Reversed Cholesterol-Death Rate Link Revealed
In a finding that defies conventional wisdom, puzzled researchers say lower cholesterol levels match increased death rates
By Ed Edelson
THURSDAY, Aug. 2 (HealthScoutNews) — In a finding that appears to stand a basic health recommendation on its ear, researchers who have been tracking a group of old men for decades now say low blood cholesterol is associated with an increased death rate.
A study of more than 3,500 Japanese-American men over the age of 70 found a steadily increasing death rate from all causes when cholesterol levels drop, reports a group led by Dr. Irwin J. Schatz, a professor of medicine at the University of Hawaii.
“We have been unable to explain our results,” they write in the Aug. 4 issue of The Lancet.
One proposed explanation that has to be ruled out is that the finding is somehow linked to this particular ethnic group, Schatz says.
“We think that the risk factors for all-cause mortality are the same the world over,” he says. “There is no information that these people are different in terms of susceptibility to any chronic disease. We think it is reasonable to expand the conclusion to all Caucasian men.”
The Lancet report comes from the Hawaiian Heart Study, which has been measuring cholesterol levels in a group of Japanese-American men since 1972. After the latest measurements, the researchers reviewed the entire group on the basis of the blood cholesterol levels.
The death rate for those with the highest cholesterol reading was 35 percent lower than for those with the lowest readings, the researchers report: In the highest cholesterol group, there were 43 deaths per 1,000 each year; in the lowest cholesterol group, there were 68 deaths per 1,000 each year.
Schatz says he does have a possible explanation, which he describes as “pure speculation.” His explanation is based on the knowledge that high blood cholesterol levels at earlier ages are known to increase the risk of heart disease and stroke.
“I think a selection process takes place,” Schatz says. “People with high cholesterol below the ages of 70 and 75 have increased mortality, and those who remain have been selected for survival.”
Dr. Richard A. Stein, chief of cardiology at the
“Cholesterol is produced by the liver, and a variety of conditions in the elderly affect liver metabolism,” Stein says. “Any number of illnesses are associated with the geriatric process of failure of liver function.”
The frailty of old age alone can affect the liver’s ability to produce cholesterol and perform its other vital functions, Stein adds, and there also can be “confounders that have not been identified” that have the same effect.
Schatz says more research is needed to follow up the finding. “The central message is that we need a good, randomized trial of lipid lowering in the elderly,” he says.
There is no need to change the basic recommendations that older people keep their cholesterol levels in check, Schatz says. But he adds, “I would just suggest to physicians that they might want to be a little less aggressive in efforts to lower cholesterol to very low levels in old people.”
And Stein says efforts to reduce heart disease by keeping cholesterol levels low should be pursued with “appropriate moderation” in older people.
SOURCES: Interviews with Irwin J. Schatz, M.D., professor of medicine, University of Hawaii, Honolulu; Richard A. Stein, M.D., chief of cardiology, Brooklyn Medical Center, New York; Aug. 4, 2001, The Lancet
Cholesterol for Longevity
A study published in Lancet concludes that not only is cholesterol not bad for older citizens, but helps them live longer. Researchers studied 724 persons with a median age of 89, measuring total blood cholesterol levels and relating them to mortality. They found that for every 1 mmol/L increase in total cholesterol, there was a 15 percent decrease in overall mortality. Persons with high cholesterol levels were especially resistant to cancer and infections.
1. Lancet, October 18, 1997.
Low Cholesterol Leading to Strokes
Another study that should confuse average citizens was reported in the AMA’s journal Stroke this past October.2 In a study of men at retirement age, researchers found that among those who had acceptable levels of LDL (popularly known as “bad cholesterol”), the risk of stroke doubled if their HDL cholesterol levels were low. Why deficiencies of this type of cholesterol raise the likelihood of stroke is not quite clear. Unfortunately, the authors observe, physicians tend to concentrate only on LDL and total cholesterol levels; therefore many persons at risk for stroke are not getting proper information and treatment.
2. Stroke, October 1997.
Meat-Cancer Link Questioned
A seven year study by researchers at the
10. Reported to the British Medical Journal, October 18, 1997, in a letter by Brian D. Cox, director of the Health and Lifestyle Survey.