May 26 (HealthDay News) -- Although early research had suggested that the nutrient niacin might raise levels of "good" cholesterol and thwart heart attacks, a major clinical trial has been stopped 18 months early because it has shown no such benefit.
The trial, sponsored by the U.S. National Institutes of Health and a drug maker, enrolled patients with a history of heart disease who had their LDL ("bad") cholesterol under control with statin medications. The new trial hoped to use niacin (also known as vitamin B3) to boost levels of "good" HDL cholesterol while lowering blood levels of fats called triglycerides to help reduce the odds of heart attack or stroke.
Unfortunately, "this study has ended 18 months early because we have answered the primary question," Dr. Susan B. Shurin, acting director of the U.S. National Heart, Lung, and Blood Institute (NHLBI), said during a morning press conference Thursday. "While high-dose niacin raised participants' HDL cholesterol and lowered triglycerides, it did not affect the overall rate of cardiovascular events," she said.
"There was also an unexplained higher incidence of stroke in the high-dose niacin group, compared to the group on statins alone," Shurin added.
It is not clear if this trend toward stroke was merely a matter of chance, but it was a factor in the NHLBI's decision to stop the trial, especially in the face of a lack of benefit from niacin, she said.
"The U.S. Food and Drug Administration is aware of the findings and is recommending no change in labeling or practice [regarding niacin], pending full analysis of the data," Shurin said.
Prior to the trial, some observational studies had shown that low HDL cholesterol was a risk factor for heart attack and stroke, so it was thought that any drug that could boost HDL might help patients. In addition, some studies had shown that low HDL plus high triglycerides boosted the odds of cardiovascular events.
In the trial, more than 3,400 patients averaging 64 years of age were randomly assigned to high-dose niacin or a placebo. Those in the niacin arm of the trial took Abbott Laboratories' Niaspan, a time-released form of niacin that contains a much higher dose of niacin than is found in over-the-counter supplements.
All of the participants also took the cholesterol-lowering statin drug Zocor (simvastatin).
As expected, participants who took Niaspan for the 32 months of the trial saw their blood levels of HDL cholesterol rise and their triglycerides lower, compared with those who took a statin alone.
But the boost in HDL failed to translate to any reduction in heart attacks or strokes, the team said. Nor did it lower the rate of hospitalizations for heart disease or procedures to open blocked cardiac arteries, according to the NHLBI.
Worse, more people taking niacin had strokes than those on a statin alone, the researchers found. In fact, 28 participants taking Niaspan suffered strokes, compared with 12 in the placebo group. Nine of the strokes in the Niaspan group happened to participants who had stopped using the drug at least two months and up to four years before their stroke.
Earlier studies had not shown any connection between high-dose niacin and stroke risk, Shurin said. Why the uptick in strokes was seen in this study isn't clear, she said.
Shurin cautioned people who take supplemental niacin not to stop taking it. They might want to talk with their doctor, she said. But this study is no reason to change what they are doing.
