<prompt> Hyperlipidemias are treated by administering the following vitamin in megadosesB12FolateThiamineNiacin  <response>: High doses of niacin are effective in lowering serum triglyceride, low-density lipoprotein, and lipoprotein-a levels and in elevating high-density lipoprotein levels. In high doses, Niacin causes dilatation of blood vessels and flushing, along with skin irritation. Intakes of both nicotinic acid and nicotinamide in excess of 500 mgd also cause liver damage.Harper 30th edition Pg: 557 