Hello. I'm Dr Sandra Fryhofer. Welcome to Medicine Matters. The topic: Niacin—from wishful thinking to facing facts. Here is why it matters.
Niacin, also known as nicotinic acid or vitamin B3, is an essential human nutrient. It increases good high-density lipoprotein cholesterol (HDL-C). It modestly lowers bad low-density lipoprotein cholesterol (LDL-C). It substantially lowers triglycerides. Niacin also causes flushing—severe flushing—but adding the no-flush chemical laropiprant can help, especially if you have to take high doses.
If you think about the lipid effects, niacin should lower the risk for heart disease, but several new studies (the latest and largest published in the New England Journal of Medicine) tell a different story. HPS2-THRIVE stands for Heart Protection Study 2, Treatment of HDL to Reduce the Incidence of Vascular Events. It looked at more than 25,000 adults aged 50 to 80 years. All had some sort of clinical manifestation of cardiovascular disease: a history of heart attacks, cerebrovascular disease, peripheral vascular disease, or diabetes with symptomatic coronary disease. All received standard statin therapy, with prestudy LDLs averaging about 63 mg/dL. They then received either niacin along with the antiflush agent or a placebo. Not surprisingly, the group getting niacin had better lipid profiles. On average, HDLs were 6 points better, LDLs were 10 points lower, and triglycerides were 33 points lower. Patients were followed for nearly 4 years.
Based on the better lipid profiles, and looking at several meta-analyses of statin trials, you would probably expect better cardiac outcomes—maybe a 6% reduction in risk for major vascular events. Not so. That is not what happened.
Despite the better lipid profiles, those on niacin did not have better outcomes and no significant reduction in major vascular events. That is not all the bad news for those taking niacin. They also had more adverse events way beyond flushing: more myopathy, which was 10 times more likely in Chinese participants compared with those of European descent; more bleeding, including gastrointestinal bleeding and bleeding in intracranial and other sites; more diabetes—new diabetes diagnoses were increased by a third. And very surprising and unexpected: There was also an excess of serious infections in the niacin group.
So, not only did niacin not significantly reduce the risk for major vascular events, but the risk for serious adverse events was greatly increased.
As Donald Lloyd-Jones says in his accompanying editorial, it is time to face facts. For niacin and vascular effects, there is a consistent lack of benefit. Perhaps HDL-C level is a risk marker rather than a risk factor. The study researcher's final word: Although niacin might still be relevant for patients at high risk for vascular events who have high LDLs, any potential benefit should be considered in the context of observed hazards.
For Medicine Matters, I'm Dr Sandra Fryhofer.
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Cite this: Is Niacin Done? - Medscape - Dec 18, 2014.