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Many people know too much salt in their diet is a bad thing. Not nearly as many know exactly why.
"They're surprised at the degree to which it can affect them," said Dr. Cheryl Laffer, a professor of medicine at Vanderbilt University in Nashville, Tennessee. "And at the amount of salt that there is in the American diet."
According to the Centers for Disease Control and Prevention, about 90% of Americans age 2 and older eat too much sodium. Most of it is in the form of salt, also known as sodium chloride.
Here are six things salt does to the body – and what you can do to protect yourself.
Let's start with the heart.
With the circulatory system, salt's effects are "a very simple plumbing problem," said Dr. Fernando Elijovich, a professor of medicine at Vanderbilt University.
The heart is the pump and blood vessels are the pipes, he said. Blood pressure goes up if you increase how much blood has to move through the pipes. Blood pressure also rises if you shrink those pipes.
Salt does both. When there's excess salt in your system, the heart pumps more blood in a given time, boosting blood pressure. And over time, salt narrows the vessels themselves, which is the most common "plumbing" feature of high blood pressure.
The harm can come quickly. And over time.
Within 30 minutes of eating excess salt, your blood vessels' ability to dilate is impaired, Elijovich said. The damage from persistent high blood pressure shows up down the road, in the form of heart attacks, strokes and other problems.
The good news, Laffer said, is the benefits of cutting back on excess salt also show up quickly. If you significantly reduce how much salt you eat, your blood pressure goes down within hours or days.