Sodium

Functions

• Regulation of fluid balance
• Maintenance of acid-base balance
• Carbon dioxide transport
• Muscle contraction
• Nerve impulse transmission

Recommended Intake

No recommended intake has been established, but intakes up to 2.4 grams per day are believed to be adequate for healthy adults. The average American consumes 3-7 g/day.

The recommended dietary allowance (RDA) committee has set the following minimum daily requirements for healthy people:

Too Little Sodium

The typical American diet is rich in sodium, and therefore deficiencies are uncommon.

A sodium deficiency may accompany extreme water loss, such as in the case of starvation, profuse sweating, or excess vomiting or diarrhea. In this case, symptoms include:

• Low blood volume
• Low blood pressure
• Muscle cramping
• High hematocrit (a measure of iron levels in the blood)

Note: Only when weight loss from perspiration exceeds six pounds should sodium losses raise concern. Even then, merely salting foods can remedy the situation.

If sodium levels are low, independent of body water loss, water intoxication can result. Symptoms of water intoxication include:

• Mental apathy
• Muscle twitching
• Loss of appetite

Other symptoms of sodium deficiency include:

• Muscle weakness
• Poor memory and concentration
• Loss of appetite
• Acidosis (a disruption in the body's normal acid-base balance, resulting in a more acidic pH)
• Dehydration

Too Much Sodium

High sodium intakes have been correlated with elevated blood pressure and edema (cell and tissue swelling caused by excess water accumulation).

Major Food Sources

Table salt (sodium chloride; NaCl) is the major source of dietary sodium�about 1/3 to 1/2 of the sodium we consume is added during cooking or at the table. Fast foods and commercially processed foods�canned, frozen, instant�also add a significant amount of sodium to the typical American diet. These include:

• Beef broth
• Catsup
• Commercial soups
• French fries
• Gravies
• Olives
• Pickles
• Potato chips
• Salted snack foods
• Sandwich meats
• Sauces
• Sauerkraut
• Tomato-based products

Sodium occurs naturally in:

• Eggs
• Fish
• Meats
• Milk products
• Poultry
• Shellfish
• Soft water

Other sources of sodium in the diet:

• Baking powder
• Baking soda
• Monosodium glutamate (MSG)
• Sodium alginate
• Sodium citrate
• Sodium nitrate and nitrate
• Sodium propionate
• Sodium sulfite
• Soy sauce

Reading Food Labels

All food products contain a Nutrition Facts label, which states a food's sodium content. The following terms are also used on food packaging:

Health Implications

Hypertension
Sodium intake may be a primary factor in the development of high blood pressure (hypertension). About half of the people with hypertension and 30% of the general public are described as "salt sensitive." This means that their blood pressures are likely to increase when they eat a high-sodium diet, and conversely, their blood pressures may be lowered by limiting dietary sodium. Salt sensitivity is difficult to accurately diagnose. Therefore, appropriate sodium recommendations are a subject of great debate among nutrition experts. Some believe that all people should limit their sodium intakes (to 2400 mg/day) to either treat or prevent hypertension, regardless of their present blood pressure level. Others, though, advise that only people with hypertension or those who are believed to be salt sensitive need to limit sodium in their diets.

Nutrition researchers are still trying to tease out the exact role of sodium in hypertension. One such study is DASH�Dietary Approaches to Stop Hypertension.

Kidney stones
Increasing dietary salt intake might raise the risk of kidney stones by increasing urinary calcium excretion.

Tips for Lowering Your Sodium Intake

1. Gradually cut down on the amount of salt you use. Your taste buds will adjust to less salt.
2. Taste your food before you salt it; it may not need the salt.
3. Substitute flavorful ingredients for salt in cooking, such as garlic, oregano, lemon or lime juice, and other herbs, spices, and seasonings.
4. Select fresh or plain frozen vegetables and meats instead of those canned with salt.
5. Look for low sodium or reduced sodium, or no salt added versions of such foods as: canned vegetables, vegetable juices, dried soup mixes, bouillon, condiments (catsup, soy sauce), snack foods (chips, nuts, pretzels), crackers and bakery products, canned soups, butter, margarine, cheeses, canned tuna, and processed meats.
6. Cook rice, pasta, and hot cereals without salt or with less salt than the package calls for (try 1/8 teaspoon for two servings.) Flavored rice, pasta, and cereal mixes generally already contain added salt.
7. Adjust your recipes to gradually cut down on the amount of salt you use. If some of the ingredients already contain salt, such as canned soup, canned vegetables, or cheese, you do not need to add more salt.
8. Limit your use of condiments such as soy sauce, dill pickles, salad dressings, and packaged sauces.
9. When dining out, ask for sauces and dressings to be served on the side, so that you can control the amount that you add