Vitamin B3 (niacin)
Vitamin B3 is water-soluble and because it does not get stored in the body we depend on regular intake of the nutrient. Niacin is a common term for nicotinic acid and nicotinamide. The body's metabolism is able to synthesise part of its required niacin from vitamin B6 and tryptophan, an amino acid which is primarily found in meat. Vitamin B3 is destroyed by heating.
Functions and importance for
- Energy metabolism (turnover of carbohydrate, fat, and protein)
- Energy levels
- Vasodilation
- Circulation and cholesterol balance
- Nervous system
- Mental balance
- Skin and mucous membranes
- Reduction of fatigue and exhaustion
Deficiencies and poor utilisation may be caused by
- Overconsumption of alcohol
- Unbalanced diets and long-term weigh loss programmes
- Liver ailments
- Old age
- Hartnup disease (rare and hereditary)
- Carcinoid syndrome (rare cancer disease)
- Long-term use of diuretics and medical drugs such as
Levodopa against Parkinson's disease
Busulfan and mercaptopurine against cancer
Isoniazid against tuberculosis
Deficiency symptoms
Minor deficiency
- Fatigue
- Digestive problems
- Nausea and vomiting
Major deficiency
- Pellagra (characterised by the three Ds):
- Diarrhea
- Dermatitis - skin infection with redness, blisters, and pustules
- Dementia - mental impairment including apathy, headaches, memory loss, and depression.
Left untreated, pellagra may lead to extreme weight loss, heart failure, and eventually death.
Pellagra is particularly common in countries where the population consumes unbalanced diets (mainly corn) and the body has difficulty with absorbing the vitamin. Lack of the amino acid tryptophan (mainly from animal protein) and poisoning caused by mycotoxins that grow on corn that has not dried properly increase the risk of pellagra.
Sources
Mainly foods that are rich in protein, for instance meat, fish, poultry, nuts, kernels, and sprouts. Other sources are eggs, whole-grain products, and fruit.
Content of vitamin B3 (niacin) in mg per 100 grams
| Calf liver | 20 |
| Chicken | 12 |
| Salmon | 10 |
| Pumpkin seeds | 9 |
| Oats | 3 |
Recommended daily allowance (RDA)
Adults: 11 years of age and older: 16 mg
Pregnancy and lactation: 17 and 19 mg
Children: 1-10 years of age: 9 mg
Important information
The declaration often lists NE or niacin equivalents instead of mg (milligram). This is because the amino acid tryptophan can also get turned into niacin in the body. The tryptophan content in a product is therefore converted in such a way that 60 mg of tryptophan equals 1 mg of niacin. NE represents the combined amount of niacin and converted tryptophan.
Increased need
- The above mentioned deficiency symptoms and with use of medical drugs
- Pregnancy and lactation
- Overconsumption of alcohol
- Unbalanced diets and long-term weight loss programmes
- Increased energy turnover
Important
Supplements of vitamin B3 should normally be taken together with other B vitamins and not together with antacids.
Precautions
Pregnant women should not ingest large doses of niacin, as it may harm the fetus.
Overdosing - side effect (very large doses)
- "Niacin flush": Transient itching and skin redness caused by vasodilation (only nicotinic acid and nicotinamide)
- Very large doses (e.g. 3,000 - 6,000 mg) may drain the body's sugar stores and lower the body's fat content.
- Drop in blood pressure because of vasodilation.
- Liver damage and stomach ulcer