Let's follow the salt into the digestive system and see what happens. In the wall of the small intestine, the salt is absorbed into your bloodstream, making your blood saltier than it was before.

As the saltier blood circulates through the body, it makes the fluid outside of our body cells saltier than the fluid inside the cells. The cells notice the change right away. That's because the extra salt outside acts like a magnet, pulling water out of the cells. The cells try to hold in the water and they send chemical messengers to the brain, protesting the saltiness of the fluid around them.

There are also sensors in the thirst center in the brain that keep tabs on the saltiness of the blood. When the thirst center goes on alert because things are too salty and the body needs water to dilute the salt, that's when you start to feel thirsty. The kidneys help dilute the salt too, by slowing down urine production and conserving water.

The constant balancing of salt and water in the body helps maintain the right amount of water in our cells and in the bloodstream. That controls our blood pressure. If salt performs such vital functions, why does it get such a bad rap?

Next time: the health effects of salt-and why salt isn't quite the guilty culprit it was once thought to be.  

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