Niacin

Like riboflavin and thiamin, niacin is a vitamin that acts as a coenzyme.

A severe shortage of niacin leads to pellagra, a disease triggering skin problems, diarrhea, mental confusion, irritability, swelling of the mouth, and a smooth tongue.

Large amounts of niacin appear to be harmless when they come naturally from food, but a large dose from supplements may cause severe itching, nausea, and flushing of the skin, especially around the face and neck. Prolonged megadosing can lead to liver failure, although this is rare.

Good sources of niacin include peanuts, fortified cereals, liver, poultry, meat, eggs, pasta, nuts, tuna, dried peas and beans, and enriched or whole-grain breads.

Your Daily Allowance

Diet Power sets your Personal Daily Allowance (PDA) of niacin at the Food and Nutrition Board's Recommended Dietary Allowance (RDA), measured in milligrams: 16 for males aged 14* and older, 14 for women 14* and older, 18 for pregnant women, and 17 throughout lactation. (People using hemodialysis or peritoneal dialysis, as well as those who have malabsorption syndrome, may need extra niacin.)

Upper Limit

The Tolerable Upper Intake Level (UL) for niacin, in milligrams per day, is 30 for people 14* to 18 years old and 35 for people 19 and older, regardless of sex or reproductive state. The UL applies only to synthetic niacin obtained from supplements or fortified foods, however.

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

Revising Your Allowance

If your doctor recommends a different PDA, you can change it with the Personal Daily Allowance Editor.

Color Coding of This Nutrient

The niacin 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

·    yellow for "caution" if you've logged more than 150 percent of your PDA

·    missing if you've logged no niacin.

In the nutrient profile of a food or recipe, the niacin 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 niacin

·    magenta for "bad" if getting all your calories from the item would give you less than 50 percent of your PDA of niacin

·    blue for "neutral" otherwise

·    missing if the amount of niacin is either zero or (when the word Niacin is grayed out) unknown.

How Complete Are Diet Power's Niacin Readings?

For the 8500 generic items in the Food Dictionary: very complete. Only 1 percent list their niacin content as "unknown."

For the 2500 chain-restaurant items: totally incomplete. All list niacin as "unknown."

For all 11,000 items combined: not terribly complete. About 21 percent list niacin as "unknown."

These figures mean that if you frequently log chain-restaurant foods (or user-added foods with missing niacin readings), your Nutrient History may underreport your intake of niacin by a few points.

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

Niacin on Food Labels

Foods are not required to report niacin content, but many do. They may cite the amount in milligrams, percent of Daily Value (DV), or both.

The Daily Value for niacin is 20 milligrams. This is not necessarily right for you, however¾it's a rough estimate meant to cover most of the U.S. population.

For more on label regulations, see Labels, Food.