What many people have not heard: New studies are very specific about the health impact of excess salt. The results are startling...

• If US residents cut their daily sodium intake by 1,200 milligrams (mg) on average -- that’s only about half a teaspoon of salt per day -- each year, there would be 32,000 to 66,000 fewer strokes... 54,000 to 99,000 fewer heart attacks... and 44,000 to 92,000 fewer deaths from any cause. Also: National health-care costs would decrease by $10 billion to $24 billion.

• An analysis of 13 studies involved 177,025 participants from around the world who were followed for 3.5 to 19 years. Conclusion: Compared to people with an average daily salt intake of about two teaspoons, those who consumed only about half that much salt had a 23% lower risk for stroke and a 17% lower risk for cardiovascular disease.

• A multicenter clinical trial involved more than 3,000 participants who followed a fairly typical American diet or a reduced-sodium diet for 18 to 48 months. Those in the reduced-sodium group made only modest changes -- decreasing their intake on average by less than half a teaspoon of salt per day. Yet this was enough to lower their risk for stroke, heart attack or other major cardiovascular event by 30% over the next 10 to 15 years.

To function properly, the body does need some sodium -- but only about 500 mg per day. When sodium consumption is excessive, the kidneys cannot eliminate all of it. Fluid is retained in the blood vessels, which increases blood pressure. This damages blood vessel walls, accelerating the progression of atherosclerosis (thickening and hardening of the arteries). Salt also appears to thicken the muscle in the heart’s left ventricle, the chamber that pumps blood throughout the body. In addition, a high-salt diet may contribute to a decline in kidney function and an increased risk for kidney stones.

The right number for you: Some people are more sensitive to salt than others. As a general guideline, the American Heart Association recommends...

• If you are age 40 or older, are African-American or have high blood pressure, limit yourself to 1,500 mg of sodium (about two-thirds of a teaspoon of salt) per day. Note: About 70% of the US population falls into this group.

• If you do not meet any of the conditions in the preceding paragraph, limit yourself to 2,300 mg of sodium (just under one teaspoon of salt) per day.

Troubling comparison: Among US women, the average daily intake of sodium jumped nearly 70% from 1971 to 2000. The typical American woman now consumes about 3,000 mg per day -- twice the amount that’s recommended for most people.

About 80% of the sodium in the average American’s diet comes from canned and processed foods and restaurant meals. Vigilance is required to avoid sodium overload.

When you shop...

• Buy whole foods whenever possible, rather than processed foods.

• If you must buy frozen entrées, choose ones with no more than 600 mg to 800 mg of sodium per serving.

• Select snack foods with no more than 200 mg of sodium per serving (and limit your portion to a single serving).

• Notoriously salty processed foods include canned goods (soups, vegetables, beans)... deli meats and sausage... condiments (ketchup, pickle relish, soy sauce)... bottled salad dressings... and snack foods (popcorn, chips). Avoid these or look for low-sodium or unsalted versions.

When you dine out, remember...

• Some fast-food meals contain nearly triple the salt limit recommended for an entire day! If you visit a fast-food restaurant, forgo the fries in favor of a salad (going light on the dressing)... choose a hamburger instead of a cheeseburger (one slice of American cheese adds almost 400 mg of sodium)... skip the pickles and mayonnaise.

• Check to see if the menu includes a section of low-sodium dishes. If not, request that your meal be prepared with little or no added salt.

At home...

• Put away the saltshaker. When cooking or at the table, use other seasonings -- spices, herbs, vinegar, lemon juice -- to bring out food’s flavor.