Aging and dietary influences on plasma lipoproteins and apolipoproteins in nonhuman primates

Nineteen young (3 to 4-years-old), 25 adult (8 to 14-years-old), and 22 aged (18 years and older) pig-tailed macaques (Macaca nemestrina) were fed a semipurified control diet stringent in fat, cholesterol, refined sugar, and sodium for six months. Each group was almost equally divided by sex. Thereafter, half of each age group was fed a test diet high in fat (41% of calories), cholesterol (865 mg/kg), sodium, and refined sugar, while the rest consumed the control diet. After three years of dietary treatment, plasma and blood volumes were determined and fasting blood samples were collected for lipoprotein analysis. The protein content of very low density lipoproteins (VLDL) was increased in the test animals as compared to the controls. In general, low density lipoprotein (LDL) cholesterol, protein, and apolipoprotein B-100 values were markedly elevated by the test diet. However, these elevations were mainly confined to the young and adult groups, with little or no increases observed in the old group. The test diet also induced small but significant increases in high density lipoprotein (HDL) cholesterol, protein, and apolipoprotein A-I values. In addition, HDL cholesterol and protein values were higher in young females than males, whereas this trend was not observed in adults.