Recently, two leading heart organizations changed the definition of what it means to have high blood pressure. Because of this change, the number of Americans with high blood pressure jumped from 32 percent to 46 percent.

Doctors at the American Heart Association and the American College of Cardiology now classify anyone with a blood pressure reading of 130 over 80 as having high blood pressure.

Before, the cutoffs for high blood pressure had been a top number of 140 and a lower number of 90.

Health experts at the website Science Daily say blood pressure is defined by two numbers. The top number, called systolic, represents the force with which your heart pumps blood into the blood vessels. The bottom, called diastolic, is a measure of the resistance to the blood flow in the body's blood vessels.

The American Heart Association says the new guidelines are designed to help people take steps to control their blood pressure earlier. High blood pressure can cause heart disease and stroke -- the two leading causes of death in the world.

The new guidelines set blood pressures in these categories:
Normal Blood Pressure: Under 120 over 80
Elevated Blood Pressure: Top number 120-129 and bottom number less than 80

High Blood Pressure / Stage 1: Top number of 130-139 or bottom number 80-89
High Blood Pressure / Stage 2: Top number at least 140 or bottom number at least 90

A 2016 study by the World Health Organization and hundreds of scientists found that the number of people in the world with high blood pressure had reached 1.13 billion.

However, the study defined high blood pressure as 140 over 90. Should they adopt the new guidelines, the number of people with high blood pressure worldwide will most likely increase.

Scientists at Imperial College London led the study and looked at blood pressure measurements from nearly 20 million people from the years 1975 to 2015.

In this study, they found that the number of people with high blood pressure nearly doubled in 40 years.

Researchers found that over half of the world's adults with high blood pressure lived in Asia. Around 226 million people in China have high blood pressure, along with 200 million in India.

This study also found that in 2015 people in South Korea, the USA and Canada had the lowest high blood pressure rates in the world. With the new U.S. guidelines, the U.S. ranking in the world could change.

The researchers from Imperial College London published their findings from the study in the January 2017 edition of the medical journal The Lancet.

Health experts are warning people to not rush to medication to lower their high blood pressure. They advise that there are many lifestyle changes a person can make to effectively keep their blood pressure at a healthy level.

Regular exercise and losing weight can lower your blood pressure. In some people, making changes in diet can make a big difference. Eating more fruits, vegetables, fish, beans, nuts and seeds can help. Eating less sodium and drinking less alcohol can also help.