Vitamin B3, also known as niacin, is a food supplement with tremendous health benefits when taken in prescribed quantities. Vitamin B3 is one of the constituents of the multivitamin B-complex. Intake of vitamin B3 can sometimes cause a stomach upset. It is advisable to take the vitamin with food. Vitamin B3 can cause harmless flushing when used for the first time. Vitamin B3 is a naturally occurring substance found in meat, poultry, fish, eggs, and green vegetables. Vitamin B3 deficiency may cause pellagra, a disorder of the digestive and nervous system.
Temporary flushing or warming of the skin may occur upon initial use and is a normal effect of niacin.