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.
Calcium is probably the nutrient you think of first. But vitamin D is just as important for keeping bones strong and preventing the bone disease osteoporosis. Vitamin D helps your intestines absorb calcium from the food you eat. Getting enough of both nutrients is an important part of making sure your bones are dense and strong. Unlike calcium, which you only get through food, your body makes vitamin D when sunlight hits your skin.