Sodium Introduction

Sodium in an electrolyte is essential for all living things, and is consumed more than any other mineral. It is estimated that Americans consume nearly four pounds of sodium each year. Sodium is also a positively charged ion found outside of our body’s cellular structures. The most abundant form of sodium in diet is salt, or sodium chloride (60 % salt, 40% chloride). Other forms of dietary sodium are added to a variety of liquids and foods. These sources include:

• sodium benzoate
• baking soda (sodium bicarbonate)
• monosodium glutamate
• sodium saccharin
• and sodium nitrate

Because sodium is found in nearly all dietary sources, its bioavailability (amount of a mineral/nutrient capable for absorption in any given food) in the body is very high.

An excessive intake of sodium is more common than a deficiency. It is suggested that the average American “consumes from 2,300 to 6,900 milligrams of sodium daily.” (1) The body absorbs sodium in the small intestine and a large amount is deposited in the skeletal system. The remainder of consumed sodium is either found in tissues and cells; or is constantly circulating in the blood.

The amount of sodium needed for proper functioning of cellular processes may be in direct relation to the physical activity of a person or the overall health on an individual. This is, in part, due to the amount of fluids lost through sweating during exercise, and fluid loss in conditions associated with certain illnesses (i.e. vomiting, diarrhea).

Like the electrolyte potassium, sodium is critical in maintaining proper fluid balance in our bodies. Its main function is in the regulation and allowance of potassium ions in intracellular structures. This process allows us to utilize the majority of fluids contained in our bodies. Sodium controls the balance of fluids across and through all tissue and cell structures.

All foods listed below are based upon a 3.5 oz serving size (100 grams). Sodium is listed on the nutritional labels of all purchased food sources and is measured in milligrams. For example, 1 teaspoon of salt (sodium chloride) is equal to approximately 2,300 mgs of sodium.[2]

-Sodium is added to the majority of foods we consume, especially processed foods. Processed, canned, and pre-packed foods with added sodium contribute to ¾ of our daily allowance.

Proper dietary intake of sodium gives the body the ability to accomplish a variety of significant processes. These tasks include (and are not limited to):

• Treatment of dehydration [3]
• Transmission of nerve impulses
• Muscle contraction (esp. heart)
• Balancing acidity (PH) levels in the body,
• Regulating blood volume and pressure
• Contraction of certain blood vessels
• Absorption of glucose (via small intestine)

According to the National Academy of Sciences, tolerable dietary intakes of sodium may range from 120- 500 milligrams per day, and should not exceed 3 grams (3.000 milligrams/day). An actual dietary requirement in humans has not been established, but research suggests the minimal requirements of sodium in healthy persons are:

The Committee on Dietary Allowances has, however, established the ESADDI, or Estimated Safe and Adequate Intake(s), for sodium. (1,100-3,300 mg/day). [4]

Sodium Deficiencies

Hyponatremia, or a low level of sodium levels in the blood, is very rare. Deficiencies may occur in those persons suffering from dehydration, illness, or from the lack of sodium absorption due to certain medications. Signs and symptoms of a deficiency are muscle cramps, fatigue, and weakness. Sodium deficiency is many times associated with the lack of the other two electrolytes, potassium and chloride.

Sodium Toxicities

The most important and controversial condition associated with excessive intakes of dietary sodium (hypernatremia), is hypertension (high blood pressure). Excessive amounts of sodium consumed in the diet result in increased fluid retention. This may be especially important because of the heart’s responsibility in the transportation of fluids throughout the bloodstream. Excessive intakes may lead to the elevation of blood pressure and edema (swelling of face, legs and feet).[5] Clinical applications suggest that a reduction of 2.300 milligrams per day (one teaspoon), may lead to an overall reduction in systolic blood pressure levels.[6]

In healthy individuals, excessive sodium intake rarely results in toxicity. Sodium is readily excreted in our urine. Adverse reactions to excess dietary sodium intake may be of greater concern for those who are sodium sensitive. It is estimated that “30 to 50 percent of those who have hypertension may be particularly sensitive to sodium.”[1]

1. Hammock Delia, M.S., R.D. “Sugar and Salt” Total Nutrition Ed. Victor Herbert, M.D., Genell J. Subak-Sharpe, M.S. New York: Saint Martin’s Griffin, 1995. 119-138.

2. High potassium foods. Foods High in potassium. Table of foods rich in Potassium. 2003. www. weightlossforall.com/potassium- rich-food.htm

3. Backer HD, et al. Exertional Heat Illness and Hyponatremia in Hikers. Am J Emerg Med. Oct 1999; 17(6): 532-39.

4. Committee on Dietary Allowances, and Food and Nutrition Board: Recommended Dietary Allowances. Washington, DC: National Academy of Sciences, 1980.

5. De Wardener HE. The hypothalamus and hypertension. Physiol Rev. Oct 2001; 81(4): 1599-658.

6. The Trials of Hypotension Prevention Collaborative Research Group. (1997) Effects of weight loss and sodium reduction intervention on blood pressure and hypertension incidence in overweight people with high normal blood pressure. The Trials of Hypertension Prevention, Phase II. Arch. Inter. Med. 157: 657-667.