Following a diet low in sodium but high in potassium can help lower blood pressure and, in turn, reduce your risk of a heart attack.
The typical American consumes 3,000 to 5,000 mg of sodium a day—much more than the body needs. When the kidneys cannot efficiently eliminate this excess sodium, the volume of blood that flows through your circulatory system increases. The extra pressure that the larger blood volume puts on your arteries causes blood pressure to rise. If you simply stop adding salt to the food you eat, you can lower your systolic blood pressure by 2 to 5 mm Hg and your diastolic blood pressure by 1 to 3 mm Hg on average. Restricting sodium is particularly effective in reducing blood pressure in older people with high blood pressure.
You should consume no more than 2,300 mg of sodium per day (which is equivalent to a little more than a teaspoon of table salt daily). If you have high blood pressure, you should aim for less than 1,500 mg of sodium a day.
Salt added to food during cooking or at the table is an obvious source of dietary sodium (salt is made up of 40% sodium and 60% chloride). But you should do more than just free yourself from the salt shaker. Sodium occurs naturally in many foods and, more importantly, is used extensively in food processing. For example, cold cuts, canned vegetables and soups, cheeses, and snack foods can all be concentrated sources of sodium. Check food labels carefully for the amount of sodium. When buying packaged or processed foods, choose the low- or no-salt versions when possible.
Studies show that a diet high in potassium can lower blood pressure and reduce the rise in blood pressure caused by dietary sodium. If you have high blood pressure, you should increase your intake of fresh fruits and vegetables, which are rich in potassium and have the added benefit of being low in sodium and high in dietary fiber (see below) and antioxidants. Citrus fruits and bananas are particularly good sources of potassium, as are spinach, winter squash, and lima beans.
You should consume at least 4.7 g of potassium a day. You can reach this level by eating the recommended 2 cups each of fruits and vegetables a day. Potassium supplements are available but are not recommended for lowering blood pressure because they can be dangerous for people with kidney disease.