Atherosclerosis, or hardening of the arteries, is a key component of coronary heart disease, the leading cause of death among both men and women. The protection against atherosclerosis came despite a higher cholesterol level in primates fed the fish oil diet compared to those on the monounsaturated diet, according to Lawrence L. Rudel, Ph.D., professor of comparative medicine and biochemistry.
"There is a paradoxical decrease in atherosclerosis in cynomolgus monkeys fed a diet enriched with omega 3 fatty acids compared to a diet enriched in monounsaturated fat, in spite of an increased LDL cholesterol and decreased HDL cholesterol," said Rudel.
Ordinarily, increasing LDL cholesterol, or decreasing HDL cholesterol are considered signs of increased risk of heart disease. "These data is counter to everyone's biases," he noted.
He presented his findings today at the American Heart Association meeting in Orlando.
For four years, the cynomolgus monkeys in the study were fed diets that were 35 percent fat -- but the fat either was rich in omega 3 fatty acids -- the fish oil ? or monounsaturated fat. A 35 percent fat diet causes atherosclerosis in these monkeys.
Rudel and his colleagues measured the amount of atherosclerosis in the arteries at the study's end and found the amount of atherosclerosis in monkeys on the monounsaturated fat diet was nearly double that of monkeys on the omega 3 diet.
They found that liver cholesterol concentrations were dramatically higher. Monkeys on the monounsaturated diet had 13 times the cholesterol concentration in their livers as monkeys on the fish oil diet.
In the blood, HDL, the good cholesterol, was 25 percent lower in the omega 3 monkeys than in the monounsaturated monkeys, and the LDL cholesterol, the bad cholesterol, was 25 percent higher, which originally had led the researchers to predict more atherosclerosis in the omega 3 group.
"These data show that the reduction by omega 3 fatty acids of cholesterol accumulation in liver and artery were significant, in spite of an atherogenic [atherosclerosis-causing] lipoprotein profile, and suggest that omega 3 fatty acids may exert protection from atherosclerosis through alterations in tissue cholesterol metabolism."
Rudel's research is largely supported by a major program project, Lipoprotein Metabolism in Atherosclerosis, funded by the National Heart Lung and Blood Institute (NHLBI), and a second NHLBI project called Nutrition and Lipoprotein Metabolism in Atherosclerosis.
Rudel also is chair of the scientific committee of the Center for Research on Human Nutrition and Chronic Disease Prevention at the Medical Center.
For further information, contact Robert Conn, Mark Wright or Jim Steele at 910-716-4977.