwise.

I endorse these new guidelines. The only exception I make is for people ages 75 and over, especially if they are taking blood pressure medication.

Such people can experience fatigue and depression. In those cases, a blood pressure program needs to be tailored to individual needs.