Strong increase in hydroxy fatty acids derived from linoleic acid in human low density lipoproteins of atherosclerotic patients.

Linoleic acid is the most abundant fatty acid in human low density lipoproteins (LDL). Oxidation of LDL transforms linoleic acid to hydroperoxyderivatives. These are converted to 9-hydroxy-10,12-octadecadienoic acid (9-HODE) and 13-hydroxy-9,11-octadecadienoic acid (13-HODE). 9-HODE is much more abundant in oxidized LDL than other lipid peroxidation products and therefore an indicator of lipid peroxidation (LPO). In this study the 9-HODE content in the LDL of 19 obviously healthy volunteers and 17 atherosclerotic patients was investigated. The level of 9-HODE obtained from LDL of young atherosclerotic patients (aged 36-47 years) was increased by a factor of 20 when compared with samples from healthy volunteers of the same age group. The content of 9-HODE in the LDL of atherosclerotic patients aged between 69 and 94 years increased 30-100 fold when compared with young healthy individuals, but when compared with 'healthy' individuals of the same age group it was only 2-3 fold increased. Obviously, as individuals grow older LDL becomes more and more oxidized. Consequently, assuming that LDL oxidation is a precondition for atherosclerosis--older individuals will suffer from atherosclerosis, even if no easy detectable visible signs of this disease are recognizable. According to 9-HODE determination, the onset of the disease starts slowly in most individuals at around 50 years of age.