Sodium and potassium are another pair of minerals that complement each other's action of the body function, and are concerned with water balance, and is essential for life. The sodium is chiefly found in extra cellular fluids and very little inside the cells. This is in reverse order as compared to potassium, which is mainly found inside the cells, and very little in the extra cellular fluids.



The total sodium in a body is equal to 0.1% of body weight, i.e. about 100 mg and is present in all body fluids. Its spread is: as Sodium -340 mg % in plasma, 65 mg % in corpuscles, 200 mg % in whole blood, 330 mg %, in cerebrospinal fluid; as Sodium Chloride?560-630 mg in plasma, 35?550 mg in whole blood, 650-750 mg in cerebrospinal fluid, all per 100 ml.

Recommended Daily Allowance: The daily requirement as sodium chloride is 10-15 but normally the consumption is much above this. The requirement of sodium chloride depends upon climate, occupation and physical activity. People engaged in hard work would need more.

Its excessive intake is far more dangerous than its depletion, which gets corrected with food. If taken in excess, it can raise blood pressure, liver cirrhosis, and congestive cardiac disorders, and renal diseases, water retention, even stomach ulcers.

Dietary Sources: Sodium occurs in many foods like milk and vegetables, and is added as common salts during cooking. It is present in whole meal flour, bread, celery, bananas, water, milk, lotus, dry stem, pulses, and legumes, green and leafy vegetables; beetroot, fruits, fish and meat, and all ordinary articles of diet. Sodium present in the food items is not enough to meet the daily seeds, and thus sodium chloride is added in the diet.

Functions of the body: Sodium is necessary for digestion, and elimination of carbon dioxide. The sodium in plasma provides over 90% of the total base of the body. It works in the body either as sodium ions, or as sodium compounds. As sodium ions, its functions are:

1) Essential for the normal functions of the cells.

2) Is essential for the contraction of the muscles.

3) Initiates and maintains contraction of heart.

4) Excites nerves, being neuro-excitatory as opposed to calcium ions.

5) Helps in glucose absorption and for the transportation of other nutrients across cell membranes.

As sodium compounds like chlorides, bicarbonates, phosphates, proteinates etc., its function is to:

1) Maintain blood reaction, by acting as buffer and phenomenon of chloride shift.

2) Control reaction of urine, by altering the proportion of acid and alkaline phosphates in the kidneys.

3) Regulate reaction of pancreatic juice and bile due to sodium carbonate.

4) Maintain osmotic pressure, as sodium chloride is the chief regulator of the pressure of the body fluids.

5) Helps in the formation of hydrochloric acid of gastric juice, since sodium chloride takes part in various reactions in the stomach.

6) Rectifies defective fat absorption.

7) Maintains water balance.

When carbon-di-oxide enters blood, chlorine from plasma enters the red cells, while the base (Sodium) is left behind. When carbon-di-oxide escapes from blood, chlorine leaves the cells, enters the plasma and combines with the base (Sodium) again. Due to this alternate movement of chlorine ion, this phenomenon is called chloride shift.

Deficiency Indicators: The average intake is more and hence natural sodium deficiency is rare. Deficiency of sodium is caused with excessive sweating, prolonged use of diuretics, or chronic diarrhoea. The sodium deficiency shows reduction in fat deposit, atrophy of muscles and testis, lung infection, retarded bone growth, and reduction in osteoid tissue. Depletion of sodium chloride causes muscular cramps, nausea, mental apathy, oedema, and heat exhaustion in hot weather and exertion.