HE-426, Reprinted December 1993. Recommended for Extension use by Barbara Struempler, Extension Nutritionist, Professor, Nutrition and Food Science, Auburn University. Originally prepared by Dorothy Tate, former State Leader-Home Economics, and Virginia White, former Head, Foods and Nutrition.

Sodium & Potassium

Sodium is the mineral in salt that can cause health problems. However, sodium is also essential for normal body functions. Sodium and potassium work together to help control the body's water balance and to regulate pressure within and between the cells. Sodium is the main mineral in the fluid around the cells while potassium is inside the cells. Doctors often recommend that people with high blood pressure or those taking diuretic drugs (water pills) eat foods rich in potassium. Sodium and potassium also help transmit nerve impulses so that muscles can function.

Sodium

Sodium is only one of fifteen or more required minerals in the body. It is found naturally in many foods, mostly as sodium chloride, which is the same as common table salt. Table salt is the most concentrated form of sodium. It is 40 percent sodium and 60 percent chlorine. The average American eats about 10 to 15 grams of salt (2 to 3 teaspoons) each day. This is 4000 to 6000 milligrams of sodium.

Sources of Sodium in Foods

We get sodium through the following three sources:

1. The salt shaker. A level teaspoon of table salt contains 2,000 milligrams of sodium. It is recommended that the salt shaker be kept off the table. But when you do use salt for seasoning, use iodized salt because that is your main source of iodine, another essential mineral.

2. Foods that naturally contain sodium. All foods that come from animals contain sodium. And some plants, such as beets, carrots, celery, spinach, and turnips, contain sodium. Check Table I for the amount of sodium that is found naturally in foods.

3. Processed foods. Salt or other sodium products are usually added to foods by the processor for flavor or preservative. These foods include cured meats (hot dogs, bacon, sausage, lunch meat), pickled foods (pickled cucumbers, olives, and sauerkraut), salted snacks (potato chips, crackers, corn chips), soy and other sauces, baking soda, baking powder, monosodium glutamate (MSG), and other seasonings. In addition to these foods, many beverages (including water) and medications contribute greatly to your sodium intake.

Reducing Your Sodium Intake

The easiest way to reduce sodium in your diet is to use less table salt. Also, cut down on those foods that have had large amounts of sodium added. Remember that up to half of the sodium in foods may be "hidden." This is because of the amount that is naturally in foods and the amount that is in the preservatives and flavorings that have been added.

The following suggestions may help you:

• Keep the salt shaker off the table.
• Learn to enjoy the unsalted flavors of foods.
• Carefully measure the salt you use for cooking and use only small amounts.
• Use spices and herbs for flavor instead of salt.
• Limit your intake of salty foods, such as potato chips, pretzels, salted nuts, popcorn, condiments (soy sauce, steak sauce, garlic salt), cheese, pickles, and cured meats.
• Read food labels carefully to see if sodium has been added.
• Read labels on over-the-counter medications. Avoid those that contain sodium.
• Only use a salt substitute if a doctor has recommended it.

What To Look For on Labels

Salt and other sodium products are common additives and preservatives in foods. The following list contains sodium products. Use it to help identify them.

Sodium chloride - table salt.
MSG (Monosodium glutamate) - a flavor enhancer used in many foods.
Baking powder - a leavening agent in baked products.
Baking soda; sodium bicarbonate; bicarbonate of soda - a leavening agent in baked products.
Brine - a preservative of saturated salt water.
Sodium citrate - an emulsifier in cheese products; also used in some jellies.
Sodium erythorbate - an antioxidant used in meat products, beverages, and baked goods.
Disodium phosphate - a texturizer in some quick-cooking cereals and puddings.
Sodium pyrophosphate - an emulsifier for cheese and pudding mixes.
Sodium saccharin - an artificial sweetener.
Sodium benzoate - a preservative.

Sodium in Baby Food

A concern before the 1970s was the amount of sodium being added to baby foods. The sodium content of commercial baby food has been reduced. Parents should not add salt to suit their own tastes. Too much salt is an extra burden on a baby's body, especially the kidneys.

Sodium and High Blood Pressure

As mentioned earlier, sodium tends to increase blood pressure which can lead to kidney disease, heart disease, and stroke. However, not everyone is equally susceptible. In the United States, approximately 25 percent of all adults have high blood pressure. Sodium intake is only one of the factors known to affect blood pressure. Obesity also seems to play a role.

Among people who use very little sodium, high blood pressure is rare. In contrast, high blood pressure is more common among people with high-sodium intake. When people with high blood pressure severely restrict their sodium intake, their blood pressure will usually fall, although not always to a normal level.

At present, we cannot reliably predict who will develop high blood pressure. However, certain groups of people, such as blacks, do have a higher rate. A low-salt diet might help some of these people avoid high blood pressure if they start the diet before they develop the condition.

