Niacin has become a highly contested drug. It has powerful effects to treat elevated triglycerides, but the clinical benefit of this effect is questionable.

What is niacin? It is a B vitamin, specifically B3. It is one of the few supplements regulated by the FDA in higher doses as a medication. It is also known as nicotinic acid and is a coenzyme involved in oxidation-reduction, where electrons are exchanged. These reactions provide a source of energy for organisms (1).

Just like with triglycerides, niacin seems to have a powerful effect on HDL “good” cholesterol, by raising HDL levels as much 30-35 percent (2). While this is an impressive number, once again, it has become debatable whether this raising of HDL is clinically beneficial.

In several trials, niacin showed unexpectedly disappointing results in reducing the potential for cardiovascular disease and events. It also demonstrated significant side effects. In other words, this is not a harmless drug.

Interestingly, as the benefit of niacin for cardiovascular disease has been debated, the number of scripts has increased almost threefold, or 200 percent, in the seven years from 2002 to 2009, according to IMS data for both the U.S. and Canada (3). The majority of the scripts were for extended-release niacin (Niaspan). The rest were mainly for Simcor (simvastatin-niacin combination) and Advicor (lovastatin-niacin combination). Let’s look at the evidence.

Is raising HDL beneficial or not?

The paradigm has always been that higher HDL is better, but this may not be the case. It is not the first time that HDL’s protectiveness has been debated. An observational study showed that those who have genetically high levels of HDL may not benefit any more than those with normal levels (4).

In a randomized controlled trial, the HPS2-THRIVE study, the results showed an increase of 6 mg/dL in HDL levels and a decrease of 10 mg/dL in LDL, “bad” cholesterol when extended-release niacin plus laropiprant was added to statin therapy (5). This is considered by some to be a relatively small change. Also, there was no reduction in vascular events seen with the combination, even though there was improvement in both HDL and LDL when compared to the placebo.

Laropiprant is a drug used to help reduce the flushing with niacin. The dose used was 2 g of extended-release niacin and 40 mg of laropiprant. The demographics included a patient population that had vascular disease, and therefore was at greater risk of vascular events, such as nonfatal heart attacks, strokes, arterial revascularization and mortality from cardiovascular disease. There were over 25,000 patients involved in the study, and its duration was 3.9 years. LDL was already low in the participants at the start of the trial.

To make matters worse, the serious side effects were greater with the extended-release niacin compared to the placebo. There was a greater propensity toward diabetes — 32 percent relative increase — as well as exacerbation of diabetes — 55 percent increase in impaired sugar or glucose control — in patients who already had the disease. There were also increases in ulcers and diarrhea by 28 percent, muscle damage and gout by 26 percent, rashes and ulcerations by 67 percent, gastrointestinal bleeding or other bleeds by 38 percent and infection rates by 22 percent. Using niacin to raise HDL may be ineffective, at least in vascular patients, those with atherosclerosis, who already have low LDL. It does not foretell what happens in patients with high LDL at the start.

Other studies have shown questionable efficacy and increased adverse events with niacin use in raising HDL levels to limit cardiovascular events. In the AIM-HIGH study, similarly disappointing results were seen. When extended-release niacin was added for patients with stable coronary artery disease, high triglycerides and low HDL who were already on statins, there was no clinical change in cardiovascular events (6).

Also, there were more serious adverse effects seen in the niacin group compared to the placebo group in a post-hoc analysis (7). These side effects included gastrointestinal disorders, infection, and infestations. However, there was no difference in bleed or hemorrhage, though the absolute number was small.

In yet another study, this a meta-analysis of 39 studies, including HPS2-THRIVE and AIM-HIGH, comparing the benefits of niacin, cholesteryl ester transfer protein inhibitors and fibrates, results showed that even though these drugs may raise HDL levels, there was no improvement in terms of cardiovascular end points when they were added to statin therapy (8). There were about 117,000 patients involved in the meta-analysis. The drugs and drug classes, niacin, CETP and fibrates, did not demonstrate any reduction in all-cause mortality or coronary heart disease mortality, nor did they reduce heart attacks or stroke risk. These drugs were added to statins as adjunct therapy.

Possible HDL explanation

Investigating a theory as to why raising HDL may not be effective when using niacin, a small study looked at cholesterol efflux capacity — the ability of HDL to garner cholesterol from macrophages, a type of white blood cells, compared to the HDL inflammatory index (9). The results showed that cholesterol efflux capacity may be a better indicator for vascular disease than HDL levels. There was an increase in HDL-C, where C stands for cholesterol, but no change in HDL inflammatory index, nor cholesterol efflux capacity, when niacin was used.

In conclusion, if you are on niacin to raise HDL levels and are already on a statin, you may want to talk to your physician about the evidence that refutes the clinical benefits in reducing cardiovascular events. The European Union has recently banned the use of niacin-laropiprant combination (10). Niacin alone does not seem to be harmless either. Whether HDL is as important as we thought is now in debate. Know that a change in a biomarker, such as HDL levels, is not synonymous with better clinical outcomes. This disappointing clinical result also holds true for niacin’s effects on triglycerides.

This article is only addressing niacin in regard to HDL and the cholesterol profile in general, not other roles for the drug. Of course, never discontinue your medication without first discussing it with your doctor.

References:

(1) “Present Knowledge in Nutrition,” 10th ed. 2012;293-306. (2) Arch Intern Med. 1994;154:1586-1595. (3) JAMA Intern Med. 2013;173:1379-1381. (4) Lancet online. 2012 May 17. (5) New Engl J Med. 2014;371:203-212. (6) New Engl J Med. 2011;365:2255-2267. (7) New Engl J Med. 2014;371:288-290. (8) BMJ 2014;349:g4379. (9) J Am Coll Cardiol. 2013;62:1909-1910. (10) European Medicines Agency 2013 Jan. 18.

Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, go to the website www.medicalcompassmd.com or consult your personal physician.