Harvard Health Letter

Niacin trial stopped early: Now what?

Niacin, also known as vitamin B3 and nicotinic acid, is an essential nutrient. We need a small amount of it to ward off a disease called pellagra.

But like many vitamins these days, niacin has gotten more attention lately because of the benefits it might have when consumed in large amounts. Daily doses of 1,000 milligrams (mg) or more increase "good" HDL cholesterol and also reduce triglycerides. Many people, including quite a few doctors, view niacin as a useful, inexpensive — and perhaps more natural — way to bring about desirable cholesterol levels and reduce the risk of heart disease. Research going back to the early 1980s has shown that to be the case. Drug companies have sensed an opportunity and are selling products like Advicor (niacin plus lovastatin) and Simcor (niacin plus simvastatin) that combine high doses of HDL-raising niacin with statin drugs that lower "bad" LDL cholesterol.

But in May 2011, some new — and unexpected — doubts about niacin emerged after officials at the National Heart, Lung, and Blood Institute (NHLBI) stopped an important study of its effects 18 months earlier than planned. The study, called AIM-HIGH, included about 3,400 people at high risk for having a heart attack or stroke because of high blood pressure, a past heart attack, or other reasons. Researchers randomly assigned half of the study volunteers to take Niaspan, an extended-release, prescription version of niacin, while the other half were assigned to take a placebo. All the volunteers also took the brand-name version of simvastatin, called Zocor, and about 500 took an additional LDL-lowering drug, ezetimibe (sold as Zetia), in order to reach the study's target LDL level of 40 to 80 mg/dL.

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