Niacin-Nicotinic Acid, Niacinamide
The terms niacin and niacinamide have replaced the older terms nicotinic acid and nicotinic acid amide (nicotinamide). The latter names were found to be undesirable because of confusion and the unwarranted belief by many that they were physiologically related to nicotine. Niacin deficiency in humans leads to serious consequences. It is perhaps the most deleterious of the vitamin deficiencies in North America. Although such a deficiency is involved in pellagra (from the Italian pelle agra, rough skin), the disease is perhaps never, except experimentally, uncomplicated by other dietary deficiencies. Early in this century the incidence of pellagra, especially in many of our southern states, grew at an alarming rate.
As late as 1941 there were nearly 2000 reported deaths in the United States from this disease. How many more unrecognized pellagra deaths occurred can scarcely be estimated. Funk had isolate nicotinic acid from rice polishings as early as 1914, but he did not realize that it was a vitamin. He was studying polyneuritis primarily at this time, and nicotinic acid did not cure ihis disease, although he noticed a beneficial response when it was given with antineuritic substances. The earliest demonstration that pellagra results from nutritional deficiency was given by Goldberger and others in 1915. It is difficult to overemphasize the significance of this report.
It was the forerunner of the clinical experimental approach to the study of pellagra control.
These workers studied the effect of a marked change in diet at two orphanages, one in Mississippi and one in Georgia, on the incidence of pellagra among the inmates. The change of diet to one with marked increase in "animal and leguminous protein foods" almost completely eliminated a reoccurrence of pellagra in the high percentage of individuals who had demonstrated the typical syndrome the previous year. Canine blacklongue, a deficiency syndrome in dogs described by Chittendon and Under Hill in 1917, has much in common with human pellagra.
It is readily produced by maintaining young dogs on the Goldberger diet. It was observed shortly after this that many of the foods and preparations effective in curing blacktongue were likewise curative for pellagra and that, whatever the active substances might be, they always occurred together in natural foods. In 1935 Warburg and Christian showed that nicotinic acid amide (niacinamide) is an essential constituent of a coenzyme concerned in hydrogen transport (oxidation-reduction system). Now two enzyme prosthetic groups containing niacinamide, coenzyme I and coenzyme II, are known. Niacinamide was isolated from a liver concentrate by Elvehjem and co-workers and they demonstrated that the or the free acid were effective cures for blacktongue in dogs and also that dogs could be maintained in a normal condition on the basal blacktongue-producing by the addition to the diet of small amounts of either compound. Very soon after publication of the initial paper on this subject by Elvehjem an coworkers the first report concerning the use of niacin in pellagrins appeared.
The success of the treatment heralded a new era in the clinical approach to treatment of pellagra. Nicotinic acid had been known to chemists since 1867, and many laboratories had supplies of the product during the many years that thousands and thousands of individuals were suffering from a lack of it. It is an ironical situation. By no logical reasoning, however, one can cast aspersions for the finding not having been made earlier.