Sodium and Sweating

Sodium is lost in sweat at a rate of about 1000 milligrams per liter. In general, your body will adapt itself during sweating so that you will not lose too much sodium. If you are healthy, a well-balanced diet will give you enough sodium. Sometimes, though, you may need more salt if you are working under extremely hot conditions and sweating excessively.

Sweating off weight to meet a weight classification in sports is not recommended. This can cause stress to the heart and blood vessels and result in poor performance. This is especially true for children or teenagers. Severe weight reduction during the growing years can be dangerous. If you sweat off weight over a period of several hours, you are losing body water, not body fat. Drinking water will quickly restore the weight loss. Instead of losing weight through water and salt restriction, reduce your calories so that you lose 1 or 2 pounds a week until you reach the weight you want.

Sodium and Pregnancy

At one time, doctors advised pregnant women to reduce the amount of salt they used. It was thought this would limit water retention and body swelling. And some pregnant women now think they can keep from gaining extra weight by restricting their salt intake. However, restricting salt intake too much can be harmful to the baby and mother. Some pregnant women may need to limit their use of salt. But they should not do it on their own or because their friends do. The bodies of both the mother and the baby need sodium to function normally. Salt intake should be restricted only under a doctor's orders.

Potassium

The average American consumes between 2000 to 6000 milligrams of potassium a day. Since
potassium is naturally in many foods, a healthy person usually gets enough just from eating a good variety.

Sources of Potassium in Foods

Potassium is in many plant and animal foods. There are good sources of potassium in each of the food groups-vegetables and fruits; milk and cheese; meat, poultry, fish, and beans; breads and cereals. Dried dates, bananas, cantaloupes, apricots, and citrus fruits are exceptionally good sources of potassium. Small amounts are found in whole grains. Whole grains have more than refined grains because potassium is lost in milling. Check Table I to find the amounts of potassium in foods.

Potassium is soluble in water. For example, cheese has less potassium than milk because the potassium is lost in the liquid whey during processing. When foods are peeled and boiled in a small amount of water, about a fourth of the potassium is lost. Even greater amounts are lost if the food is cooked in a large amount of water or for a long period of time. The lost potassium is in the cooking water, so use it if possible. Table II shows how boiling a white potato affects its potassium content.

Fats and sweets contain little or no potassium. Therefore, margarine, butter, vegetable oils, candy, sugar, and jellies do not contribute potassium to the diet. Synthetic foods and many carbonated beverages do not contain much potassium. Neither do they contain many of the other vitamins and minerals important for good health.

Excessive Potassium

Having too much potassium in the body is not common. This may occur, however, in a person with kidney failure or severe dehydration. Dehydration occurs when fever, vomiting, and diarrhea continue for a long period of time, causing a great loss of body fluids, or during hard physical work. Dehydration may be especially dangerous to infants and small children.

A person with too much potassium in the body will have burning and prickling of the scalp, face, tongue, hands, and feet; muscle weakness; poor breathing; and an irregular heart beat.

Potassium Deficiency

Low potassium levels can result from a muscle-wasting disease, malnutrition, diabetic acidosis, or diuretics. Potassium is also lost in injuries such as cuts, scratches, and burns because of the breakdown of tissue cells. Thus, your body needs more potassium when it is building or repairing muscle; after starvation, injury, and some diseases; and when taking diuretics.

Most high blood pressure drugs are diuretics medicines which help the body lose water. These are often called "water pills." Many diuretics cause a loss of potassium from the body tissues. If you use diuretics almost daily, you may have symptoms of potassium deficiency. A person with low potassium levels in the muscles will feel tired and weak. If you are taking water pills or if you have frequent vomiting or diarrhea, you may be losing too much potassium and should see a doctor.

Frequently, the doctor will recommend that a person on diuretics or high blood pressure medicine eat foods rich in potassium but low in sodium. In Table I foods that are low in sodium and high in potassium are starred.

Potassium and Sweating

The body protects itself from losing too much potassium during heavy sweating. When you sweat too much as with exercise, the body gradually adjusts so that less potassium is lost in the sweat. Also, when body potassium is low, less potassium is lost in the urine. Because of the body's ability to adjust and because potassium is widely distributed in foods, healthy people do not need special potassium foods or pills.

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References

"Dietary Salt"; Scientific Status Summary by the IFT Expert Panel on Food Safety & Nutrition; January 1980.

"Nutrition and Your Health, Dietary Guidelines for Americans"; U.S. Department of Agriculture and U.S. Department of Health, Education and Welfare; February 1980.

Church, C.F., and Church, H.M.; "Food Values of Portions Commonly Used" (Formerly Bowes and Church); J.B. Lippincott, Philadelphia; 1975.

Hertzler, Ann; "Sodium in the Body" (1979) and "Potassium in the Body" (1974); University of Missouri, Columbia, Extension Division.

Jackson, Yvonne; "Nutrition and Your Health: Avoid Too Much Salt"; unpublished; 1980.