Sodium is a metal found in many foods, most commonly as part of the compound sodium chloride¾table salt¾which is 40-percent sodium by weight. Sodium ions (atoms that are electrically charged because some of their electrons are missing) play a crucial role in regulating your body's water balance (the proportion of water inside the cells to that between the cells). Sodium ions also figure in the transmission of nerve impulses and in muscle contractions.
Besides the salt shaker, the biggest source of sodium in our diet is processed foods, to which manufacturers often add surprisingly large amounts of salt.
Most people eat far more salt than they need. The average adult, when not actively sweating, can get by for long periods on 500 milligrams of sodium per day¾the amount in one-quarter teaspoon of table salt. (You can get the same dose from any of the following: one average hot dog, four cups of milk, one slice of pizza, two ounces of cheddar cheese, half a cup of canned soup, one-third cup of sauerkraut, half of a large dill pickle, or a cup of vanilla pudding.) A typical American consumes eight or ten times that much. While this amount is not toxic (as are much larger doses), it probably does the body no good, and may cause you to feel weaker and more tired than you would otherwise.
Sodium and Blood Pressure
Getting too much sodium is widely believed to cause hypertension, but the connection isn't cut-and-dried. Studies show that some people's blood pressure is sensitive to salt intake, while others' is not.
Your Daily Allowance
In February 2004 the Food and Nutrition Board (FNB) announced an official Adequate Intake of sodium. For everyone aged 14 to 50, it's 1500 milligrams per day. For people 51 through 70 it drops to 1300 milligrams (except in the rare event they're pregnant or lactating, when it stays at 1500). For everyone over 70 it's 1200 milligrams. Diet Power sets your Personal Daily Allowance (PDA) at these same levels. All are close to the amount of sodium in ¾ teaspoon of salt
Also in February 2000, the FNB announced a Tolerable Upper Intake Level (UL) for sodium. It's 2300 milligrams—far below what many of us average.
Revising Your Allowance
You may want to reset your PDA to a lower figure if your body is small, but get your doctor's advice. For instructions on resetting PDAs, see Personal Daily Allowances, Editing Your.
Color Coding of This Nutrient
The sodium bar in your personal Nutrient History is:
blue for "good"
if you've logged 90 to 150 percent of your PDA
red for "bad"
if you've logged more than 150 percent of your PDA
yellow for "caution"
if you've logged less than 90 percent of your PDA
missing if you've logged no sodium
In the nutrient profile of a food or recipe, the sodium bar is:
green for "good"
if getting your entire PDA of calories from this item would give you less
than 50 percent of your PDA of sodium
magenta for "bad"
if getting all your calories from the item would give you more than 150
percent of your PDA of sodium
blue for "neutral"
missing if the amount of sodium is either zero or (when the word Sodium is grayed out) unknown
How Complete Are Diet Power's Sodium Readings?
For the 8500 generic items in the Food Dictionary: very complete. Only 0.3 percent list their sodium content as "unknown."
For the 2500 chain-restaurant items: very complete. Only 1.3 percent list sodium as "unknown."
For all 11,000 items combined: very complete. Only 0.5 percent list sodium as "unknown."
(The percentage of unknowns will be higher, of course, if most of the foods that you've added to the dictionary lack sodium figures.)
To see whether a particular food has a sodium reading, open the Food Dictionary and check the food's nutrient profile. If you find a question mark beside "Sodium," it means the amount is unknown. (To see all foods with unknown sodium readings, click the dictionary's PowerFoods tab and sort the foods by sodium power; then scroll toward the bottom of the list until you see foods with question marks in the "Power Rating" column.)
Sodium on Food Labels
Virtually all food labels are required to report sodium content, in both milligrams and percent of Daily Value.
The Daily Value for sodium is 2400 milligrams. This is not necessarily right for you, however¾it's a rough estimate meant to cover most of the U.S. population. It was not changed when the FNB announced the first Adequate Intake in February 2004, but some experts think it will eventually be lowered.
For more on label regulations, see Labels, Food.
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