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Vitamin B3 (Niacin)
Found in:
Green peas, liver, red meat, poultry, mackerel, mullet, salmon, swordfish,
sardines, kidney beans, lima beans, all purpose flour, whole wheat flour,
peanuts, and soybeans. In addition to the niacin content of foods, the content
of its precursor tryptophan must be considered. For example, milk and eggs are
low in niacin but are good sources of tryptophan.
What is known to be good for:
It participates in at least 200 different chemical reactions involved in
energy production. It is necessary for the production and breakdown of glucose,
fats, and amino acids; it is required for the maintenance and function of the skin,
gastrointestinal tract and nervous system. Also, it helps in manufacturing DNA
(the substance that makes our gene).
Other functions of Vitamin B3:
Treatment of high blood-cholesterol levels, dizziness and ringing in the ears.
Also to prevent menstrual headaches.
Lack of Vitamin B3 can:
The deficiency of Niacin is also known as Pellagra. It includes: Fatigue,
loss of appetite, weakness, mild diarrhea, anxiety, irritability, and sometimes
depression. The lining of the mouth may become inflamed and sore and have a burning
sensation. In severe cases, symptoms may then include severe diarrhea, skin rashes,
delirium, and death if not treated.
Excess of Vitamin B3 can:
Both niacin and niacinamide are harmful when taken in large doses.
Megadoses of niacin (3-6 g/day) produce a flushing and itching reaction.
Pharmacological doses of niacin, but not niacinamide lower total serum cholesterol,
LDL and triglycerides. However, they also produce increased incidence of arrhythmias,
biochemical alterations and gastrointestinal disturbances.
Thus, use of niacin as a pharmacological drug should only be done under strict
medical supervision. Large doses of niacinamide do not produce the itching and
flushing reaction seen with niacin. Doses of 50-250 mg niacinamide have been used
therapeutically in deficient subjects. Doses of 3-9 g have been reported to cause
liver toxicity.
Storage and manipulation of suppliers of Vitamin B3:
Niacin is stable to air, heat, light, oxidation, acids and alkalis and is not
destroyed in ordinary cooking processes.
Absorption, Storage and Excretion
Readily absorbed by diffusion in the stomach and upper intestine.
The conversion of tryptophan to niacin may be altered under certain conditions.
The conversion is less efficient when intake of niacin and tryptophan is low and
is more efficient during pregnancy or oral contraceptive use. In vitamin B6
deficiency, formation of niacin from tryptophan is reduced due to lack of the
coenzyme pyridoxal phosphate. It is excreted via the urine.
Sources: Nutrition for Life, The no-fad, no-nonsense approach to eating well and reaching your healthy weight, LisaHark, PhD, RD and Darwin Deen, MD
HEINZ HANDBOOK Of Nutrition, 9th EDITION, Edited by David L. Yeung, Ph.D. and Idamarie Laquatra, Ph.D., R.D.
Adapted by Editorial Department, June 2007
Last update, August 2008
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