The smallest blood vessels in your body are called
Itâs important to note that the flush caused by niacin is not harmful or dangerous. It is actually a sign of improved blood flow and circulation. Also niacin oxygenates the blood. When you get a niacin âflushâ it is an indication that the niacin is causing small blood vessels in your body to expand in size.Many of your small blood vessels, called capillaries, are so small that blood cells can only go through them in single file or if they are flexible enough to fold over.t is actually a sign of improved blood flow and circulation. Also niacin oxygenates the blood. When you get a niacin âflushâ it is an indication that the niacin is causing small blood vessels in your body to expand in size.