How the Heart Works (2/2)

A healthy adult heart is about the size of two fists and looks like a piece of red meat. But in overweight people, it can look yellow because of fat. Rates of heart disease started growing sharply in the second half of the twentieth century. As machines did more and more work, people did less and less. Not only did physical activity decrease, but people started eating more and more processed foods.

Experts say a diet low in fats and high in fruits, vegetables, proteins and whole grains may help reduce the risk of heart disease. At least thirty minutes a day of physical activity, enough to work up a sweat, can also help. Also important to good health is a good night's sleep.

Cardiovascular disease is caused by disorders of the heart and blood vessels. It includes heart attacks, strokes and high blood pressure. The World Health Organization says there are three major causes: tobacco use, physical inactivity and an unhealthy diet.

The W.H.O. says cardiovascular disease is the world's leading cause of death. And it is predicted to remain that way unless more action is taken. Experts estimate that it could kill twenty million people a year by twenty fifteen. An estimated seventeen and a half million people died in the year two thousand five. Around eighty percent of them died in low- and middle-income countries.