Sodium is an essential nutrient, but it's also a problem because most people get far more of it than than they need. The substance, found in salt and other compounds used in preservation, appears in high levels in most prepared and processed foods. Too much of it can lead to heart disease, kidney disease and stroke, so it's a substance you should monitor closely in your diet.
Function
Sodium helps your body maintain a proper balance of fluids, your muscles move properly and your nerves transmit impulses, according to the Mayo Clinic website. Your kidneys regulate your sodium levels, storing it when you aren't getting enough and excreting it via urine when your levels are too high. Sodium deficiency can cause muscle cramps, dehydration and low blood pressure. Because it appears in so many food sources, however, very few people have trouble with sodium deficiency.
Sources
Processed foods and restaurant foods account for more than three-quarters of the sodium we consume, according to the U.S. Centers for Disease Control and Prevention, or CDC. Sodium comes from a number of preservatives and ingredients besides salt, such as monosodium glutamate, disodium phosphate and sodium nitrate. Sodium also occurs naturally in some foods, such as celery and milk, but this accounts for only about 12 percent of the sodium in the average diet. The remaining 11 percent of sodium in the average diet comes from salt and other ingredients added while cooking or at the table.
Size
The U.S. Department of Agriculture's dietary guidelines recommend that you limit your sodium intake to 2,300 mg per day, the equivalent of about a teaspoon of salt. Processed foods can cause you to surpass this number quickly. A single bowl of canned soup, for example, might contain more than half that amount. Additionally, high-risk populations--including people over 40, people with high blood pressure or diabetes and African-Americans, according to the Harvard School of Public Health--should lower that daily intake to 1,500 mg per day. About 70 percent of U.S. adults fall into that high-risk population.
Effects
When you consume more sodium than your kidneys can remove, it starts to build up in your blood, according to the Mayo Clinic. The sodium in your blood attracts and holds water from your cells, giving your blood a higher volume. As a result, it's tougher for your blood to move through the arteries, which causes high blood pressure. This can lead to a stroke, heart disease or congestive heart failure. High-sodium diets also can cause kidney disease because you are straining the organs with extra work to remove the sodium.
Considerations
Since most sodium intake comes from processed foods, reading product labels is your key to maintaining proper sodium levels, according to the CDC. Food labels show sodium levels per serving, and restaurants also should provide such information if you ask for it. Prepared foods often come with a variety of labels such as "low sodium," "reduced sodium" or "light in sodium." Generally, "low sodium" means fewer than 140 mg per serving, and "very low sodium" means fewer than 35 mg. "Reduced" or "light in sodium," on the other hand, means that it's a lower-sodium version of a standard product that still could have high levels of sodium per serving. The CDC also recommends adding more fruit to your diet, particularly those high in potassium like bananas, to curtail sodium levels.
References
- Mayo Clinic: Sodium: How to Tame Your Salt Habit Now
- Expert Group on Vitamins and Minerals: Risk Assessment: Sodium Chloride
- U.S. Centers for Disease Contral and Prevention: Most Americans Should Consume Less Sodium
- U.S. Department of Agriculture: Dietary Guidelines for Americans 2005
- Harvard School of Public Health: Salt and Sodium
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