Nutrition Science and Everyday Application - beta v 0.1

VITAMINS AND MINERALS INVOLVED IN FLUID AND ELECTROLYTE BALANCE 467
the nerve signals the muscle cell membrane to open and sodium rushes in, creating another
current that travels along the muscle and eventually leading to muscle contraction. In both
nerve and muscle cells, the sodium that went in during a stimulus now has to be moved
out by the sodium-potassium pump in order for the nerve and muscle cell to be stimulated
again.
SODIUM
Although sodium often gets vilianized because of its link to hypertension, it is an essential
nutrient that is vital for survival. As previously discussed, it is not only important for fluid
balance, but also nerve impulse transmission and muscle contraction.
Food Sources of Sodium
Sodium can be found naturally in a variety of whole foods, but most sodium in the typical
American diet comes from processed and prepared foods. Manufacturers add salt to foods
to improve texture and flavor, and also to act as a preservative. Even foods that you wouldn’t
consider to be salty, like breakfasts cereals, can have greater than 10% of the DV for
sodium. Most Americans exceed the adequate intake recommendation of 1500 mg per day,
averaging 3,393 mg per day. 1 The sources of sodium in the American diet are shown below.
Figure 8.10. Top sources and average intake of sodium in the U.S. population, ages 1 year and
older. 6