Not enough salt = what?

Originally Published: February 14, 2003
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Dear Alice,

What happens if we have too little or no salt?

Dear Reader,

The minerals sodium and chloride make up table salt. Inside our bodies, salt dissociates into these two minerals, which carry electrical charges, hence their name electrolytes. Electrolytes play vital roles in fluid balance, nerve transmission, and muscle contractions. Our needs for them are small, especially compared to the amount most people take in. There is no Recommended Dietary Allowance (RDA) in the United States for sodium; however, the estimated requirement for adults is 500 mg/day. This amount may be found in ¼ teaspoon of salt or ½ cup canned chicken broth. A large study — NHANES III (National Health and Nutrition Examination Survey) — found the median sodium intake of adults 20 and older ranged from a low of 2172 mg/day for women 80 years and older, to a high of 4126 mg/day for men 20 - 29 years.

Processed foods are the greatest source of sodium in our diets. You may be surprised to discover that some of the following items are high in sodium: cheese, ham, canned tomato products (e.g., ketchup, sauces, juice), soups, milk, salad dressing, mayonnaise, cereals, cakes, cookies, quick breads, and donuts. Sodium also occurs naturally in some vegetables, such as celery, although not in as large amounts.

Healthy bodies are quite efficient at conserving sodium. The first mechanisms for sodium regulation are thirst and other fluid shifts. Hormones act more slowly to regulate sodium levels. For example, aldosterone regulates the concentration of sodium in the blood and ADH (anti-diuretic hormone) works to control fluid balance. In the event of low sodium levels, the kidneys receive the signal to conserve sodium and return it to the bloodstream. In rare instances, when large amounts of fluid are lost, imbalances may occur. Large losses of fluids can result in low sodium levels (hyponatremia). Some causes are vomiting, diarrhea, and extremely excessive sweating. Symptoms of hyponatremia include nausea, dizziness, loss of appetite, and muscle cramps. When an individual drinks excessively large quantities of water, low blood sodium levels may result. More people, however, experience the effects of sodium excess rather than deficiency.

Alice