How Much Sodium Is Too Much?

Of all the issues related to high blood pressure, none is more controversial than salt, more specifically the sodium in salt. Since the 1970s, health organizations have advised Americans - especially those with high blood pressure - to limit their intake of sodium. The recommendation stems from studies showing that a reduction in sodium can lower your blood pressure if you're "sodium-sensitive." But what if you're not sodium-sensitive? And how should you interpret more recent studies suggesting that your weight and other aspects of your diet may be more important than limiting sodium?

Sodium is an essential mineral. Its main role is to help maintain the right balance of fluids in your body. It also helps transmit nerve impulses that influence contraction and relaxation of your muscles. You get sodium from the foods you eat. Many foods naturally contain some sodium. However, most sodium comes from sodium compounds added to food during commercial processing and meal preparation at home.

Salt (sodium chloride) is the most common source of sodium. It's made up of 40 percent sodium and 60 percent chloride. You need a minimum of 500 milligrams (mg) of sodium each day. That's a little more than teaspoon of salt. However, most Americans consume 3,000 to 4,000 mg of sodium daily.

Your kidneys regulate the amount of sodium in your body. When your sodium levels are low, they conserve sodium. When your levels are high, they excrete the excess amount in your urine. Sometimes your kidneys can't eliminate enough sodium. Extra sodium starts to accumulate in your blood, and because sodium attracts and holds water, your blood volume increases. Your heart has to work harder to move the increased volume of blood through your blood vessels, increasing pressure on your arteries. Heart, kidney, liver and lung disease can all lead to an inability to regulate sodium. In addition, some people are simply more sensitive to the presence of high levels of sodium in their blood.

How people react to sodium varies. Some people, both healthy adults and people with high blood pressure, can consume as much sodium as they like and it has no or little effect on their blood pressure. For others, too much sodium quickly leads to an increase in blood pressure, often triggering the development of high blood pressure. This condition is referred to as sodium or salt sensitivity.