The need for niacin was first established as a consequence of the discovery of a severe disease. This disease, called pellagra or “rough skin”, was originally described during the 18th century by a Spanish physician. Pellagra was well known to American physicians of the early 20th century, since it was one of the leading causes of illness and death. However, pellagra was unique compared to most of the diseases of that era. It is exclusively a disease of poor diet, the consequence of the refinement of whole grains, corn, and rice. Pellagra is a sort of final proof, however crude and destructive, that “man cannot live on bread alone”—white bread, that is.
Niacin is readily absorbed throughout most of the small intestine. However, mental stress, alcohol/drug abuse, prescription drugs, and processed foods all cause the depletion of this vitamin. Since little niacin is stored in the body, a deficiency may readily occur. As a result, tissue levels must be continually replenished.
Niacin is essential for fat metabolism, transport, and digestion. It helps mobilize fat from adipose tissue, so that it can be burned as energy. It prevents the buildup of cholesterol within the liver and arteries and, thus, is a natural cholesterol-lowering agent. Niacin is also involved in the synthesis of the protective fatty covering of the nerves, the myelin sheath.
This B vitamin exists in nature in several forms. The most well researched are nicotic acid and niacinamide. The amino acid tryptophan may be regarded as a form of niacin. This is because if niacin stores are depleted, tryptophan is readily converted into it. Thus, a diet rich in tryptophan may provide sufficient niacin, even though the diet is low in the actual vitamin. This is why corn-rich diets induce niacin deficiency, since corn is low in both niacin and tryptophan. Additionally, small amounts of niacin are synthesized in the intestines by normal bacteria flora. Top sources of tryptophan include red meats, poultry, fish, rabbit, cheese, eggs, and sesame seeds. Excellent sources of niacin include organ meats, fresh muscle meats, rice polishings, eggs, and cheeses. Vegetation is relatively low in this vitamin.