Fight Raynaud's disease and other circulatory conditions - It has been reported that niacin can improve circulation by relaxing arteries and veins, and is helpful for other conditions characterized by circulation difficulties. For those suffering from Raynaud's disease, niacin's ability to improve blood flow to the extremities may help counter the numbness and pain in the hands and feet that can occur when blood vessels overreact to cold temperatures. The inositol hexaniacinate form of niacin is believed to work best for circulation-related discomforts.