Types of Niacin
Regular, immediate-release niacin (IR niacin) is very effective for improving cholesterol. However, it is difficult to tolerate. Most people who take IR niacin develop a bothersome and sometimes intolerable niacin flush reaction. This can be minimized by starting with a low dose and very gradually increasing it to an effective dose or by taking aspirin 30 minute before each dose. Also, it must be taken several times a day. Available forms of IR niacin include the prescription medication Niacor as well as numerous different non-prescription supplements.
In order to decrease flushing, sustained-release niacin (SR niacin, also known as timed-release, slow-release, or controlled-release) was developed. These products release niacin very slowly and are taken just once a day. They do seem to reduce flushing, but they also seem to increase the risk of liver damage. Available forms of SR niacin include Slo-Niacin and various other non-prescription supplements. There are no prescription versions of SR niacin.
Lastly, in order to balance the safety of IR niacin with the improved tolerability of SR niacin, an extended-release form (ER niacin, available as Niaspan) was developed. This product releases niacin slower than IR niacin but faster than SR niacin. This product is available only by prescription.
Of all three types, IR niacin seems to work best for increasing HDL and lowering triglycerides, with ER niacin a very close second. SR niacin is less effective than IR niacin for increasing HDL cholesterol (and, therefore, probably less effective than ER niacin). However, SR niacin may be better than IR niacin for decreasing LDL cholesterol.