How Vitamin B3 Works

Foods That Contain Vitamin B3

The vitamin B3 we get from food includes preformed niacin and the amino acid tryptophan, which can be converted to niacin in the body. Food composition tables, however, list only preformed niacin. Niacin equivalent is the term used to refer to either 1 mg of niacin or to 60 mg of tryptophan (it takes 60 mg of tryptophan to make 1 mg of niacin).

Most proteins contain tryptophan. In the average protein-rich American diet, tryptophan provides about 60 percent of the niacin you need. If a diet is adequate in protein, then it will surely supply enough niacin equivalents from both sources to meet daily needs. The best sources of niacin are foods with a high protein content, such as meat, eggs, and peanuts. Other good sources of vitamin B3 equivalents, such as milk, actually provide more tryptophan than niacin. Mushrooms and greens are good vegetable sources. Vitamin B3 is also added to enriched breads and cereals to replace that lost during processing.

Diets that are adequate in protein will most likely supply enough niacin to satisfy your daily needs.
©2007 Publications International, Ltd.
Diets that are adequate in protein will most likely supply enough niacin
 to satisfy your daily needs.

Dietary Requirements for Vitamin B3

The RDA takes into account both preformed niacin and that available from tryptophan. Together they account for the recommendation of 6.6 mg of niacin for each 1,000 calories eaten. For women, this should total no less than 14 mg and for men 16 mg (niacin equivalents). Pregnant and lactating women require slightly more. Human milk contains about 7 niacin equivalents per 1,000 calories, which is enough for infants.

Use this chart to find foods that are rich in niacin:

 Food Quantity
Niacin (mg)
 Peanut halves, roasted, salted  1 cup  20.6
 Product 19 cereal  1 ounce  20
 Tuna, canned, water drained  31/2 ounces  12.2
 Chicken, white meat, no skin  31/2 ounces  9.5
 Beef liver  3 ounces  9.1
 Turkey, all meat, no skin  31/2 ounces  7.3
 Lamb chops, cooked  31/2 ounces  6.1
 Beef round, bottom, broiled  4 ounces  5.3
 Cheerios cereal  1 ounce  5
 Ground beef  3 ounces  5

A niacin deficiency brings on the disease pellagra, which causes weakness, loss of appetite, and rough, red skin. Go to the next page to learn more about the symptoms of a niacin deficiency.

isn't the only vitamin you need to maintain overall health. Visit these links to learn about other essentail nutrients you need to include in your diet.
  • Vitamin B5, or pantothenic acid, can be found in all living cells and in all foods. Learn about its importance to your diet in How Vitamin B5 Works.
  • Vitamin B6 is actually three substances, pyridoxine, pyridoxamine, and pyridoxal, that work to metabolize protein and amino acids. Read more in How Vitamin B6 Works.
  • In How Biotin Works, learn how biotin acts as a coenzyme in several metabolic reactions, such as the metabolism of fats and carbohydrates.
  • Read How Folate Works to learn about folacin, folic acid, and folate and how a folate deficiency can cause megaloblastic anemia.
  • Vitamin B12, also called cyanocobalamin or cobalamin, is essential because it assists folate in making DNA and RNA. Read more in How Vitamin B12 Works.

  • To learn about the many vitamins in our diet, how much you should be eating, and where to find them, go to our general Vitamins page.
  • To find the best prices on B vitamin supplements, click here.
This information is solely for informational purposes. IT IS NOT INTENDED TO PROVIDE MEDICAL ADVICE. Neither the Editors of Consumer Guide (R), Publications International, Ltd., the author nor publisher take responsibility for any possible consequences from any treatment, procedure, exercise, dietary modification, action or application of medication which results from reading or following the information contained in this information. The publication of this information does not constitute the practice of medicine, and this information does not replace the advice of your physician or other health care provider. Before undertaking any course of treatment, the reader must seek the advice of their physician or other health care provider.