This light-gray metal enters into the building of more than 100 enzymes. It also helps to maintain the molecular structure of proteins and to regulate gene expression.
The best sources of zinc are red meat, liver, poultry, eggs, certain seafoods, whole grains, and fortified cereals.
Zinc deficiency causes slow healing of wounds, a dulled sense of taste, and loss of appetite. In pregnant women, it can also bring about abnormal development of the fetal brain.
An acute overdose of zinc can cause nausea, vomiting, and diarrhea. Chronic oversupply leads to anemia, depressed immune function, abdominal pain, and fever. Oversupply of zinc can also aggravate a copper deficiency and bring about premature birth or stillbirth.
Your Daily Allowance
Diet Power sets your Personal Daily Allowance (PDA) of zinc at the Food and Nutrition Board's (FNB's) Recommended Dietary Allowance (RDA). In January 2001, the FNB lowered the RDA. For males 14* and older it is now 11 milligrams. For females aged 14* to 18 it is 9 milligrams; for those 19 and older, 8 milligrams. For pregnant women 18 or younger it is 12 milligrams; for those 19 to 50, 11 milligrams. For nursing mothers 18 or younger it is 13 milligrams; for those 19 to 50, 12 milligrams. (In the rare even that you are over 50 and pregnant or nursing, Diet Power will assign you the 19-to-50 PDA for that reproductive state.)
Zinc and Vegetarians
The FNB advises: "Zinc absorption is lower for those consuming vegetarian diets than for those eating nonvegetarian diets. Therefore, it has been suggested that the zinc requirement for those consuming a vegetarian diet is approximately two-fold greater than for those consuming a nonvegetarian diet."
Notice, however, that the FNB does not urge such a doubling itself, and that it uses the word suggested instead of recommended. The implication is that, at least to some extent, vegetarians are on their own when it comes to deciding their zinc intake. Ask your doctor for advice.
Also in January 2001, the FNB announced a Tolerable Upper Intake Level (UL) for zinc. People 14* to 18 should get no more than 34 milligrams per day; people 19 and older, no more than 40 milligrams per day. (The same figures apply to women who are pregnant or lactating.)
* Please remember that Diet Power is not designed for people under 15.
Revising Your Allowance
Diet Power automatically sets your Personal Daily Allowance of zinc when you enroll in the program, but you can change your PDA to reflect your physician's recommendation. See Personal Daily Allowances, Editing Your.
Color Coding of This Nutrient
The zinc bar in your personal Nutrient History is:
· blue for "good" if you've logged 100 to 150 percent of your PDA
· red for "bad" if you've logged less than 100 percent of your PDA or more than the Tolerable Upper Intake Level (UL)
· yellow for "caution" if you've logged more than 150 percent of your PDA
· missing if you've logged no zinc.
In the nutrient profile of a food or recipe, the zinc bar is:
· green for "good" if getting your entire PDA of calories from this item would give you more than 150 percent of your PDA of zinc
· magenta for "bad" if getting all your calories from the item would give you less than 50 percent of your PDA of zinc
· blue for "neutral" otherwise
· missing if the amount of zinc is either zero or (when the word Zinc is grayed out) unknown.
How Complete Are Diet Power's Zinc Readings?
For the 8500 generic items in the Food Dictionary: fairly complete. Only 11 percent list their zinc content as "unknown."
For the 2500 chain-restaurant items: totally incomplete. All list zinc as "unknown."
For all 11,000 items combined: not terribly complete. About 29 percent list zinc as "unknown."
These figures mean that if you frequently log chain-restaurant foods (or user-added foods with missing zinc readings), your Nutrient History may underreport your intake of zinc by a few points.
To see whether a particular food has a zinc reading, open the Food Dictionary and check the food's nutrient profile. If you find a question mark beside "Zinc," it means the amount is unknown. (To see all foods with unknown zinc readings, click the dictionary's PowerFoods tab and sort the foods by zinc power; then scroll toward the bottom of the list until you see foods with question marks in the "Power Rating" column.)
Zinc on Food Labels
Food labels are not required to report zinc levels, though some do voluntarily. They may cite the amount in milligrams, percent of Daily Value, or both.
The Daily Value for zinc is 15 milligrams. (Why so much higher than the RDAs? Because all Daily Values are based on the RDAs of 1968, which for some nutrients were different from today's.) The Daily Value is not necessarily right for you, however¾it's a rough estimate meant to cover most of the U.S. population. (Remember, too, that the Daily Value does not yet reflect the January 2001 decrease in this mineral's RDA. See above.)
For more on label regulations, see Labels, Food.