A HIGH LINOLEIC-ACID DIET INCREASES OXIDATIVE STRESS IN-VIVO AND AFFECTS NITRIC-OXIDE METABOLISM IN HUMANS

Evidence from in vitro studies shows that increased intake of polyunsa turated fatty acids leads to increased oxidative stress, which may be associated with endothelial damage. We measured the urinary levels of 8-iso-PGF(2 alpha) and nitric oxide metabolites as well as plasma sICA M-1 levels from healthy subjects after strictly controlled diets rich in either linoleic acid (LA, C18:2 n-6) or oleic acid (OA, C18:1 n-9). Thirty-eight volunteers (20 women and 18 men, mean age 27 years) cons umed a baseline diet rich in saturated fatty acids (SFA) for 4 weeks a nd were then switched to either a high LA diet (11.5 en%) or a high OA diet (18.0 en%) also for 4 weeks. During the LA and OA diets, nearly all food was provided for the whole day. A control group of 13 subject s consumed their habitual diet throughout the study. Urinary excretion of 8-iso-PGF(2 alpha) was significantly increased after the LA diet ( 170 vs 241 ng/mmol creatinine, P=0.04), whereas the urinary concentrat ion of nitric oxide metabolites decreased (4.2 vs 2.6 mg/mmol creatini ne, P=0.03). No significant changes were seen in the OA group. Signifi cant differences between the LA and control group were found for both 8-oxo-PGF(2 alpha) (P=0.03) and NO (P=0.02), whereas the OA and LA gro ups did not differ with respect to any parameter. Also plasma sICAM-1 remained unchanged in both groups throughout the study. In conclusion, the high-LA diet increased oxidative stress and affected endothelial function in a way which may in the long-term predispose to endothelial dysfunction.