Niacin is an important B vitamin that may raise levels of high-density lipoprotein — also called HDL — cholesterol, the "good" cholesterol, and lower triglycerides.

Niacin has long been used to lower triglycerides and to increase high-density lipoprotein, also called HDL, cholesterol. This "good" cholesterol helps remove low-density lipoprotein, also called LDL, cholesterol, the "bad" cholesterol, from the bloodstream.

But niacin isn't for everyone. People who take niacin in addition to common cholesterol medicines see very little additional benefit. And niacin can cause uncomfortable and sometimes dangerous side effects.