NOW Niacin - Vitamin B3 is an essential B-group vitamin necessary for good health. Vitamin B3 is involved in a range of metabolic processes and is a coenzyme in several important biochemical functions. Niacin is needed to maintain proper circulation, healthy skin, and a healthy gastrointestinal tract and nervous system. Studies have shown that Niacin is effective in reducing cholesterol and triglyceride levels in the blood, and aids in lowering high blood pressure. Vitamin B3, in the form of Niacin is a vasodilator that widens the blood vessels and increases the blood flow to the extremities. A Niacin flush, usually harmless, may occur after supplementing with Niacin and can be accompanied by a red rash on the skin, and a tingling sensation.