Niacin deficiency is characterized by lethargy, loss of appetite, weight loss, and a sore or inflamed mouth in the early stages. If it progresses, the deficiency can cause an illness known as pellagra. The major symptoms of pellagra are sometimes called the "four D's": diarrhea, dementia, dermatitis, and death. It is important to have a healthy diet with adequate amounts of niacin to avoid developing a deficiency.
Niacin, also known as Vitamin B3 or Vitamin P, is an essential nutrient. In other words, the body requires niacin for its normal metabolic function, but does not produce any on its own. Niacin, like the other essential nutrients, can only be obtained through one's diet.
If one has a healthy, balanced diet, niacin deficiency is not a concern. It is, however, widespread in developing countries including Mexico, Indonesia, parts of China, and some African countries. In developed nations, alcoholics, and the very poor, are most susceptible to niacin deficiency. A diet poor in tryptophan or leucine, two amino acids, can also cause a deficiency.
The main symptoms of niacin deficiency are diarrhea, dementia, and dermatitis. Diarrhea can lead to dehydration and prevent sufferers from absorbing other nutrients. Dementia may take the form of irritability, poor memory, or fatigue, or it may cause hallucinations and aggression. Dermatitis is a skin condition characterized by dry, dark, scaly patches, especially on areas of the skin exposed to sunlight. Other possible symptoms of pellagra include insomnia, sensitivity to sunlight, hair loss, swelling or edema, and ataxia or lack of control over muscle movement.
If untreated, pellagra will result in death within five years. Niacin deficiency is treated with oral niacin or nicotinamide, a related chemical. In addition, a person suffering from this deficiency should try to add more niacin to the diet. Foods high in niacin include dairy products, meats or other high-protein foods, whole grain cereals, beans nuts, mushrooms, and a variety of vegetables.
It is important to have adequate niacin in the diet, but most people with relatively balanced diets do not need to supplement niacin. In fact, too much can be toxic. Anything over 35 mg. a day can be dangerous for adults. The recommended daily allowance of niacin is 16 mg. for men, 14 mg. for women, 2-12 mg. for children, and 18 mg. for pregnant women.