Vitamin B3

Because vitamin B3 (also known as niacin) can be produced in the body by the conversion of tryptophan, many nutritionists do not consider this vitamin to be an essential nutrient as long as a person is consuming enough tryptophan. 

Niacin functions in the body as a component in the coenzymes nicotinamide adenine dinucleotide, or NAD, and nicotinamide adenine dinucleotide phosphate, or NADP.  These coenzymes are involved in more than 50 different chemical reactions that take place in the body.  They play an important part in energy production; cholesterol, fat and carbohydrate metabolism; and the manufacture of many compounds in the body, including adrenal and sex hormones.

Why the Body Needs Vitamin B3

Most of the processes for which the body needs niacin boil down to turning the foods that are consumed into energy.  Niacin makes the enzymes which help the cells turn carbohydrates into energy.  This important vitamin also helps to control how much glucose is in the bloodstream, which also aids in giving the body the energy it needs, when it is needed.  An example is extra energy for when a person is exercising.

Niacin also functions as an antioxidant within the cells, and everyone needs as much help as they can get when it comes to fighting free radicals.  Niacin only works against free radicals as an on-the-spot antioxidant for “mopping up” the free radicals that are produced when niacin is being used to release energy.  Other vitamins are more powerful as antioxidants, including vitamin C.

This vitamin works in close conjunction with some of the other B vitamins, but it works especially well with riboflavin and pyridoxine.  These three vitamins work together in maintaining overall good health for a person.  Together, they play an important role in maintaining the nervous system, skin and digestive system at optimum health. 

At extremely high doses (much more than the current RDA) vitamin B3 can be a valuable tool for lowering high cholesterol.  However, research is ongoing regarding niacin and cholesterol.  Other studies are being conducted to see if vitamin B3 can be beneficial in treating people with Type 1 diabetes.

For some people who may not want to take high cholesterol medication, they may want to consult their health care practitioners about taking large doses of nicotinic acid (between 2 and 3 g a day) to lower LDL (bad cholesterol) and increase the HDL (good cholesterol).  While anyone should consult their physician before undertaking this regimen, those people who have Type 2 diabetes should not take extra niacin as it can cause their blood sugar to raise. 

Other health problems that may be helped by niacin include:

  • Intermittent claudication - This is a circulatory problem that makes the legs ache and the calf muscles to cramp up when walking.

  • Dizziness and ringing in the ears - Niacin has been known to help these problems, although physicians are not sure why.

  • Alzheimer's disease - A high consumption of foods rich in niacin may reduce the risk for this disease.

Requirements for Vitamin B3

Niacin’s RDA is based on how many calories are consumed in any given day.  A person typically needs 7 to 8 mg of niacin per 1,000 calories eaten.  About half of the niacin the body needs comes from the foods that are directly eaten.  The rest comes from conversion of tryptophan.  About 60 mg of tryptophan is equal to 1 mg of niacin.  Most people convert about 8 to 17 mg of niacin from tryptophan per day.  To ensure enough niacin is being consumed, eat a diet rich in niacin or consider taking supplements.

Vitamin B3 Deficiencies

Because the body does not need very much niacin, and due to the fact that humans make some of their vitamin B3 from the tryptophan in the proteins that are eaten, real deficiencies of niacin are rare in the developed world. 

In the 18th century - when corn became a staple in Africa, Europe, and North America - niacin deficiencies became rampant because corn is very low in this vitamin and in tryptophan.  In the 1940s researchers finally found the cause for this problem (called pellagra), and today this disease is found mainly in impoverished areas of Asia and Africa.

Some people may be prone to niacin deficiencies if they:

  • Abuse alcohol - Alcohol blocks the uptake of all the B vitamins, including niacin.  Alcohol abusers also tend to have poor overall nutrition.

  • Vegetarians and vegans - Those people who do not eat a lot of protein from animal sources (such as milk, eggs, fish and meat) may also be low in niacin.  This problem especially holds true for children.  Vegetarian or vegan children should probably take niacin supplements.

People who are low in niacin are usually low in all the B vitamins.  The reason for this is almost always because of a poor diet.  A supplement containing all of the B vitamins should be taken.

Foods Containing Vitamin B3

Niacin can be found in many foods, particularly meat, fish, poultry, eggs and whole grains.  This vitamin is also added to many breakfast cereals, as well as bread, baked goods and rice.  Tryptophan can be found in nearly all protein foods, such as dairy foods, milk and eggs. 

People who are strict vegetarians or vegans should eat plenty of nuts and whole grains (such as oatmeal) to meet the RDA for niacin.



  1. Alan H. Pressman and Sheila Buff.(2007). The Complete Idiot's guide to vitamins and minerals. New York : Alpha Books
  2. Brewer, S. (2010). The essential guide to vitamins, minerals and herbal supplements. London : Right Way
  3. Elson M. Haas, Md & Buck Levin, Phd, Rd.(2006). Staying Healthy with Nutrition: The Complete Guide to diet and nutritional medicine. Berkeley, Calif. : Celestial Art
  4. Holford, P. (2004). The optimum nutrition bible. London : Piatkus
  5. Holford, P & Lawson, S.(2008). Optimum Nutrition Made Easy How to achieve optimum health. London : Piatkus
  6. Lieberman, S. & Bruning, N. (2003). The Real Vitamin & Mineral Book. New York : Avery
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  10. Werbach, M. (1993). Nutritional Influences on Illness. 2nd ed. Los Angeles: Third Line Press

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