Sodium

Sodium, potassium, and chloride are collectively referred to as electrolytes because when dissolved in body fluids, they separate into positively or negatively charged particles called ions. Potassium, which is positively charged, is found mainly within the cells. Sodium (positively charged) and chloride (negatively charged) are found mostly in the fluid outside the cells.

• Electrolytes— Chemical elements or compounds that ionize in solution and can carry an electric current; they include sodium, potassium, and chloride.
• Ion— An atom or group of atoms carrying a positive or electric charge.

The electrolytes maintain two critical balancing acts in the body: water balance and acid-base balance. Water balance means maintaining the proper amount of water in each of the body's three "compartments": inside the cells, outside the cells, and in the blood vessels. Electrolytes maintain the water balance by moving the water around in the body. Electrolytes are also able to buffer, or neutralize, various acids and bases in the body. In addition to its roles in water and acid-base balance, sodium is needed for muscle contraction and transmission of nerve impulses.

• Water balance— The process of maintaining the proper amount of water in each of three body "compartments": inside the cells, outside the cells, and in the blood vessels.
• Acid-base balance— The process by which the body buffers the acids and bases normally produced in the body so that the blood is neither too acidic nor basic.

The major source of sodium in the diet is salt—a compound made of sodium and chloride. Salt by weight is 39 percent sodium, and 1 teaspoon contains 2300 milligrams (a little more than 2 grams) of sodium. Many processed foods have high amounts of sodium added during processing and manufacturing, and it is estimated that these foods provide fully 75 percent of the sodium in most people's diets. The following is a list of processed foods high in sodium:

• Canned, cured, and/or smoked meats and fish, such as bacon, salt pork, sausage, scrapple, ham, bologna, corned beef, frankfurters, luncheon meats, canned tuna fish and salmon, and smoked salmon
• Many cheeses, especially processed cheeses such as processed American cheese
• Salted snack foods, such as potato chips, pretzels, popcorn, nuts, and crackers
• Food prepared in brine, such as pickles, olives, and sauerkraut
• Canned vegetables, tomato products, soups, and vegetable juices
• Prepared mixes for stuffings, rice dishes, and breading
• Dried soup mixes and bouillon cubes
• Certain seasonings such as salt, sea salt, garlic salt, onion salt, celery salt, seasoned salt, soy sauce, Worcestershire sauce, horseradish, ketchup, and mustard

In addition to the sodium in salt, sodium appears in monosodium glutamate (MSG), baking powder, and baking soda. Other possible sources of dietary sodium include the sodium found in some local water systems and in medications, such as some antacids. Unprocessed foods also contain natural sodium, but in small amounts (with the exception of milk and some milk products).

The Nutrition Facts Label lists a Daily Value of 2400 mg per day for sodium. Overconsumption of sodium, particularly as salt, is common and is a concern because a high sodium intake aggravates high blood pressure in individuals who are salt sensitive.

The salt content of food in the various food groups. Salt is also used in food preparation and at the table for seasoning.

Where's the Salt? 

Food Groups	Sodium, mg
Bread, Cereal, Rice, and Pasta
Cooked cereal, rice, pasta, unsalted, 1/2 cup	Trace
Ready-to-eat cereal, 1 oz	100–360
Bread, 1 Slice	110-175
Vegetable
Vegetables, fresh or frozen, cooked without salt, 1/2 cup	Less than 70
Vegetables, canned or frozen with sauce, 1/2 cup	140–460
Tomato juice, canned, 3/4 cup	660
Vegetable soup, canned, 1 cup	820
Fruit
Fruit, fresh, frozen, canned 1/2 cup	Trace
Milk, Yogurt, and Cheese
Milk, 1 cup	120
Yogurt, 8 oz.	160
Natural Cheeses, 1-1/2 oz.	110–450
Process Cheeses, 2 oz.	800
Meat, Poultry, Fish, Dry Beans, Eggs, and Nuts
Fresh meat, poultry, fish, 3 oz.	Less than 90
Tuna, canned, water pack, 3 oz.	300
Bologna, 2 oz.	580
Ham, lean, roasted, 3 oz.	1020
Other
Salad dressing, 1 tbsp.	75-220
Ketchup, mustard, steak sauce, 1 tbsp.	130–230
Soy sauce, 1 tbsp.	1030
Salt, 1 tsp.	2000
Dill pickle, 1 medium	930
Potato chips, salted, 1 oz.	130
Corn chips, salted, 1 oz.	235
Peanuts, roasted in oil, salted, 1 oz.	120
Source: U.S. Department of Agriculture.