Fundamentals of Food Technology

SODIUM

Extracellular fluid contains sodium for the maintenance of normal osmotic pressure and water balance. Approximately 50% of the body’s sodium is present in the extracellular fluid, 40% in bones and 10% or less in intracellular fluid.

Functions

• Sodium along with chloride is major constituent in the extracelluar fluid. It is responsible to maintain osmotic pressure.
• Acid and base balance is regulated by sodium. Sodium along with calcium, magnesium and potassium are basic in reaction; but chloride with phosphate and sulphate are acidic in reaction. Thus, acid-base balance is maintained
• Sodium is concerned in the maintenance of water balance, muscle irritability contraction of muscles.
• It regulates permeability of cell membrane
• Maintenance of heart beat
• It contributes alkalinity to the gastro-intestinal secretions.

Deficiency

• Sodium deficiency occurs when the intake is poor or excessive amount is lost.
• Sodium loss through excessive sweating causes deficiency unless salt intake is not increased.
• Vomiting, severe diarrhoea, Addison’s disease is also responsible for sodium deficiency.
• There is giddiness, cramps in muscles, collapsed veins, low blood pressure, dryness of mouth, inelastic skin and oliguria.

Excess of Sodium

• Any excess of sodium in the body accumulates in the extra cellular fluids.
• The increased concentration of sodium is partially offset by an increase in these fluids.
• Sodium excess may result in oedema.
• In some the kidneys are enlarged and glomerulo nephritis may occur.
• Persons consuming 10-25 gm of salt have been found to have a high incidence of raised blood pressure.

Sources

• Excellent source: Fresh meat, fish, poultry, egg, nuts, bakery products, milk and milk products, green leafy vegetables Salt used during cooking is the commonest source of sodium.

Requirements

• Adult - 500 mg
• Children - 58 mg/day
• Infants - 2.5 mmol/day