Niacin B3
(Niacinamide/Nicotinic Acid)

Description

Two related compounds - nicotinic acid and niacinamide (nicotinamide) are both called niacin. Niacin is also commonly known as vitamin B3, the water-soluble vitamin that prevents the deficiency disease pellagra.

Niacin may also be made in the body from the essential amino acid tryptophan. Sixty molecules of tryptophan are needed to make one molecule of niacin. (The exception is pregnant women, where the conversion is twice as efficient).

The conversion of tryptophan to niacin also requires the presence of other nutrients - such as Thiamin , Pyridoxine (Vitamin B6 ) and Biotin.

STABILITY

Niacin is one of the most stable B vitamins, being unaffected by light, air or alkalis. The only appreciable loss of niacin occurs when it leaches into cooking water.

Functions

Niacin forms two coenzymes in the body, namely nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). These coenzymes, like the ones formed by Thiamin and Riboflavin , are involved in the release of energy from food.

Deficiency

Symptoms of minor niacin deficiency are tiredness, Depression and loss of memory. The disease pellagra results from a severe deficiency of niacin, and is characterised by the three D’s - Diarrhoea, Dermatitis and dementia. Niacin deficiency is common in certain maize-eating populations because the niacin in maize (and other cereal grains) is bound in such a way as to make it unavailable to the body. To compound this problem, maize is also a relatively poor source of tryptophan.

Requirements

Upper safe level for daily supplementation:
(niacinamide) = 450 mg
(nicotinic acid) = 150 mg

Recommended Daily Allowance = 18mg

Supplemental Uses

Alcoholics:
Alcoholics are commonly deficient in niacin and often need to be given a supplement of this vitamin (1) - preferably along with other members of the B complex.

High Cholesterol:
Niacin (as nicotinic acid) has been used to very good effect in the lowering of cholesterol (2) . However "megadoses" (usually grams per day) need to be used for this purpose and any such supplementation should therefore only be done under full medical supervision.

N.B. Only nicotinic acid (NOT niacinamide) can lower blood fat levels.

Mental Health:
High levels of niacin have been advocated in certain schizophrenic conditions (1) and although the information on this subject is conflicting, there are reported cases of quite remarkable recoveries using niacin.

Arthritis:
Osteoarthritis and other painful joint conditions may also respond to niacin treatment (as niacinamide) (1).

Safety

Very high doses of nicotinic acid (3-6 g per day) may cause changes in liver structure, with the timed release form of the vitamin seeming more likely to be implicated in this respect. However, safety data on niacinamide confirms that this form of niacin may be taken at higher supplement levels than nicotinic acid.

Interactions and Contra-Indications

At levels above 20 mg, nicotinic acid (NOT niacinamide) may cause dilation of blood vessels in the skin with resultant skin flushing. This effect usually wears off after days of repeated administration and occurs to a much lesser degree if the nicotinic acid is taken with food.

Supplements of nicotinic acid should not be taken by people suffering from the following conditions:

Gout
Diabetes
Stomach Ulcers
Liver disease

Food Sources

Food (mg/100g)
Rice bran 18.5
Tuna 11.6
Chicken liver 9.3
Chicken, light meat 8.1
Wheatgerm 5.6
Brown rice 4.7
Broccoli 0.8
Dried figs 0.4

The main sources of niacin in the diet are meat and meat products, potatoes, bread and fortified breakfast cereals.

References

1. "Handbook of Dietary Supplements", Pamela Mason, Blackwell Science, 1995.
2. Crouse JR 3rd, New developments in the use of niacin for treatment of hyperlipidaemia: new considerations in the use of an old drug. Coron Artery Dis, 1996,7;4:321-326.