a narrow opening produced by cleavage or separation of parts. 2. cleavage (def 1). 3. Anatomy. a natural division or groove in an organ, as in the brain. verb (used with object), fissured, fissuring. 4. to make fissures in; cleave; split.
A diet rich in potassium helps to counterbalance some of sodium's harmful effects on blood pressure. Foods that are good sources of potassium are listed in the Food Sources of Potassium table on the next page.
Sodium plays many important roles in the body. It maintains fluid balance and is a main nutrient used in nerve impulse transmission and muscle contraction. Too much sodium normally leads to hypertension and kidney damage. Most of the sodium consumed in the American diet is from processed food. Even low sodium foods, such as bread and pastas, can also lead to high sodium intake if consumed in large quantities.