Niacin: synthesis, active forms, and metabolic function

THE CONTEXT

Niacin was identified during studies of pellagra. Its synthesis from tryptophan means that it is not strictly a vitamin.

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Niacin can be synthesized in the body from the essential amino acid tryptophan.

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Nicotinic acid and nicotinamide both have the biological activity of niacin.

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Niacin functions as the nicotinamide ring of the coenzymes NAD and NADP in oxidation/reduction reactions.

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Approximately 60 mg of tryptophan is equivalent to 1 mg of dietary niacin.

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Most niacin in cereals is biologically unavailable and is therefore discounted when expressing food niacin content.

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