Low Cholesterol Can Be a Danger Signal

To reduce the risk of heart disease, millions of Americans work hard to keep their cholesterol levels within the bounds recommended by the American Heart Assn. They eat healthfully and exercise regularly.

But 20 million others have a different situation--rock-bottom cholesterol levels, far below the maximum of 200 milligrams per deciliter generally recommended. These low levels sometimes persist no matter how poor the diet or infrequent the exercise.

To egg-lovers, that might sound like a dream come true. But a spate of studies is reigniting debate over how low might be too low. Cholesterol levels below 160 milligrams per deciliter of blood have been linked with personality changes such as aggression and a higher risk of death from causes other than heart disease.

No one is claiming a cause-and-effect relationship, and experts say the findings warrant closer study. The research, some say, also raises more questions than answers.

“We don’t know whether a very low cholesterol level is the cause or is the result of another underlying medical condition,” says Dr. John LaRosa, professor of medicine at the George Washington University Medical Center and chair of the American Heart Assn. task force on cholesterol issues.

A special task force of the American Heart Assn. is studying low cholesterol and expects to issue a statement within a few months.

Here is a sampling of the studies and reports recently published:

* An editorial published last month in Circulation, an American Heart Assn. journal, suggests that a cholesterol-lowering diet might not be prudent for adults with very low cholesterol levels.

* A report published in the same issue summarized the data presented at a 1990 federal conference on low blood cholesterol. Researchers from 19 studies reported on links between low cholesterol levels and increased rates of death from non-cardiac causes.

* Men with very low cholesterol were more likely to die of cerebral hemorrhage, alcoholism and liver cancer, according to a 12-year study of 350,000 men enrolled in the Multiple Risk Factor Intervention Trial. These men were also more likely to commit suicide, according to a report of the study published in July in the Archives of Internal Medicine.

* In a 14-year study of more than 10,000 people, published in June in the Journal of Clinical Epidemiology, low cholesterol levels were associated with increased risk of death, but the team speculates that it was because of underlying health problems rather than low cholesterol itself, says research leader Dr. Tamara Harris, chief of geriatric epidemiology at the National Institute on Aging.

* A link between low cholesterol and aggressive behavior has been found in several studies, University of Rhode Island researcher Cheryl A. Stoukides reported in the June Annals of Pharmacotherapy. The behavior might spring, she and others speculate, from a low concentration of the neurotransmitter serotonin, which has been associated with impulsive, aggressive behavior.

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“What we have found so far is an interesting scientific puzzle that will get more attention,” says Dr. James I. Cleeman, coordinator of the National Cholesterol Education Program at the National Heart Lung and Blood Institute.

The findings should not discourage people from participating in health programs aimed at lowering high cholesterol levels, Harris says, because the excess death risk might be tied to underlying health status, not to low cholesterol itself.

The possible links between low blood cholesterol and increased death risk are many, Stoukides says. “Is it the lowering of the cholesterol (in patients who previously had high levels) or the low cholesterol itself?” she asks. “When people become health conscious and try to lower their cholesterol, they open themselves up for more injuries,” Stoukides says. “They’re out jogging, for instance.”

Says Harris: “As people get older and sicker, (low) cholesterol not only reflects dietary intake and other factors but seems to be an indicator of poor health.”

There are multiple health problems that can cause cholesterol to decline, she notes. People with AIDS might experience a decline, for example. “There is a need to distinguish between healthy low cholesterol and sick low cholesterol,” Harris concludes.

It’s also wise to remember, other experts say, that cholesterol measurements aren’t perfect--readings can vary from test to test even when analyzed by the best laboratories.

She suggests that you pay attention to big decreases and variations in cholesterol readings. “If cholesterol begins to drop spontaneously, it’s a little like spontaneous weight loss,” Harris says. Both bear checking out with a health professional.

LaRosa says: “There are some times when science is not ready to tell people what to do. We don’t know (yet) what this means. We will have a better idea probably in the next two years.”

Meanwhile, he recommends a diet low in saturated fat and low in cholesterol, with an emphasis on complex carbohydrates.

Advises Cleeman: “If your cholesterol is very low, say 110, the obvious guideline is you should not make a fetish of cholesterol-lowering.

“If you are older and you have always had a low cholesterol, there is no evidence to suggest raising it. If you are older and your cholesterol drops for no reason (without diet or exercise changes), that is something to look at. The drop might be due to something serious or something trivial, like a slight viral illness.”