Niacin helps the body break down carbohydrates, fats and proteins into energy, according to the University of Maryland Medical Center. In addition, it plays a role in gland and liver function. Niacin has a role in producing certain hormones in the adrenal glands and helps remove harmful chemicals from the liver.
Also used for treating migraine headaches, circulation problems and dizziness, and to reduce the diarrhea associated with cholera.
Symptoms of mild niacin deficiency include fatigue, canker sores, vomiting, depression, poor circulation and indigestion. More severe niacin deficiency can cause a condition called pellagra. The symptoms of pellagra include digestive problems, inflamed or flakey skin, diarrhea and mental impairment.