sodium is an essential nutrient that regulates
- blood volume
- blood pressure
- osmotic equilibrium
The minimum physiological requirement for sodium is 500 mg per day.
Sodium chloride is the principal source of sodium in the diet, and is used as seasoning and preservative, such as for pickling and jerky; most of it comes from processed foods.
The DRI for sodium is 2.3 grams per day, but on average people in the United States consume 3.4 grams per day, the minimum amount that promotes hypertension; this in turn causes 7.6 million premature deaths worldwide.
The renin-angiotensin system regulates the amount of fluids and sodium in the body.
Reduction of blood pressure and sodium concentration in the kidney result in the production of renin, which in turn produces aldosterone and angiotensin, retaining sodium in the urine. Because of the increase in sodium concentration, the production of renin decreases, and the sodium concentration returns to normal.
Sodium is also important in neuron function and osmoregulation between cells and the extracellular fluid, their distribution mediated in all animals by Na+/K+-ATPase; hence, sodium is the most prominent cation in extracellular fluid.