Sodium's role in the body: Sodium is considered a "major mineral". It assists with transmitting nerve impulses, helps regulate blood pressure, helps your muscles and heart relax, and assists regulate body fluids to move in and out of the body's cells.

RDA: 1500 mg for adults, unless you have medical problems, then it can be less. 500 mg is the minimum recommendation for adults.

Sodium and blood pressure: Hypertension, or high blood-pressure, can greatly increase your risk of heart disease, stroke, blindness, kidney disease, and impotence. Reducing sodium intake is an important step in preventing and treating hypertension.

Toxicity: For most people, most sodium that is eaten is absorbed and what isn't used is excreted in the urine. But for some people who are sodium-sensitive, too much sodium can lead to high blood-pressure, fluid retention and edema (swelling).

Deficiency: Not common in the US, but symptoms are dizziness, nausea, vomiting, and muscle cramps. This may occur if you underconsume sodium, perspire excessively (such as in a hot climate), have long-term diarrhea or vomiting, or have kidney problems.

Food sources: Most people need to reduce their sodium intake, in which case it's best to minimize intake from table salt and most processed foods, such as canned soups, chips, and pretzels, which contain lots of sodium. Deli meats, dairy products and many soft drinks also have sodium. Antacid tablets, such as Alka-Seltzer, can contain 500mg of sodium per tablet. Healthy sources of sodium include celery, seaweed, and low-fat/nonfat dairy.