Niacin (Vitamin B3) is a water soluble B vitamin and is unique among B vitamins in that the body can make it from an amino acid, tryptophan.
Niacin is effective in improving circulation and has been professionally prescribed in cholesterol-lowering treatment, where it is carefully monitered. It is also widely used as a vasodilator drug in chilblains and other vascular disorders.
Niacin should be avoided by individuals with hepatic dysfunction or a history of liver disease, diabetes mellitus and alcohol abuse.