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Overview :
Niacin (nicotinic acid) deficiency (pellagra) is rare today
but can occur in patients with one or more risk factors.
Risk factors for niacin deficiency - decreased intake of
niacin or tryptophan:
(1) diet low in niacin (limited to cultures whose diet
consists mostly of millet or maize)
(2) alcohol abuse
(3) Crohn's disease (defective absorption of tryptophan)
Risk factors for niacin deficiency - decreased conversion of
tryptophan to nicotinic acid:
(1) therapy with isoniazid (INH)
(2) deficiency of pyridoxine (vitamin B6)
(3) riboflavin deficiency (vitamin B2)
(4) copper deficiency
(5) Hartnup disease
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