In medicine, a vitamin B3 deficiency is a nutritional deficiency of vitamin B3, which is also called niacin. Vitamin B3 deficiency symptoms may include nausea, skin and mouth lesions, anemia, headaches, and tiredness. Left untreated, a chronic deficiency of vitamin B3 may lead to a disease called pellagra.
Pellagra is a serious condition that starts with lesions that appear on the skin where it has been exposed to sunlight. Further symptoms include inflammation of the skin and mucous membranes, stomach problems, and depression or other mental problems. Chronic vitamin B3 deficiency and pellagra are most commonly found in people with a poor diet, particularly in areas of South America where many people have diets consisting mostly of maize. While maize does contain niacin, it is not present in a form that is readily absorbed by the body unless the maize is treated with lime prior to milling. Another group of people at risk of niacin deficiency are long-term alcoholics, where pellagra is most often observed in affluent societies.
Some of the important functions of vitamin B3 include energy metabolism, cholesterol level management, and regulation of the hormone insulin, which helps to regulate blood sugar. In addition, niacin plays a vital role in maintaining the genetic material deoxyribose nucleic acid (DNA) in living cells. This suggests that niacin may have a role to play in the prevention of DNA damage and cancer.
The treatment of a vitamin B3 deficiency is usually straightforward. In a healthy adult, if sufficient protein is consumed, vitamin B3 is normally present in plentiful supplies. Vitamin B3 can be absorbed directly from protein sources, or it can be produced in the liver from the amino acid tryptophan.
Some good dietary sources of tryptophan and niacin include red meat, milk, eggs, nuts, and legumes. As niacin is a stable substance, it is not usually destroyed by cooking. Dietary vitamin supplements can be taken to increase niacin intake, but supplementation is not usually considered necessary if a normal and varied diet is being consumed.
In addition to specific vitamin B3 deficiency syndromes, the lack of niacin may also be observed in pandemic deficiency disease, a condition where five crucial vitamins are in short supply in the body. These key vitamins are niacin, thiamin, vitamin C, vitamin A, and vitamin D. Both pandemic deficiency disease and vitamin B3 deficiency usually occur in regions where there are widespread conditions of poverty and malnutrition.