Doctors have long felt justified urging Americans to lower their cholesterol. Even though many of them probably won't benefit, cutting fat out of the diet certainly cannot hurt anyone.

Or can it?Evidence is mounting that people who lower their cholesterol do indeed reduce their risk of dying from heart disease. But a new report concludes that is completely offset by a striking increase in another way of death.

For reasons no one can explain, when people reduce their cholesterol, they seem to become more likely to die from accidents, suicides, murders and other violent tragedies.

"The questions about adverse effects of cholesterol reduction are not at all answered," said Dr. Matthew F. Muldoon, who directed the study. "That causes a lot of problems for the strategy that you give cholesterol reduction to everybody because it doesn't do any harm. That can't be said with much confidence."

Could it be that by at least one measure, lowering cholesterol does as much harm as good?

The discovery is so difficult to understand that experts are cautioning people against suddenly going back to wolfing down slabs of roast beef and gobs of ice cream. Stick to the low-fat regimen, they urge, until they sort out what's happening.

"It's an interesting and disturbing phenomenon," said Dr. John LaRosa, dean for research at George Washington University Medical Center. "Expressing concern is appropriate but not making policy changes based on this."

Health policy rarely changes as a result of a single study. And in this case, Muldoon and a few other skeptics are up against the inertia of public belief in the evils of cholesterol as well as the interests of a corps of influential heart specialists who want to change Americans' way of eating.

Hints that lower cholesterol is linked with some forms of cancer and strokes have not cooled anti-cholesterol zeal. Neither have niggling doubts about whether old people, women and children need to worry about their cholesterol.

The chief vehicle for promoting the mainstream view is the government's 5-year-old National Cholesterol Education Program. Its goal is to persuade people to get their cholesterol checked, eat less saturated fat and lower their average cholesterol level by 10 percent.

"It is a very prudent public health policy," said Dr. James Cleeman, the program's coordinator. "This study does not shake my confidence in the wisdom of that approach."

Nonetheless, the latest research increases doubts for some.

"The finding that there is no clear benefit in total mortality is of concern," said Dr. Paul Meier, a statistician at the University of Chicago. "It's cause for being more circumspect in insisting that everybody has got to get his cholesterol down."

Lowering cholesterol reduces the risk of heart attacks. Since heart attacks kill 500,000 Americans a year, many assume that lower cholesterol also helps people live longer. But proof is skimpy. Several studies that have delved into the health effects of cholesterol reduction have been too small or too short to yield definite conclusions.

So Muldoon, a University of Pittsburgh researcher, decided to combine results of several studies to seeif a statistically meaningful picture emerges.

His report, published recently in the British Medical Journal, joined the statistics of six comparison studies conducted on a total of 24,847 healthy men. These people either reduced their cholesterol levels an average of 10 percent or carried on without change.

Muldoon calculates that for every 100,000 people who cut their cholesterol, there are 28 fewer deaths each year from heart disease. But there are also 29 more deaths from suicides, homicides and accidents.

Thus, as many lives are lost as are saved.

"It hasn't been a large enough increase to cause a national cry of alarm, but anybody carefully analyzing the facts has to be concerned about it," said Dr. Thomas James, president of the medical branch of the University of Texas at Galveston.

One of the most puzzling aspects of this discovery is that there is no obvious scientific explanation. Muldoon raises three possibilities:

- Cholesterol is an important ingredient of the body's cells. Perhaps lowering the body's supply changes brain chemistry and behavior, and this somehow makes people more reckless or aggressive.

- People find it "chronically frustrating" to give up the food they like, and this also makes them more apt to die tragically.

- The cholesterol-lowering drugs tested in the studies tasted awful and caused intestinal problems. "There may be a susceptible group of folks where this pushes them over the edge," Muldoon said.

Actually, the study's findings are no surprise to people who have followed the major cholesterol experiments of the 1980s.

The first strong evidence that lowering cholesterol cuts the risk of heart disease came in 1984 when researchers finished the Lipid Research Clinics Coronary Primary Prevention Trial.

Men who took cholesterol-lowering drugs in this experiment reduced their heart disease rate by 19 percent, but they didn't live longer. While they experienced eight fewer coronary deaths than a comparison group, they suffered seven more violent deaths. At the time, researchers dismissed the increase in violent deaths as a statistical fluke.

There was no obvious connection among these unfortunate people. One was murdered. Others committed suicide. Some died in car accidents, including ones in which they were not even behind the wheel.

However, three years later, the Helsinki Heart Study found something similar: 11 violent deaths in those with lower cholesterol, four in the comparison group.

In all, researchers have conducted six studies to test the effects of lowering cholesterol alone on otherwise healthy people. When Muldoon combined their results, he found the chance of dying from suicide or violence nearly doubled after cholesterol reduction.

Muldoon said other lines of research also have suggested links between behavioral problems and cholesterol. Unusually low cholesterol levels have been seen in criminals, murderers and people with aggressive conduct disorders or poor self-control.

A study by Dr. J.R. Kaplan of Bowman Gray School of Medicine looked at the effects of cholesterol on monkeys. He found that animals fed a low-fat diet like the one recommended by the American Heart Association to lower their cholesterol committed 50 percent more aggressive acts than did those eating fat levels closer to the typical American diet.

Even if Muldoon's theory is correct, backers of the war on cholesterol argue that too much is made of death. By warding off heart attacks, cholesterol reduction saves money, reduces misery and helps people lead healthier lives.

Dr. William Castelli, director of the Framingham Heart Study, said Muldoon "is trying to make the public believe that all that happens to you is death. Well, it's the least that happens to you.

"When you have your heart attack, you're not going to die," he said. "You're going to be alive and chronically ill for the rest of your life. We can prevent that."