Sodium is an essential mineral found predominantly in the extracellular fluids; the vascular fluids within the blood vessels, arteries, veins, and capillaries; and the intestinal fluids surrounding the cells. About 50 percent of the body's sodium is found in these fluids and the remaining amount is found within the bones. Sodium functions with potassium to equalize the acid-alkali factor in the blood. Along with potassium, it helps regulate water balance within the body; that is, it helps regulate the distribution of fluids on either side of the cell walls. Sodium and potassium are also involved in muscle contraction and expansion and in nerve stimulation.
Another important function of sodium is keeping the other blood minerals soluble, so that they will not build up as deposits in the bloodstream. It acts with chlorine to improve blood and lymph health, helps purge carbon dioxide from the body, and aids digestion. Sodium is also necessary for hydrochloric acid production in the stomach.
An excess of sodium in the diet may cause potassium to be lost. Sodium is found in virtually all foods, especially sodium chloride, or salt. High concentrations are contained in seafoods, poultry, and meat. Kelp is an excellent supplemental source of sodium.
Sodium is readily absorbed in the small intestine and the stomach and is carried by the blood to the kidneys, where it is filtered out and returned to the blood in amounts needed to maintain blood levels required by the body. The absorption of sodium requires energy. Any excess, which usually amounts to 90 to 95 percent of ingested sodium, is- excreted in the urine.
The adrenal hormone aldosterone is an important regulator of sodium metabolism. Excessive salt in food interferes with absorption and utilization, especially in the case of protein foods. Vomiting, diarrhea, or excessive perspiration may result in a depletion of sodium. Sodium supplements to prevent sodium deficiency may be needed in such cases. The levels of sodium in the urine reflect the dietary intake; therefore when there is a high intake of sodium the rate of excretion is high, and if the intake is low the excretion rate is low.
There is no established dietary requirement for sodium, but it is generally observed that the usual intake far exceeds the need. The average American ingests 3 to 7 grams of sodium and 6 to 18 grams of sodium chloride each day. The National Research Council recommends a daily sodium chloride intake of 1 gram per kilogram of water consumed. in the urine. Abnormal fluid retention accompanied by dizziness and swelling of such areas as legs and face can also occur. An intake of 14 to 28 grams of salt (sodium chloride) daily is considered
Diets containing excessive amounts of sodium contribute to the increasing incidences of high blood pressure. The simplest way to reduce sodium intake is to eliminate the use of table salt.
Deficiency Effects and Symptoms
Deficiencies are very uncommon because nearly all foods contain some sodium, with meats containing especially high amounts. A sodium deficiency can cause intestinal gas, weight loss, vomiting, and muscle skrinkage. The conversion of carbohydrates into fat for digestion is impaired when sodium is absent. Arthritis, rheumatism, and neuralgia, a sharp pain along a nerve, may be caused by acids that accumulate in the absence of sodium.
Beneficial Effect on Ailments
An individual suffering from high blood pressure is 1 advised to maintain a low-sodium diet, since sodium I may aggravate this ailment. Resistance to heat cramps I and heat strokes may be increased by moderate sodium 1 intake. Sodium helps keep calcium in a solution that 1 is necessary for nerve strength. Clinical studies indicate that low-sodium diets are effective in preventing \ or relieving the symptoms of toxemia (bacterial poisoning), edema (swelling), proteinuria (albumin in the j urine), and blurred vision.