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vitamin B3 Alternative Names
niacin, nicotinic acid, nicotinamide
Definition
Niacin is a water-soluble vitamin. It is one of eight members of the B complex of vitamins. These include vitamins B1, B2, B6, B12, folate, biotin and pantothenic acid. Water-soluble vitamins are not stored in the body.
What food source is the nutrient found in?
Good sources of niacin include: - meats, especially organ meats, like liver, kidney
- poultry
- fish
- peanut butter, peanuts
Niacin can be made in the body out of the amino acid known as tryptophan. Vitamin B6 is needed to convert niacin to tryptophan. Amino acids are building blocks of proteins. Therefore, protein-rich foods can be good sources of niacin. Examples of these of food include: - 100 grams lean beef, lamb, pork, veal = 8-10 mg niacin equivalents
- 100 grams fish, chicken = 8-9 mg niacin equivalents
- 1/2 cup legumes (baked beans, chick peas) = 2.5 - 5 mg niacin equivalents
- 1/2 cup milk (any variety) = 2.3 mg niacin equivalents
- 1/2 cup mixed nuts = 8 mg niacin equivalents
How does the nutrient affect the body?
Niacin works closely with vitamin B1, B2, B6, pantothenic acid and biotin in the breakdown of food for energy. It helps the body use carbohydrates, fats and proteins. It does this by aiding reactions that break them down into energy. Without niacin, the body would not be able to breakdown the food we eat into energy. It helps enzymes function normally in the body. Enzymes are involved in many reactions in the body. Niacin helps keep the skin, digestive tract and nerves healthy.
Information
Niacin deficiency is rare in Australia, but in the early 1900's, a disease called pellagra was common in the southern United States. At this time, corn was a staple of the diet. Pellagra was caused by significant niacin deficiency. This diet, high in corn, created widespread niacin deficiency. This was because it provided neither niacin-rich foods like meats and certain vegetables, nor protein-rich foods containing tryptophan. Again, tryptophan is converted to niacin in the body. Pellagra is uncommon today. This is due to widespread niacin enrichment of most cereals, flours, pastas and corn meals.
For people who eat adequate amounts of protein, niacin deficiency is not common. Niacin deficiency symptoms include: - weakness
- loss of appetite
- digestive upsets
- insomnia
- headaches
- irritability
- frequently, a sore, swollen, purple-red tongue.
More drastic niacin shortfall leads to pellagra: skin and gastrointestinal lesions, swollen mucous membranes, diarrhoea, dementia and death. But, as mentioned above, pellagra is rare in Australia.
In recent years, niacin has been used with some success to treat people with high cholesterol levels. The high dose required to bring about any change in cholesterol, up to 3,000 mg per day, can bring on side effects. Common side effects include nausea, flushing of the skin and itching. High doses of niacin may also cause liver damage or stomach ulcers. Because of these potentially dangerous side effects, niacin should only be used to control cholesterol in people under the care of a doctor.
The Recommended Dietary Intake (RDI) for niacin is the following, expressed as mg niacin equivalents: - for males aged 19-64 years, 19mg
- for males aged 64+ years, 16mg
- for females aged 19-54 years, 13mg
- - in pregnancy, add 2mg
- - during lactation, add 5mg
- for females aged 54+ years, 11mg
Author: Clare Armstrong, MS, RD
Reviewer: HealthAnswers Australia Medical Review Panel
Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia
Last Updated: 1/10/2001
Contributors
Potential conflict of interest information for reviewers available on request |
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