Sodium has many functions since it is the major extracellular electrolyte. The total amount of sodium is not as important as its placement. Weakness, Anorexia, Abdominal cramps, Muscle cramps upon exercising, Apathy, Fatigue, and Disorientation. Deficiency symptoms are seen more frequently than one would expect. Many people today, hearing so much about decreasing salt intake, have actually lowered their sodium intake to a dangerous level.
Sources are salt and salty foods, celery and milk.
Absorption is complete and rapid. Excess excreted through the kidneys. If you taste food and think it would taste better with a little salt and then add it, you are probably o.k. If you add salt before tasting the food you are probably eating too much sodium.