A new study strongly suggests that a link previously found between very low blood cholesterol levels and increased deaths from disease, accidents and suicide does not result from efforts to achieve or maintain a low cholesterol level to prevent heart attacks.
Rather, according to the findings described Friday at a scientific conference in Santa Fe, N.M., certain health problems and harmful living habits account for the increase in deaths among men with low cholesterol levels.
Dr. Carlos Iribarren of the University of Southern California at Los Angeles found in a study of 8,000 Japanese-American men in Hawaii that among those with cholesterol levels below 189 milligrams per deciliter of blood serum, disorders of the gastrointestinal tract, heavy smoking and heavy drinking largely accounted for their higher death rate.
But among the 5,347 men who neither had these disorders nor the health-damaging habits, no association was found between very low cholesterol levels and increased death rates.
Several recent studies have noted that men with the lowest cholesterol levels, as well as those with the highest cholesterol levels, faced an increased risk of early death. Very low cholesterol levels were linked especially to deaths from suicide and violent causes like accidents and homicide.
In the study, heavy smoking was defined as smoking an average of two packs of cigarettes a day for 30 years, and heavy alcohol use was defined as consuming more than 40 ounces of alcohol a month.
Participants in the study were divided into four groups: healthy men, those with medical conditions, heavy smokers and heavy drinkers. Then the groups were stratified according to their cholesterol levels. On average, the healthy men had slightly higher cholesterol levels than those in the other three groups.
The participants were followed for 23 years, from 1965 through 1988. During that period 1,193 men died in the healthy group, and 624 died in the other, much smaller, groups combined. There was no significant increase in deaths overall among the healthy men with the lowest cholesterol levels, nor was there an elevated death rate due specifically to suicide, accidents or violence, Iribarren said.