Cardiovascular diseases are the leading cause of death worldwide, and high blood pressure is a major risk factor. In some people, sodium increases blood pressure because it holds excess fluid in the body, creating an added burden on the heart. Too much sodium in the diet may also have other harmful health effects, including increased risk for stroke, heart failure, osteoporosis, stomach cancer and kidney disease.
Healthy kidneys are usually able to excrete excess sodium intake. There is concern about persistent excessive sodium intake, which has been implicated in development of hypertension. In addition to its role in hypertension, excessive salt intake has been associated with increased urinary calcium excretion. Studies linking salt intake to bone mineral density suggest that high salt intake may be a risk factor for osteoporosis.
3 g of the daily salt intake exists naturally in foods, 3 g is added during processing, and 4 g is added by the individual. Increased reliance on restaurants, fast food, and commercially prepared convenience foods has contributed to this high salt intake. Processed meats, such as bacon, sausage, and ham, and canned soups and vegetables are all examples of foods that contain added sodium. Fast foods are generally very high in sodium.
Sodium (Na) is the major cation of extracellular fluid. Various intestinal secretions such as bile and pancreatic juice contain substantial amounts of sodium. Approximately 35% - 40% of the body sodium is in the skeleton. Contrary to common belief, sweat is hypotonic and contains a relatively small amount of sodium.
Sodium is important in neuromuscular function and maintenance of acid-base balance. The body uses sodium to control blood pressure and blood volume. Sodium is also needed for your muscles and nerves to work properly.
The major source of sodium is sodium chloride (table salt), of which sodium constitutes 40% by weight. Sodium occurs naturally in most foods. Milk, beets, and celery also naturally contain sodium, as does drinking water, although the amount varies depending on the source. Protein foods generally contain more naturally existing sodium than do vegetables and grains, whereas fruits contain little or none. The addition of table salt, flavored salts, flavor enhancers, and preservatives during food processing accounts for the high sodium content of most convenience and fast-food products. For instance ½ cup of frozen vegetables prepared without salt contains 10 mg sodium, whereas ½ cup of canned vegetables contains approximately 260 mg of sodium. 1 ounce of plain meat contains 30 mg of sodium, whereas 1 ounce of luncheon meat contains approximately 400 mg of sodium.
Dietary reference intake
Adult 19-49 years old 1.5 g/day (salt 3.8 g/day)
Adult 50-70 years old 1.3 g/day (salt 3.2 g/day)
Adult 71 and older 1.2 g/day (salt 2.9 g/day)
Adult with high blood pressure 1 g/day (salt 2.4 g/day)
Adult with diabetes 1 g/day (salt 2.4 g/day)
Adult with heart failure <0.8 g/day (salt <2 g/day)
Adult with kidney disease <0.8 g/day (salt <2 g/day)