Quote Originally Posted by rocinante
Large doses of niacin can cause liver damage, peptic ulcers, and skin rashes. Even normal doses can be associated with skin flushing. It can be prescribed as a treatment for elevated total cholesterol and other types of lipid disorders, but it should only be used with medical supervision due to its potential for severe side effects.

Niacin is a water-soluble vitamin necessary for many aspects of health, growth, and reproduction. It is part of the vitamin B complex.

Niacin assists in the functioning of the digestive system, skin, and nerves. It is also important for the conversion of food to energy.

Niacin (also known as vitamin B-3) is found in dairy products, poultry, fish, lean meats, nuts, and eggs. Legumes and enriched breads and cereals also supply some niacin. (Rice Crispies is a major niacin source).

The RDA (recommended daily allowance) for niacin is 14 mg for women and 16 mg for men.
He is right, but I don't think no matter what he says will make you stop.
Good Luck though and stay healthy