Niacin no good at curbing risk of heart attack, stroke

(CBS/AP) Niacin seems to be no good, at least when it comes to lower the risk for heart attack. On Thursday the NIH stopped a study because people taking high doses of the B-vitamin saw no benefit.

LDL cholesterol is the main cause of clogged arteries. Statin drugs, including brand names like Zocor and Lipitor as well as generic forms - are mainstays in lowering LDL. But many statin users have heart attacks, because LDL isn't the whole story. Low levels of HDL, as well as high levels of fatty substances known as triglycerides, also increase heart risk.

So scientists are testing whether adding various drugs to statins would increase HDL enough to protect the heart.

The study tested Niaspan, an extended-release form of the B-vitamin niacin that is a far higher dose than is found in dietary supplements. The drug has been sold for years, and previous studies showed that it boosts HDL levels.

More than 3,400 statin users in the U.S. and Canada - people still at risk for heart attack because of low HDL levels - were given Niaspan or a dummy pill in addition to their usual medication. As expected, HDL levels rose and triglyceride levels dropped in the Niaspan users - more than in people who took a statin alone. But the combination treatment didn't reduce heart attacks, strokes or the need for artery-clearing procedures such as angioplasty, the NIH said.

The University of Washington's Dr. Jeffrey Probstfield, who helped lead the study, said the finding "is unexpected and a striking contrast to the results of previous trials."

There was a small rise in stroke risk in the Niaspan users - 28 among 1,718 people compared with 12 among the 1,696 placebo users. The NIH said it was unclear whether that small difference was a coincidence, as previous studies have shown no stroke risk from niacin. In fact, some of the strokes occurred after the Niaspan users quit taking that drug.

Researchers said patients shouldn't stop taking their Niaspan without talking to a doctor first.

The Mayo Clinic has more on niacin and cholesterol.