First I think distilled water is the best for flushing stuff out but I find niacin flushes very effective in re-opening those capillaries.
The niacin "flush"
It's important to note that this niacin flush is not harmful or dangerous. Some people worry about it, but it is actually a sign of improved blood flow.
When you get the niacin "flush", it's an indication that the niacin is causing small blood vessels in your body to be expanded in size. Many of your small blood vessels, called "capilaries" are so small that blood cells can only go through them in single file. Sometimes, in fact, that small capilary passageway is clogged and blood doesn't get through at all.