NEW ORLEANS (Reuters) - Popping vitamins does little to lower high cholesterol and the risk of heart disease, researchers reported Monday, but adding one vitamin -- niacin -- multiplies the effects of cholesterol-lowering drugs.

Patients who took niacin plus a statin drug, designed to lower cholesterol and the risk of heart disease, experienced plunging cholesterol levels.

After three years on the combination, fatty buildups in the patients' arteries had stopped growing and they were 70 percent less likely than patients taking dummy pills to have a heart attack or other heart ``event'' such as stroke or the need to have heart bypass surgery, researchers said.

Patients who took a cocktail of vitamins E, C, beta-carotene, which the body turns into vitamin A, and selenium experienced no such effect, researchers said.

And, strangely, adding the vitamin cocktail to a combination of simvastatin and niacin seemed to blunt its effects, the researchers told an annual scientific meeting of the American Heart Association. Simvastatin is made by Merck and Co. Inc. under the trade name Zocor.

We can prevent 35 percent of the heart attacks with statins,'' Dr. Greg Brown, a professor of medicine and cardiology at the University of Washington in Seattle, told a news conference.

He said niacin alone in some studies had been shown to prevent about 20 percent of non-fatal heart attacks, but the results his group produced with simvastatin and niacin combined suggested a reduction of between 60 and 90 percent -- which points to a synergistic effect between the two drugs.

Brown's team used simvastatin, but he said the studies suggested the effect would be similar with any of the statin drugs and even with non-statin cholesterol-lowering drugs, such as gemfibrizol.

He said patients should not try to treat themselves with niacin, also known as vitamin B3. For one thing, it can cause frightening flushes when taken in the high doses given in the trial.

Niacin, used as a drug, requires a little bit of patient education,'' Brown said.

If you take one dose, you may say, 'That's it -- I'll never take another dose,''' Brown said.

There is also a slight risk of an effect on liver enzymes, which must be watched by a doctor. But he said 90 percent of patients who took niacin in his study stuck with it.

　　GOOD CHOLESTEROL GOES UP AND BAD GOES DOWN

Overall cholesterol went down with the combination, but there were even more detailed effects. For instance, high-density lipoprotein (HDL), the so-called good cholesterol, went up 30 percent in the patients who received the combination.

Statins alone generally raise HDL by about 5 to 7 percent. Low density lipoprotein (''bad'' cholesterol or LDL) fell to an average of 83 in the group that got niacin plus simvastatin.

It's a good way to get LDL way down,'' Brown told reporters. In fact, in 28 percent of the volunteers LDL fell to below 40, which is considered too low. ``We had to back off some,'' Brown said.

All the volunteers also were advised to follow a Mediterranean-style diet high in fruits and vegetables and low in meat, although the researchers did not keep tabs on them.

Brown said he could not explain why adding vitamins to the mix interfered. It had been believed that vitamins such as A, C and E helped prevent fat in the blood from oxidizing -- a chemical reaction that can make it more damaging.

Antioxidant vitamins, for an unknown reason, prevent a rise in HDL,'' Brown said. When you add antioxidant vitamins, the HDL rise is actually blunted.''

(From Reuters)