Sodium

About Sodium

Sodium is the main cation in the fluid outside cells and is essential for fluid balance, nerve impulse transmission and muscle function. The physiological requirement is small, yet typical intake in many countries is well above dietary guideline recommendations, which advise limiting sodium. Blood volume and blood pressure are regulated in part through the renin angiotensin aldosterone system. High sodium intake is a major contributor to high blood pressure, and the DASH Sodium trial showed that lowering sodium reduces blood pressure, with larger effects in people with hypertension. Salt sensitivity varies between individuals and is more common in older adults and people with hypertension or kidney disease. Most dietary sodium in industrialized countries comes from processed and restaurant foods rather than salt added at the table or in home cooking. Low blood sodium, hyponatremia, usually reflects water retention rather than sodium loss and occurs in heart failure, cirrhosis and endurance exercise, with symptoms from headache to seizures and coma.