Calcium is the most abundant mineral in the body, comprising 2 percent of the average adult's weight. Although it is known chiefly as a building block for bones and teeth, it also plays an essential role in blood clotting, muscle contraction, and nerve transmission.


Good sources of calcium include milk and other dairy products, sardines, canned salmon that includes the bones, dried beans and peas, corn tortillas, calcium-set tofu, Chinese cabbage, citrus fruits, and dark green, leafy vegetables such as kale and broccoli.


Getting too little calcium leads to osteoporosis, which depletes bone mass and invites fractures, especially of the hips, arms, and vertebrae. Symptoms late in life ("dowager's hump," for example) can often be traced to poor calcium intake in earlier years. Women, especially, should make sure they get enough calcium when they are young.


An excess of calcium will cause your body to absorb less of other minerals you need, and may eventually lead to kidney stones, renal insufficiency, hypercalcemia, or milk-alkali syndrome.


Your Daily Allowance


Diet Power sets your Personal Daily Allowance (PDA) of calcium at the Food and Nutrition Board's Adequate Intake (AI), measured in milligrams: 1300 for people aged 14* to 18, 1000 for people 19 to 50, and 1200 for those 51 and older. For women 50 and younger, the same figures apply during pregnancy and lactation. (In the rare event that you're over 50 and pregnant or lactating, Diet Power will assign you the 50-and-younger PDA for that reproductive state.)


* But remember that Diet Power is not designed for people under 15.


Revising Your Allowance


You can revise your PDA if your doctor recommends. See Personal Daily Allowances, Editing Your.


Upper Limit


The Tolerable Upper Intake Level (UL) of calcium is 2500 milligrams per day for teenagers and adults. Getting more than the UL may harm your health.


Color Coding of This Nutrient


The calcium bar in your personal Nutrient History is:


   image\diet0036.gif blue for "good" if you've logged 100 to 150 percent of your PDA


   image\diet0037.gif red for "bad" if you've logged less than 100 percent of your PDA or more than the Tolerable Upper Intake Level (UL)


   image\diet0042.gif yellow for "caution" if you've logged more than 150 percent of your PDA


   image\diet0038.gif missing if you've recorded no calcium.


In a food or recipe's nutrient profile, the calcium bar is:


   image\diet0039.gif green for "good" if getting your entire PDA of calories from this item would give you more than 150 percent of your PDA of calcium


   image\diet0040.gif magenta for "bad" if getting all your calories from the item would give you less than 50 percent of your PDA of calcium


   image\diet0036.gif blue for "neutral" otherwise


   image\diet0038.gif missing if the amount of calcium is either zero or (when the word Calcium is grayed out) unknown.

How Complete Are Diet Power's Calcium Readings?


For the 8500 generic items in the Food Dictionary: very complete. Only 0.5 percent list their calcium content as "unknown."


For the 2500 chain-restaurant items: not terribly complete. About 28 percent list calcium as "unknown."


For all 11,000 items combined: fairly complete. About 6 percent list calcium as "unknown."


(The percentage of unknowns will be higher, of course, if most of the foods that you've added to the dictionary lack calcium figures.)


To see whether a particular food has a calcium reading, open the Food Dictionary and check the food's nutrient profile. If you find a question mark beside "Calcium," it means the amount is unknown. (To see all foods with unknown calcium readings, click the dictionary's PowerFoods tab and sort the foods by calcium power; then scroll toward the bottom of the list until you see foods with question marks in the "Power Rating" column.)


Calcium on Food Labels


Almost all food labels are required to report calcium content, as a percentage of the Daily Value (DV) of 1000 milligrams. (The Daily Value is not necessarily right for youit's a rough estimate meant to cover most of the U.S. population.)


For more on label regulations, see Labels, Food.