You know that too much salt contributes to high blood pressure, but you might not realize how easily eating out could put you and your kids at risk.

Many entrees at leading restaurants and fast food places contain almost a full day's allotment of salt, according to the U.S. Centers for Disease Control and Prevention. Remember, that's 2,300 milligrams, or about one teaspoon.

With many Americans eating out an average of five times a week, all that salt adds up. And the more salt you eat, the greater the odds for high blood pressure (hypertension), a major contributor to heart disease and stroke.

By some estimates, the average American takes in 50 percent more salt than the daily limit, and this excess starts in childhood. Kids between 6 and 10 years of age take in 2,900 mg a day, while teens top out at about 3,700 mg.

Studies done around the world have looked at salt consumption and high blood pressure. A study of 500 people, aged 18 to 40, found that the more restaurant meals people ate every week, the higher their odds of pre-hypertension. Young people with even a slightly elevated blood pressure level are at very high risk of full-blown hypertension.

About 80 percent of the salt consumed has been added by manufacturers of processed foods or at restaurants. While the salt in hundreds of processed foods has gone down slightly in recent years, a Harvard study reported that it has gone up in many fast food items.

To protect yourself and your family when dining out, ask about the salt content of meals you're thinking of ordering. Restaurants with 20 or more locations must provide this on request, and many chains post the numbers online. Finally, resist reaching for the salt shaker.